components/metrics: Add runtime memory leak detector

components/metrics/leak_detector/leak_detector_impl.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 "leak_detector_impl.h"
+
+#include <inttypes.h>
+#include <stddef.h>
+#include <stdint.h>

[wtc, 2015/08/21 20:02:12]

Nit: <stdint.h> can be omitted since we already include <inttypes.h>, which is a
superset.

See http://pubs.opengroup.org/onlinepubs/009604599/basedefs/inttypes.h.html

[Simon Que, 2015/08/22 22:41:51]

Done.

+
+#include <algorithm>
+#include <new>
+
+#include "base/hash.h"
+#include "components/metrics/leak_detector/call_stack_table.h"
+#include "components/metrics/leak_detector/ranked_list.h"
+
+namespace leak_detector {
+
+namespace {
+
+// Look for leaks in the the top N entries in each tier, where N is this value.
+const int kRankedListSize = 16;
+
+// Initial hash table size for |LeakDetectorImpl::address_map_|.
+const int kAddressMapNumBuckets = 100003;
+
+// Number of entries in the alloc size table. As sizes are aligned to 32-bits
+// the max supported allocation size is (kNumSizeEntries * 4 - 1). Any larger
+// sizes are ignored. This value is chosen high enough that such large sizes
+// are rare if not nonexistent.
+const int kNumSizeEntries = 2048;
+
+using ValueType = LeakDetectorValueType;
+
+// Prints the input string buffer using RAW_LOG, pre-fixing each line with the
+// process id.
+void PrintWithPidOnEachLine(char* buf) {
+  char *ptr = strchr(buf, '\n');
+  do {
+    // Break up the string.
+    if (ptr)
+      *ptr = '\0';
+    // Print out the former part.
+    char line[1024];
+    snprintf(line, sizeof(line), "%d: %s\n", getpid(), buf);
+    RAW_LOG(ERROR, line);
+
+    // Re-point |buf| to the latter part.
+    if (ptr)
+      buf = ptr + 1;
+    ptr = strchr(buf, '\n');
+  } while (ptr);
+}
+
+// Functions to convert an allocation size to/from the array index used for
+// |LeakDetectorImpl::size_entries_|.
+int SizeToIndex(size_t size){
+  int result = static_cast<int>(size /= sizeof(uint32_t));
+  if (result < kNumSizeEntries)
+    return result;
+  return 0;
+}
+
+size_t IndexToSize(int index){
+  return sizeof(uint32_t) * index;
+}
+
+}  // namespace
+
+LeakDetectorImpl::LeakDetectorImpl(uintptr_t mapping_addr,
+                                   size_t mapping_size,
+                                   int size_suspicion_threshold,
+                                   int call_stack_suspicion_threshold,
+                                   bool verbose)
+    : num_stack_tables_(0),
+      address_map_(kAddressMapNumBuckets),
+      size_leak_analyzer_(kRankedListSize, size_suspicion_threshold),
+      size_entries_(kNumSizeEntries, {0}),
+      mapping_addr_(mapping_addr),
+      mapping_size_(mapping_size),
+      call_stack_suspicion_threshold_(call_stack_suspicion_threshold),
+      verbose_(verbose) {
+}
+
+LeakDetectorImpl::~LeakDetectorImpl() {
+  for (CallStack* call_stack : call_stacks_)
+    CustomAllocator::Free(call_stack, sizeof(CallStack));
+
+  // Free any call stack tables.
+  for (AllocSizeEntry& entry : size_entries_) {
+    CallStackTable* table = entry.stack_table;
+    if (!table)
+      continue;
+    table->~CallStackTable();
+    CustomAllocator::Free(table, sizeof(CallStackTable));
+  }
+}
+
+bool LeakDetectorImpl::ShouldGetStackTraceForSize(size_t size) const {
+  return size_entries_[SizeToIndex(size)].stack_table != nullptr;
+}
+
+void LeakDetectorImpl::RecordAlloc(
+    const void* ptr, size_t size,
+    int stack_depth, const void* const stack[]) {
+  AllocInfo alloc_info;
+  alloc_info.size = size;
+
+  alloc_size_ += alloc_info.size;
+  ++num_allocs_;
+
+  AllocSizeEntry* entry = &size_entries_[SizeToIndex(size)];
+  ++entry->num_allocs;
+
+  if (stack_depth > 0) {
+    CallStack* call_stack = GetCallStack(stack_depth, stack);
+    alloc_info.call_stack = call_stack;
+
+    ++num_allocs_with_call_stack_;
+
+    if (entry->stack_table)
+      entry->stack_table->Add(call_stack);
+  }
+
+  address_map_.insert(std::pair<const void*, AllocInfo>(ptr, alloc_info));
+}
+
+void LeakDetectorImpl::RecordFree(const void* ptr) {
+  // Look up entry.
+  auto iter = address_map_.find(ptr);
+  if (iter == address_map_.end())
+    return;
+
+  const AllocInfo& alloc_info = iter->second;
+
+  AllocSizeEntry* entry = &size_entries_[SizeToIndex(alloc_info.size)];
+  ++entry->num_frees;
+
+  const CallStack* call_stack = alloc_info.call_stack;
+  if (call_stack) {
+    if (entry->stack_table)
+      entry->stack_table->Remove(call_stack);
+  }
+  ++num_frees_;
+  free_size_ += alloc_info.size;
+
+  address_map_.erase(iter);
+}
+
+void LeakDetectorImpl::TestForLeaks() {
+  // Add net alloc counts for each size to a ranked list.
+  RankedList size_ranked_list(kRankedListSize);
+  for (size_t i = 0; i < size_entries_.size(); ++i) {
