base/trace_event/process_memory_dump.cc

// 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.

#include "base/trace_event/process_memory_dump.h"

#include <errno.h>
#include <vector>

#include "base/process/process_metrics.h"
#include "base/trace_event/process_memory_totals.h"
#include "base/trace_event/trace_event_argument.h"

#if defined(OS_POSIX)
#include <sys/mman.h>
#endif

namespace base {
namespace trace_event {

namespace {

const char kEdgeTypeOwnership[] = "ownership";

std::string GetSharedGlobalAllocatorDumpName(
    const MemoryAllocatorDumpGuid& guid) {
  return "global/" + guid.ToString();
}

}  // namespace

#if defined(COUNT_RESIDENT_BYTES_SUPPORTED)
// static
size_t ProcessMemoryDump::CountResidentBytes(void* start_address,
                                             size_t mapped_size) {
  const size_t page_size = GetPageSize();
  const uintptr_t start_pointer = reinterpret_cast<uintptr_t>(start_address);
  DCHECK_EQ(0u, start_pointer % page_size);

  // This function allocates a char vector of size number of pages in the given
  // mapped_size. To avoid allocating a large array, the memory is split into
  // chunks. Maximum size of vector allocated, will be
  // kPageChunkSize / page_size.
  const size_t kMaxChunkSize = 32 * 1024 * 1024;
  size_t offset = 0;
  size_t total_resident_size = 0;
  int result = 0;
  while (offset < mapped_size) {
    void* chunk_start = reinterpret_cast<void*>(start_pointer + offset);
    const size_t chunk_size = std::min(mapped_size - offset, kMaxChunkSize);
    const size_t page_count = (chunk_size + page_size - 1) / page_size;
    size_t resident_page_count = 0;

#if defined(OS_MACOSX) || defined(OS_IOS)
    std::vector<char> vec(page_count + 1);
    // mincore in MAC does not fail with EAGAIN.
    result = mincore(chunk_start, chunk_size, vec.data());
    if (result)
      break;

    for (size_t i = 0; i < page_count; i++)
      resident_page_count += vec[i] & MINCORE_INCORE ? 1 : 0;
#else   // defined(OS_MACOSX) || defined(OS_IOS)
    std::vector<unsigned char> vec(page_count + 1);
    int error_counter = 0;
    // HANDLE_EINTR tries for 100 times. So following the same pattern.
    do {
      result = mincore(chunk_start, chunk_size, vec.data());
    } while (result == -1 && errno == EAGAIN && error_counter++ < 100);
    if (result)
      break;

    for (size_t i = 0; i < page_count; i++)
      resident_page_count += vec[i];
#endif  // defined(OS_MACOSX) || defined(OS_IOS)

    total_resident_size += resident_page_count * page_size;
    offset += kMaxChunkSize;
  }

  DCHECK_EQ(0, result);
  if (result) {
    total_resident_size = 0;
    LOG(ERROR) << "mincore() call failed. The resident size is invalid";
  }
  return total_resident_size;
}
#endif  // defined(COUNT_RESIDENT_BYTES_SUPPORTED)

ProcessMemoryDump::ProcessMemoryDump(
    const scoped_refptr<MemoryDumpSessionState>& session_state)
    : has_process_totals_(false),
      has_process_mmaps_(false),
      session_state_(session_state) {
}

ProcessMemoryDump::~ProcessMemoryDump() {
}

MemoryAllocatorDump* ProcessMemoryDump::CreateAllocatorDump(
    const std::string& absolute_name) {
  MemoryAllocatorDump* mad = new MemoryAllocatorDump(absolute_name, this);
  AddAllocatorDumpInternal(mad);  // Takes ownership of |mad|.
  return mad;
}

MemoryAllocatorDump* ProcessMemoryDump::CreateAllocatorDump(
    const std::string& absolute_name,
    const MemoryAllocatorDumpGuid& guid) {
  MemoryAllocatorDump* mad = new MemoryAllocatorDump(absolute_name, this, guid);
  AddAllocatorDumpInternal(mad);  // Takes ownership of |mad|.
  return mad;
}

void ProcessMemoryDump::AddAllocatorDumpInternal(MemoryAllocatorDump* mad) {
  DCHECK_EQ(0ul, allocator_dumps_.count(mad->absolute_name()));
  allocator_dumps_storage_.push_back(mad);
  allocator_dumps_[mad->absolute_name()] = mad;
}

MemoryAllocatorDump* ProcessMemoryDump::GetAllocatorDump(
    const std::string& absolute_name) const {
  auto it = allocator_dumps_.find(absolute_name);
  return it == allocator_dumps_.end() ? nullptr : it->second;
}

MemoryAllocatorDump* ProcessMemoryDump::GetOrCreateAllocatorDump(
    const std::string& absolute_name) {
  MemoryAllocatorDump* mad = GetAllocatorDump(absolute_name);
  return mad ? mad : CreateAllocatorDump(absolute_name);
}

