1771

Committed 20 Oct 2023 08:58AM UTC coverage: 91.567% (-0.009%) from 91.576%

Build # 1771

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web-flow

Commit Message

Fix blocked DB::open on multiprocess access on exFAT filesystem (#6959)

Fix double file lock and DB::open being blocked with multiple concurrent realm access on fat32/exfat file systems.

When file is truncated on fat32/exfat its uid is available for other files. With multiple processes opening and truncating the same set of files could lead to the situation when within one process get_unique_id will return the same value for different files in timing is right. This breaks proper initialization of static data for interprocess mutexes, so that subsequent locks will hang by trying to lock essentially the same file twice.

Run Details

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53 existing lines in 13 files now uncovered.

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70.21

/src/realm/sync/instruction_applier.cpp

#include <realm/sync/instruction_applier.hpp>
#include <realm/set.hpp>
#include <realm/util/scope_exit.hpp>

#include <realm/transaction.hpp>

namespace realm::sync {
namespace {

REALM_NORETURN void throw_bad_transaction_log(std::string msg)
{
    throw BadChangesetError{std::move(msg)};
}

} // namespace

REALM_NORETURN void InstructionApplier::bad_transaction_log(const std::string& msg) const
{
    if (m_last_object_key) {
        // If the last_object_key is valid then we should have a changeset and a current table
        REALM_ASSERT(m_log);
        REALM_ASSERT(m_last_table_name);
        std::stringstream ss;
        util::Optional<InternString> field_name;
        if (m_last_field_name) {
            field_name = m_last_field_name;
        }
        const instr::Path* cur_path = m_current_path ? &(*m_current_path) : nullptr;
        m_log->print_path(ss, m_last_table_name, *m_last_object_key, field_name, cur_path);
        throw_bad_transaction_log(
            util::format("%1 (instruction target: %2, version: %3, last_integrated_remote_version: %4, "
                         "origin_file_ident: %5, timestamp: %6)",
                         msg, ss.str(), m_log->version, m_log->last_integrated_remote_version,
                         m_log->origin_file_ident, m_log->origin_timestamp));
    }
    else if (m_last_table_name) {
        // We should have a changeset if we have a table name defined.
        REALM_ASSERT(m_log);
        throw_bad_transaction_log(
            util::format("%1 (instruction table: %2, version: %3, last_integrated_remote_version: %4, "
                         "origin_file_ident: %5, timestamp: %6)",
                         msg, m_log->get_string(m_last_table_name), m_log->version,
                         m_log->last_integrated_remote_version, m_log->origin_file_ident, m_log->origin_timestamp));
    }
    else if (m_log) {
        // If all we have is a changeset, then we should log whatever we can about it.
        throw_bad_transaction_log(util::format("%1 (version: %2, last_integrated_remote_version: %3, "
                                               "origin_file_ident: %4, timestamp: %5)",
                                               msg, m_log->version, m_log->last_integrated_remote_version,
                                               m_log->origin_file_ident, m_log->origin_timestamp));
    }
    throw_bad_transaction_log(std::move(msg));
}

template <class... Params>
REALM_NORETURN void InstructionApplier::bad_transaction_log(const char* msg, Params&&... params) const
{
    // FIXME: Avoid throwing in normal program flow (since changesets can come
    // in over the network, defective changesets are part of normal program
    // flow).
    bad_transaction_log(util::format(msg, std::forward<Params>(params)...));
}

StringData InstructionApplier::get_string(InternString str) const
{
    auto string = m_log->try_get_intern_string(str);
    if (REALM_UNLIKELY(!string))
        bad_transaction_log("string read fails");
    return m_log->get_string(*string);
}

StringData InstructionApplier::get_string(StringBufferRange range) const
{
    auto string = m_log->try_get_string(range);
    if (!string)
        bad_transaction_log("string read error");
    return *string;
}

BinaryData InstructionApplier::get_binary(StringBufferRange range) const
{
    auto string = m_log->try_get_string(range);
    if (!string)
        bad_transaction_log("binary read error");
    return BinaryData{string->data(), string->size()};
}

TableRef InstructionApplier::table_for_class_name(StringData class_name) const
{
    if (class_name.size() >= Group::max_table_name_length - 6)
        bad_transaction_log("class name too long");
    Group::TableNameBuffer buffer;
    return m_transaction.get_table(Group::class_name_to_table_name(class_name, buffer));
}

template <typename T>
struct TemporarySwapOut {
    explicit TemporarySwapOut(T& target)
        : target(target)
        , backup()
    {
        std::swap(target, backup);
    }

    ~TemporarySwapOut()
    {
        std::swap(backup, target);
    }

    T& target;
    T backup;
};

void InstructionApplier::operator()(const Instruction::AddTable& instr)
{
    auto table_name = get_table_name(instr);

    // Temporarily swap out the last object key so it doesn't get included in error messages
    TemporarySwapOut<decltype(m_last_object_key)> last_object_key_guard(m_last_object_key);

    auto add_table = util::overload{
        [&](const Instruction::AddTable::TopLevelTable& spec) {
            auto table_type = (spec.is_asymmetric ? Table::Type::TopLevelAsymmetric : Table::Type::TopLevel);
            if (spec.pk_type == Instruction::Payload::Type::GlobalKey) {
                log("sync::create_table(group, \"%1\", %2);", table_name, table_type);
                m_transaction.get_or_add_table(table_name, table_type);
            }
            else {
                if (!is_valid_key_type(spec.pk_type)) {
                    bad_transaction_log("Invalid primary key type '%1' while adding table '%2'", int8_t(spec.pk_type),
                                        table_name);
                }
                DataType pk_type = get_data_type(spec.pk_type);
                StringData pk_field = get_string(spec.pk_field);
                bool nullable = spec.pk_nullable;

                log("group.get_or_add_table_with_primary_key(group, \"%1\", %2, \"%3\", %4, %5);", table_name,
                    pk_type, pk_field, nullable, table_type);
                if (!m_transaction.get_or_add_table_with_primary_key(table_name, pk_type, pk_field, nullable,
                                                                     table_type)) {
                    bad_transaction_log("AddTable: The existing table '%1' has different properties", table_name);
                }
            }
        },
        [&](const Instruction::AddTable::EmbeddedTable&) {
            if (TableRef table = m_transaction.get_table(table_name)) {
                if (!table->is_embedded()) {
                    bad_transaction_log("AddTable: The existing table '%1' is not embedded", table_name);
                }
            }
            else {
                log("group.add_embedded_table(\"%1\");", table_name);
                m_transaction.add_table(table_name, Table::Type::Embedded);
            }
        },
    };

    mpark::visit(std::move(add_table), instr.type);
}

void InstructionApplier::operator()(const Instruction::EraseTable& instr)
{
    auto table_name = get_table_name(instr);
    // Temporarily swap out the last object key so it doesn't get included in error messages
    TemporarySwapOut<decltype(m_last_object_key)> last_object_key_guard(m_last_object_key);

    if (REALM_UNLIKELY(REALM_COVER_NEVER(!m_transaction.has_table(table_name)))) {
        // FIXME: Should EraseTable be considered idempotent?
        bad_transaction_log("table does not exist");
    }

    log("sync::erase_table(m_group, \"%1\")", table_name);
    m_transaction.remove_table(table_name);
}

