30631770050

Committed 31 Jul 2026 12:45PM UTC coverage: 83.079% (+0.8%) from 82.321%

Build # 30631770050

Build Type

Pull #81

github

Committed by

web-flow

Commit Message

Merge 3e7b86efb into be7540808

Pull Request Pull Request #81: Add a durable skipped job state

Coverage Stats

125 of 133 new or added lines in 10 files covered. (93.98%)

5 existing lines in 3 files now uncovered.

7473 of 8995 relevant lines covered (83.08%)

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Source File
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90.39

/src/Immediate.Jobs.Shared/InMemoryJobStorage.cs

namespace Immediate.Jobs.Shared;

// TODO: remove and fix diagnostics
#pragma warning disable MA0015 // Specify the parameter name in ArgumentException

/// <summary>
/// A best-effort, non-durable, single-node provider intended for development and tests.
/// </summary>
/// <param name="timeProvider">The clock used for scheduling, leases, and timestamps.</param>
public sealed class InMemoryJobStorage(TimeProvider timeProvider) :
        IRecurringJobStorage,
        IJobGraphStorage,
        IJobStorageReplica
{
        private readonly Lock _gate = new();
        private readonly Dictionary<string, JobRecord> _jobs = new(StringComparer.Ordinal);
        private readonly Dictionary<string, JobBatchRecord> _batches = new(StringComparer.Ordinal);
        private readonly List<JobContinuationEdge> _edges = [];
        private readonly HashSet<JobContinuationEdge> _settledEdges = [];
        private readonly Dictionary<string, RecurringJobSchedule> _recurring = new(StringComparer.Ordinal);
        private readonly Dictionary<string, JobServerSnapshot> _servers = new(StringComparer.Ordinal);
        private readonly HashSet<string> _recurringKeys = new(StringComparer.Ordinal);
        private readonly Dictionary<(string QueueName, string GroupId), long> _fairQueueLastServed = [];

        /// <inheritdoc />
        public ValueTask DisposeAsync() => ValueTask.CompletedTask;

        /// <inheritdoc />
        public ValueTask InitializeAsync(CancellationToken cancellationToken = default)
        {
                cancellationToken.ThrowIfCancellationRequested();
                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask EnqueueAsync(JobRecord job, CancellationToken cancellationToken = default)
        {
                ArgumentNullException.ThrowIfNull(job);
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (!_jobs.TryAdd(job.Id, job))
                                throw new ImmediateJobException($"Job '{job.Id}' already exists.");
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public async ValueTask<IReadOnlyList<JobContinuationEdge>> GetIncomingEdgesAsync(
                IReadOnlyCollection<string> childJobIds,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentNullException.ThrowIfNull(childJobIds);
                foreach (var childJobId in childJobIds)
                        ArgumentException.ThrowIfNullOrWhiteSpace(childJobId, paramName: nameof(childJobIds));

                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (childJobIds.Count == 0)
                                return [];

                        var distinctIds = new HashSet<string>(StringComparer.Ordinal);
                        foreach (var childJobId in childJobIds)
                                _ = distinctIds.Add(childJobId);

                        return [.. _edges.Where(edge => distinctIds.Contains(edge.ChildJobId))];
                }
        }

        /// <inheritdoc />
        public ValueTask EnqueueContinuationAsync(
                JobRecord job,
                IReadOnlyList<JobContinuationEdge> edges,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentNullException.ThrowIfNull(job);
                ArgumentNullException.ThrowIfNull(edges);
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        ValidateNewJob(job);
                        ValidateEdges([job], edges, batchId: null);

                        var restoreExistingState = HasTerminalParent(edges) &&
                                (job.State != JobState.AwaitingContinuation || job.RemainingDependencies < edges.Count);
                        _jobs.Add(job.Id, restoreExistingState ? job : NormalizeWaitingJob(job, edges.Count));
                        _edges.AddRange(edges);
                        if (restoreExistingState)
                                MarkTerminalParentEdgesSettled(edges);
                        else
                                EvaluateAlreadyTerminalParents(edges);
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask EnqueueBatchAsync(
                JobBatchRecord batch,
                IReadOnlyList<JobRecord> jobs,
                IReadOnlyList<JobContinuationEdge> edges,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentNullException.ThrowIfNull(batch);
                ArgumentNullException.ThrowIfNull(jobs);
                ArgumentNullException.ThrowIfNull(edges);
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        ValidateBatch(batch, jobs, edges);

                        var restoreExistingState = IsRecoveredBatch(batch, jobs, edges);
                        _batches.Add(batch.Id, batch);
                        var incomingCounts = edges
                                .GroupBy(static edge => edge.ChildJobId, StringComparer.Ordinal)
                                .ToDictionary(static group => group.Key, static group => group.Count(), StringComparer.Ordinal);
                        foreach (var job in jobs)
                        {
                                _jobs.Add(
                                        job.Id,
                                        restoreExistingState
                                                ? job
                                                : incomingCounts.TryGetValue(job.Id, out var dependencyCount)
                                                ? NormalizeWaitingJob(job, dependencyCount)
                                                : job with { BatchId = batch.Id, RemainingDependencies = 0, FailedDependencies = 0 }
                                );
                        }

                        _edges.AddRange(edges);
                        if (restoreExistingState)
                                MarkTerminalParentEdgesSettled(edges);
                        else
                                EvaluateAlreadyTerminalParents(edges);
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public async ValueTask<IReadOnlyList<JobRecord>> AcquireDueJobsAsync(
                JobAcquisitionRequest request,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentNullException.ThrowIfNull(request);
                ArgumentException.ThrowIfNullOrWhiteSpace(request.WorkerId, nameof(request));
                ArgumentOutOfRangeException.ThrowIfLessThanOrEqual(request.Lease, TimeSpan.Zero, nameof(request));
                ArgumentOutOfRangeException.ThrowIfLessThanOrEqual(request.BatchSize, 0, nameof(request));

                cancellationToken.ThrowIfCancellationRequested();
                var now = timeProvider.GetUtcNow();
                lock (_gate)
                {
                        foreach (var expired in _jobs.Values.Where(x => x.State == JobState.Active && x.LeaseExpiresAt <= now).ToArray())
                        {
                                _jobs[expired.Id] = expired with
                                {
                                        State = JobState.Pending,
                                        WorkerId = null,
                                        LeaseExpiresAt = null,
                                };
                        }

                        if (request.FairQueues is null)
                                return AcquireInExistingOrder(request, now);

                        var acquired = new List<JobRecord>(request.BatchSize);
                        foreach (var queue in request.Queues)
                        {
                                var queueCapacity = Math.Min(queue.Capacity, request.BatchSize - acquired.Count);
                                if (queueCapacity <= 0)
                                        continue;

                                var jobCapacities = queue.JobCapacities.ToDictionary(static pair => pair.Key, static pair => pair.Value, StringComparer.Ordinal);
                                if (!HasEligibleGroupedJob(queue.QueueName, jobCapacities, now))
                                {
                                        AcquireQueueInExistingOrder(
                                                request,
                                                queue.QueueName,
                                                jobCapacities,
                                                queueCapacity,
                                                now,
                                                acquired
                                        );
                                        continue;
                                }

                                AcquireQueueFairly(
                                        request,
                                        queue.QueueName,
                                        jobCapacities,
                                        queueCapacity,
                                        now,
                                        acquired
                                );
                        }