+    const AllocSizeEntry& entry = size_entries_[i];
+    ValueType size_value(IndexToSize(i));
+    size_ranked_list.Add(size_value, entry.num_allocs - entry.num_frees);
+  }
+  size_leak_analyzer_.AddSample(size_ranked_list);
+
+  // Dump out the top entries.
+  char buf[0x4000];
+  if (verbose_) {
+    buf[0] = '\0';
+    size_leak_analyzer_.Dump(buf, sizeof(buf));
+    PrintWithPidOnEachLine(buf);
+  }
+
+  // Get suspected leaks by size.
+  for (const ValueType& size_value : size_leak_analyzer_.suspected_leaks()) {
+    uint32_t size = size_value.size();
+    AllocSizeEntry* entry = &size_entries_[SizeToIndex(size)];
+    if (entry->stack_table)
+      continue;
+    snprintf(buf, sizeof(buf), "Adding stack table for size %u\n", size);
+    PrintWithPidOnEachLine(buf);
+    entry->stack_table = new(CustomAllocator::Allocate(sizeof(CallStackTable)))
+        CallStackTable(call_stack_suspicion_threshold_);
+    ++num_stack_tables_;
+  }
+
+  // Check for leaks in each CallStackTable. It makes sense to this before
+  // checking the size allocations, because that could potentially create new
+  // CallStackTable. However, the overhead to check a new CallStackTable is
+  // small since this function is run very rarely. So handle the leak checks of
+  // Tier 2 here.
+  for (size_t i = 0; i < size_entries_.size(); ++i) {
+    const AllocSizeEntry& entry = size_entries_[i];
+    CallStackTable* stack_table = entry.stack_table;
+    if (!stack_table || stack_table->empty())
+      continue;
+
+    if (verbose_) {
+      // Dump table info.
+      snprintf(buf, sizeof(buf), "Stack table for size %zu:\n", IndexToSize(i));
+      PrintWithPidOnEachLine(buf);
+
+      buf[0] = '\0';
+      stack_table->Dump(buf, sizeof(buf));
+      PrintWithPidOnEachLine(buf);
+    }
+
+    // Get suspected leaks by call stack.
+    stack_table->TestForLeaks();
+    const LeakAnalyzer& leak_analyzer = stack_table->leak_analyzer();
+    for (const ValueType& call_stack_value : leak_analyzer.suspected_leaks()) {
+      const CallStack* call_stack = call_stack_value.call_stack();
+      int offset = snprintf(buf, sizeof(buf),
+                            "Suspected call stack for size %zu, %p:\n",
+                            IndexToSize(i), call_stack);
+      for (size_t j = 0; j < call_stack->depth; ++j) {
+        offset += snprintf(buf + offset, sizeof(buf) - offset,
+                           "\t%" PRIxPTR "\n", GetOffset(call_stack->stack[j]));
+      }
+      PrintWithPidOnEachLine(buf);
+    }
+  }
+}
+
+void LeakDetectorImpl::DumpStats() const {
+  char buf[1024];
+  snprintf(buf, sizeof(buf),
+           "Alloc size: %" PRIu64"\n"
+           "Free size: %" PRIu64 "\n"
+           "Net alloc size: %" PRIu64 "\n"
+           "Number of stack tables: %u\n"
+           "Percentage of allocs with stack traces: %.2f%%\n"
+           "Number of call stack buckets: %zu\n",
+           alloc_size_, free_size_, alloc_size_ - free_size_, num_stack_tables_,
+           num_allocs_ ? 100.0f * num_allocs_with_call_stack_ / num_allocs_ : 0,
+           call_stacks_.bucket_count());
+  PrintWithPidOnEachLine(buf);
+}
+
+size_t LeakDetectorImpl::AddressHash::operator() (const void* ptr) const {
+  return base::Hash(reinterpret_cast<const char*>(&ptr), sizeof(ptr));
+}
+
+size_t LeakDetectorImpl::CallStackHash::operator() (
+    const CallStack* call_stack) const {
+  // Generate hash from call stack.
+  return base::Hash(reinterpret_cast<const char*>(call_stack->stack),
+                    sizeof(*(call_stack->stack)) * call_stack->depth);
+}
+
+CallStack* LeakDetectorImpl::GetCallStack(
+    int depth, const void* const stack[]) {
+  // Temporarily create a call stack object for lookup in |call_stacks_|.
+  CallStack temp;
+  temp.depth = depth;
+  temp.stack = const_cast<const void**>(stack);
+
+  auto iter = call_stacks_.find(&temp);
+  if (iter != call_stacks_.end())
+    return *iter;
+
+  // Since |call_stacks_| stores CallStack pointers rather than actual objects,
+  // create new call objects manually here.
+  CallStack* new_call_stack =
+      new(CustomAllocator::Allocate(sizeof(CallStack))) CallStack;
+  memset(new_call_stack, 0, sizeof(*new_call_stack));
+  new_call_stack->depth = depth;
+  new_call_stack->hash = call_stacks_.hash_function()(&temp);
+  new_call_stack->stack =
+      reinterpret_cast<const void**>(
+          CustomAllocator::Allocate(sizeof(*stack) * depth));
+  std::copy(stack, stack + depth, new_call_stack->stack);
+
+  call_stacks_.insert(new_call_stack);
+  return new_call_stack;
+}
+
+uintptr_t LeakDetectorImpl::GetOffset(const void *ptr) const {
+  uintptr_t ptr_value = reinterpret_cast<uintptr_t>(ptr);
+  if (ptr_value >= mapping_addr_ && ptr_value < mapping_addr_ + mapping_size_)
+    return ptr_value - mapping_addr_;
+  return ptr_value;
+}
+
+}  // namespace leak_detector