commit 25fe4acf6ffb6d0b7c93773040a89816b66999c7
author Yabin Cui <yabinc@google.com> Mon Feb 13 21:41:37 2017 +0000
committer android-build-merger <android-build-merger@google.com> Mon Feb 13 21:41:37 2017 +0000
tree 8ab6275e827e8702ccb2e3d00e73a2d70bb93016
parent d3ac884459e618135a460b818a94e33bfa0d6de5
parent 988df508dd72aff82cc62d193c6111503229878d

Merge "libbacktraceoffline: make it thread-safe." am: a3e4977325 am: 47ac9e420f am: b850b9d589
am: e769f0b564

Change-Id: I6ebfa49bd5ff944a229ddaa8b81919c446c27078

libbacktrace/BacktraceOffline.cpp

diff --git a/libbacktrace/BacktraceOffline.cpp b/libbacktrace/BacktraceOffline.cpp
index 53ea796..0a2f5a3 100644
--- a/libbacktrace/BacktraceOffline.cpp
+++ b/libbacktrace/BacktraceOffline.cpp
@@ -31,6 +31,7 @@
 #include <unistd.h>
 
 #include <memory>
+#include <mutex>
 #include <string>
 #include <vector>
 
@@ -91,9 +92,6 @@
       has_debug_frame(false), has_gnu_debugdata(false) { }
 };
 
-static std::unordered_map<std::string, std::unique_ptr<DebugFrameInfo>>& g_debug_frames =
-    *new std::unordered_map<std::string, std::unique_ptr<DebugFrameInfo>>;
-
 void Space::Clear() {
   start = 0;
   end = 0;
@@ -557,18 +555,31 @@
   return "";
 }
 
+static std::mutex g_lock;
+static std::unordered_map<std::string, std::unique_ptr<DebugFrameInfo>>* g_debug_frames = nullptr;
+
 static DebugFrameInfo* ReadDebugFrameFromFile(const std::string& filename);
 
 DebugFrameInfo* BacktraceOffline::GetDebugFrameInFile(const std::string& filename) {
   if (cache_file_) {
-    auto it = g_debug_frames.find(filename);
-    if (it != g_debug_frames.end()) {
-      return it->second.get();
+    std::lock_guard<std::mutex> lock(g_lock);
+    if (g_debug_frames != nullptr) {
+      auto it = g_debug_frames->find(filename);
+      if (it != g_debug_frames->end()) {
+        return it->second.get();
+      }
     }
   }
   DebugFrameInfo* debug_frame = ReadDebugFrameFromFile(filename);
   if (cache_file_) {
-    g_debug_frames.emplace(filename, std::unique_ptr<DebugFrameInfo>(debug_frame));
+    std::lock_guard<std::mutex> lock(g_lock);
+    if (g_debug_frames == nullptr) {
+      g_debug_frames = new std::unordered_map<std::string, std::unique_ptr<DebugFrameInfo>>;
+    }
+    auto pair = g_debug_frames->emplace(filename, std::unique_ptr<DebugFrameInfo>(debug_frame));
+    if (!pair.second) {
+      debug_frame = pair.first->second.get();
+    }
   }
   return debug_frame;
 }