                        return acquired;
                }
        }

        private List<JobRecord> AcquireInExistingOrder(JobAcquisitionRequest request, DateTimeOffset now)
        {
                var acquired = new List<JobRecord>(request.BatchSize);
                foreach (var queue in request.Queues)
                {
                        var queueCapacity = Math.Min(queue.Capacity, request.BatchSize - acquired.Count);
                        if (queueCapacity <= 0)
                                continue;

                        var jobCapacities = queue.JobCapacities.ToDictionary(static pair => pair.Key, static pair => pair.Value, StringComparer.Ordinal);
                        AcquireQueueInExistingOrder(
                                request,
                                queue.QueueName,
                                jobCapacities,
                                queueCapacity,
                                now,
                                acquired
                        );
                }

                return acquired;
        }

        private void AcquireQueueInExistingOrder(
                JobAcquisitionRequest request,
                string queueName,
                Dictionary<string, int> jobCapacities,
                int queueCapacity,
                DateTimeOffset now,
                List<JobRecord> acquired
        )
        {
                foreach (var candidate in _jobs.Values
                        .Where(job => string.Equals(job.QueueName, queueName, StringComparison.Ordinal) &&
                                jobCapacities.ContainsKey(job.JobName) &&
                                job.State is JobState.Pending or JobState.Scheduled &&
                                job.DueAt <= now)
                        .OrderBy(job => job.DueAt)
                        .ThenBy(job => job.CreatedAt)
                        .ThenBy(job => job.Id, StringComparer.Ordinal))
                {
                        if (queueCapacity == 0)
                                break;
                        if (jobCapacities[candidate.JobName] <= 0)
                                continue;

                        acquired.Add(Acquire(candidate, request, now));
                        jobCapacities[candidate.JobName]--;
                        queueCapacity--;
                }
        }

        private bool HasEligibleGroupedJob(
                string queueName,
                Dictionary<string, int> jobCapacities,
                DateTimeOffset now
        ) =>
                _jobs.Values.Any(job => string.Equals(job.QueueName, queueName, StringComparison.Ordinal) &&
                        job.GroupId is not null &&
                        jobCapacities.TryGetValue(job.JobName, out var capacity) &&
                        capacity > 0 &&
                        job.State is JobState.Pending or JobState.Scheduled &&
                        job.DueAt <= now);

        private void AcquireQueueFairly(
                JobAcquisitionRequest request,
                string queueName,
                Dictionary<string, int> jobCapacities,
                int queueCapacity,
                DateTimeOffset now,
                List<JobRecord> acquired
        )
        {
                var policy = request.FairQueues!;
                while (queueCapacity > 0)
                {
                        var eligible = _jobs.Values
                                .Where(job => string.Equals(job.QueueName, queueName, StringComparison.Ordinal) &&
                                        jobCapacities.TryGetValue(job.JobName, out var capacity) &&
                                        capacity > 0 &&
                                        job.State is JobState.Pending or JobState.Scheduled &&
                                        job.DueAt <= now)
                                .ToArray();
                        if (eligible.Length == 0)
                                break;

                        var activeCounts = _jobs.Values
                                .Where(job => string.Equals(job.QueueName, queueName, StringComparison.Ordinal) &&
                                        job.GroupId is not null &&
                                        job.State == JobState.Active &&
                                        job.LeaseExpiresAt > now)
                                .GroupBy(static job => job.GroupId!, StringComparer.Ordinal)
                                .ToDictionary(static group => group.Key, static group => group.Count(), StringComparer.Ordinal);
                        var totalActive = _jobs.Values.Count(job => string.Equals(job.QueueName, queueName, StringComparison.Ordinal) &&
                                job.State == JobState.Active &&
                                job.LeaseExpiresAt > now);
                        var groupedHeads = eligible
                                .Where(static job => job.GroupId is not null)
                                .GroupBy(static job => job.GroupId!, StringComparer.Ordinal)
                                .Select(static group => group
                                        .OrderBy(static job => job.DueAt)
                                        .ThenBy(static job => job.CreatedAt)
                                        .ThenBy(static job => job.Id, StringComparer.Ordinal)
                                        .First());
                        var ungroupedHead = eligible
                                .Where(static job => job.GroupId is null)
                                .OrderBy(static job => job.DueAt)
                                .ThenBy(static job => job.CreatedAt)
                                .ThenBy(static job => job.Id, StringComparer.Ordinal)
                                .Take(1);
                        var candidates = groupedHeads.Concat(ungroupedHead);

                        var candidate = candidates
                                .OrderBy(job => IsNoisy(job.GroupId, activeCounts, totalActive, policy))
                                .ThenBy(job => GetNoisyInflight(job.GroupId, activeCounts, totalActive, policy))
                                .ThenBy(job => policy.GroupRoundRobin ? GetLastServed(queueName, job.GroupId) : 0)
                                .ThenBy(static job => job.DueAt)
                                .ThenBy(static job => job.CreatedAt)
                                .ThenBy(static job => job.Id, StringComparer.Ordinal)
                                .First();

                        var job = Acquire(candidate, request, now);
                        acquired.Add(job);
                        jobCapacities[job.JobName]--;
                        queueCapacity--;
                        if (policy.GroupRoundRobin && job.GroupId is { } groupId)
                                _fairQueueLastServed[(queueName, groupId)] = GetNextSequence(queueName);
                }
        }

        private static bool IsNoisy(
                string? groupId,
                Dictionary<string, int> activeCounts,
                int totalActive,
                FairQueuePolicy policy
        ) =>
                groupId is not null &&
                totalActive > 0 &&
                activeCounts.TryGetValue(groupId, out var groupActive) &&
                groupActive >= policy.MinInflightForNoisy &&
                (double)groupActive / totalActive > policy.ConcurrencyShareThreshold;

        private static int GetNoisyInflight(
                string? groupId,
                Dictionary<string, int> activeCounts,
                int totalActive,
                FairQueuePolicy policy
        ) =>
                IsNoisy(groupId, activeCounts, totalActive, policy) ? activeCounts[groupId!] : 0;

        private long GetLastServed(string queueName, string? groupId) =>
                groupId is not null && _fairQueueLastServed.TryGetValue((queueName, groupId), out var sequence)
                        ? sequence
                        : 0;

        private long GetNextSequence(string queueName) =>
                _fairQueueLastServed
                        .Where(pair => string.Equals(pair.Key.QueueName, queueName, StringComparison.Ordinal))
                        .Select(static pair => pair.Value)
                        .DefaultIfEmpty()
                        .Max() + 1;

        private JobRecord Acquire(JobRecord candidate, JobAcquisitionRequest request, DateTimeOffset now)
        {
                var job = candidate with
                {
                        State = JobState.Active,
                        Attempt = candidate.Attempt + 1,
                        WorkerId = request.WorkerId,
                        LeaseExpiresAt = now + request.Lease,
                        ExecutionTraceId = null,
                        ExecutionSpanId = null,
                        ExecutionStartedAt = null,
                };
                _jobs[job.Id] = job;
                MarkBatchStarted(job.BatchId, now);
                return job;
        }