void InstructionApplier::operator()(const Instruction::CreateObject& instr)
{
    auto table = get_table(instr);
    ColKey pk_col = table->get_primary_key_column();
    m_last_object_key = instr.object;

    mpark::visit(
        util::overload{
            [&](mpark::monostate) {
                if (!pk_col) {
                    bad_transaction_log("CreateObject(NULL) on table without a primary key");
                }
                if (!table->is_nullable(pk_col)) {
                    bad_transaction_log("CreateObject(NULL) on a table with a non-nullable primary key");
                }
                log("sync::create_object_with_primary_key(group, get_table(\"%1\"), realm::util::none);",
                    table->get_name());
                m_last_object = table->create_object_with_primary_key(util::none);
            },
            [&](int64_t pk) {
                if (!pk_col) {
                    bad_transaction_log("CreateObject(Int) on table without a primary key");
                }
                if (table->get_column_type(pk_col) != type_Int) {
                    bad_transaction_log("CreateObject(Int) on a table with primary key type %1",
                                        table->get_column_type(pk_col));
                }
                log("sync::create_object_with_primary_key(group, get_table(\"%1\"), %2);", table->get_name(), pk);
                m_last_object = table->create_object_with_primary_key(pk);
            },
            [&](InternString pk) {
                if (!pk_col) {
                    bad_transaction_log("CreateObject(String) on table without a primary key");
                }
                if (table->get_column_type(pk_col) != type_String) {
                    bad_transaction_log("CreateObject(String) on a table with primary key type %1",
                                        table->get_column_type(pk_col));
                }
                StringData str = get_string(pk);
                log("sync::create_object_with_primary_key(group, get_table(\"%1\"), \"%2\");", table->get_name(),
                    str);
                m_last_object = table->create_object_with_primary_key(str);
            },
            [&](const ObjectId& id) {
                if (!pk_col) {
                    bad_transaction_log("CreateObject(ObjectId) on table without a primary key");
                }
                if (table->get_column_type(pk_col) != type_ObjectId) {
                    bad_transaction_log("CreateObject(ObjectId) on a table with primary key type %1",
                                        table->get_column_type(pk_col));
                }
                log("sync::create_object_with_primary_key(group, get_table(\"%1\"), %2);", table->get_name(), id);
                m_last_object = table->create_object_with_primary_key(id);
            },
            [&](const UUID& id) {
                if (!pk_col) {
                    bad_transaction_log("CreateObject(UUID) on table without a primary key");
                }
                if (table->get_column_type(pk_col) != type_UUID) {
                    bad_transaction_log("CreateObject(UUID) on a table with primary key type %1",
                                        table->get_column_type(pk_col));
                }
                log("sync::create_object_with_primary_key(group, get_table(\"%1\"), %2);", table->get_name(), id);
                m_last_object = table->create_object_with_primary_key(id);
            },
            [&](GlobalKey key) {
                if (pk_col) {
                    bad_transaction_log("CreateObject(GlobalKey) on table with a primary key");
                }
                log("sync::create_object_with_primary_key(group, get_table(\"%1\"), GlobalKey{%2, %3});",
                    table->get_name(), key.hi(), key.lo());
                m_last_object = table->create_object(key);
            },
        },
        instr.object);
}

void InstructionApplier::operator()(const Instruction::EraseObject& instr)
{
    // FIXME: Log actions.
    // Note: EraseObject is idempotent.
    if (auto obj = get_top_object(instr, "EraseObject")) {
        // This call will prevent incoming links to be nullified/deleted
        obj->invalidate();
    }
    m_last_object.reset();
}

template <class F>
void InstructionApplier::visit_payload(const Instruction::Payload& payload, F&& visitor)
{
    using Type = Instruction::Payload::Type;

    const auto& data = payload.data;
    switch (payload.type) {
        case Type::ObjectValue:
            return visitor(Instruction::Payload::ObjectValue{});
        case Type::Dictionary:
            return bad_transaction_log("Nested dictionaries not supported yet");
        case Type::Erased:
            return visitor(Instruction::Payload::Erased{});
        case Type::GlobalKey:
            return visitor(realm::util::none); // FIXME: Not sure about this
        case Type::Null:
            return visitor(realm::util::none);
        case Type::Int:
            return visitor(data.integer);
        case Type::Bool:
            return visitor(data.boolean);
        case Type::String: {
            StringData value = get_string(data.str);
            return visitor(value);
        }
        case Type::Binary: {
            BinaryData value = get_binary(data.binary);
            return visitor(value);
        }
        case Type::Timestamp:
            return visitor(data.timestamp);
        case Type::Float:
            return visitor(data.fnum);
        case Type::Double:
            return visitor(data.dnum);
        case Type::Decimal:
            return visitor(data.decimal);
        case Type::Link: {
            StringData class_name = get_string(data.link.target_table);
            Group::TableNameBuffer buffer;
            StringData target_table_name = Group::class_name_to_table_name(class_name, buffer);
            TableRef target_table = m_transaction.get_table(target_table_name);
            if (!target_table) {
                bad_transaction_log("Link with invalid target table '%1'", target_table_name);
            }
            if (target_table->is_embedded()) {
                bad_transaction_log("Link to embedded table '%1'", target_table_name);
            }
            ObjKey target = get_object_key(*target_table, data.link.target);
            ObjLink link = ObjLink{target_table->get_key(), target};
            return visitor(link);
        }
        case Type::ObjectId:
            return visitor(data.object_id);
        case Type::UUID:
            return visitor(data.uuid);
    }
}

void InstructionApplier::operator()(const Instruction::Update& instr)
{
    struct UpdateResolver : public PathResolver {
        UpdateResolver(InstructionApplier* applier, const Instruction::Update& instr)
            : PathResolver(applier, instr, "Update")
            , m_instr(instr)
        {
        }
        void on_property(Obj& obj, ColKey col) override
        {
            // Update of object field.

            auto table = obj.get_table();
            auto table_name = table->get_name();
            auto field_name = table->get_column_name(col);
            auto data_type = DataType(col.get_type());

            auto visitor = [&](const mpark::variant<ObjLink, Mixed, Instruction::Payload::ObjectValue,
                                                    Instruction::Payload::Erased>& arg) {
                if (const auto link_ptr = mpark::get_if<ObjLink>(&arg)) {
                    if (data_type == type_Mixed || data_type == type_TypedLink) {
                        obj.set_any(col, *link_ptr, m_instr.is_default);
                    }
                    else if (data_type == type_Link) {
                        // Validate target table.
                        auto target_table = table->get_link_target(col);
                        if (target_table->get_key() != link_ptr->get_table_key()) {
                            m_applier->bad_transaction_log(
                                "Update: Target table mismatch (expected %1, got %2)", target_table->get_name(),
                                m_applier->m_transaction.get_table(link_ptr->get_table_key())->get_name());
                        }
                        obj.set<ObjKey>(col, link_ptr->get_obj_key(), m_instr.is_default);
                    }
                    else {
                        m_applier->bad_transaction_log("Update: Type mismatch in '%2.%1' (expected %3, got %4)",
                                                       field_name, table_name, col.get_type(), type_Link);
                    }
                }
                else if (const auto mixed_ptr = mpark::get_if<Mixed>(&arg)) {
                    if (mixed_ptr->is_null()) {
                        if (col.is_nullable()) {
                            obj.set_null(col, m_instr.is_default);
                        }
                        else {
                            m_applier->bad_transaction_log("Update: NULL in non-nullable field '%2.%1'", field_name,
                                                           table_name);
                        }
                    }
                    else if (data_type == type_Mixed || mixed_ptr->get_type() == data_type) {
                        obj.set_any(col, *mixed_ptr, m_instr.is_default);
                    }
                    else {
                        m_applier->bad_transaction_log("Update: Type mismatch in '%2.%1' (expected %3, got %4)",
                                                       field_name, table_name, col.get_type(), mixed_ptr->get_type());
                    }
                }
                else if (const auto obj_val_ptr = mpark::get_if<Instruction::Payload::ObjectValue>(&arg)) {
                    if (obj.is_null(col)) {
                        obj.create_and_set_linked_object(col);
                    }
                }
                else if (const auto erase_ptr = mpark::get_if<Instruction::Payload::Erased>(&arg)) {
                    m_applier->bad_transaction_log("Update: Dictionary erase at object field");
                }
            };

            m_applier->visit_payload(m_instr.value, visitor);
        }
        Status on_list_index(LstBase& list, uint32_t index) override
        {
            // Update of list element.

