commit e278da130ce2f40533dfdb64f7f2240beacf1691
author Matt Buckley <mattbuckley@google.com> Tue Jun 20 22:51:05 2023 +0000
committer Matt Buckley <mattbuckley@google.com> Mon Jun 26 22:21:16 2023 +0000
tree 547794f757706511feee7e13f2f0b545af1ee690
parent 334d43412236fdbf44271a0b5f032881d758ec01

Update ShaderCache to support shared locking

Currently, the shadercache can lock for a long time when writing the
cache to disk while vulkan is trying to access it, causing frame drops.
However, neither operation actually requires write access. By using
shared_locks, both operations can happen concurrently eliminating this
contention and saving the frame(s).

Test: atest hwui_unit_tests:ShaderCacheTest
Bug: 288252750

Change-Id: I26c5bee001d44cdd75766e9cb5974bd9337819ab

libs/hwui/tests/unit/ShaderCacheTests.cpp

diff --git a/libs/hwui/tests/unit/ShaderCacheTests.cpp b/libs/hwui/tests/unit/ShaderCacheTests.cpp
index 7bcd45c..9aa2e1d 100644
--- a/libs/hwui/tests/unit/ShaderCacheTests.cpp
+++ b/libs/hwui/tests/unit/ShaderCacheTests.cpp
@@ -49,7 +49,7 @@
      */
     static void reinitializeAllFields(ShaderCache& cache) {
         ShaderCache newCache = ShaderCache();
-        std::lock_guard<std::mutex> lock(cache.mMutex);
+        std::lock_guard lock(cache.mMutex), newLock(newCache.mMutex);
         // By order of declaration
         cache.mInitialized = newCache.mInitialized;
         cache.mBlobCache.reset(nullptr);
@@ -72,7 +72,7 @@
      * manually, as seen in the "terminate" testing helper function.
      */
     static void setSaveDelayMs(ShaderCache& cache, unsigned int saveDelayMs) {
-        std::lock_guard<std::mutex> lock(cache.mMutex);
+        std::lock_guard lock(cache.mMutex);
         cache.mDeferredSaveDelayMs = saveDelayMs;
     }
 
@@ -81,7 +81,7 @@
      * Next call to "initShaderDiskCache" will load again the in-memory cache from disk.
      */
     static void terminate(ShaderCache& cache, bool saveContent) {
-        std::lock_guard<std::mutex> lock(cache.mMutex);
+        std::lock_guard lock(cache.mMutex);
         if (saveContent) {
             cache.saveToDiskLocked();
         }
@@ -93,6 +93,7 @@
      */
     template <typename T>
     static bool validateCache(ShaderCache& cache, std::vector<T> hash) {
+        std::lock_guard lock(cache.mMutex);
         return cache.validateCache(hash.data(), hash.size() * sizeof(T));
     }
 
@@ -108,7 +109,7 @@
      */
     static void waitForPendingSave(ShaderCache& cache, const int timeoutMs = 50) {
         {
-            std::lock_guard<std::mutex> lock(cache.mMutex);
+            std::lock_guard lock(cache.mMutex);
             ASSERT_TRUE(cache.mSavePending);
         }
         bool saving = true;
@@ -123,7 +124,7 @@
             usleep(delayMicroseconds);
             elapsedMilliseconds += (float)delayMicroseconds / 1000;
 
-            std::lock_guard<std::mutex> lock(cache.mMutex);
+            std::lock_guard lock(cache.mMutex);
             saving = cache.mSavePending;
         }
     }