        /// <inheritdoc />
        public async ValueTask<IReadOnlyList<JobRecord>> AcquireJobsAsync(
                IReadOnlyCollection<string> jobIds,
                string workerId,
                TimeSpan lease,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentNullException.ThrowIfNull(jobIds);
                ArgumentException.ThrowIfNullOrWhiteSpace(workerId);
                ArgumentOutOfRangeException.ThrowIfLessThanOrEqual(lease, TimeSpan.Zero);
                cancellationToken.ThrowIfCancellationRequested();
                var now = timeProvider.GetUtcNow();
                lock (_gate)
                {
                        var acquired = new List<JobRecord>(jobIds.Count);
                        foreach (var id in jobIds)
                        {
                                if (!_jobs.TryGetValue(id, out var job))
                                        continue;
                                if (job.State == JobState.Active && job.LeaseExpiresAt <= now)
                                {
                                        job = job with { State = JobState.Pending, WorkerId = null, LeaseExpiresAt = null };
                                        _jobs[id] = job;
                                }

                                if (job.State is not (JobState.Pending or JobState.Scheduled) || job.DueAt > now)
                                        continue;

                                job = job with
                                {
                                        State = JobState.Active,
                                        Attempt = job.Attempt + 1,
                                        WorkerId = workerId,
                                        LeaseExpiresAt = now + lease,
                                        ExecutionTraceId = null,
                                        ExecutionSpanId = null,
                                        ExecutionStartedAt = null,
                                };
                                _jobs[id] = job;
                                MarkBatchStarted(job.BatchId, now);
                                acquired.Add(job);
                        }

                        return acquired;
                }
        }

        /// <inheritdoc />
        public ValueTask SetExecutionTelemetryAsync(
                string jobId,
                string workerId,
                string? traceId,
                string? spanId,
                DateTimeOffset startedAt,
                CancellationToken cancellationToken = default
        )
        {
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        var job = GetOwnedActive(jobId, workerId);
                        _jobs[jobId] = job with
                        {
                                ExecutionTraceId = traceId,
                                ExecutionSpanId = spanId,
                                ExecutionStartedAt = startedAt,
                        };
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask RenewLeaseAsync(string jobId, string workerId, TimeSpan lease, CancellationToken cancellationToken = default)
        {
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        var job = GetOwnedActive(jobId, workerId);
                        _jobs[jobId] = job with { LeaseExpiresAt = timeProvider.GetUtcNow() + lease };
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask CompleteAsync(string jobId, string workerId, CancellationToken cancellationToken = default)
                => CompleteWithContinuationsAsync(jobId, workerId, [], cancellationToken);

        /// <inheritdoc />
        public ValueTask CompleteWithContinuationsAsync(
                string jobId,
                string workerId,
                IReadOnlyList<JobContinuationAddition> additions,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentNullException.ThrowIfNull(additions);
                foreach (var addition in additions)
                {
                        ArgumentNullException.ThrowIfNull(addition, nameof(additions));
                        ArgumentNullException.ThrowIfNull(addition.Job, nameof(additions));
                }

                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        var current = GetOwnedActive(jobId, workerId);
                        var existingWaiters = GetUnsettledWaiters(jobId);
                        var newJobIds = new HashSet<string>(StringComparer.Ordinal);
                        var dependencyEdges = new List<JobContinuationEdge>(additions.Count);
                        var trackedAdditions = 0;

                        foreach (var addition in additions)
                        {
                                ValidateNewJob(addition.Job);
                                if (!newJobIds.Add(addition.Job.Id))
                                        throw new ImmediateJobException($"Job '{addition.Job.Id}' occurs more than once in the completion buffer.");
                                if (addition.Job.State is not (JobState.Pending or JobState.Scheduled))
                                        throw new ImmediateJobException($"Dynamic continuation '{addition.Job.Id}' has invalid state '{addition.Job.State}'.");
                                if (!Enum.IsDefined(addition.Trigger))
                                        throw new ArgumentOutOfRangeException(nameof(additions), "Unknown continuation trigger.");

                                if (addition.Options == ContinuationOptions.Detached)
                                {
                                        if (addition.Job.BatchId is not null)
                                                throw new ImmediateJobException("A detached continuation cannot belong to a batch.");
                                }
                                else if (addition.Options is ContinuationOptions.BesideContinuations or ContinuationOptions.BeforeContinuations)
                                {
                                        if (current.BatchId is null || !string.Equals(addition.Job.BatchId, current.BatchId, StringComparison.Ordinal))
                                                throw new ImmediateJobException("A batch-tracked continuation must belong to the current job's batch.");
                                        trackedAdditions++;
                                }
                                else
                                {
                                        throw new ArgumentOutOfRangeException(nameof(additions), "Unknown continuation option.");
                                }

                                dependencyEdges.Add(new()
                                {
                                        ChildJobId = addition.Job.Id,
                                        ParentJobId = jobId,
                                        Trigger = addition.Trigger,
                                });
                        }

                        if (dependencyEdges.Count != 0)
                                ValidateEdges([.. additions.Select(static addition => addition.Job)], dependencyEdges, current.BatchId);
                        ValidateSplice(existingWaiters, additions.Count(static addition => addition.Options == ContinuationOptions.BeforeContinuations));

                        IncrementBatchMembers(current.BatchId, trackedAdditions);
                        foreach (var addition in additions)
                        {
                                _jobs.Add(addition.Job.Id, NormalizeWaitingJob(addition.Job, dependencyCount: 1));
                                if (addition.Options == ContinuationOptions.BeforeContinuations)
                                        SpliceBeforeWaiters(addition.Job.Id, existingWaiters);
                        }

                        _edges.AddRange(dependencyEdges);
                        TransitionToTerminal(jobId, JobState.Succeeded, error: null, timeProvider.GetUtcNow());
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask AddBatchJobAsync(
                string currentJobId,
                JobRecord job,
                ContinuationOptions options,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentNullException.ThrowIfNull(job);
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (!_jobs.TryGetValue(currentJobId, out var current) || current.State != JobState.Active)
                                throw new ImmediateJobException($"Job '{currentJobId}' is not currently active.");
                        if (current.BatchId is null || !_batches.ContainsKey(current.BatchId))
                                throw new ImmediateJobException("The current job does not belong to a batch.");
                        if (options == ContinuationOptions.Detached)
                                throw new ImmediateJobException("AddToBatchAsync(JobDetails, ...) cannot create detached work.");
                        if (options is not (ContinuationOptions.BesideContinuations or ContinuationOptions.BeforeContinuations))
                                throw new ArgumentOutOfRangeException(nameof(options));
                        ValidateNewJob(job);
                        if (!string.Equals(job.BatchId, current.BatchId, StringComparison.Ordinal))
                                throw new ImmediateJobException("The new job must belong to the current job's batch.");
                        if (job.State is JobState.Active or JobState.AwaitingContinuation || IsTerminal(job.State))
                                throw new ImmediateJobException($"Concurrent batch member '{job.Id}' has invalid state '{job.State}'.");

