components/metrics: Add runtime memory leak detector

third_party/tcmalloc/chromium/src/call_stack_table.h

+// Copyright (c) 2015 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.
+
+#ifndef _CALL_STACK_TABLE_H_
+#define _CALL_STACK_TABLE_H_
+
+#include <unordered_map>
+#include <functional>
+
+#include "base/basictypes.h"
+#include "base/custom_allocator.h"
+#include "base/stl_allocator.h"
+#include "heap-profile-stats.h"
+#include "leak_analyzer.h"
+
+namespace leak_detector {
+
+// Contains a hash table where the key is the call stack and the value is the
+// number of allocations from that call stack.
+class CallStackTable {
+ public:
+  // Represents a unique call stack.
+  using CallStack = HeapProfileBucket;
+
+  struct Hash {
+    long operator() (const CallStack* call_stack) const {
+      // The call stack object should already have a hash computed when it was
+      // created.
+      return call_stack->hash;
+    }
+  };
+
+  CallStackTable();
+  ~CallStackTable();
+
+  // Add/Remove an allocation for the given call stack.
+  void Add(const CallStack* call_stack);
+  void Remove(const CallStack* call_stack);
+
+  // Dump contents to log buffer |buffer| of size |size|.
+  int Dump(char* buffer, int size) const;
+
+  // Check for leak patterns in the allocation data.
+  void TestForLeaks();
+
+  const LeakAnalyzer& leak_analyzer() const {
+    return leak_analyzer_;
+  }
+
+ private:
+  // Hash table entry used to track number of allocs and frees for a call stack.
+  // Do not use the fields of struct HeapProfileBucket for this purpose; one
+  // call stack object can have different entries in multiple CallStackTables.
+  struct Entry {
+    // Number of allocs/frees for the call stack.
+    uint32 num_allocs;
+    uint32 num_frees;
+  };
+
+  // The total number of recorded allocations when this object was created. This
+  // acts as a timestamp of sorts.
+  uint64_t total_num_allocs_at_creation_;
+
+  // Total number of allocs and frees in this table.
+  uint32 num_allocs_;
+  uint32 num_frees_;
+
+  // Hash table containing entries.
+  using TableEntryAllocator =
+      STL_Allocator<std::pair<const CallStack*, Entry>, CustomAllocator>;
+  std::unordered_map<const CallStack*,
+                     Entry,
+                     Hash,
+                     std::equal_to<const CallStack*>,
+                     TableEntryAllocator> entry_map_;
+
+  // For detecting leak patterns in incoming allocations.
+  LeakAnalyzer leak_analyzer_;
+
+  DISALLOW_COPY_AND_ASSIGN(CallStackTable);
+};
+
+}  // namespace leak_detector
+
+#endif  // _CALL_STACK_TABLE_H_