base/trace_event/process_memory_dump.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 BASE_TRACE_EVENT_PROCESS_MEMORY_DUMP_H_
#define BASE_TRACE_EVENT_PROCESS_MEMORY_DUMP_H_

#include <stddef.h>

#include <unordered_map>
#include <vector>

#include "base/base_export.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_vector.h"
#include "base/trace_event/memory_allocator_dump.h"
#include "base/trace_event/memory_allocator_dump_guid.h"
#include "base/trace_event/memory_dump_request_args.h"
#include "base/trace_event/memory_dump_session_state.h"
#include "base/trace_event/process_memory_maps.h"
#include "base/trace_event/process_memory_totals.h"
#include "build/build_config.h"

// Define COUNT_RESIDENT_BYTES_SUPPORTED if platform supports counting of the
// resident memory.
#if (defined(OS_POSIX) && !defined(OS_NACL)) || defined(OS_WIN)
#define COUNT_RESIDENT_BYTES_SUPPORTED
#endif

namespace base {
namespace trace_event {

class MemoryDumpSessionState;
class TracedValue;

// ProcessMemoryDump is as a strongly typed container which holds the dumps
// produced by the MemoryDumpProvider(s) for a specific process.
class BASE_EXPORT ProcessMemoryDump {
 public:
  struct MemoryAllocatorDumpEdge {
    MemoryAllocatorDumpGuid source;
    MemoryAllocatorDumpGuid target;
    int importance;
    const char* type;
  };

  // Maps allocator dumps absolute names (allocator_name/heap/subheap) to
  // MemoryAllocatorDump instances.
  using AllocatorDumpsMap =
      std::unordered_map<std::string, std::unique_ptr<MemoryAllocatorDump>>;

  using HeapDumpsMap =
      std::unordered_map<std::string, std::unique_ptr<TracedValue>>;

#if defined(COUNT_RESIDENT_BYTES_SUPPORTED)
  // Returns the number of bytes in a kernel memory page. Some platforms may
  // have a different value for kernel page sizes from user page sizes. It is
  // important to use kernel memory page sizes for resident bytes calculation.
  // In most cases, the two are the same.
  static size_t GetSystemPageSize();

  // Returns the total bytes resident for a virtual address range, with given
  // |start_address| and |mapped_size|. |mapped_size| is specified in bytes. The
  // value returned is valid only if the given range is currently mmapped by the
  // process. The |start_address| must be page-aligned.
  static size_t CountResidentBytes(void* start_address, size_t mapped_size);
#endif

  ProcessMemoryDump(scoped_refptr<MemoryDumpSessionState> session_state,
                    const MemoryDumpArgs& dump_args);
  ~ProcessMemoryDump();

  // Creates a new MemoryAllocatorDump with the given name and returns the
  // empty object back to the caller.
  // Arguments:
  //   absolute_name: a name that uniquely identifies allocator dumps produced
  //       by this provider. It is possible to specify nesting by using a
  //       path-like string (e.g., v8/isolate1/heap1, v8/isolate1/heap2).
  //       Leading or trailing slashes are not allowed.
  //   guid: an optional identifier, unique among all processes within the
  //       scope of a global dump. This is only relevant when using
  //       AddOwnershipEdge() to express memory sharing. If omitted,
  //       it will be automatically generated.
  // ProcessMemoryDump handles the memory ownership of its MemoryAllocatorDumps.
  MemoryAllocatorDump* CreateAllocatorDump(const std::string& absolute_name);
  MemoryAllocatorDump* CreateAllocatorDump(const std::string& absolute_name,
                                           const MemoryAllocatorDumpGuid& guid);

  // Looks up a MemoryAllocatorDump given its allocator and heap names, or
  // nullptr if not found.
  MemoryAllocatorDump* GetAllocatorDump(const std::string& absolute_name) const;

  MemoryAllocatorDump* GetOrCreateAllocatorDump(
      const std::string& absolute_name);

  // Creates a shared MemoryAllocatorDump, to express cross-process sharing.
  // Shared allocator dumps are allowed to have duplicate guids within the
  // global scope, in order to reference the same dump from multiple processes.
  // See the design doc goo.gl/keU6Bf for reference usage patterns.
  MemoryAllocatorDump* CreateSharedGlobalAllocatorDump(
      const MemoryAllocatorDumpGuid& guid);

  // Creates a shared MemoryAllocatorDump as CreateSharedGlobalAllocatorDump,
  // but with a WEAK flag. A weak dump will be discarded unless a non-weak dump
  // is created using CreateSharedGlobalAllocatorDump by at least one process.
  // The WEAK flag does not apply if a non-weak dump with the same GUID already
  // exists or is created later. All owners and children of the discarded dump
  // will also be discarded transitively.
  MemoryAllocatorDump* CreateWeakSharedGlobalAllocatorDump(
      const MemoryAllocatorDumpGuid& guid);