                        var existingWaiters = options == ContinuationOptions.BeforeContinuations
                                ? GetUnsettledWaiters(currentJobId)
                                : [];
                        ValidateSplice(existingWaiters, options == ContinuationOptions.BeforeContinuations ? 1 : 0);
                        IncrementBatchMembers(current.BatchId, 1);
                        _jobs.Add(job.Id, job with { RemainingDependencies = 0 });
                        if (options == ContinuationOptions.BeforeContinuations)
                                SpliceBeforeWaiters(job.Id, existingWaiters);
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask FailAsync(
                string jobId,
                string workerId,
                string error,
                DateTimeOffset? nextRetryAt,
                CancellationToken cancellationToken = default
        )
        {
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        var job = GetOwnedActive(jobId, workerId);
                        if (nextRetryAt.HasValue)
                        {
                                var now = timeProvider.GetUtcNow();
                                _jobs[jobId] = job with
                                {
                                        State = nextRetryAt <= now ? JobState.Pending : JobState.Scheduled,
                                        DueAt = nextRetryAt.Value,
                                        WorkerId = null,
                                        LeaseExpiresAt = null,
                                        LastError = error,
                                        CompletedAt = null,
                                };
                        }
                        else
                        {
                                TransitionToTerminal(jobId, JobState.Failed, error, timeProvider.GetUtcNow());
                        }
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask UpsertRecurringAsync(RecurringJobSchedule schedule, CancellationToken cancellationToken = default)
        {
                ArgumentNullException.ThrowIfNull(schedule);
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (_recurring.TryGetValue(schedule.Name, out var current))
                        {
                                if (current.IsCodeDefined && !schedule.IsCodeDefined)
                                        throw new ImmediateJobException("Code-defined recurring schedules cannot be replaced by dynamic schedules.");

                                schedule = schedule with { IsPaused = current.IsPaused, LastRunAt = current.LastRunAt };
                        }

                        _recurring[schedule.Name] = schedule;
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask RemoveObsoleteCodeDefinedRecurringAsync(
                IReadOnlyCollection<string> activeScheduleNames,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentNullException.ThrowIfNull(activeScheduleNames);
                cancellationToken.ThrowIfCancellationRequested();
                var activeNames = activeScheduleNames.ToHashSet(StringComparer.Ordinal);
                lock (_gate)
                {
                        var obsoleteNames = _recurring
                                .Where(schedule => schedule.Value.IsCodeDefined && !activeNames.Contains(schedule.Key))
                                .Select(static schedule => schedule.Key)
                                .ToArray();
                        foreach (var name in obsoleteNames)
                                _ = _recurring.Remove(name);
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask RemoveRecurringAsync(string name, CancellationToken cancellationToken = default)
        {
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (_recurring.TryGetValue(name, out var schedule) && schedule.IsCodeDefined)
                                throw new ImmediateJobException("Code-defined recurring schedules cannot be deleted.");

                        _ = _recurring.Remove(name);
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask PauseRecurringAsync(string name, CancellationToken cancellationToken = default) =>
                SetRecurringPausedAsync(name, isPaused: true, cancellationToken);

        /// <inheritdoc />
        public ValueTask ResumeRecurringAsync(string name, CancellationToken cancellationToken = default) =>
                SetRecurringPausedAsync(name, isPaused: false, cancellationToken);

        /// <inheritdoc />
        public async ValueTask<IReadOnlyList<RecurringJobSchedule>> GetDueRecurringAsync(
                DateTimeOffset now,
                int batchSize,
                CancellationToken cancellationToken = default
        )
        {
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        return
                        [
                                .. _recurring.Values.Where(x => !x.IsPaused && x.NextRunAt <= now).OrderBy(x => x.NextRunAt).Take(batchSize),
                        ];
                }
        }

        /// <inheritdoc />
        public async ValueTask<bool> MaterializeRecurringAsync(
                RecurringJobSchedule schedule,
                JobRecord job,
                DateTimeOffset nextRunAt,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentNullException.ThrowIfNull(schedule);
                ArgumentNullException.ThrowIfNull(job);
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (!_recurring.TryGetValue(schedule.Name, out var current) || current.NextRunAt != schedule.NextRunAt)
                                return false;

                        var inserted = job.RecurringKey is null || _recurringKeys.Add(job.RecurringKey);
                        if (inserted)
                                _jobs[job.Id] = job;
                        _recurring[schedule.Name] = current with { LastRunAt = schedule.NextRunAt, NextRunAt = nextRunAt };
                        return inserted;
                }
        }

        /// <inheritdoc />
        public async ValueTask<JobMonitoringSnapshot> GetMonitoringSnapshotAsync(CancellationToken cancellationToken = default)
        {
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        var counts = Enum.GetValues<JobState>().ToDictionary(state => state, state => _jobs.Values.LongCount(x => x.State == state));
                        var cutoff = timeProvider.GetUtcNow() - TimeSpan.FromMinutes(2);
                        IReadOnlyList<JobServerSnapshot> servers = [.. _servers.Values.Where(x => x.LastHeartbeat >= cutoff)];
                        return new(timeProvider.GetUtcNow(), counts, [.. _recurring.Values], servers)
                        {
                                Capabilities = this.GetCapabilities(),
                        };
                }
        }

        /// <inheritdoc />
        public async ValueTask<IReadOnlyList<JobRecord>> QueryJobsAsync(JobQuery query, CancellationToken cancellationToken = default)
        {
                ArgumentNullException.ThrowIfNull(query);
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        var jobs = _jobs.Values.AsEnumerable();
                        if (query.Id is { } id)
                                jobs = jobs.Where(x => string.Equals(x.Id, id, StringComparison.Ordinal));
                        if (query.State is { } state)
                                jobs = jobs.Where(x => x.State == state);
                        if (!string.IsNullOrWhiteSpace(query.QueueName))
                                jobs = jobs.Where(x => string.Equals(x.QueueName, query.QueueName, StringComparison.Ordinal));
                        if (!string.IsNullOrWhiteSpace(query.JobName))
                                jobs = jobs.Where(x => string.Equals(x.JobName, query.JobName, StringComparison.Ordinal));

                        if (!string.IsNullOrWhiteSpace(query.Search))
                                jobs = jobs.Where(x => x.JobName.Contains(query.Search, StringComparison.OrdinalIgnoreCase));

                        return
                        [
                                .. jobs.OrderByDescending(x => x.CreatedAt)
                                        .ThenBy(x => x.Id, StringComparer.Ordinal)
                                        .Skip(Math.Max(0, query.Skip))
                                        .Take(Math.Clamp(query.Take, 1, 1000)),
                        ];
                }
        }

        /// <inheritdoc />
        public async ValueTask<BatchStatus?> GetBatchStatusAsync(
                string batchId,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentException.ThrowIfNullOrWhiteSpace(batchId);
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (!_batches.TryGetValue(batchId, out var batch))
                                return null;

                        return ToStatus(batch);
                }
        }

        /// <inheritdoc />
        public async ValueTask<IReadOnlyList<BatchStatus>> QueryBatchesAsync(
                JobBatchQuery query,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentNullException.ThrowIfNull(query);
                ArgumentOutOfRangeException.ThrowIfNegative(query.Skip, nameof(query));
                ArgumentOutOfRangeException.ThrowIfLessThanOrEqual(query.Take, 0, nameof(query));

                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        var batches = _batches.Values.AsEnumerable();
                        if (query.State is { } state)
                                batches = batches.Where(batch => batch.State == state);
                        return
                        [
                                .. batches.OrderByDescending(static batch => batch.CreatedAt)
                                        .ThenBy(static batch => batch.Id, StringComparer.Ordinal)
                                        .Skip(query.Skip)
                                        .Take(query.Take)
                                        .Select(ToStatus),
                        ];
                }
        }