            auto col = list.get_col_key();
            auto data_type = DataType(col.get_type());
            auto table = list.get_table();
            auto table_name = table->get_name();
            auto field_name = table->get_column_name(col);

            auto visitor = util::overload{
                [&](const ObjLink& link) {
                    if (data_type == type_TypedLink) {
                        REALM_ASSERT(dynamic_cast<Lst<ObjLink>*>(&list));
                        auto& link_list = static_cast<Lst<ObjLink>&>(list);
                        link_list.set(index, link);
                    }
                    else if (data_type == type_Mixed) {
                        REALM_ASSERT(dynamic_cast<Lst<Mixed>*>(&list));
                        auto& mixed_list = static_cast<Lst<Mixed>&>(list);
                        mixed_list.set(index, link);
                    }
                    else if (data_type == type_LinkList || data_type == type_Link) {
                        REALM_ASSERT(dynamic_cast<Lst<ObjKey>*>(&list));
                        auto& link_list = static_cast<Lst<ObjKey>&>(list);
                        // Validate the target.
                        auto target_table = table->get_link_target(col);
                        if (target_table->get_key() != link.get_table_key()) {
                            m_applier->bad_transaction_log(
                                "Update: Target table mismatch (expected '%1', got '%2')", target_table->get_name(),
                                m_applier->m_transaction.get_table(link.get_table_key())->get_name());
                        }
                        link_list.set(index, link.get_obj_key());
                    }
                    else {
                        m_applier->bad_transaction_log(
                            "Update: Type mismatch in list at '%2.%1' (expected link type, was %3)", field_name,
                            table_name, data_type);
                    }
                },
                [&](Mixed value) {
                    if (value.is_null()) {
                        if (col.is_nullable()) {
                            list.set_null(index);
                        }
                        else {
                            m_applier->bad_transaction_log("Update: NULL in non-nullable list '%2.%1'", field_name,
                                                           table_name);
                        }
                    }
                    else {
                        if (data_type == type_Mixed || value.get_type() == data_type) {
                            list.set_any(index, value);
                        }
                        else {
                            m_applier->bad_transaction_log(
                                "Update: Type mismatch in list at '%2.%1' (expected %3, got %4)", field_name,
                                table_name, data_type, value.get_type());
                        }
                    }
                },
                [&](const Instruction::Payload::ObjectValue&) {
                    // Embedded object creation is idempotent, and link lists cannot
                    // contain nulls, so this is a no-op.
                },
                [&](const Instruction::Payload::Erased&) {
                    m_applier->bad_transaction_log("Update: Dictionary erase of list element");
                },
            };

            m_applier->visit_payload(m_instr.value, visitor);
            return Status::Pending;
        }
        Status on_dictionary_key(Dictionary& dict, Mixed key) override
        {
            // Update (insert) of dictionary element.

            auto visitor = util::overload{
                [&](Mixed value) {
                    if (value.is_null()) {
                        // FIXME: Separate handling of NULL is needed because
                        // `Mixed::get_type()` asserts on NULL.
                        dict.insert(key, value);
                    }
                    else if (value.get_type() == type_Link) {
                        m_applier->bad_transaction_log("Update: Untyped links are not supported in dictionaries.");
                    }
                    else {
                        dict.insert(key, value);
                    }
                },
                [&](const Instruction::Payload::Erased&) {
                    dict.erase(key);
                },
                [&](const Instruction::Payload::ObjectValue&) {
                    dict.create_and_insert_linked_object(key);
                },
            };

            m_applier->visit_payload(m_instr.value, visitor);
            return Status::Pending;
        }

    private:
        const Instruction::Update& m_instr;
    };
    UpdateResolver resolver(this, instr);
    resolver.resolve();
}

void InstructionApplier::operator()(const Instruction::AddInteger& instr)
{
    // FIXME: Implement increments of array elements, dictionary values.
    struct AddIntegerResolver : public PathResolver {
        AddIntegerResolver(InstructionApplier* applier, const Instruction::AddInteger& instr)
            : PathResolver(applier, instr, "AddInteger")
            , m_instr(instr)
        {
        }
        void on_property(Obj& obj, ColKey col)
        {
            // Increment of object field.
            if (!obj.is_null(col)) {
                try {
                    obj.add_int(col, m_instr.value);
                }
                catch (const LogicError&) {
                    auto table = obj.get_table();
                    m_applier->bad_transaction_log("AddInteger: Not an integer field '%2.%1'",
                                                   table->get_column_name(col), table->get_name());
                }
            }
        }

    private:
        const Instruction::AddInteger& m_instr;
    };
    AddIntegerResolver resolver(this, instr);
    resolver.resolve();
}

void InstructionApplier::operator()(const Instruction::AddColumn& instr)
{
    using Type = Instruction::Payload::Type;
    using CollectionType = Instruction::AddColumn::CollectionType;

    // Temporarily swap out the last object key so it doesn't get included in error messages
    TemporarySwapOut<decltype(m_last_object_key)> last_object_key_guard(m_last_object_key);

    auto table = get_table(instr, "AddColumn");
    auto col_name = get_string(instr.field);

    if (ColKey existing_key = table->get_column_key(col_name)) {
        DataType new_type = get_data_type(instr.type);
        ColumnType existing_type = existing_key.get_type();
        if (existing_type == col_type_LinkList) {
            existing_type = col_type_Link;
        }
        if (existing_type != ColumnType(new_type)) {
            bad_transaction_log("AddColumn: Schema mismatch for existing column in '%1.%2' (expected %3, got %4)",
                                table->get_name(), col_name, existing_type, new_type);
        }
        bool existing_is_list = existing_key.is_list();
        if ((instr.collection_type == CollectionType::List) != existing_is_list) {
            bad_transaction_log(
                "AddColumn: Schema mismatch for existing column in '%1.%2' (existing is%3 a list, the other is%4)",
                table->get_name(), col_name, existing_is_list ? "" : " not", existing_is_list ? " not" : "");
        }
        bool existing_is_set = existing_key.is_set();
        if ((instr.collection_type == CollectionType::Set) != existing_is_set) {
            bad_transaction_log(
                "AddColumn: Schema mismatch for existing column in '%1.%2' (existing is%3 a set, the other is%4)",
                table->get_name(), col_name, existing_is_set ? "" : " not", existing_is_set ? " not" : "");
        }
        bool existing_is_dict = existing_key.is_dictionary();
        if ((instr.collection_type == CollectionType::Dictionary) != existing_is_dict) {
            bad_transaction_log("AddColumn: Schema mismatch for existing column in '%1.%2' (existing is%3 a "
                                "dictionary, the other is%4)",
                                table->get_name(), col_name, existing_is_dict ? "" : " not",
                                existing_is_dict ? " not" : "");
        }
        if (new_type == type_Link) {
            Group::TableNameBuffer buffer;
            auto target_table_name = Group::class_name_to_table_name(get_string(instr.link_target_table), buffer);
            if (target_table_name != table->get_link_target(existing_key)->get_name()) {
                bad_transaction_log("AddColumn: Schema mismatch for existing column in '%1.%2' (link targets differ)",
                                    table->get_name(), col_name);
            }
        }
        return;
    }

