[draft] Patch to check potential memory leak

mojo/edk/system/channel.cc

Index: mojo/edk/system/channel.cc
diff --git a/mojo/edk/system/channel.cc b/mojo/edk/system/channel.cc
index 8a44d36024e2346b3eab90a48f1eb77a35adcd63..77605667573707d34a32b6822c96901f445df331 100644
--- a/mojo/edk/system/channel.cc
+++ b/mojo/edk/system/channel.cc
@@ -22,6 +22,8 @@
 #include "base/win/win_util.h"
 #endif
 
+#include "base/atomicops.h"
+
 namespace mojo {
 namespace edk {
 
@@ -52,12 +54,24 @@ const size_t kMaxUnusedReadBufferCapacity = 4096;
 const size_t kMaxChannelMessageSize = 256 * 1024 * 1024;
 const size_t kMaxAttachedHandles = 128;
 
+static base::subtle::Atomic32 message_count_ = 0;
+
 Channel::Message::Message(size_t payload_size, size_t max_handles)
 #if defined(MOJO_EDK_LEGACY_PROTOCOL)
     : Message(payload_size, max_handles, MessageType::NORMAL_LEGACY) {

[erikchen, 2017/03/27 19:10:35]

this constructor calls another constructor, so we double count constructors :(

+  base::subtle::Barrier_AtomicIncrement(&message_count_, 1);
+  if ((message_count_ % 1024) == 0) {
+    LOG(ERROR) << "Message: " << message_count_ << " ["
+        << base::GetCurrentProcId() << "]";
+  }
 }
 #else
     : Message(payload_size, max_handles, MessageType::NORMAL) {
+  base::subtle::Barrier_AtomicIncrement(&message_count_, 1);
+  if ((message_count_ % 1024) == 0) {
+    LOG(ERROR) << "Message: " << message_count_ << " ["
+        << base::GetCurrentProcId() << "]";
+  }
 }
 #endif
 
@@ -66,6 +80,11 @@ Channel::Message::Message(size_t payload_size,
                           MessageType message_type)
     : max_handles_(max_handles) {
   DCHECK_LE(max_handles_, kMaxAttachedHandles);
+  base::subtle::Barrier_AtomicIncrement(&message_count_, 1);
+  if ((message_count_ % 1024) == 0) {
+    LOG(ERROR) << "Message: " << message_count_ << " ["
+        << base::GetCurrentProcId() << "]";
+  }
 
   const bool is_legacy_message = (message_type == MessageType::NORMAL_LEGACY);
   size_t extra_header_size = 0;
@@ -136,6 +155,7 @@ Channel::Message::Message(size_t payload_size,
 }
 
 Channel::Message::~Message() {
+  base::subtle::Barrier_AtomicIncrement(&message_count_, -1);
   base::AlignedFree(data_);
 }