        /// <inheritdoc />
        public async ValueTask<IReadOnlyList<BatchMemberStatus>> QueryBatchMembersAsync(
                string batchId,
                BatchMemberQuery query,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentException.ThrowIfNullOrWhiteSpace(batchId);
                ArgumentNullException.ThrowIfNull(query);
                ArgumentOutOfRangeException.ThrowIfNegative(query.Skip, nameof(query));
                ArgumentOutOfRangeException.ThrowIfLessThanOrEqual(query.Take, 0, nameof(query));

                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (!_batches.ContainsKey(batchId))
                                return [];

                        var members = _jobs.Values.Where(job => string.Equals(job.BatchId, batchId, StringComparison.Ordinal));
                        if (query.State is { } state)
                                members = members.Where(job => job.State == state);

                        return
                        [
                                .. members
                                        .OrderBy(job => job.CreatedAt)
                                        .ThenBy(job => job.Id, StringComparer.Ordinal)
                                        .Skip(query.Skip)
                                        .Take(query.Take)
                                        .Select(static job => new BatchMemberStatus(
                                                job.Id,
                                                job.JobName,
                                                job.QueueName,
                                                job.State,
                                                job.Attempt,
                                                job.CreatedAt,
                                                job.CompletedAt,
                                                job.LastError
                                        )),
                        ];
                }
        }

        /// <inheritdoc />
        public async ValueTask<BatchGraph?> GetBatchGraphAsync(
                string batchId,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentException.ThrowIfNullOrWhiteSpace(batchId);
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (!_batches.ContainsKey(batchId))
                                return null;

                        var members = _jobs.Values
                                .Where(job => string.Equals(job.BatchId, batchId, StringComparison.Ordinal))
                                .OrderBy(job => job.CreatedAt)
                                .ThenBy(job => job.Id, StringComparer.Ordinal)
                                .ToArray();
                        var memberIds = members.Select(static job => job.Id).ToHashSet(StringComparer.Ordinal);
                        return new(
                                batchId,
                                [.. members.Select(static job => new BatchGraphNode(job.Id, job.JobName, job.State))],
                                [.. _edges.Where(edge => memberIds.Contains(edge.ChildJobId)).Select(ToGraphEdge)]
                        );
                }
        }

        /// <inheritdoc />
        public async ValueTask<JobStatus?> GetJobStatusAsync(
                string jobId,
                CancellationToken cancellationToken = default
        )
        {
                ArgumentException.ThrowIfNullOrWhiteSpace(jobId);
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (!_jobs.TryGetValue(jobId, out var job))
                                return null;

                        return new(
                                job.Id,
                                job.JobName,
                                job.QueueName,
                                job.State,
                                job.Attempt,
                                MaxAttempts: null,
                                job.CreatedAt,
                                job.DueAt,
                                job.CompletedAt,
                                job.LastError,
                                job.BatchId,
                                [.. _edges.Where(edge => string.Equals(edge.ChildJobId, jobId, StringComparison.Ordinal)).Select(ToGraphEdge)]
                        );
                }
        }

        /// <inheritdoc />
        public ValueTask CancelBatchAsync(string batchId, CancellationToken cancellationToken = default)
        {
                ArgumentException.ThrowIfNullOrWhiteSpace(batchId);
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (!_batches.TryGetValue(batchId, out var batch))
                                throw new KeyNotFoundException($"Batch '{batchId}' was not found.");
                        if (batch.State != BatchState.Executing)
                                throw new ImmediateJobException("Only an executing batch can be cancelled.");

                        var now = timeProvider.GetUtcNow();
                        var jobIds = _jobs.Values
                                .Where(job => string.Equals(job.BatchId, batchId, StringComparison.Ordinal) && !IsTerminal(job.State))
                                .Select(static job => job.Id)
                                .ToArray();
                        foreach (var jobId in jobIds)
                        {
                                TransitionToTerminal(jobId, JobState.Cancelled, error: null, now, propagateContinuations: false);
                        }

                        foreach (var jobId in jobIds)
                                ProcessTerminalJob(jobId);
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask DeleteBatchAsync(string batchId, CancellationToken cancellationToken = default)
        {
                ArgumentException.ThrowIfNullOrWhiteSpace(batchId);
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (!_batches.TryGetValue(batchId, out var batch))
                                throw new KeyNotFoundException($"Batch '{batchId}' was not found.");
                        if (batch.State == BatchState.Executing)
                                throw new ImmediateJobException("Only a terminal batch can be deleted.");

                        var jobIds = _jobs.Values
                                .Where(job => string.Equals(job.BatchId, batchId, StringComparison.Ordinal))
                                .Select(static job => job.Id)
                                .ToHashSet(StringComparer.Ordinal);
                        foreach (var jobId in jobIds)
                                _ = _jobs.Remove(jobId);
                        _ = _batches.Remove(batchId);
                        RemoveEdgesForJobs(jobIds, [batchId]);
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask RetryAsync(string jobId, CancellationToken cancellationToken = default)
        {
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (!_jobs.TryGetValue(jobId, out var job))
                                throw new KeyNotFoundException($"Job '{jobId}' was not found.");
                        if (job.State != JobState.Failed)
                                throw new ImmediateJobException("Only failed jobs can be retried.");

                        _jobs[jobId] = job with
                        {
                                State = JobState.Pending,
                                DueAt = timeProvider.GetUtcNow(),
                                CompletedAt = null,
                                LastError = null,
                        };
                        if (job.BatchId is { } batchId && _batches.TryGetValue(batchId, out var batch))
                        {
                                _batches[batchId] = batch with
                                {
                                        State = BatchState.Executing,
                                        PendingCount = batch.PendingCount + 1,
                                        FailedCount = Math.Max(0, batch.FailedCount - 1),
                                        CompletedAt = null,
                                };
                        }
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask DeleteAsync(string jobId, CancellationToken cancellationToken = default)
        {
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (!_jobs.TryGetValue(jobId, out var job))
                                throw new KeyNotFoundException($"Job '{jobId}' was not found.");
                        if (!IsTerminal(job.State))
                                throw new ImmediateJobException("Only terminal jobs can be deleted.");
                        if (job.BatchId is not null)
                                throw new ImmediateJobException("Batch members cannot be deleted individually.");

                        _ = _jobs.Remove(jobId);
                        RemoveEdgesForJobs(new(StringComparer.Ordinal) { jobId });
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask PurgeJobsAsync(
                TimeSpan succeededRetention,
                TimeSpan failedRetention,
                CancellationToken cancellationToken = default
        )
        {
                cancellationToken.ThrowIfCancellationRequested();
                var now = timeProvider.GetUtcNow();
                lock (_gate)
                {
                        var standaloneJobIds = _jobs.Values
                                .Where(static job => job.BatchId is null)
                                .Where(
                                        x =>
                                                x.CompletedAt is { } completed
                                                && (
                                                        (x.State is JobState.Succeeded && completed < now - succeededRetention)
                                                        || (x.State is JobState.Failed or JobState.Cancelled or JobState.Skipped && completed < now - failedRetention)
                                                )
                                )
                                .Select(static job => job.Id)
                                .ToHashSet(StringComparer.Ordinal);