  // Looks up a shared MemoryAllocatorDump given its guid.
  MemoryAllocatorDump* GetSharedGlobalAllocatorDump(
      const MemoryAllocatorDumpGuid& guid) const;

  // Returns the map of the MemoryAllocatorDumps added to this dump.
  const AllocatorDumpsMap& allocator_dumps() const { return allocator_dumps_; }

  // Dumps heap usage with |allocator_name|.
  void DumpHeapUsage(const base::hash_map<base::trace_event::AllocationContext,
                                          base::trace_event::AllocationMetrics>&
                         metrics_by_context,
                     base::trace_event::TraceEventMemoryOverhead& overhead,
                     const char* allocator_name);

  // Adds an ownership relationship between two MemoryAllocatorDump(s) with the
  // semantics: |source| owns |target|, and has the effect of attributing
  // the memory usage of |target| to |source|. |importance| is optional and
  // relevant only for the cases of co-ownership, where it acts as a z-index:
  // the owner with the highest importance will be attributed |target|'s memory.
  void AddOwnershipEdge(const MemoryAllocatorDumpGuid& source,
                        const MemoryAllocatorDumpGuid& target,
                        int importance);
  void AddOwnershipEdge(const MemoryAllocatorDumpGuid& source,
                        const MemoryAllocatorDumpGuid& target);

  const std::vector<MemoryAllocatorDumpEdge>& allocator_dumps_edges() const {
    return allocator_dumps_edges_;
  }

  // Utility method to add a suballocation relationship with the following
  // semantics: |source| is suballocated from |target_node_name|.
  // This creates a child node of |target_node_name| and adds an ownership edge
  // between |source| and the new child node. As a result, the UI will not
  // account the memory of |source| in the target node.
  void AddSuballocation(const MemoryAllocatorDumpGuid& source,
                        const std::string& target_node_name);

  const scoped_refptr<MemoryDumpSessionState>& session_state() const {
    return session_state_;
  }

  // Removes all the MemoryAllocatorDump(s) contained in this instance. This
  // ProcessMemoryDump can be safely reused as if it was new once this returns.
  void Clear();

  // Merges all MemoryAllocatorDump(s) contained in |other| inside this
  // ProcessMemoryDump, transferring their ownership to this instance.
  // |other| will be an empty ProcessMemoryDump after this method returns.
  // This is to allow dump providers to pre-populate ProcessMemoryDump instances
  // and later move their contents into the ProcessMemoryDump passed as argument
  // of the MemoryDumpProvider::OnMemoryDump(ProcessMemoryDump*) callback.
  void TakeAllDumpsFrom(ProcessMemoryDump* other);

  // Called at trace generation time to populate the TracedValue.
  void AsValueInto(TracedValue* value) const;

  ProcessMemoryTotals* process_totals() { return &process_totals_; }
  bool has_process_totals() const { return has_process_totals_; }
  void set_has_process_totals() { has_process_totals_ = true; }

  ProcessMemoryMaps* process_mmaps() { return &process_mmaps_; }
  bool has_process_mmaps() const { return has_process_mmaps_; }
  void set_has_process_mmaps() { has_process_mmaps_ = true; }

  const HeapDumpsMap& heap_dumps() const { return heap_dumps_; }

  const MemoryDumpArgs& dump_args() const { return dump_args_; }

 private:
  FRIEND_TEST_ALL_PREFIXES(ProcessMemoryDumpTest, BackgroundModeTest);

  MemoryAllocatorDump* AddAllocatorDumpInternal(
      std::unique_ptr<MemoryAllocatorDump> mad);

  MemoryAllocatorDump* GetBlackHoleMad();

  ProcessMemoryTotals process_totals_;
  bool has_process_totals_;

  ProcessMemoryMaps process_mmaps_;
  bool has_process_mmaps_;

  AllocatorDumpsMap allocator_dumps_;
  HeapDumpsMap heap_dumps_;

  // State shared among all PMDs instances created in a given trace session.
  scoped_refptr<MemoryDumpSessionState> session_state_;

  // Keeps track of relationships between MemoryAllocatorDump(s).
  std::vector<MemoryAllocatorDumpEdge> allocator_dumps_edges_;

  // Level of detail of the current dump.
  const MemoryDumpArgs dump_args_;

  // This allocator dump is returned when an invalid dump is created in
  // background mode. The attributes of the dump are ignored and not added to
  // the trace.
  std::unique_ptr<MemoryAllocatorDump> black_hole_mad_;

  // When set to true, the DCHECK(s) for invalid dump creations on the
  // background mode are disabled for testing.
  static bool is_black_hole_non_fatal_for_testing_;

  DISALLOW_COPY_AND_ASSIGN(ProcessMemoryDump);
};

}  // namespace trace_event
}  // namespace base

#endif  // BASE_TRACE_EVENT_PROCESS_MEMORY_DUMP_H_