#20050

Committed 04 Nov 2025 05:16PM UTC coverage: 88.521% (-0.009%) from 88.53%

Build # #20050

Build Type

push

github

Committed by

ejona86

Commit Message

xds: Detect negative ref count for xds client

If the refcount goes negative, then the next getObject() will return
null. This was noticed during code inspection when investigating a
NullPointerException in b/454396128, although it is unclear if this is
actually happening.

Run Details

34964 of 39498 relevant lines covered (88.52%)

0.89 hits per line

Source File
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91.18

/../xds/src/main/java/io/grpc/xds/SharedXdsClientPoolProvider.java

/*
 * Copyright 2020 The gRPC Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.grpc.xds;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableList;
import com.google.errorprone.annotations.concurrent.GuardedBy;
import io.grpc.CallCredentials;
import io.grpc.MetricRecorder;
import io.grpc.internal.ExponentialBackoffPolicy;
import io.grpc.internal.GrpcUtil;
import io.grpc.internal.ObjectPool;
import io.grpc.internal.SharedResourceHolder;
import io.grpc.internal.TimeProvider;
import io.grpc.xds.client.Bootstrapper;
import io.grpc.xds.client.Bootstrapper.BootstrapInfo;
import io.grpc.xds.client.XdsClient;
import io.grpc.xds.client.XdsClientImpl;
import io.grpc.xds.client.XdsInitializationException;
import io.grpc.xds.internal.security.TlsContextManagerImpl;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ScheduledExecutorService;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.annotation.Nullable;
import javax.annotation.concurrent.ThreadSafe;

/**
 * The global factory for creating a singleton {@link XdsClient} instance to be used by all gRPC
 * clients in the process.
 */
@ThreadSafe
final class SharedXdsClientPoolProvider implements XdsClientPoolFactory {
  private static final boolean LOG_XDS_NODE_ID = Boolean.parseBoolean(
      System.getenv("GRPC_LOG_XDS_NODE_ID"));
  private static final Logger log = Logger.getLogger(XdsClientImpl.class.getName());
  private static final ExponentialBackoffPolicy.Provider BACKOFF_POLICY_PROVIDER =
      new ExponentialBackoffPolicy.Provider();

  @Nullable
  private final Bootstrapper bootstrapper;
  private final Object lock = new Object();
  private final Map<String, ObjectPool<XdsClient>> targetToXdsClientMap = new ConcurrentHashMap<>();

  SharedXdsClientPoolProvider() {
    this(null);
  }

  @VisibleForTesting
  SharedXdsClientPoolProvider(@Nullable Bootstrapper bootstrapper) {
    this.bootstrapper = bootstrapper;
  }

  static SharedXdsClientPoolProvider getDefaultProvider() {
    return SharedXdsClientPoolProviderHolder.instance;
  }

  @Override
  @Nullable
  public ObjectPool<XdsClient> get(String target) {
    return targetToXdsClientMap.get(target);
  }

  @Deprecated
  public ObjectPool<XdsClient> getOrCreate(
      String target, MetricRecorder metricRecorder, CallCredentials transportCallCredentials)
      throws XdsInitializationException {
    BootstrapInfo bootstrapInfo;
    if (bootstrapper != null) {
      bootstrapInfo = bootstrapper.bootstrap();
    } else {
      bootstrapInfo = GrpcBootstrapperImpl.defaultBootstrap();
    }
    return getOrCreate(target, bootstrapInfo, metricRecorder, transportCallCredentials);
  }

  @Override
  public ObjectPool<XdsClient> getOrCreate(
      String target, BootstrapInfo bootstrapInfo, MetricRecorder metricRecorder) {
    return getOrCreate(target, bootstrapInfo, metricRecorder, null);
  }

  public ObjectPool<XdsClient> getOrCreate(
      String target,
      BootstrapInfo bootstrapInfo,
      MetricRecorder metricRecorder,
      CallCredentials transportCallCredentials) {
    ObjectPool<XdsClient> ref = targetToXdsClientMap.get(target);
    if (ref == null) {
      synchronized (lock) {
        ref = targetToXdsClientMap.get(target);
        if (ref == null) {
          ref =
              new RefCountedXdsClientObjectPool(
                  bootstrapInfo, target, metricRecorder, transportCallCredentials);
          targetToXdsClientMap.put(target, ref);
        }
      }
    }
    return ref;
  }