                        foreach (var id in standaloneJobIds)
                                _ = _jobs.Remove(id);
                        RemoveEdgesForJobs(standaloneJobIds);
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask PurgeBatchesAsync(
                TimeSpan batchSucceededRetention,
                TimeSpan batchFailedRetention,
                CancellationToken cancellationToken = default
        )
        {
                cancellationToken.ThrowIfCancellationRequested();
                var now = timeProvider.GetUtcNow();
                lock (_gate)
                {
                        var batchIds = _batches.Values
                                .Where(
                                        batch =>
                                                batch.CompletedAt is { } completed
                                                && (
                                                        (batch.State is BatchState.Succeeded && completed < now - batchSucceededRetention)
                                                        || (batch.State is BatchState.Failed or BatchState.Cancelled && completed < now - batchFailedRetention)
                                                )
                                )
                                .Select(static batch => batch.Id)
                                .ToHashSet(StringComparer.Ordinal);

                        var batchJobIds = _jobs.Values
                                .Where(job => job.BatchId is { } batchId && batchIds.Contains(batchId))
                                .Select(static job => job.Id)
                                .ToHashSet(StringComparer.Ordinal);
                        foreach (var id in batchJobIds)
                                _ = _jobs.Remove(id);
                        foreach (var batchId in batchIds)
                                _ = _batches.Remove(batchId);
                        RemoveEdgesForJobs(batchJobIds, batchIds);
                }

                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public ValueTask HeartbeatAsync(JobServerSnapshot server, CancellationToken cancellationToken = default)
        {
                ArgumentNullException.ThrowIfNull(server);
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                        _servers[server.WorkerId] = server;
                return ValueTask.CompletedTask;
        }

        /// <inheritdoc />
        public async ValueTask<bool> IsHealthyAsync(CancellationToken cancellationToken = default)
        {
                cancellationToken.ThrowIfCancellationRequested();
                return true;
        }

        private void ValidateNewJob(JobRecord job)
        {
                ArgumentException.ThrowIfNullOrWhiteSpace(job.Id);
                ArgumentException.ThrowIfNullOrWhiteSpace(job.JobName);
                if (_jobs.ContainsKey(job.Id))
                        throw new ImmediateJobException($"Job '{job.Id}' already exists.");
        }

        private void ValidateBatch(
                JobBatchRecord batch,
                IReadOnlyList<JobRecord> jobs,
                IReadOnlyList<JobContinuationEdge> edges
        )
        {
                ArgumentException.ThrowIfNullOrWhiteSpace(batch.Id);
                if (_batches.ContainsKey(batch.Id))
                        throw new ImmediateJobException($"Batch '{batch.Id}' already exists.");
                if (jobs.Count == 0)
                        throw new ImmediateJobException("An atomic batch cannot be empty.");

                var succeeded = jobs.Count(static job => job.State == JobState.Succeeded);
                var failed = jobs.Count(static job => job.State == JobState.Failed);
                var cancelled = jobs.Count(static job => job.State == JobState.Cancelled);
                var skipped = jobs.Count(static job => job.State == JobState.Skipped);
                var pending = jobs.Count - succeeded - failed - cancelled - skipped;

                var expectedState = true switch
                {
                        _ when pending != 0 => BatchState.Executing,
                        _ when failed != 0 => BatchState.Failed,
                        _ when cancelled != 0 => BatchState.Cancelled,
                        _ => BatchState.Succeeded,
                };

                if (
                        batch.TotalJobs != jobs.Count ||
                        batch.PendingCount != pending ||
                        batch.SucceededCount != succeeded ||
                        batch.FailedCount != failed ||
                        batch.CancelledCount != cancelled ||
                        batch.SkippedCount != skipped ||
                        batch.State != expectedState ||
                        ((pending == 0) != (batch.CompletedAt is not null))
                )
                {
                        throw new ImmediateJobException("A batch header does not match its members or aggregate state.");
                }

                var jobIds = new HashSet<string>(StringComparer.Ordinal);
                foreach (var job in jobs)
                {
                        ValidateNewJob(job);
                        if (!jobIds.Add(job.Id))
                                throw new ImmediateJobException($"Job '{job.Id}' occurs more than once in the batch.");
                        if (!string.Equals(job.BatchId, batch.Id, StringComparison.Ordinal))
                                throw new ImmediateJobException($"Job '{job.Id}' does not belong to batch '{batch.Id}'.");
                }

                ValidateEdges(jobs, edges, batch.Id);
        }

        private void ValidateEdges(
                IReadOnlyList<JobRecord> newJobs,
                IReadOnlyList<JobContinuationEdge> edges,
                string? batchId
        )
        {
                if (batchId is null && edges.Count == 0)
                        throw new ImmediateJobException("A continuation must have at least one parent.");

                var newJobIds = newJobs.Select(static job => job.Id).ToHashSet(StringComparer.Ordinal);
                var logicalEdges = new HashSet<(string Child, string ParentKind, string Parent)>(
                        EqualityComparer<(string Child, string ParentKind, string Parent)>.Default
                );
                var outgoing = newJobIds.ToDictionary(static id => id, static _ => new List<string>(), StringComparer.Ordinal);
                var incoming = newJobIds.ToDictionary(static id => id, static _ => 0, StringComparer.Ordinal);
                foreach (var edge in edges)
                {
                        ArgumentNullException.ThrowIfNull(edge);
                        ArgumentException.ThrowIfNullOrWhiteSpace(edge.ChildJobId);
                        if (!Enum.IsDefined(edge.Trigger))
                                throw new ArgumentOutOfRangeException(nameof(edges), "Unknown continuation trigger.");
                        if (!newJobIds.Contains(edge.ChildJobId))
                                throw new ImmediateJobException($"Continuation child '{edge.ChildJobId}' is not part of the atomic insert.");

                        var hasJobParent = !string.IsNullOrWhiteSpace(edge.ParentJobId);
                        var hasBatchParent = !string.IsNullOrWhiteSpace(edge.ParentBatchId);
                        if (hasJobParent == hasBatchParent)
                                throw new ImmediateJobException("A continuation edge must have exactly one job or batch parent.");

                        if (hasJobParent)
                        {
                                var parentId = edge.ParentJobId!;
                                if (string.Equals(parentId, edge.ChildJobId, StringComparison.Ordinal))
                                        throw new ImmediateJobException($"Continuation job '{edge.ChildJobId}' cannot depend on itself.");
                                if (!newJobIds.Contains(parentId) && !_jobs.ContainsKey(parentId))
                                        throw new KeyNotFoundException($"Continuation parent job '{parentId}' was not found.");
                                if (!logicalEdges.Add((edge.ChildJobId, "job", parentId)))
                                        throw new ImmediateJobException($"Duplicate continuation edge '{parentId}' -> '{edge.ChildJobId}'.");

