commit 88f643c422b018716ac9f228f8aeda64b4e27897
author Ulf Adams <ulfjack@google.com> Thu Sep 17 10:55:52 2015 +0000
committer David Chen <dzc@google.com> Thu Sep 17 19:33:32 2015 +0000
tree 7cf8fcdaebc3812f7e94e5329aabf4e6bf01359d
parent 8bbfe737a4662e0425af4450717e5a63442d8db7

Make the module environment invoked exit code path thread-safe.

The module environment can be called from any number of threads, not
necessarily from the main thread. I don't know if it's a problem right now -
we don't have any problem reports that could be caused by this - but better be
safe than sorry.

--
MOS_MIGRATED_REVID=103277567

src/main/java/com/google/devtools/build/lib/runtime/CommandEnvironment.java

diff --git a/src/main/java/com/google/devtools/build/lib/runtime/CommandEnvironment.java b/src/main/java/com/google/devtools/build/lib/runtime/CommandEnvironment.java
index 5d402a1..381225c 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/CommandEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/CommandEnvironment.java
@@ -43,6 +43,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.UUID;
+import java.util.concurrent.atomic.AtomicReference;
 
 /**
  * Encapsulates the state needed for a single command. The environment is dropped when the current
@@ -55,7 +56,7 @@
   private final BlazeModule.ModuleEnvironment blazeModuleEnvironment;
   private final Map<String, String> clientEnv = new HashMap<>();
 
-  private AbruptExitException pendingException;
+  private AtomicReference<AbruptExitException> pendingException = new AtomicReference<>();
 
   private class BlazeModuleEnvironment implements BlazeModule.ModuleEnvironment {
     @Override
@@ -69,8 +70,7 @@
 
     @Override
     public void exit(AbruptExitException exception) {
-      Preconditions.checkState(pendingException == null);
-      pendingException = exception;
+      pendingException.compareAndSet(null, exception);
     }
   }
 
@@ -175,8 +175,9 @@
     eventBus.post(new CommandPrecompleteEvent(originalExit));
     // If Blaze did not suffer an infrastructure failure, check for errors in modules.
     ExitCode exitCode = originalExit;
-    if (!originalExit.isInfrastructureFailure() && pendingException != null) {
-      exitCode = pendingException.getExitCode();
+    AbruptExitException exception = pendingException.get();
+    if (!originalExit.isInfrastructureFailure() && exception != null) {
+      exitCode = exception.getExitCode();
     }
     return exitCode;
   }
@@ -189,8 +190,9 @@
    * the exception this way.
    */
   public void throwPendingException() throws AbruptExitException {
-    if (pendingException != null) {
-      throw pendingException;
+    AbruptExitException exception = pendingException.get();
+    if (exception != null) {
+      throw exception;
     }
   }
 }