1 files changed, 66 insertions, 0 deletions
diff --git a/java/com/google/gerrit/server/logging/LoggingContextAwareCallable.java b/java/com/google/gerrit/server/logging/LoggingContextAwareCallable.java
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+++ b/java/com/google/gerrit/server/logging/LoggingContextAwareCallable.java
@@ -0,0 +1,66 @@
+// Copyright (C) 2018 The Android Open Source Project
+//
+// 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 com.google.gerrit.server.logging;
+
+import com.google.common.collect.ImmutableSetMultimap;
+import java.util.concurrent.Callable;
+
+/**
+ * Wrapper for a {@link Callable} that copies the {@link LoggingContext} from the current thread to
+ * the thread that executes the callable.
+ *
+ * <p>The state of the logging context that is copied to the thread that executes the callable is
+ * fixed at the creation time of this wrapper. If the callable is submitted to an executor and is
+ * executed later this means that changes that are done to the logging context in between creating
+ * and executing the callable do not apply.
+ *
+ * <p>See {@link LoggingContextAwareRunnable} for an example.
+ *
+ * @see LoggingContextAwareRunnable
+ */
+class LoggingContextAwareCallable<T> implements Callable<T> {
+  private final Callable<T> callable;
+  private final Thread callingThread;
+  private final ImmutableSetMultimap<String, String> tags;
+  private final boolean forceLogging;
+
+  LoggingContextAwareCallable(Callable<T> callable) {
+    this.callable = callable;
+    this.callingThread = Thread.currentThread();
+    this.tags = LoggingContext.getInstance().getTagsAsMap();
+    this.forceLogging = LoggingContext.getInstance().isLoggingForced();
+  }
+
+  @Override
+  public T call() throws Exception {
+    if (callingThread.equals(Thread.currentThread())) {
+      // propagation of logging context is not needed
+      return callable.call();
+    }
+
+    // propagate logging context
+    LoggingContext loggingCtx = LoggingContext.getInstance();
+    ImmutableSetMultimap<String, String> oldTags = loggingCtx.getTagsAsMap();
+    boolean oldForceLogging = loggingCtx.isLoggingForced();
+    loggingCtx.setTags(tags);
+    loggingCtx.forceLogging(forceLogging);
+    try {
+      return callable.call();
+    } finally {
+      loggingCtx.setTags(oldTags);
+      loggingCtx.forceLogging(oldForceLogging);
+    }
+  }
+}