                                if (newJobIds.Contains(parentId))
                                {
                                        outgoing[parentId].Add(edge.ChildJobId);
                                        incoming[edge.ChildJobId]++;
                                }
                        }
                        else
                        {
                                var parentId = edge.ParentBatchId!;
                                if (!_batches.ContainsKey(parentId))
                                        throw new KeyNotFoundException($"Continuation parent batch '{parentId}' was not found.");
                                if (!logicalEdges.Add((edge.ChildJobId, "batch", parentId)))
                                        throw new ImmediateJobException($"Duplicate continuation edge from batch '{parentId}' to '{edge.ChildJobId}'.");
                        }
                }

                var ready = new Queue<string>(incoming.Where(static pair => pair.Value == 0).Select(static pair => pair.Key));
                var visited = 0;
                while (ready.TryDequeue(out var parentId))
                {
                        visited++;
                        foreach (var childId in outgoing[parentId])
                        {
                                if (--incoming[childId] == 0)
                                        ready.Enqueue(childId);
                        }
                }

                if (visited != newJobIds.Count)
                        throw new ImmediateJobException("The continuation graph contains a dependency cycle.");
        }

        private static JobRecord NormalizeWaitingJob(JobRecord job, int dependencyCount) => job with
        {
                State = dependencyCount == 0 ? job.State : JobState.AwaitingContinuation,
                RemainingDependencies = dependencyCount,
                FailedDependencies = 0,
                WorkerId = null,
                LeaseExpiresAt = null,
                CompletedAt = null,
        };

        private bool IsRecoveredBatch(
                JobBatchRecord batch,
                IReadOnlyList<JobRecord> jobs,
                IReadOnlyList<JobContinuationEdge> edges
        )
        {
                if (batch.StartedAt is not null ||
                        batch.CompletedAt is not null ||
                        batch.SucceededCount != 0 ||
                        batch.FailedCount != 0 ||
                        batch.CancelledCount != 0 ||
                        batch.SkippedCount != 0 ||
                        jobs.Any(static job => job.State is JobState.Active or JobState.Succeeded or JobState.Failed or JobState.Cancelled or JobState.Skipped))
                {
                        return true;
                }

                if (!HasTerminalParent(edges))
                        return false;

                var incomingCounts = edges
                        .GroupBy(static edge => edge.ChildJobId, StringComparer.Ordinal)
                        .ToDictionary(static group => group.Key, static group => group.Count(), StringComparer.Ordinal);
                return jobs.Any(job => incomingCounts.TryGetValue(job.Id, out var incoming) &&
                        (job.State != JobState.AwaitingContinuation || job.RemainingDependencies < incoming));
        }

        private bool HasTerminalParent(IEnumerable<JobContinuationEdge> edges) =>
                edges.Any(IsTerminal);

        private void MarkTerminalParentEdgesSettled(IEnumerable<JobContinuationEdge> edges)
        {
                foreach (var edge in edges)
                {
                        if (IsTerminal(edge))
                        {
                                _ = _settledEdges.Add(edge);
                        }
                }
        }

        private bool IsTerminal(JobContinuationEdge edge)
        {
                return (
                        edge.ParentJobId is { } parentJobId
                        && _jobs.TryGetValue(parentJobId, out var parentJob)
                        && IsTerminal(parentJob.State)
                ) || (
                        edge.ParentBatchId is { } parentBatchId
                        && _batches.TryGetValue(parentBatchId, out var parentBatch)
                        && IsTerminal(parentBatch.State)
                );
        }

        private void EvaluateAlreadyTerminalParents(IReadOnlyList<JobContinuationEdge> edges)
        {
                foreach (var parentId in edges
                        .Where(static edge => edge.ParentJobId is not null)
                        .Select(static edge => edge.ParentJobId!)
                        .Distinct(StringComparer.Ordinal)
                        .Where(parentId => _jobs.TryGetValue(parentId, out var parent) && IsTerminal(parent.State))
                        .ToArray())
                {
                        ProcessTerminalJob(parentId);
                }

                foreach (var parentId in edges
                        .Where(static edge => edge.ParentBatchId is not null)
                        .Select(static edge => edge.ParentBatchId!)
                        .Distinct(StringComparer.Ordinal)
                        .Where(parentId => _batches.TryGetValue(parentId, out var parent) && IsTerminal(parent.State))
                        .ToArray())
                {
                        ProcessTerminalBatch(parentId);
                }
        }

        private void TransitionToTerminal(
                string jobId,
                JobState terminalState,
                string? error,
                DateTimeOffset completedAt,
                bool propagateContinuations = true
        )
        {
                if (!IsTerminal(terminalState))
                        throw new ArgumentOutOfRangeException(nameof(terminalState));
                if (!_jobs.TryGetValue(jobId, out var job) || IsTerminal(job.State))
                        return;

                _jobs[jobId] = job with
                {
                        State = terminalState,
                        WorkerId = null,
                        LeaseExpiresAt = null,
                        LastError = error,
                        CompletedAt = completedAt,
                };
                UpdateBatchAfterTerminal(job.BatchId, terminalState, completedAt);
                if (propagateContinuations)
                        ProcessTerminalJob(jobId);
                RemoveFairQueueCursorWhenBacklogClears(job.QueueName, job.GroupId);
        }

        private void RemoveFairQueueCursorWhenBacklogClears(string queueName, string? groupId)
        {
                if (groupId is null ||
                        _jobs.Values.Any(job =>
                                string.Equals(job.QueueName, queueName, StringComparison.Ordinal) &&
                                string.Equals(job.GroupId, groupId, StringComparison.Ordinal) &&
                                job.State is JobState.Pending or JobState.Scheduled or JobState.Active))
                {
                        return;
                }

                _ = _fairQueueLastServed.Remove((queueName, groupId));
        }

        private void UpdateBatchAfterTerminal(string? batchId, JobState state, DateTimeOffset completedAt)
        {
                if (batchId is null || !_batches.TryGetValue(batchId, out var batch))
                        return;

                var pending = Math.Max(0, batch.PendingCount - 1);
                batch = batch with
                {
                        PendingCount = pending,
                        SucceededCount = batch.SucceededCount + (state == JobState.Succeeded ? 1 : 0),
                        FailedCount = batch.FailedCount + (state == JobState.Failed ? 1 : 0),
                        CancelledCount = batch.CancelledCount + (state == JobState.Cancelled ? 1 : 0),
                        SkippedCount = batch.SkippedCount + (state == JobState.Skipped ? 1 : 0),
                };
                if (pending == 0)
                {
                        batch = batch with
                        {
                                State = batch.FailedCount != 0
                                        ? BatchState.Failed
                                        : batch.CancelledCount != 0 ? BatchState.Cancelled : BatchState.Succeeded,
                                CompletedAt = completedAt,
                        };
                }

                _batches[batchId] = batch;
                if (pending == 0)
                        ProcessTerminalBatch(batchId);
        }

        private void ProcessTerminalJob(string parentJobId)
        {
                if (!_jobs.TryGetValue(parentJobId, out var parent) || !IsTerminal(parent.State))
                        return;

                foreach (var edge in _edges
                        .Where(edge => string.Equals(edge.ParentJobId, parentJobId, StringComparison.Ordinal) && !_settledEdges.Contains(edge))
                        .ToArray())
                {
                        _ = _settledEdges.Add(edge);
                        SettleEdge(edge, parentFailed: parent.State == JobState.Failed);
                }
        }

        private void ProcessTerminalBatch(string parentBatchId)
        {
                if (!_batches.TryGetValue(parentBatchId, out var parent) || !IsTerminal(parent.State))
                        return;

                foreach (var edge in _edges
                        .Where(edge => string.Equals(edge.ParentBatchId, parentBatchId, StringComparison.Ordinal) && !_settledEdges.Contains(edge))
                        .ToArray())
                {
                        _ = _settledEdges.Add(edge);
                        SettleEdge(edge, parentFailed: parent.State == BatchState.Failed);
                }
        }

        private void SettleEdge(JobContinuationEdge edge, bool parentFailed)
        {
                if (!_jobs.TryGetValue(edge.ChildJobId, out var child) || IsTerminal(child.State))
                        return;

                var remaining = Math.Max(0, child.RemainingDependencies - 1);
                if (remaining != 0)
                {
                        _jobs[child.Id] = child with
                        {
                                RemainingDependencies = remaining,
                                FailedDependencies = child.FailedDependencies + (parentFailed ? 1 : 0),
                        };
                        return;
                }

