Add support to create memory allocator dump in base::DiscardableMemory

content/common/discardable_shared_memory_heap.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/common/discardable_shared_memory_heap.h"
 
 #include <algorithm>
 
 #include "base/format_macros.h"
 #include "base/memory/discardable_shared_memory.h"
@@ skipping 42 matching lines @@
 }
 
 bool DiscardableSharedMemoryHeap::ScopedMemorySegment::IsUsed() const {
   return heap_->IsMemoryUsed(shared_memory_.get(), size_);
 }
 
 bool DiscardableSharedMemoryHeap::ScopedMemorySegment::IsResident() const {
   return heap_->IsMemoryResident(shared_memory_.get());
 }
 
+base::trace_event::MemoryAllocatorDump*
+DiscardableSharedMemoryHeap::ScopedMemorySegment::CreateMemoryAllocatorDump(
+    Span* span,
+    const char* name,
+    base::trace_event::ProcessMemoryDump* pmd) const {
+  if (shared_memory_ != span->shared_memory())
+    return nullptr;
+
+  base::trace_event::MemoryAllocatorDump* dump = pmd->CreateAllocatorDump(name);
+  dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
+                  base::trace_event::MemoryAllocatorDump::kUnitsBytes,
+                  static_cast<uint64_t>(span->length()));
+
+  pmd->AddSuballocation(dump->guid(),
+                        base::StringPrintf("discardable/segment_%d", id_));
+  return dump;
+}
+
 void DiscardableSharedMemoryHeap::ScopedMemorySegment::OnMemoryDump(
     base::trace_event::ProcessMemoryDump* pmd) const {
   heap_->OnMemoryDump(shared_memory_.get(), size_, id_, pmd);
 }
 
 DiscardableSharedMemoryHeap::DiscardableSharedMemoryHeap(size_t block_size)
     : block_size_(block_size), num_blocks_(0), num_free_blocks_(0) {
   DCHECK_NE(block_size_, 0u);
   DCHECK(IsPowerOfTwo(block_size_));
 }
@@ skipping 318 matching lines @@
 }
 
 // static
 base::trace_event::MemoryAllocatorDumpGuid
 DiscardableSharedMemoryHeap::GetSegmentGUIDForTracing(uint64 tracing_process_id,
                                                       int32 segment_id) {
   return base::trace_event::MemoryAllocatorDumpGuid(base::StringPrintf(
       "discardable-x-process/%" PRIx64 "/%d", tracing_process_id, segment_id));
 }
 
+base::trace_event::MemoryAllocatorDump*
+DiscardableSharedMemoryHeap::CreateMemoryAllocatorDump(
+    Span* span,
+    const char* name,
+    base::trace_event::ProcessMemoryDump* pmd) const {
+  if (span->shared_memory() == nullptr)

[reveman, 2015/08/21 18:05:24]

nit: !span->shared_memory()

[ssid, 2015/08/24 14:52:10]

Done.

+    return nullptr;
+
+  base::trace_event::MemoryAllocatorDump* allocator_dump;
+  std::for_each(

[reveman, 2015/08/21 18:05:24]

can you instead do a std:::find_if for span->shared_memory() and then create the
dump here instead of adding a ScopedMemorySegment function for it? as there
should only be one match..

[ssid, 2015/08/21 19:02:30]

I cannot do it because I have to match the span->shared_memory() with
ScopedMemorySegment::shared_memory_ : this is a private member and not exposed.
That is why I moved the implementation inside ScopedMemorySegment. I can either
expose the memory_segment and the id from ScopedMemorySegment, which will void
the purpose of the class, or get a callback from ScopedMemorySegment with
segment and id and create dump here. But creating there looked simpler.

[reveman, 2015/08/22 14:21:16]

How about adding a "bool ScopedMemorySegment::ContainsBlock(size_t start) const"
function? and keep ScopedMemorySegment::CreateMemoryAllocatorDump but remove the
"if (shared_memory_ != span->shared_memory())" check from it?

[ssid, 2015/08/22 14:50:19]

Yes I planned that at first, but I also need to add a subAllocation to the
segment, for which i need the segment id. That is why i moved the implementation
in there. If you want it to be implemented outside then I would have to make a
callback into the heap with id, if segment matches.

[reveman, 2015/08/22 15:04:07]

I was thinking you could use the ScopedMemorySegment::ContainsBlock to find the
correct segment and then use a ScopedMemorySegment::CreateMemoryAllocatorDump
function to create the dump. That function would have access to the id..

[ssid, 2015/08/22 15:13:00]

Ah sorry, I see what you meant now, sounds good, thanks

[ssid, 2015/08/24 14:52:10]

Done.

+      memory_segments_.begin(), memory_segments_.end(),
+      [span, name, pmd, &allocator_dump](const ScopedMemorySegment* segment) {
+        base::trace_event::MemoryAllocatorDump* dump =
+            segment->CreateMemoryAllocatorDump(span, name, pmd);
+        if (dump != nullptr)
+          allocator_dump = dump;
+      });
+
+  // Span with a shared memory should be found in some segment.
+  DCHECK(allocator_dump != nullptr);
+  return allocator_dump;
+}
+
 }  // namespace content