[tracing] Add memory statistics from level db clients to tracing.

The major clients of level database are leveldb value store
(just a wrapper around leveldb). This CL adds memory
statistics of the opened databases to tracing.

BUG=547066

Review URL: https://codereview.chromium.org/1310513004

Cr-Commit-Position: refs/heads/master@{#358303}

2 files changed, 47 insertions, 1 deletions

diff --git a/extensions/browser/value_store/leveldb_value_store.cc b/extensions/browser/value_store/leveldb_value_store.cc
index 39a1346..c11e655 100644
--- a/extensions/browser/value_store/leveldb_value_store.cc
+++ b/extensions/browser/value_store/leveldb_value_store.cc
@@ -8,9 +8,13 @@
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/logging.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/sys_string_conversions.h"
+#include "base/thread_task_runner_handle.h"
+#include "base/trace_event/memory_dump_manager.h"
+#include "base/trace_event/process_memory_dump.h"
 #include "content/public/browser/browser_thread.h"
 #include "extensions/browser/value_store/value_store_util.h"
 #include "third_party/leveldatabase/env_chromium.h"
@@ -59,10 +63,14 @@ LeveldbValueStore::LeveldbValueStore(const std::string& uma_client_name,
       "Extensions.Database.Open." + uma_client_name, 1,
       leveldb_env::LEVELDB_STATUS_MAX, leveldb_env::LEVELDB_STATUS_MAX + 1,
       base::Histogram::kUmaTargetedHistogramFlag);
+  base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
+      this, "LeveldbValueStore", base::ThreadTaskRunnerHandle::Get());
 }
 
 LeveldbValueStore::~LeveldbValueStore() {
   DCHECK_CURRENTLY_ON(BrowserThread::FILE);
+  base::trace_event::MemoryDumpManager::GetInstance()->UnregisterDumpProvider(
+      this);
 
   // Delete the database from disk if it's empty (but only if we managed to
   // open it!). This is safe on destruction, assuming that we have exclusive
@@ -325,6 +333,38 @@ bool LeveldbValueStore::WriteToDbForTest(leveldb::WriteBatch* batch) {
   return !WriteToDb(batch).get();
 }
 
+bool LeveldbValueStore::OnMemoryDump(
+    const base::trace_event::MemoryDumpArgs& args,
+    base::trace_event::ProcessMemoryDump* pmd) {
+  DCHECK_CURRENTLY_ON(BrowserThread::FILE);
+
+  // Return true so that the provider is not disabled.
+  if (!db_)
+    return true;
+
+  std::string value;
+  uint64 size;
+  bool res = db_->GetProperty("leveldb.approximate-memory-usage", &value);
+  DCHECK(res);
+  res = base::StringToUint64(value, &size);
+  DCHECK(res);
+
+  auto dump = pmd->CreateAllocatorDump(
+      base::StringPrintf("leveldb/value_store/%s/%p",
+                         open_histogram_->histogram_name().c_str(), this));
+  dump->AddScalar(base::trace_event::MemoryAllocatorDump::kNameSize,
+                  base::trace_event::MemoryAllocatorDump::kUnitsBytes, size);
+
+  // Memory is allocated from system allocator (malloc).
+  const char* system_allocator_name =
+      base::trace_event::MemoryDumpManager::GetInstance()
+          ->system_allocator_pool_name();
+  if (system_allocator_name)
+    pmd->AddSuballocation(dump->guid(), system_allocator_name);
+
+  return true;
+}
+
 scoped_ptr<ValueStore::Error> LeveldbValueStore::EnsureDbIsOpen() {
   DCHECK_CURRENTLY_ON(BrowserThread::FILE);
 
diff --git a/extensions/browser/value_store/leveldb_value_store.h b/extensions/browser/value_store/leveldb_value_store.h
index 2901660..e763714 100644
--- a/extensions/browser/value_store/leveldb_value_store.h
+++ b/extensions/browser/value_store/leveldb_value_store.h
@@ -11,6 +11,7 @@
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/trace_event/memory_dump_provider.h"
 #include "extensions/browser/value_store/value_store.h"
 #include "third_party/leveldatabase/src/include/leveldb/db.h"
 
@@ -20,7 +21,8 @@ class HistogramBase;
 
 // Value store area, backed by a leveldb database.
 // All methods must be run on the FILE thread.
-class LeveldbValueStore : public ValueStore {
+class LeveldbValueStore : public ValueStore,
+                          public base::trace_event::MemoryDumpProvider {
  public:
   // Creates a database bound to |path|. The underlying database won't be
   // opened (i.e. may not be created) until one of the get/set/etc methods are
@@ -56,6 +58,10 @@ class LeveldbValueStore : public ValueStore {
   // corruption in the database.
   bool WriteToDbForTest(leveldb::WriteBatch* batch);
 
+  // base::trace_event::MemoryDumpProvider implementation.
+  bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
+                    base::trace_event::ProcessMemoryDump* pmd) override;
+
  private:
   // Tries to open the database if it hasn't been opened already.
   scoped_ptr<ValueStore::Error> EnsureDbIsOpen();