commit adc69617ad5a68f2265cacabc13495485cfd1e52
author Yichi Chen <yichichen@google.com> Sat Sep 15 14:51:18 2018 +0800
committer Yichi Chen <yichichen@google.com> Thu Sep 20 10:10:14 2018 +0800
tree 089b5c609b5bf498182bbbf4ad7493640425e6a5
parent 84ae607b7a77f4b77b70052d39a46231893d045a

SF: Enforce a size limitation on SurfaceTracing

SurfaceTracing records operations of each frame update. It can exhaust
more than 2GB on memory heap in 5 mins if display keeps updating.
Enforce a size limitation on it and stop automatically to prevent memory
and stroage from exhausting.

Bug: b/115434782
Test: adb shell service call SurfaceFlinger 1025 i32 1
Result: SurfaceTracing can be disabled after running for a while.

Change-Id: I52d945f86a7bc501590b7c311f63a6273b9192fd

services/surfaceflinger/SurfaceFlinger.cpp

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index f17710e..7022c36 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -4695,6 +4695,12 @@
     result.append("\n");
 
     /*
+     * Tracing state
+     */
+    mTracing.dump(result);
+    result.append("\n");
+
+    /*
      * HWC layer minidump
      */
     for (const auto& [token, display] : mDisplays) {
@@ -5083,12 +5089,12 @@
             case 1025: { // Set layer tracing
                 n = data.readInt32();
                 if (n) {
-                    ALOGV("LayerTracing enabled");
+                    ALOGD("LayerTracing enabled");
                     mTracing.enable();
                     doTracing("tracing.enable");
                     reply->writeInt32(NO_ERROR);
                 } else {
-                    ALOGV("LayerTracing disabled");
+                    ALOGD("LayerTracing disabled");
                     status_t err = mTracing.disable();
                     reply->writeInt32(err);
                 }

services/surfaceflinger/SurfaceTracing.cpp

diff --git a/services/surfaceflinger/SurfaceTracing.cpp b/services/surfaceflinger/SurfaceTracing.cpp
index 0e9b04e..370b3b8 100644
--- a/services/surfaceflinger/SurfaceTracing.cpp
+++ b/services/surfaceflinger/SurfaceTracing.cpp
@@ -52,7 +52,7 @@
     return err;
 }
 
-bool SurfaceTracing::isEnabled() {
+bool SurfaceTracing::isEnabled() const {
     return mEnabled;
 }
 
@@ -65,6 +65,15 @@
     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.Clear();
+    }
 }
 
 status_t SurfaceTracing::writeProtoFileLocked() {
@@ -84,4 +93,11 @@
     return NO_ERROR;
 }
 
+void SurfaceTracing::dump(String8& result) const {
+    std::lock_guard<std::mutex> protoGuard(mTraceMutex);
+
+    result.appendFormat("Tracing state: %s\n", mEnabled ? "enabled" : "disabled");
+    result.appendFormat("  number of entries: %d\n", mTrace.entry_size());
+}
+
 } // namespace android

services/surfaceflinger/SurfaceTracing.h

diff --git a/services/surfaceflinger/SurfaceTracing.h b/services/surfaceflinger/SurfaceTracing.h
index 590ab96..27e2c9e 100644
--- a/services/surfaceflinger/SurfaceTracing.h
+++ b/services/surfaceflinger/SurfaceTracing.h
@@ -18,6 +18,7 @@
 
 #include <layerproto/LayerProtoHeader.h>
 #include <utils/Errors.h>
+#include <utils/String8.h>
 
 #include <mutex>
 
@@ -32,9 +33,10 @@
 public:
     void enable();
     status_t disable();
-    bool isEnabled();
+    bool isEnabled() const;
 
     void traceLayers(const char* where, LayersProto);
+    void dump(String8& result) const;
 
 private:
     static constexpr auto DEFAULT_FILENAME = "/data/misc/wmtrace/layers_trace.pb";
@@ -43,7 +45,7 @@
 
     bool mEnabled = false;
     std::string mOutputFileName = DEFAULT_FILENAME;
-    std::mutex mTraceMutex;
+    mutable std::mutex mTraceMutex;
     LayersTraceFileProto mTrace;
 };