    if (instr.collection_type == CollectionType::Dictionary && instr.key_type != Type::String) {
        bad_transaction_log("AddColumn '%1.%3' adding dictionary column with non-string keys", table->get_name(),
                            col_name);
    }

    if (instr.type != Type::Link) {
        DataType type = get_data_type(instr.type);
        switch (instr.collection_type) {
            case CollectionType::Single: {
                table->add_column(type, col_name, instr.nullable);
                break;
            }
            case CollectionType::List: {
                table->add_column_list(type, col_name, instr.nullable);
                break;
            }
            case CollectionType::Dictionary: {
                DataType key_type = get_data_type(instr.key_type);
                table->add_column_dictionary(type, col_name, instr.nullable, key_type);
                break;
            }
            case CollectionType::Set: {
                table->add_column_set(type, col_name, instr.nullable);
                break;
            }
        }
    }
    else {
        Group::TableNameBuffer buffer;
        auto target_table_name = get_string(instr.link_target_table);
        if (target_table_name.size() != 0) {
            TableRef target = m_transaction.get_table(Group::class_name_to_table_name(target_table_name, buffer));
            if (!target) {
                bad_transaction_log("AddColumn(Link) '%1.%2' to table '%3' which doesn't exist", table->get_name(),
                                    col_name, target_table_name);
            }
            if (instr.collection_type == CollectionType::List) {
                table->add_column_list(*target, col_name);
            }
            else if (instr.collection_type == CollectionType::Set) {
                table->add_column_set(*target, col_name);
            }
            else if (instr.collection_type == CollectionType::Dictionary) {
                table->add_column_dictionary(*target, col_name);
            }
            else {
                REALM_ASSERT(instr.collection_type == CollectionType::Single);
                table->add_column(*target, col_name);
            }
        }
        else {
            if (instr.collection_type == CollectionType::List) {
                table->add_column_list(type_TypedLink, col_name);
            }
            else {
                REALM_ASSERT(instr.collection_type == CollectionType::Single);
                table->add_column(type_TypedLink, col_name);
            }
        }
    }
}

void InstructionApplier::operator()(const Instruction::EraseColumn& instr)
{
    // Temporarily swap out the last object key so it doesn't get included in error messages
    TemporarySwapOut<decltype(m_last_object_key)> last_object_key_guard(m_last_object_key);

    auto table = get_table(instr, "EraseColumn");
    auto col_name = get_string(instr.field);

    ColKey col = table->get_column_key(col_name);
    if (!col) {
        bad_transaction_log("EraseColumn '%1.%2' which doesn't exist", table->get_name(), col_name);
    }

    table->remove_column(col);
}

void InstructionApplier::operator()(const Instruction::ArrayInsert& instr)
{
    struct ArrayInsertResolver : public PathResolver {
        ArrayInsertResolver(InstructionApplier* applier, const Instruction::ArrayInsert& instr)
            : PathResolver(applier, instr, "ArrayInsert")
            , m_instr(instr)
        {
        }
        Status on_list_index(LstBase& list, uint32_t index) override
        {
            auto col = list.get_col_key();
            auto data_type = DataType(col.get_type());
            auto table = list.get_table();
            auto table_name = table->get_name();
            auto field_name = table->get_column_name(col);

            if (index > m_instr.prior_size) {
                m_applier->bad_transaction_log("ArrayInsert: Invalid insertion index (index = %1, prior_size = %2)",
                                               index, m_instr.prior_size);
            }

            if (index > list.size()) {
                m_applier->bad_transaction_log("ArrayInsert: Index out of bounds (%1 > %2)", index, list.size());
            }

            if (m_instr.prior_size != list.size()) {
                m_applier->bad_transaction_log("ArrayInsert: Invalid prior_size (list size = %1, prior_size = %2)",
                                               list.size(), m_instr.prior_size);
            }

            auto inserter = util::overload{
                [&](const ObjLink& link) {
                    if (data_type == type_TypedLink) {
                        REALM_ASSERT(dynamic_cast<Lst<ObjLink>*>(&list));
                        auto& link_list = static_cast<Lst<ObjLink>&>(list);
                        link_list.insert(index, link);
                    }
                    else if (data_type == type_Mixed) {
                        REALM_ASSERT(dynamic_cast<Lst<Mixed>*>(&list));
                        auto& mixed_list = static_cast<Lst<Mixed>&>(list);
                        mixed_list.insert(index, link);
                    }
                    else if (data_type == type_LinkList || data_type == type_Link) {
                        REALM_ASSERT(dynamic_cast<Lst<ObjKey>*>(&list));
                        auto& link_list = static_cast<Lst<ObjKey>&>(list);
                        // Validate the target.
                        auto target_table = table->get_link_target(col);
                        if (target_table->get_key() != link.get_table_key()) {
                            m_applier->bad_transaction_log(
                                "ArrayInsert: Target table mismatch (expected '%1', got '%2')",
                                target_table->get_name(),
                                m_applier->m_transaction.get_table(link.get_table_key())->get_name());
                        }
                        link_list.insert(index, link.get_obj_key());
                    }
                    else {
                        m_applier->bad_transaction_log(
                            "ArrayInsert: Type mismatch in list at '%2.%1' (expected link type, was %3)", field_name,
                            table_name, data_type);
                    }
                },
                [&](Mixed value) {
                    if (value.is_null()) {
                        if (col.is_nullable()) {
                            list.insert_null(index);
                        }
                        else {
                            m_applier->bad_transaction_log("ArrayInsert: NULL in non-nullable list '%2.%1'",
                                                           field_name, table_name);
                        }
                    }
                    else {
                        if (data_type == type_Mixed || value.get_type() == data_type) {
                            list.insert_any(index, value);
                        }
                        else {
                            m_applier->bad_transaction_log(
                                "ArrayInsert: Type mismatch in list at '%2.%1' (expected %3, got %4)", field_name,
                                table_name, data_type, value.get_type());
                        }
                    }
                },
                [&](const Instruction::Payload::ObjectValue&) {
                    if (col.get_type() == col_type_LinkList || col.get_type() == col_type_Link) {
                        auto target_table = list.get_table()->get_link_target(col);
                        if (!target_table->is_embedded()) {
                            m_applier->bad_transaction_log(
                                "ArrayInsert: Creation of embedded object of type '%1', which is not "
                                "an embedded table",
                                target_table->get_name());
                        }