MemoryAllocatorDump* ProcessMemoryDump::CreateSharedGlobalAllocatorDump(
    const MemoryAllocatorDumpGuid& guid) {
  // A shared allocator dump can be shared within a process and the guid could
  // have been created already.
  MemoryAllocatorDump* allocator_dump = GetSharedGlobalAllocatorDump(guid);
  return allocator_dump ? allocator_dump
                        : CreateAllocatorDump(
                              GetSharedGlobalAllocatorDumpName(guid), guid);
}

MemoryAllocatorDump* ProcessMemoryDump::GetSharedGlobalAllocatorDump(
    const MemoryAllocatorDumpGuid& guid) const {
  return GetAllocatorDump(GetSharedGlobalAllocatorDumpName(guid));
}

void ProcessMemoryDump::AddHeapDump(const std::string& absolute_name,
                                    scoped_refptr<TracedValue> heap_dump) {
  DCHECK_EQ(0ul, heap_dumps_.count(absolute_name));
  heap_dumps_[absolute_name] = heap_dump;
}

void ProcessMemoryDump::Clear() {
  if (has_process_totals_) {
    process_totals_.Clear();
    has_process_totals_ = false;
  }

  if (has_process_mmaps_) {
    process_mmaps_.Clear();
    has_process_mmaps_ = false;
  }

  allocator_dumps_storage_.clear();
  allocator_dumps_.clear();
  allocator_dumps_edges_.clear();
  heap_dumps_.clear();
}

void ProcessMemoryDump::TakeAllDumpsFrom(ProcessMemoryDump* other) {
  DCHECK(!other->has_process_totals() && !other->has_process_mmaps());

  // Moves the ownership of all MemoryAllocatorDump(s) contained in |other|
  // into this ProcessMemoryDump.
  for (MemoryAllocatorDump* mad : other->allocator_dumps_storage_) {
    // Check that we don't merge duplicates.
    DCHECK_EQ(0ul, allocator_dumps_.count(mad->absolute_name()));
    allocator_dumps_storage_.push_back(mad);
    allocator_dumps_[mad->absolute_name()] = mad;
  }
  other->allocator_dumps_storage_.weak_clear();
  other->allocator_dumps_.clear();

  // Move all the edges.
  allocator_dumps_edges_.insert(allocator_dumps_edges_.end(),
                                other->allocator_dumps_edges_.begin(),
                                other->allocator_dumps_edges_.end());
  other->allocator_dumps_edges_.clear();

  heap_dumps_.insert(other->heap_dumps_.begin(), other->heap_dumps_.end());
  other->heap_dumps_.clear();
}

void ProcessMemoryDump::AsValueInto(TracedValue* value) const {
  if (has_process_totals_) {
    value->BeginDictionary("process_totals");
    process_totals_.AsValueInto(value);
    value->EndDictionary();
  }

  if (has_process_mmaps_) {
    value->BeginDictionary("process_mmaps");
    process_mmaps_.AsValueInto(value);
    value->EndDictionary();
  }

  if (allocator_dumps_storage_.size() > 0) {
    value->BeginDictionary("allocators");
    for (const MemoryAllocatorDump* allocator_dump : allocator_dumps_storage_)
      allocator_dump->AsValueInto(value);
    value->EndDictionary();
  }

  if (heap_dumps_.size() > 0) {
    value->BeginDictionary("heaps");
    for (const auto& name_and_dump : heap_dumps_)
      value->SetValueWithCopiedName(name_and_dump.first, *name_and_dump.second);
    value->EndDictionary();  // "heaps"
  }

  value->BeginArray("allocators_graph");
  for (const MemoryAllocatorDumpEdge& edge : allocator_dumps_edges_) {
    value->BeginDictionary();
    value->SetString("source", edge.source.ToString());
    value->SetString("target", edge.target.ToString());
    value->SetInteger("importance", edge.importance);
    value->SetString("type", edge.type);
    value->EndDictionary();
  }
  value->EndArray();
}

void ProcessMemoryDump::AddOwnershipEdge(const MemoryAllocatorDumpGuid& source,
                                         const MemoryAllocatorDumpGuid& target,
                                         int importance) {
  allocator_dumps_edges_.push_back(
      {source, target, importance, kEdgeTypeOwnership});
}

void ProcessMemoryDump::AddOwnershipEdge(
    const MemoryAllocatorDumpGuid& source,
    const MemoryAllocatorDumpGuid& target) {
  AddOwnershipEdge(source, target, 0 /* importance */);
}

void ProcessMemoryDump::AddSuballocation(const MemoryAllocatorDumpGuid& source,
                                         const std::string& target_node_name) {
  std::string child_mad_name = target_node_name + "/__" + source.ToString();
  MemoryAllocatorDump* target_child_mad = CreateAllocatorDump(child_mad_name);
  AddOwnershipEdge(source, target_child_mad->guid());
}

}  // namespace trace_event
}  // namespace base