  @Override
  public ImmutableList<String> getTargets() {
    return ImmutableList.copyOf(targetToXdsClientMap.keySet());
  }

  private static class SharedXdsClientPoolProviderHolder {
    private static final SharedXdsClientPoolProvider instance = new SharedXdsClientPoolProvider();
  }

  @ThreadSafe
  @VisibleForTesting
  class RefCountedXdsClientObjectPool implements ObjectPool<XdsClient> {

    private final BootstrapInfo bootstrapInfo;
    private final String target; // The target associated with the xDS client.
    private final MetricRecorder metricRecorder;
    private final CallCredentials transportCallCredentials;
    private final Object lock = new Object();
    @GuardedBy("lock")
    private ScheduledExecutorService scheduler;
    @GuardedBy("lock")
    private XdsClient xdsClient;
    @GuardedBy("lock")
    private int refCount;
    @GuardedBy("lock")
    private XdsClientMetricReporterImpl metricReporter;

    @VisibleForTesting
    RefCountedXdsClientObjectPool(
        BootstrapInfo bootstrapInfo, String target, MetricRecorder metricRecorder) {
      this(bootstrapInfo, target, metricRecorder, null);
    }

    @VisibleForTesting
    RefCountedXdsClientObjectPool(
        BootstrapInfo bootstrapInfo,
        String target,
        MetricRecorder metricRecorder,
        CallCredentials transportCallCredentials) {
      this.bootstrapInfo = checkNotNull(bootstrapInfo, "bootstrapInfo");
      this.target = target;
      this.metricRecorder = checkNotNull(metricRecorder, "metricRecorder");
      this.transportCallCredentials = transportCallCredentials;
    }

    @Override
    public XdsClient getObject() {
      synchronized (lock) {
        if (refCount == 0) {
          if (LOG_XDS_NODE_ID) {
            log.log(Level.INFO, "xDS node ID: {0}", bootstrapInfo.node().getId());
          }
          scheduler = SharedResourceHolder.get(GrpcUtil.TIMER_SERVICE);
          metricReporter = new XdsClientMetricReporterImpl(metricRecorder, target);
          GrpcXdsTransportFactory xdsTransportFactory =
              new GrpcXdsTransportFactory(transportCallCredentials);
          xdsClient =
              new XdsClientImpl(
                  xdsTransportFactory,
                  bootstrapInfo,
                  scheduler,
                  BACKOFF_POLICY_PROVIDER,
                  GrpcUtil.STOPWATCH_SUPPLIER,
                  TimeProvider.SYSTEM_TIME_PROVIDER,
                  MessagePrinter.INSTANCE,
                  new TlsContextManagerImpl(bootstrapInfo),
                  metricReporter);
          metricReporter.setXdsClient(xdsClient);
        }
        refCount++;
        return xdsClient;
      }
    }

    @Override
    public XdsClient returnObject(Object object) {
      synchronized (lock) {
        refCount--;
        if (refCount == 0) {
          xdsClient.shutdown();
          xdsClient = null;
          metricReporter.close();
          metricReporter = null;
          targetToXdsClientMap.remove(target);
          scheduler = SharedResourceHolder.release(GrpcUtil.TIMER_SERVICE, scheduler);
        } else if (refCount < 0) {
          assert false; // We want our tests to fail
          log.log(Level.SEVERE, "Negative reference count. File a bug", new Exception());
          refCount = 0;
        }
        return null;
      }
    }

    @VisibleForTesting
    @Nullable
    XdsClient getXdsClientForTest() {
      synchronized (lock) {
        return xdsClient;
      }
    }