                        REALM_ASSERT(dynamic_cast<LnkLst*>(&list));
                        auto& link_list = static_cast<LnkLst&>(list);
                        link_list.create_and_insert_linked_object(index);
                    }
                    else {
                        m_applier->bad_transaction_log(
                            "ArrayInsert: Creation of embedded object in non-link list field '%2.%1'", field_name,
                            table_name);
                    }
                },
                [&](const Instruction::Payload::Dictionary&) {
                    m_applier->bad_transaction_log("Dictionary payload for ArrayInsert");
                },
                [&](const Instruction::Payload::Erased&) {
                    m_applier->bad_transaction_log("Dictionary erase payload for ArrayInsert");
                },
            };

            m_applier->visit_payload(m_instr.value, inserter);
            return Status::Pending;
        }

    private:
        const Instruction::ArrayInsert& m_instr;
    };
    ArrayInsertResolver(this, instr).resolve();
}

void InstructionApplier::operator()(const Instruction::ArrayMove& instr)
{
    struct ArrayMoveResolver : public PathResolver {
        ArrayMoveResolver(InstructionApplier* applier, const Instruction::ArrayMove& instr)
            : PathResolver(applier, instr, "ArrayMove")
            , m_instr(instr)
        {
        }
        Status on_list_index(LstBase& list, uint32_t index) override
        {
            if (index >= list.size()) {
                m_applier->bad_transaction_log("ArrayMove from out of bounds (%1 >= %2)", m_instr.index(),
                                               list.size());
            }
            if (m_instr.ndx_2 >= list.size()) {
                m_applier->bad_transaction_log("ArrayMove to out of bounds (%1 >= %2)", m_instr.ndx_2, list.size());
            }
            if (index == m_instr.ndx_2) {
                // FIXME: Does this really need to be an error?
                m_applier->bad_transaction_log("ArrayMove to same location (%1)", m_instr.index());
            }
            if (m_instr.prior_size != list.size()) {
                m_applier->bad_transaction_log("ArrayMove: Invalid prior_size (list size = %1, prior_size = %2)",
                                               list.size(), m_instr.prior_size);
            }
            list.move(index, m_instr.ndx_2);
            return Status::Pending;
        }

    private:
        const Instruction::ArrayMove& m_instr;
    };
    ArrayMoveResolver(this, instr).resolve();
}

void InstructionApplier::operator()(const Instruction::ArrayErase& instr)
{
    struct ArrayEraseResolver : public PathResolver {
        ArrayEraseResolver(InstructionApplier* applier, const Instruction::ArrayErase& instr)
            : PathResolver(applier, instr, "ArrayErase")
            , m_instr(instr)
        {
        }
        Status on_list_index(LstBase& list, uint32_t index) override
        {
            if (index >= m_instr.prior_size) {
                m_applier->bad_transaction_log("ArrayErase: Invalid index (index = %1, prior_size = %2)", index,
                                               m_instr.prior_size);
            }
            if (index >= list.size()) {
                m_applier->bad_transaction_log("ArrayErase: Index out of bounds (%1 >= %2)", index, list.size());
            }
            if (m_instr.prior_size != list.size()) {
                m_applier->bad_transaction_log("ArrayErase: Invalid prior_size (list size = %1, prior_size = %2)",
                                               list.size(), m_instr.prior_size);
            }
            list.remove(index, index + 1);
            return Status::Pending;
        }

    private:
        const Instruction::ArrayErase& m_instr;
    };
    ArrayEraseResolver(this, instr).resolve();
}

void InstructionApplier::operator()(const Instruction::Clear& instr)
{
    struct ClearResolver : public PathResolver {
        ClearResolver(InstructionApplier* applier, const Instruction::Clear& instr)
            : PathResolver(applier, instr, "Clear")
        {
        }
        void on_list(LstBase& list) override
        {
            list.clear();
        }
        void on_dictionary(Dictionary& dict) override
        {
            dict.clear();
        }
        void on_set(SetBase& set) override
        {
            set.clear();
        }
    };
    ClearResolver(this, instr).resolve();
}

bool InstructionApplier::allows_null_links(const Instruction::PathInstruction& instr,
                                           const std::string_view& instr_name)
{
    struct AllowsNullsResolver : public PathResolver {
        AllowsNullsResolver(InstructionApplier* applier, const Instruction::PathInstruction& instr,
                            const std::string_view& instr_name)
            : PathResolver(applier, instr, instr_name)
            , m_allows_nulls(false)
        {
        }
        Status on_list_index(LstBase&, uint32_t) override
        {
            return Status::Pending;
        }
        void on_list(LstBase&) override {}
        void on_set(SetBase&) override {}
        void on_dictionary(Dictionary&) override
        {
            m_allows_nulls = true;
        }
        Status on_dictionary_key(Dictionary&, Mixed) override
        {
            m_allows_nulls = true;
            return Status::Pending;
        }
        void on_property(Obj&, ColKey) override
        {
            m_allows_nulls = true;
        }
        bool allows_nulls()
        {
            resolve();
            return m_allows_nulls;
        }

    private:
        bool m_allows_nulls;
    };
    return AllowsNullsResolver(this, instr, instr_name).allows_nulls();
}

std::string InstructionApplier::to_string(const Instruction::PathInstruction& instr) const
{
    REALM_ASSERT(m_log);
    std::stringstream ss;
    m_log->print_path(ss, instr.table, instr.object, instr.field, &instr.path);
    return ss.str();
}

bool InstructionApplier::check_links_exist(const Instruction::Payload& payload)
{
    bool valid_payload = true;
    using Type = Instruction::Payload::Type;
    if (payload.type == Type::Link) {
        StringData class_name = get_string(payload.data.link.target_table);
        Group::TableNameBuffer buffer;
        StringData target_table_name = Group::class_name_to_table_name(class_name, buffer);
        TableRef target_table = m_transaction.get_table(target_table_name);
        if (!target_table) {
            bad_transaction_log("Link with invalid target table '%1'", target_table_name);
        }
        if (target_table->is_embedded()) {
            bad_transaction_log("Link to embedded table '%1'", target_table_name);
        }
        Mixed linked_pk =
            mpark::visit(util::overload{[&](mpark::monostate) {
                                            return Mixed{}; // the link exists and the pk is null
                                        },
                                        [&](int64_t pk) {
                                            return Mixed{pk};
                                        },
                                        [&](InternString interned_pk) {
                                            return Mixed{get_string(interned_pk)};
                                        },
                                        [&](GlobalKey) {
                                            bad_transaction_log(
                                                "Unexpected link to embedded object while validating a primary key");
                                            return Mixed{}; // appease the compiler; visitors must have a single
                                                            // return type
                                        },
                                        [&](ObjectId pk) {
                                            return Mixed{pk};
                                        },
                                        [&](UUID pk) {
                                            return Mixed{pk};
                                        }},
                         payload.data.link.target);

        if (!target_table->find_primary_key(linked_pk)) {
            valid_payload = false;
        }
    }
    return valid_payload;
}

void InstructionApplier::operator()(const Instruction::SetInsert& instr)
{
    struct SetInsertResolver : public PathResolver {
        SetInsertResolver(InstructionApplier* applier, const Instruction::SetInsert& instr)
            : PathResolver(applier, instr, "SetInsert")
            , m_instr(instr)
        {
        }
        void on_set(SetBase& set) override
        {
            auto col = set.get_col_key();
            auto data_type = DataType(col.get_type());
            auto table = set.get_table();
            auto table_name = table->get_name();
            auto field_name = table->get_column_name(col);

