imprecise mark and sweep native memory leak detector

libmemunreachable uses an imprecise mark and sweep pass over all memory
allocated by jemalloc in order to find unreachable allocations.

Change-Id: Ia70bbf31f5b40ff71dab28cfd6cd06c5ef01a2d4

1 files changed, 56 insertions, 0 deletions

diff --git a/libmemunreachable/Semaphore.h b/libmemunreachable/Semaphore.h
new file mode 100644
index 000000000..45e8c819d
--- /dev/null
+++ b/libmemunreachable/Semaphore.h
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef LIBMEMUNREACHABLE_SEMAPHORE_H_
+#define LIBMEMUNREACHABLE_SEMAPHORE_H_
+
+#include <chrono>
+#include <mutex>
+
+#include "android-base/macros.h"
+
+class Semaphore {
+ public:
+  Semaphore(int count = 0) : count_(count) {}
+  ~Semaphore() = default;
+
+  void Wait(std::chrono::milliseconds ms) {
+    std::unique_lock<std::mutex> lk(m_);
+    cv_.wait_for(lk, ms, [&]{
+      if (count_ > 0) {
+        count_--;
+        return true;
+      }
+      return false;
+    });
+  }
+  void Post() {
+    {
+      std::lock_guard<std::mutex> lk(m_);
+      count_++;
+    }
+    cv_.notify_one();
+  }
+ private:
+  DISALLOW_COPY_AND_ASSIGN(Semaphore);
+
+  int count_;
+  std::mutex m_;
+  std::condition_variable cv_;
+};
+
+
+#endif // LIBMEMUNREACHABLE_SEMAPHORE_H_