components/metrics: Add runtime memory leak detector

components/metrics/leak_detector/call_stack_table.h

+// Copyright 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 COMPONENTS_METRICS_LEAK_DETECTOR_CALL_STACK_TABLE_H_
+#define COMPONENTS_METRICS_LEAK_DETECTOR_CALL_STACK_TABLE_H_
+
+#include <stdint.h>
+
+#include <functional>  // For std::equal_to.
+
+#include "base/containers/hash_tables.h"
+#include "base/macros.h"
+#include "components/metrics/leak_detector/custom_allocator.h"
+#include "components/metrics/leak_detector/leak_analyzer.h"
+#include "components/metrics/leak_detector/stl_allocator.h"
+
+namespace metrics {
+namespace leak_detector {
+
+struct CallStack;
+
+// Contains a hash table where the key is the call stack and the value is the
+// number of allocations from that call stack.
+// Not thread-safe.
+class CallStackTable {
+ public:
+  struct StoredHash {
+    size_t operator()(const CallStack* call_stack) const;
+  };
+
+  explicit CallStackTable(int call_stack_suspicion_threshold);
+  ~CallStackTable();
+
+  // Add/Remove an allocation for the given call stack.
+  // Note that this class does NOT own the CallStack objects. Instead, it
+  // identifies different CallStacks by their hashes.
+  void Add(const CallStack* call_stack);
+  void Remove(const CallStack* call_stack);
+
+  // Check for leak patterns in the allocation data.
+  void TestForLeaks();
+
+  const LeakAnalyzer& leak_analyzer() const { return leak_analyzer_; }
+
+  size_t size() const { return entry_map_.size(); }
+  bool empty() const { return entry_map_.empty(); }
+
+  uint32_t num_allocs() const { return num_allocs_; }
+  uint32_t num_frees() const { return num_frees_; }
+
+ private:
+  // Hash table entry used to track allocation stats for a given call stack.
+  struct Entry {
+    // Net number of allocs (allocs minus frees).
+    uint32_t net_num_allocs;
+  };
+
+  // Total number of allocs and frees in this table.
+  uint32_t num_allocs_;
+  uint32_t num_frees_;
+
+  // Hash table containing entries.
+  using TableEntryAllocator =
+      STLAllocator<std::pair<const CallStack*, Entry>, CustomAllocator>;
+  base::hash_map<const CallStack*,
+                 Entry,
+                 StoredHash,
+                 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
+}  // namespace metrics
+
+#endif  // COMPONENTS_METRICS_LEAK_DETECTOR_CALL_STACK_TABLE_H_