            auto inserter = util::overload{
                [&](const ObjLink& link) {
                    if (data_type == type_TypedLink) {
                        REALM_ASSERT(dynamic_cast<Set<ObjLink>*>(&set));
                        auto& link_set = static_cast<Set<ObjLink>&>(set);
                        link_set.insert(link);
                    }
                    else if (data_type == type_Mixed) {
                        REALM_ASSERT(dynamic_cast<Set<Mixed>*>(&set));
                        auto& mixed_set = static_cast<Set<Mixed>&>(set);
                        mixed_set.insert(link);
                    }
                    else if (data_type == type_Link) {
                        REALM_ASSERT(dynamic_cast<Set<ObjKey>*>(&set));
                        auto& link_set = static_cast<Set<ObjKey>&>(set);
                        // Validate the target.
                        auto target_table = table->get_link_target(col);
                        if (target_table->get_key() != link.get_table_key()) {
                            m_applier->bad_transaction_log(
                                "SetInsert: Target table mismatch (expected '%1', got '%2')",
                                target_table->get_name(), table_name);
                        }
                        link_set.insert(link.get_obj_key());
                    }
                    else {
                        m_applier->bad_transaction_log(
                            "SetInsert: Type mismatch in set at '%2.%1' (expected link type, was %3)", field_name,
                            table_name, data_type);
                    }
                },
                [&](Mixed value) {
                    if (value.is_null() && !col.is_nullable()) {
                        m_applier->bad_transaction_log("SetInsert: NULL in non-nullable set '%2.%1'", field_name,
                                                       table_name);
                    }

                    if (data_type == type_Mixed || value.is_null() || value.get_type() == data_type) {
                        set.insert_any(value);
                    }
                    else {
                        m_applier->bad_transaction_log(
                            "SetInsert: Type mismatch in set at '%2.%1' (expected %3, got %4)", field_name,
                            table_name, data_type, value.get_type());
                    }
                },
                [&](const Instruction::Payload::ObjectValue&) {
                    m_applier->bad_transaction_log("SetInsert: Sets of embedded objects are not supported.");
                },
                [&](const Instruction::Payload::Dictionary&) {
                    m_applier->bad_transaction_log("SetInsert: Sets of dictionaries are not supported.");
                },
                [&](const Instruction::Payload::Erased&) {
                    m_applier->bad_transaction_log("SetInsert: Dictionary erase payload in SetInsert");
                },
            };

            m_applier->visit_payload(m_instr.value, inserter);
        }

    private:
        const Instruction::SetInsert& m_instr;
    };
    SetInsertResolver(this, instr).resolve();
}

void InstructionApplier::operator()(const Instruction::SetErase& instr)
{
    struct SetEraseResolver : public PathResolver {
        SetEraseResolver(InstructionApplier* applier, const Instruction::SetErase& instr)
            : PathResolver(applier, instr, "SetErase")
            , m_instr(instr)
        {
        }
        void on_set(SetBase& set) override
        {
            auto col = set.get_col_key();
            auto data_type = DataType(col.get_type());
            auto table = set.get_table();
            auto table_name = table->get_name();
            auto field_name = table->get_column_name(col);

            auto inserter = util::overload{
                [&](const ObjLink& link) {
                    if (data_type == type_TypedLink) {
                        REALM_ASSERT(dynamic_cast<Set<ObjLink>*>(&set));
                        auto& link_set = static_cast<Set<ObjLink>&>(set);
                        link_set.erase(link);
                    }
                    else if (data_type == type_Mixed) {
                        REALM_ASSERT(dynamic_cast<Set<Mixed>*>(&set));
                        auto& mixed_set = static_cast<Set<Mixed>&>(set);
                        mixed_set.erase(link);
                    }
                    else if (data_type == type_Link) {
                        REALM_ASSERT(dynamic_cast<Set<ObjKey>*>(&set));
                        auto& link_set = static_cast<Set<ObjKey>&>(set);
                        // Validate the target.
                        auto target_table = table->get_link_target(col);
                        if (target_table->get_key() != link.get_table_key()) {
                            m_applier->bad_transaction_log(
                                "SetErase: Target table mismatch (expected '%1', got '%2')", target_table->get_name(),
                                table_name);
                        }
                        link_set.erase(link.get_obj_key());
                    }
                    else {
                        m_applier->bad_transaction_log(
                            "SetErase: Type mismatch in set at '%2.%1' (expected link type, was %3)", field_name,
                            table_name, data_type);
                    }
                },
                [&](Mixed value) {
                    if (value.is_null() && !col.is_nullable()) {
                        m_applier->bad_transaction_log("SetErase: NULL in non-nullable set '%2.%1'", field_name,
                                                       table_name);
                    }

                    if (data_type == type_Mixed || value.get_type() == data_type) {
                        set.erase_any(value);
                    }
                    else {
                        m_applier->bad_transaction_log(
                            "SetErase: Type mismatch in set at '%2.%1' (expected %3, got %4)", field_name, table_name,
                            data_type, value.get_type());
                    }
                },
                [&](const Instruction::Payload::ObjectValue&) {
                    m_applier->bad_transaction_log("SetErase: Sets of embedded objects are not supported.");
                },
                [&](const Instruction::Payload::Dictionary&) {
                    m_applier->bad_transaction_log("SetErase: Sets of dictionaries are not supported.");
                },
                [&](const Instruction::Payload::Erased&) {
                    m_applier->bad_transaction_log("SetErase: Dictionary erase payload in SetErase");
                },
            };

            m_applier->visit_payload(m_instr.value, inserter);
        }

    private:
        const Instruction::SetErase& m_instr;
    };
    SetEraseResolver(this, instr).resolve();
}

StringData InstructionApplier::get_table_name(const Instruction::TableInstruction& instr,
                                              const std::string_view& name)
{
    if (auto class_name = m_log->try_get_string(instr.table)) {
        return Group::class_name_to_table_name(*class_name, m_table_name_buffer);
    }
    else {
        bad_transaction_log("Corrupt table name in %1 instruction", name);
    }
}

TableRef InstructionApplier::get_table(const Instruction::TableInstruction& instr, const std::string_view& name)
{
    if (instr.table == m_last_table_name) {
        return m_last_table;
    }
    else {
        auto table_name = get_table_name(instr, name);
        TableRef table = m_transaction.get_table(table_name);
        if (!table) {
            bad_transaction_log("%1: Table '%2' does not exist", name, table_name);
        }
        m_last_table = table;
        m_last_table_name = instr.table;
        m_last_object_key.reset();
        m_last_object.reset();
        m_last_field_name = InternString{};
        m_last_field = ColKey{};
        return table;
    }
}

util::Optional<Obj> InstructionApplier::get_top_object(const Instruction::ObjectInstruction& instr,
                                                       const std::string_view& name)
{
    if (m_last_table_name == instr.table && m_last_object_key && m_last_object &&
        *m_last_object_key == instr.object) {
        // We have already found the object, reuse it.
        return *m_last_object;
    }
    else {
        TableRef table = get_table(instr, name);
        ObjKey key = get_object_key(*table, instr.object, name);
        if (!key) {
            return util::none;
        }
        if (!table->is_valid(key)) {
            // Check if the object is deleted or is a tombstone.
            return util::none;
        }