    public String getTarget() {
      return target;
    }
  }

}

1	/*
2	* Copyright 2020 The gRPC Authors
3	*
4	* Licensed under the Apache License, Version 2.0 (the "License");
5	* you may not use this file except in compliance with the License.
6	* You may obtain a copy of the License at
7	*
8	* http://www.apache.org/licenses/LICENSE-2.0
9	*
10	* Unless required by applicable law or agreed to in writing, software
11	* distributed under the License is distributed on an "AS IS" BASIS,
12	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13	* See the License for the specific language governing permissions and
14	* limitations under the License.
15	*/
16
17	package io.grpc.xds;
18
19	import static com.google.common.base.Preconditions.checkNotNull;
20
21	import com.google.common.annotations.VisibleForTesting;
22	import com.google.common.collect.ImmutableList;
23	import com.google.errorprone.annotations.concurrent.GuardedBy;
24	import io.grpc.CallCredentials;
25	import io.grpc.MetricRecorder;
26	import io.grpc.internal.ExponentialBackoffPolicy;
27	import io.grpc.internal.GrpcUtil;
28	import io.grpc.internal.ObjectPool;
29	import io.grpc.internal.SharedResourceHolder;
30	import io.grpc.internal.TimeProvider;
31	import io.grpc.xds.client.Bootstrapper;
32	import io.grpc.xds.client.Bootstrapper.BootstrapInfo;
33	import io.grpc.xds.client.XdsClient;
34	import io.grpc.xds.client.XdsClientImpl;
35	import io.grpc.xds.client.XdsInitializationException;
36	import io.grpc.xds.internal.security.TlsContextManagerImpl;
37	import java.util.Map;
38	import java.util.concurrent.ConcurrentHashMap;
39	import java.util.concurrent.ScheduledExecutorService;
40	import java.util.logging.Level;
41	import java.util.logging.Logger;
42	import javax.annotation.Nullable;
43	import javax.annotation.concurrent.ThreadSafe;
44
45	/**
46	* The global factory for creating a singleton {@link XdsClient} instance to be used by all gRPC
47	* clients in the process.
48	*/
49	@ThreadSafe
50	final class SharedXdsClientPoolProvider implements XdsClientPoolFactory {
51	private static final boolean LOG_XDS_NODE_ID = Boolean.parseBoolean(	1✔
52	System.getenv("GRPC_LOG_XDS_NODE_ID"));	1✔
53	private static final Logger log = Logger.getLogger(XdsClientImpl.class.getName());	1✔
54	private static final ExponentialBackoffPolicy.Provider BACKOFF_POLICY_PROVIDER =	1✔
55	new ExponentialBackoffPolicy.Provider();
56
57	@Nullable
58	private final Bootstrapper bootstrapper;
59	private final Object lock = new Object();	1✔
60	private final Map<String, ObjectPool<XdsClient>> targetToXdsClientMap = new ConcurrentHashMap<>();	1✔
61
62	SharedXdsClientPoolProvider() {
63	this(null);	1✔
64	}	1✔
65
66	@VisibleForTesting
67	SharedXdsClientPoolProvider(@Nullable Bootstrapper bootstrapper) {	1✔
68	this.bootstrapper = bootstrapper;	1✔
69	}	1✔
70
71	static SharedXdsClientPoolProvider getDefaultProvider() {
72	return SharedXdsClientPoolProviderHolder.instance;	1✔
73	}
74
75	@Override
76	@Nullable
77	public ObjectPool<XdsClient> get(String target) {
78	return targetToXdsClientMap.get(target);	1✔
79	}
80
81	@Deprecated
82	public ObjectPool<XdsClient> getOrCreate(
83	String target, MetricRecorder metricRecorder, CallCredentials transportCallCredentials)
84	throws XdsInitializationException {
85	BootstrapInfo bootstrapInfo;
86	if (bootstrapper != null) {	1✔
87	bootstrapInfo = bootstrapper.bootstrap();	1✔
88	} else {
89	bootstrapInfo = GrpcBootstrapperImpl.defaultBootstrap();	×
90	}
91	return getOrCreate(target, bootstrapInfo, metricRecorder, transportCallCredentials);	1✔
92	}
93
94	@Override
95	public ObjectPool<XdsClient> getOrCreate(
96	String target, BootstrapInfo bootstrapInfo, MetricRecorder metricRecorder) {
97	return getOrCreate(target, bootstrapInfo, metricRecorder, null);	1✔
98	}
99
100	public ObjectPool<XdsClient> getOrCreate(
101	String target,
102	BootstrapInfo bootstrapInfo,
103	MetricRecorder metricRecorder,
