Prevent errors on double-close in HttpBlobStore

Attempt to fix #5711, "java.util.concurrent.RejectedExecutionException: event executor terminated", by having `HttpBlobStore.close()` no-op when called more than once.

I'm rolling a patched version of bazel for us internally based on 0.15.2. Should be able to say definitively in a couple days whether or not this addresses the issue, but it seems like it should (and @buchgr agrees).

Closes #5725.

PiperOrigin-RevId: 207089681

1 files changed, 14 insertions, 2 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/remote/blobstore/http/HttpBlobStore.java b/src/main/java/com/google/devtools/build/lib/remote/blobstore/http/HttpBlobStore.java
index 0bcc68bd64..63f1a9d071 100644
--- a/src/main/java/com/google/devtools/build/lib/remote/blobstore/http/HttpBlobStore.java
+++ b/src/main/java/com/google/devtools/build/lib/remote/blobstore/http/HttpBlobStore.java
@@ -108,6 +108,11 @@ public final class HttpBlobStore implements SimpleBlobStore {
   private final URI uri;
   private final int timeoutMillis;
 
+  private final Object closeLock = new Object();
+
+  @GuardedBy("closeLock")
+  private boolean isClosed;
+
   private final Object credentialsLock = new Object();
 
   @GuardedBy("credentialsLock")
@@ -522,8 +527,15 @@ public final class HttpBlobStore implements SimpleBlobStore {
   @SuppressWarnings("FutureReturnValueIgnored")
   @Override
   public void close() {
-    channelPool.close();
-    eventLoop.shutdownGracefully();
+    synchronized (closeLock) {
+      if (isClosed) {
+        return;
+      }
+
+      isClosed = true;
+      channelPool.close();
+      eventLoop.shutdownGracefully();
+    }
   }
 
   private boolean cacheMiss(HttpResponseStatus status) {