                var (triggersSatisfied, failedDependencies) = EvaluateIncomingTriggers(child.Id);
                _jobs[child.Id] = child with
                {
                        State = triggersSatisfied && child.State == JobState.AwaitingContinuation
                                ? GetReadyState(child)
                                : child.State,
                        RemainingDependencies = 0,
                        FailedDependencies = failedDependencies,
                };
                if (!triggersSatisfied)
                        TransitionToTerminal(child.Id, JobState.Skipped, error: null, timeProvider.GetUtcNow());
        }

        private (bool Satisfied, int FailedDependencies) EvaluateIncomingTriggers(string childJobId)
        {
                var allTerminal = true;
                var requiresFailure = false;
                var successViolated = false;
                var failedDependencies = 0;
                foreach (var edge in _edges.Where(edge => string.Equals(edge.ChildJobId, childJobId, StringComparison.Ordinal)))
                {
                        var parentTerminal = false;
                        var parentSucceeded = false;
                        var parentFailed = false;
                        if (edge.ParentJobId is { } parentJobId && _jobs.TryGetValue(parentJobId, out var parentJob))
                        {
                                parentTerminal = IsTerminal(parentJob.State);
                                parentSucceeded = parentJob.State == JobState.Succeeded;
                                parentFailed = parentJob.State == JobState.Failed;
                        }
                        else if (edge.ParentBatchId is { } parentBatchId && _batches.TryGetValue(parentBatchId, out var parentBatch))
                        {
                                parentTerminal = IsTerminal(parentBatch.State);
                                parentSucceeded = parentBatch.State == BatchState.Succeeded;
                                parentFailed = parentBatch.State == BatchState.Failed;
                        }

                        allTerminal &= parentTerminal;
                        failedDependencies += parentFailed ? 1 : 0;
                        requiresFailure |= edge.Trigger == ContinuationTrigger.Failure;
                        successViolated |= edge.Trigger == ContinuationTrigger.Success && !parentSucceeded;
                }

                return (
                        allTerminal && !successViolated && (!requiresFailure || failedDependencies != 0),
                        failedDependencies
                );
        }

        private JobState GetReadyState(JobRecord job) =>
                job.DueAt <= timeProvider.GetUtcNow() ? JobState.Pending : JobState.Scheduled;

        private JobContinuationEdge[] GetUnsettledWaiters(string parentJobId) =>
        [
                .. _edges.Where(edge => string.Equals(edge.ParentJobId, parentJobId, StringComparison.Ordinal) &&
                        !_settledEdges.Contains(edge) &&
                        _jobs.TryGetValue(edge.ChildJobId, out var child) &&
                        !IsTerminal(child.State)),
        ];

        private void SpliceBeforeWaiters(
                string newParentJobId,
                IReadOnlyList<JobContinuationEdge> existingWaiters
        )
        {
                foreach (var existingEdge in existingWaiters)
                {
                        if (!_jobs.TryGetValue(existingEdge.ChildJobId, out var child) || IsTerminal(child.State))
                                continue;

                        _jobs[child.Id] = child with
                        {
                                State = JobState.AwaitingContinuation,
                                RemainingDependencies = child.RemainingDependencies + 1,
                        };
                        _edges.Add(new()
                        {
                                ChildJobId = child.Id,
                                ParentJobId = newParentJobId,
                                Trigger = existingEdge.Trigger,
                        });
                }
        }

        private void ValidateSplice(IReadOnlyList<JobContinuationEdge> existingWaiters, int additions)
        {
                if (additions == 0)
                        return;
                foreach (var existingEdge in existingWaiters)
                {
                        if (_jobs.TryGetValue(existingEdge.ChildJobId, out var child) &&
                                child.RemainingDependencies > int.MaxValue - additions)
                        {
                                throw new ImmediateJobException($"Continuation dependency count overflow for job '{child.Id}'.");
                        }
                }
        }

        private void IncrementBatchMembers(string? batchId, int count)
        {
                if (count == 0)
                        return;
                if (batchId is null || !_batches.TryGetValue(batchId, out var batch))
                        throw new ImmediateJobException("The current job's batch was not found.");
                if (batch.TotalJobs > int.MaxValue - count || batch.PendingCount > int.MaxValue - count)
                        throw new ImmediateJobException($"Batch '{batchId}' member count overflow.");

                _batches[batchId] = batch with
                {
                        TotalJobs = batch.TotalJobs + count,
                        PendingCount = batch.PendingCount + count,
                };
        }

        private void MarkBatchStarted(string? batchId, DateTimeOffset startedAt)
        {
                if (batchId is not null && _batches.TryGetValue(batchId, out var batch) && batch.StartedAt is null)
                        _batches[batchId] = batch with { StartedAt = startedAt };
        }

        private static bool IsTerminal(JobState state) =>
                state is JobState.Succeeded or JobState.Failed or JobState.Cancelled or JobState.Skipped;

        private static bool IsTerminal(BatchState state) => state is not BatchState.Executing;

        private static BatchStatus ToStatus(JobBatchRecord batch) => new(
                batch.Id,
                batch.State,
                batch.TotalJobs,
                batch.SucceededCount,
                batch.FailedCount,
                batch.CancelledCount,
                batch.SkippedCount,
                batch.PendingCount,
                batch.CreatedAt,
                batch.StartedAt,
                batch.CompletedAt,
                BatchStatus.CalculateFractionSettled(batch.TotalJobs, batch.PendingCount)
        );

        private static BatchGraphEdge ToGraphEdge(JobContinuationEdge edge) => new(
                edge.ChildJobId,
                edge.ParentJobId,
                edge.ParentBatchId,
                edge.Trigger
        );

        private void RemoveEdgesForJobs(
                HashSet<string> jobIds,
                HashSet<string>? batchIds = null
        )
        {
                if (jobIds.Count == 0 && (batchIds is null || batchIds.Count == 0))
                        return;

                var batches = batchIds ?? [];
                for (var index = _edges.Count - 1; index >= 0; index--)
                {
                        var edge = _edges[index];
                        if (!jobIds.Contains(edge.ChildJobId) &&
                                (edge.ParentJobId is null || !jobIds.Contains(edge.ParentJobId)) &&
                                (edge.ParentBatchId is null || !batches.Contains(edge.ParentBatchId)))
                        {
                                continue;
                        }

                        _edges.RemoveAt(index);
                        _ = _settledEdges.Remove(edge);
                }
        }

        private JobRecord GetOwnedActive(string jobId, string workerId)
        {
                if (!_jobs.TryGetValue(jobId, out var job) || job.State != JobState.Active || !string.Equals(job.WorkerId, workerId, StringComparison.Ordinal))
                        throw new ImmediateJobException($"Worker '{workerId}' does not own active job '{jobId}'.");
                return job;
        }

        private ValueTask SetRecurringPausedAsync(string name, bool isPaused, CancellationToken cancellationToken)
        {
                cancellationToken.ThrowIfCancellationRequested();
                lock (_gate)
                {
                        if (!_recurring.TryGetValue(name, out var schedule))
                                throw new KeyNotFoundException($"Recurring schedule '{name}' was not found.");

                        _recurring[name] = schedule with { IsPaused = isPaused };
                }

                return ValueTask.CompletedTask;
        }
}

ImmediatePlatform / Immediate.Jobs / 30631770050

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