        Obj obj = table->get_object(key);
        m_last_object_key = instr.object;
        m_last_object = obj;
        return obj;
    }
}

std::unique_ptr<LstBase> InstructionApplier::get_list_from_path(Obj& obj, ColKey col)
{
    // For link columns, `Obj::get_listbase_ptr()` always returns an instance whose concrete type is
    // `LnkLst`, which uses condensed indexes. However, we are interested in using non-condensed
    // indexes, so we need to manually construct a `Lst<ObjKey>` instead for lists of non-embedded
    // links.
    REALM_ASSERT(col.is_list());
    std::unique_ptr<LstBase> list;
    if (col.get_type() == col_type_Link || col.get_type() == col_type_LinkList) {
        auto table = obj.get_table();
        if (!table->get_link_target(col)->is_embedded()) {
            list = obj.get_list_ptr<ObjKey>(col);
        }
        else {
            list = obj.get_listbase_ptr(col);
        }
    }
    else {
        list = obj.get_listbase_ptr(col);
    }
    return list;
}

InstructionApplier::PathResolver::PathResolver(InstructionApplier* applier, const Instruction::PathInstruction& instr,
                                               const std::string_view& instr_name)
    : m_applier(applier)
    , m_path_instr(instr)
    , m_instr_name(instr_name)
{
}

InstructionApplier::PathResolver::~PathResolver()
{
    on_finish();
}

void InstructionApplier::PathResolver::on_property(Obj&, ColKey)
{
    m_applier->bad_transaction_log(util::format("Invalid path for %1 (object, column)", m_instr_name));
}

void InstructionApplier::PathResolver::on_list(LstBase&)
{
    m_applier->bad_transaction_log(util::format("Invalid path for %1 (list)", m_instr_name));
}

InstructionApplier::PathResolver::Status InstructionApplier::PathResolver::on_list_index(LstBase&, uint32_t)
{
    m_applier->bad_transaction_log(util::format("Invalid path for %1 (list, index)", m_instr_name));
    return Status::DidNotResolve;
}

void InstructionApplier::PathResolver::on_dictionary(Dictionary&)
{
    m_applier->bad_transaction_log(util::format("Invalid path for %1 (dictionary, key)", m_instr_name));
}

InstructionApplier::PathResolver::Status InstructionApplier::PathResolver::on_dictionary_key(Dictionary&, Mixed)
{
    m_applier->bad_transaction_log(util::format("Invalid path for %1 (dictionary, key)", m_instr_name));
    return Status::DidNotResolve;
}

void InstructionApplier::PathResolver::on_set(SetBase&)
{
    m_applier->bad_transaction_log(util::format("Invalid path for %1 (set)", m_instr_name));
}

void InstructionApplier::PathResolver::on_error(const std::string& err_msg)
{
    m_applier->bad_transaction_log(err_msg);
}

void InstructionApplier::PathResolver::on_column_advance(ColKey col)
{
    m_applier->m_last_field = col;
}

void InstructionApplier::PathResolver::on_dict_key_advance(StringData) {}

InstructionApplier::PathResolver::Status InstructionApplier::PathResolver::on_list_index_advance(uint32_t)
{
    return Status::Pending;
}

InstructionApplier::PathResolver::Status InstructionApplier::PathResolver::on_null_link_advance(StringData,
                                                                                                StringData)
{
    return Status::Pending;
}

InstructionApplier::PathResolver::Status InstructionApplier::PathResolver::on_begin(const util::Optional<Obj>&)
{
    m_applier->m_current_path = m_path_instr.path;
    m_applier->m_last_field_name = m_path_instr.field;
    return Status::Pending;
}

void InstructionApplier::PathResolver::on_finish()
{
    m_applier->m_current_path.reset();
    m_applier->m_last_field_name = InternString{};
    m_applier->m_last_field = ColKey{};
}

StringData InstructionApplier::PathResolver::get_string(InternString interned)
{
    return m_applier->get_string(interned);
}

InstructionApplier::PathResolver::Status InstructionApplier::PathResolver::resolve()
{
    util::Optional<Obj> obj = m_applier->get_top_object(m_path_instr, m_instr_name);
    Status begin_status = on_begin(obj);
    if (begin_status != Status::Pending) {
        return begin_status;
    }
    if (!obj) {
        m_applier->bad_transaction_log("%1: No such object: '%2' in class '%3'", m_instr_name,
                                       format_pk(m_applier->m_log->get_key(m_path_instr.object)),
                                       get_string(m_path_instr.table));
    }

    m_it_begin = m_path_instr.path.begin();
    m_it_end = m_path_instr.path.end();
    Status status = resolve_field(*obj, m_path_instr.field);
    return status == Status::Pending ? Status::Success : status;
}

InstructionApplier::PathResolver::Status InstructionApplier::PathResolver::resolve_field(Obj& obj, InternString field)
{
    auto field_name = get_string(field);
    ColKey col = obj.get_table()->get_column_key(field_name);
    if (!col) {
        on_error(util::format("%1: No such field: '%2' in class '%3'", m_instr_name, field_name,
                              obj.get_table()->get_name()));
        return Status::DidNotResolve;
    }
    on_column_advance(col);

    if (m_it_begin == m_it_end) {
        if (col.is_list()) {
            auto list = obj.get_listbase_ptr(col);
            on_list(*list);
        }
        else if (col.is_dictionary()) {
            auto dict = obj.get_dictionary(col);
            on_dictionary(dict);
        }
        else if (col.is_set()) {
            SetBasePtr set;
            if (col.get_type() == col_type_Link) {
                // We are interested in using non-condensed indexes - as for Lists below
                set = obj.get_set_ptr<ObjKey>(col);
            }
            else {
                set = obj.get_setbase_ptr(col);
            }
            on_set(*set);
        }
        else {
            on_property(obj, col);
        }
        return Status::Pending;
    }

    if (col.is_list()) {
        if (auto pindex = mpark::get_if<uint32_t>(&*m_it_begin)) {
            std::unique_ptr<LstBase> list = InstructionApplier::get_list_from_path(obj, col);
            ++m_it_begin;
            return resolve_list_element(*list, *pindex);
        }
        on_error(util::format("%1: List index is not an integer on field '%2' in class '%3'", m_instr_name,
                              field_name, obj.get_table()->get_name()));
    }
    else if (col.is_dictionary()) {
        if (auto pkey = mpark::get_if<InternString>(&*m_it_begin)) {
            auto dict = obj.get_dictionary(col);
            ++m_it_begin;
            return resolve_dictionary_element(dict, *pkey);
        }
        on_error(util::format("%1: Dictionary key is not a string on field '%2' in class '%3'", m_instr_name,
                              field_name, obj.get_table()->get_name()));
    }
    else if (col.get_type() == col_type_Link) {
        auto target = obj.get_table()->get_link_target(col);
        if (!target->is_embedded()) {
            on_error(util::format("%1: Reference through non-embedded link in field '%2' in class '%3'", m_instr_name,
                                  field_name, obj.get_table()->get_name()));
        }
        else if (obj.is_null(col)) {
            Status null_status =
                on_null_link_advance(obj.get_table()->get_name(), obj.get_table()->get_column_name(col));
            if (null_status != Status::Pending) {
                return null_status;
            }
            on_error(util::format("%1: Reference through NULL embedded link in field '%2' in class '%3'",
                                  m_instr_name, field_name, obj.get_table()->get_name()));
        }
        else if (auto pfield = mpark::get_if<InternString>(&*m_it_begin)) {
            auto embedded_object = obj.get_linked_object(col);
            ++m_it_begin;
            return resolve_field(embedded_object, *pfield);
        }
        else {
            on_error(util::format("%1: Embedded object field reference is not a string", m_instr_name));
        }
    }
    else {
        on_error(util::format("%1: Resolving path through unstructured field '%3.%2' of type %4", m_instr_name,
                              field_name, obj.get_table()->get_name(), col.get_type()));
    }
    return Status::DidNotResolve;
}

