commit 9c696ed651e4a3d7ac17ab84ad49b59706b13e8a
author Yichi Chen <yichichen@google.com> Mon Oct 01 22:32:30 2018 +0800
committer Yichi Chen <yichichen@google.com> Mon Nov 19 20:25:04 2018 +0800
tree acf922081cfb5bdeab4c8722a8e4ca7dd022a26d
parent 6ab82a83384567d3389296a6193b6561da63aaf7

SF: Import ring buffer with size control in SurfaceTracing

Instead of disabling SurfaceTracing when its size exceeds the
limitation, we import the ring buffer as its storage and records the
latest status. The size of the ring buffer can be controlled when layer
trace is enabled.

Bug: b/115920963
Test: layer trace can keep at most 100MB without increasing memory usage
      in heap after 10 minutes.
Test: layer trace can keep last result in layers_trace.pb
Test: mTrace.enable can control the size of ring buffer

Change-Id: I8ce4b235b657429b7f1d9229befd509e976329fd

services/surfaceflinger/SurfaceTracing.cpp

diff --git a/services/surfaceflinger/SurfaceTracing.cpp b/services/surfaceflinger/SurfaceTracing.cpp
index 67dcd06..1835929 100644
--- a/services/surfaceflinger/SurfaceTracing.cpp
+++ b/services/surfaceflinger/SurfaceTracing.cpp
@@ -26,22 +26,48 @@
 
 namespace android {
 
-void SurfaceTracing::enable() {
-    ATRACE_CALL();
+void SurfaceTracing::LayersTraceBuffer::reset(size_t newSize) {
+    // use the swap trick to make sure memory is released
+    std::queue<LayersTraceProto>().swap(mStorage);
+    mSizeInBytes = newSize;
+    mUsedInBytes = 0U;
+}
+
+void SurfaceTracing::LayersTraceBuffer::emplace(LayersTraceProto&& proto) {
+    auto protoSize = proto.ByteSize();
+    while (mUsedInBytes + protoSize > mSizeInBytes) {
+        if (mStorage.empty()) {
+            return;
+        }
+        mUsedInBytes -= mStorage.front().ByteSize();
+        mStorage.pop();
+    }
+    mUsedInBytes += protoSize;
+    mStorage.emplace();
+    mStorage.back().Swap(&proto);
+}
+
+void SurfaceTracing::LayersTraceBuffer::flush(LayersTraceFileProto* fileProto) {
+    fileProto->mutable_entry()->Reserve(mStorage.size());
+
+    while (!mStorage.empty()) {
+        auto entry = fileProto->add_entry();
+        entry->Swap(&mStorage.front());
+        mStorage.pop();
+    }
+}
+
+void SurfaceTracing::enable(size_t bufferSizeInByte) {
     std::lock_guard<std::mutex> protoGuard(mTraceMutex);
 
     if (mEnabled) {
         return;
     }
     mEnabled = true;
-
-    mTrace = std::make_unique<LayersTraceFileProto>();
-    mTrace->set_magic_number(uint64_t(LayersTraceFileProto_MagicNumber_MAGIC_NUMBER_H) << 32 |
-                             LayersTraceFileProto_MagicNumber_MAGIC_NUMBER_L);
+    mBuffer.reset(bufferSizeInByte);
 }
 
 status_t SurfaceTracing::disable() {
-    ATRACE_CALL();
     std::lock_guard<std::mutex> protoGuard(mTraceMutex);
 
     if (!mEnabled) {
@@ -51,7 +77,7 @@
     status_t err(writeProtoFileLocked());
     ALOGE_IF(err == PERMISSION_DENIED, "Could not save the proto file! Permission denied");
     ALOGE_IF(err == NOT_ENOUGH_DATA, "Could not save the proto file! There are missing fields");
-    mTrace.reset();
+    mBuffer.reset(0);
     return err;
 }
 
@@ -65,32 +91,29 @@
     if (!mEnabled) {
         return;
     }
-    LayersTraceProto* entry = mTrace->add_entry();
-    entry->set_elapsed_realtime_nanos(elapsedRealtimeNano());
-    entry->set_where(where);
-    entry->mutable_layers()->Swap(&layers);
 
-    constexpr int maxBufferedEntryCount = 3600;
-    if (mTrace->entry_size() >= maxBufferedEntryCount) {
-        // TODO: flush buffered entries without disabling tracing
-        ALOGE("too many buffered frames; force disable tracing");
-        mEnabled = false;
-        writeProtoFileLocked();
-        mTrace.reset();
-    }
+    LayersTraceProto entry;
+    entry.set_elapsed_realtime_nanos(elapsedRealtimeNano());
+    entry.set_where(where);
+    entry.mutable_layers()->Swap(&layers);
+
+    mBuffer.emplace(std::move(entry));
 }
 
 status_t SurfaceTracing::writeProtoFileLocked() {
     ATRACE_CALL();
 
-    if (!mTrace->IsInitialized()) {
-        return NOT_ENOUGH_DATA;
-    }
+    LayersTraceFileProto fileProto;
     std::string output;
-    if (!mTrace->SerializeToString(&output)) {
+
+    fileProto.set_magic_number(uint64_t(LayersTraceFileProto_MagicNumber_MAGIC_NUMBER_H) << 32 |
+                               LayersTraceFileProto_MagicNumber_MAGIC_NUMBER_L);
+    mBuffer.flush(&fileProto);
+
+    if (!fileProto.SerializeToString(&output)) {
         return PERMISSION_DENIED;
     }
-    if (!android::base::WriteStringToFile(output, mOutputFileName, true)) {
+    if (!android::base::WriteStringToFile(output, kDefaultFileName, true)) {
         return PERMISSION_DENIED;
     }
 
@@ -101,7 +124,8 @@
     std::lock_guard<std::mutex> protoGuard(mTraceMutex);
 
     result.appendFormat("Tracing state: %s\n", mEnabled ? "enabled" : "disabled");
-    result.appendFormat("  number of entries: %d\n", mTrace ? mTrace->entry_size() : 0);
+    result.appendFormat("  number of entries: %zu (%.2fMB / %.2fMB)\n", mBuffer.frameCount(),
+                        float(mBuffer.used()) / float(1_MB), float(mBuffer.size()) / float(1_MB));
 }
 
 } // namespace android