Merge "BlastBufferQueue: Fix async worker deadlock" into sc-v2-dev am: 0363ad304f

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/native/+/15961340

Change-Id: I0686a922378dfd73702d3e6255b12ef7971659c5

1 files changed, 15 insertions, 3 deletions

diff --git a/libs/gui/BLASTBufferQueue.cpp b/libs/gui/BLASTBufferQueue.cpp
index 9f52487857..e8e664bd76 100644
--- a/libs/gui/BLASTBufferQueue.cpp
+++ b/libs/gui/BLASTBufferQueue.cpp
@@ -736,14 +736,26 @@ 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); }