InstructionApplier::PathResolver::Status InstructionApplier::PathResolver::resolve_list_element(LstBase& list,
                                                                                                uint32_t index)
{
    if (m_it_begin == m_it_end) {
        return on_list_index(list, index);
    }

    auto col = list.get_col_key();
    auto field_name = list.get_table()->get_column_name(col);

    if (col.get_type() == col_type_LinkList) {
        auto target = list.get_table()->get_link_target(col);
        if (!target->is_embedded()) {
            on_error(util::format("%1: Reference through non-embedded link at '%3.%2[%4]'", m_instr_name, field_name,
                                  list.get_table()->get_name(), index));
            return Status::DidNotResolve;
        }

        Status list_status = on_list_index_advance(index);
        if (list_status != Status::Pending) {
            return list_status;
        }

        REALM_ASSERT(dynamic_cast<LnkLst*>(&list));
        auto& link_list = static_cast<LnkLst&>(list);
        if (index >= link_list.size()) {
            on_error(util::format("%1: Out-of-bounds index through list at '%3.%2[%4]'", m_instr_name, field_name,
                                  list.get_table()->get_name(), index));
        }
        else if (auto pfield = mpark::get_if<InternString>(&*m_it_begin)) {
            auto embedded_object = link_list.get_object(index);
            ++m_it_begin;
            return resolve_field(embedded_object, *pfield);
        }
        on_error(util::format("%1: Embedded object field reference is not a string", m_instr_name));
    }
    else {
        on_error(util::format(
            "%1: Resolving path through unstructured list element on '%3.%2', which is a list of type '%4'",
            m_instr_name, field_name, list.get_table()->get_name(), col.get_type()));
    }
    return Status::DidNotResolve;
}

InstructionApplier::PathResolver::Status
InstructionApplier::PathResolver::resolve_dictionary_element(Dictionary& dict, InternString key)
{
    StringData string_key = get_string(key);
    if (m_it_begin == m_it_end) {
        return on_dictionary_key(dict, Mixed{string_key});
    }

    on_dict_key_advance(string_key);

    auto col = dict.get_col_key();
    auto table = dict.get_table();
    auto field_name = table->get_column_name(col);

    if (col.get_type() == col_type_Link) {
        auto target = dict.get_target_table();
        if (!target->is_embedded()) {
            on_error(util::format("%1: Reference through non-embedded link at '%3.%2[%4]'", m_instr_name, field_name,
                                  table->get_name(), string_key));
            return Status::DidNotResolve;
        }

        auto embedded_object = dict.get_object(string_key);
        if (!embedded_object) {
            Status null_link_status = on_null_link_advance(table->get_name(), string_key);
            if (null_link_status != Status::Pending) {
                return null_link_status;
            }
            on_error(util::format("%1: Unmatched key through dictionary at '%3.%2[%4]'", m_instr_name, field_name,
                                  table->get_name(), string_key));
        }
        else if (auto pfield = mpark::get_if<InternString>(&*m_it_begin)) {
            ++m_it_begin;
            return resolve_field(embedded_object, *pfield);
        }
        else {
            on_error(util::format("%1: Embedded object field reference is not a string", m_instr_name));
        }
    }
    else {
        on_error(
            util::format("%1: Resolving path through non link element on '%3.%2', which is a dictionary of type '%4'",
                         m_instr_name, field_name, table->get_name(), col.get_type()));
    }
    return Status::DidNotResolve;
}


ObjKey InstructionApplier::get_object_key(Table& table, const Instruction::PrimaryKey& primary_key,
                                          const std::string_view& name) const
{
    StringData table_name = table.get_name();
    ColKey pk_col = table.get_primary_key_column();
    StringData pk_name = "";
    DataType pk_type;
    if (pk_col) {
        pk_name = table.get_column_name(pk_col);
        pk_type = table.get_column_type(pk_col);
    }
    return mpark::visit(
        util::overload{
            [&](mpark::monostate) {
                if (!pk_col) {
                    bad_transaction_log(
                        "%1 instruction with NULL primary key, but table '%2' does not have a primary key column",
                        name, table_name);
                }
                if (!table.is_nullable(pk_col)) {
                    bad_transaction_log("%1 instruction with NULL primary key, but column '%2.%3' is not nullable",
                                        name, table_name, pk_name);
                }

                ObjKey key = table.get_objkey_from_primary_key(realm::util::none);
                return key;
            },
            [&](int64_t pk) {
                if (!pk_col) {
                    bad_transaction_log("%1 instruction with integer primary key (%2), but table '%3' does not have "
                                        "a primary key column",
                                        name, pk, table_name);
                }
                if (pk_type != type_Int) {
                    bad_transaction_log(
                        "%1 instruction with integer primary key (%2), but '%3.%4' has primary keys of type '%5'",
                        name, pk, table_name, pk_name, pk_type);
                }
                ObjKey key = table.get_objkey_from_primary_key(pk);
                return key;
            },
            [&](InternString interned_pk) {
                auto pk = get_string(interned_pk);
                if (!pk_col) {
                    bad_transaction_log("%1 instruction with string primary key (\"%2\"), but table '%3' does not "
                                        "have a primary key column",
                                        name, pk, table_name);
                }
                if (pk_type != type_String) {
                    bad_transaction_log(
                        "%1 instruction with string primary key (\"%2\"), but '%3.%4' has primary keys of type '%5'",
                        name, pk, table_name, pk_name, pk_type);
                }
                ObjKey key = table.get_objkey_from_primary_key(pk);
                return key;
            },
            [&](GlobalKey id) {
                if (pk_col) {
                    bad_transaction_log(
                        "%1 instruction without primary key, but table '%2' has a primary key column of type %3",
                        name, table_name, pk_type);
                }
                ObjKey key = table.get_objkey_from_global_key(id);
                return key;
            },
            [&](ObjectId pk) {
                if (!pk_col) {
                    bad_transaction_log("%1 instruction with ObjectId primary key (\"%2\"), but table '%3' does not "
                                        "have a primary key column",
                                        name, pk, table_name);
                }
                if (pk_type != type_ObjectId) {
                    bad_transaction_log(
                        "%1 instruction with ObjectId primary key (%2), but '%3.%4' has primary keys of type '%5'",
                        name, pk, table_name, pk_name, pk_type);
                }
                ObjKey key = table.get_objkey_from_primary_key(pk);
                return key;
            },
            [&](UUID pk) {
                if (!pk_col) {
                    bad_transaction_log("%1 instruction with UUID primary key (\"%2\"), but table '%3' does not "
                                        "have a primary key column",
                                        name, pk, table_name);
                }
                if (pk_type != type_UUID) {
                    bad_transaction_log(
                        "%1 instruction with UUID primary key (%2), but '%3.%4' has primary keys of type '%5'", name,
                        pk, table_name, pk_name, pk_type);
                }
                ObjKey key = table.get_objkey_from_primary_key(pk);
                return key;
            }},
        primary_key);
}


} // namespace realm::sync

realm / realm-core / 1771

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