104	CallCredentials transportCallCredentials) {
105	ObjectPool<XdsClient> ref = targetToXdsClientMap.get(target);	1✔
106	if (ref == null) {	1✔
107	synchronized (lock) {	1✔
108	ref = targetToXdsClientMap.get(target);	1✔
109	if (ref == null) {	1✔
110	ref =	1✔
111	new RefCountedXdsClientObjectPool(
112	bootstrapInfo, target, metricRecorder, transportCallCredentials);
113	targetToXdsClientMap.put(target, ref);	1✔
114	}
115	}	1✔
116	}
117	return ref;	1✔
118	}
119
120	@Override
121	public ImmutableList<String> getTargets() {
122	return ImmutableList.copyOf(targetToXdsClientMap.keySet());	1✔
123	}
124
125	private static class SharedXdsClientPoolProviderHolder {
126	private static final SharedXdsClientPoolProvider instance = new SharedXdsClientPoolProvider();	1✔
127	}
128
129	@ThreadSafe	1✔
130	@VisibleForTesting
131	class RefCountedXdsClientObjectPool implements ObjectPool<XdsClient> {
132
133	private final BootstrapInfo bootstrapInfo;
134	private final String target; // The target associated with the xDS client.
135	private final MetricRecorder metricRecorder;
136	private final CallCredentials transportCallCredentials;
137	private final Object lock = new Object();	1✔
138	@GuardedBy("lock")
139	private ScheduledExecutorService scheduler;
140	@GuardedBy("lock")
141	private XdsClient xdsClient;
142	@GuardedBy("lock")
143	private int refCount;
144	@GuardedBy("lock")
145	private XdsClientMetricReporterImpl metricReporter;
146
147	@VisibleForTesting
148	RefCountedXdsClientObjectPool(
149	BootstrapInfo bootstrapInfo, String target, MetricRecorder metricRecorder) {
150	this(bootstrapInfo, target, metricRecorder, null);	1✔
151	}	1✔
152
153	@VisibleForTesting
154	RefCountedXdsClientObjectPool(
155	BootstrapInfo bootstrapInfo,
156	String target,
157	MetricRecorder metricRecorder,
158	CallCredentials transportCallCredentials) {	1✔
159	this.bootstrapInfo = checkNotNull(bootstrapInfo, "bootstrapInfo");	1✔
160	this.target = target;	1✔
161	this.metricRecorder = checkNotNull(metricRecorder, "metricRecorder");	1✔
162	this.transportCallCredentials = transportCallCredentials;	1✔
163	}	1✔
164
165	@Override
166	public XdsClient getObject() {
167	synchronized (lock) {	1✔
168	if (refCount == 0) {	1✔
169	if (LOG_XDS_NODE_ID) {	1✔
170	log.log(Level.INFO, "xDS node ID: {0}", bootstrapInfo.node().getId());	×
171	}
172	scheduler = SharedResourceHolder.get(GrpcUtil.TIMER_SERVICE);	1✔
173	metricReporter = new XdsClientMetricReporterImpl(metricRecorder, target);	1✔
174	GrpcXdsTransportFactory xdsTransportFactory =	1✔
175	new GrpcXdsTransportFactory(transportCallCredentials);
176	xdsClient =	1✔
177	new XdsClientImpl(
178	xdsTransportFactory,
179	bootstrapInfo,
180	scheduler,
181	BACKOFF_POLICY_PROVIDER,	1✔
182	GrpcUtil.STOPWATCH_SUPPLIER,
183	TimeProvider.SYSTEM_TIME_PROVIDER,
184	MessagePrinter.INSTANCE,
185	new TlsContextManagerImpl(bootstrapInfo),
186	metricReporter);
187	metricReporter.setXdsClient(xdsClient);	1✔
188	}
189	refCount++;	1✔
190	return xdsClient;	1✔
191	}
192	}
193
194	@Override
195	public XdsClient returnObject(Object object) {
196	synchronized (lock) {	1✔
197	refCount--;	1✔
198	if (refCount == 0) {	1✔
199	xdsClient.shutdown();	1✔
200	xdsClient = null;	1✔
201	metricReporter.close();	1✔
202	metricReporter = null;	1✔
203	targetToXdsClientMap.remove(target);	1✔
204	scheduler = SharedResourceHolder.release(GrpcUtil.TIMER_SERVICE, scheduler);	1✔
205	} else if (refCount < 0) {	1✔
206	assert false; // We want our tests to fail	×
207	log.log(Level.SEVERE, "Negative reference count. File a bug", new Exception());	×
208	refCount = 0;	×
209	}
210	return null;	1✔
211	}
212	}
213
214	@VisibleForTesting
215	@Nullable
216	XdsClient getXdsClientForTest() {
217	synchronized (lock) {	1✔
218	return xdsClient;	1✔
219	}
220	}
221
222	public String getTarget() {
223	return target;	×
224	}
225	}
226
227	}

grpc / grpc-java / #20050

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