Added page to Observatory to display native memory allocation information.

runtime/vm/malloc_hooks.cc

Index: runtime/vm/malloc_hooks.cc
diff --git a/runtime/vm/malloc_hooks.cc b/runtime/vm/malloc_hooks.cc
index d838457889c2eb61561053c0ef251d79534492cb..09b758982c34a0e2fe3d9a1d683b4400673e785f 100644
--- a/runtime/vm/malloc_hooks.cc
+++ b/runtime/vm/malloc_hooks.cc
@@ -131,21 +131,35 @@ class MallocLocker : public ValueObject {
 //   -Stack trace corresponding to the location of allocation, if applicable
 class AllocationInfo {
  public:
-  explicit AllocationInfo(intptr_t allocation_size)
-      : sample_(NULL), allocation_size_(allocation_size) {
+  explicit AllocationInfo(uword address, intptr_t allocation_size)

[zra, 2017/03/16 20:36:37]

Don't need 'explicit' when there is more than one argument.

[bkonyi, 2017/03/21 01:53:23]

Done.

+      : sample_(NULL), address_(address), allocation_size_(allocation_size) {
     // Stack trace collection is disabled when we are in the process of creating
     // the first OSThread in order to prevent deadlocks.
     if (MallocHooksState::ProfilingEnabled() &&
         MallocHooksState::stack_trace_collection_enabled()) {
-      sample_ = Profiler::SampleNativeAllocation(kSkipCount);
+      sample_ = Profiler::SampleNativeAllocation(kSkipCount, address,
+                                                 allocation_size);
+      ASSERT(sample_->native_allocation_address() == address_);
     }
   }
 
+  ~AllocationInfo() {
+    if (sample_ == NULL) {
+      return;
+    }
+    uword allocation_address = sample_->native_allocation_address();
+    if (allocation_address != address_) {

[zra, 2017/03/16 20:36:37]

Why might this happen?

[bkonyi, 2017/03/16 20:48:40]

The samples are stored in a ring buffer and are eventually overwritten with new
samples. This is just to check if the sample has already been overwritten before
trying to mark it as a freed native allocation sample. Now that I think about it
this might be racy...

[bkonyi, 2017/03/21 01:53:23]

I've changed how this is done so that we should be able to avoid races.

+      return;
+    }
+    sample_->set_native_allocation_address(0);

[Cutch, 2017/03/16 20:38:16]

what about the size too?

[bkonyi, 2017/03/21 01:53:23]

I've changed how I check if a native allocation sample has been freed or not to
avoid races.

+  }
+
   Sample* sample() const { return sample_; }
   intptr_t allocation_size() const { return allocation_size_; }
 
  private:
   Sample* sample_;

[zra, 2017/03/16 20:36:37]

It might be worthwhile to make an explicit note here that the AllocationInfo
doesn't own the Sample object.

[bkonyi, 2017/03/21 01:53:23]

Done.

+  uword address_;
   intptr_t allocation_size_;
 
   // The number of frames that are generated by the malloc hooks and collection
@@ -154,7 +168,7 @@ class AllocationInfo {
   // malloc_hook_tests.cc might fail, particularily
   // StackTraceMallocHookLengthTest. If this value is updated, please make sure
   // that the MallocHooks test cases pass on all platforms.
-  static const intptr_t kSkipCount = 5;
+  static const intptr_t kSkipCount = 6;
 };
 
 
@@ -416,7 +430,8 @@ void MallocHooksState::RecordAllocHook(const void* ptr, size_t size) {
   // Now that we hold the lock, check to make sure everything is still active.
   if ((ptr != NULL) && MallocHooksState::Active()) {
     MallocHooksState::IncrementHeapAllocatedMemoryInBytes(size);
-    MallocHooksState::address_map()->Insert(ptr, new AllocationInfo(size));
+    MallocHooksState::address_map()->Insert(
+        ptr, new AllocationInfo(reinterpret_cast<uword>(ptr), size));
   }
 }