Merge "BlastBufferQueue: Fix async worker deadlock" am: 09fe4d2cc0

Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/1973102

Change-Id: I32ca7a1a993acd299197373e39adce3f7f910733

1 files changed, 15 insertions, 3 deletions

diff --git a/libs/gui/BLASTBufferQueue.cpp b/libs/gui/BLASTBufferQueue.cpp
index 5b59c592df..9baf79b443 100644
--- a/libs/gui/BLASTBufferQueue.cpp
+++ b/libs/gui/BLASTBufferQueue.cpp
@@ -731,14 +731,26 @@ private:
         std::unique_lock<std::mutex> lock(mMutex);
         while (!mDone) {
             while (!mRunnables.empty()) {
-                std::function<void()> runnable = mRunnables.front();
-                mRunnables.pop_front();
-                runnable();
+                std::deque<std::function<void()>> runnables = std::move(mRunnables);
+                mRunnables.clear();
+                lock.unlock();
+                // Run outside the lock since the runnable might trigger another
+                // post to the async worker.
+                execute(runnables);
+                lock.lock();
             }
             mCv.wait(lock);
         }
     }
 
+    void execute(std::deque<std::function<void()>>& runnables) {
+        while (!runnables.empty()) {
+            std::function<void()> runnable = runnables.front();
+            runnables.pop_front();
+            runnable();
+        }
+    }
+
 public:
     AsyncWorker() : Singleton<AsyncWorker>() { mThread = std::thread(&AsyncWorker::run, this); }