malloc_dump_provider.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/malloc_dump_provider.h"

#include <stddef.h>

#include "base/allocator/allocator_extension.h"
#include "base/allocator/allocator_shim.h"
#include "base/allocator/features.h"
#include "base/debug/profiler.h"
#include "base/trace_event/heap_profiler_allocation_context.h"
#include "base/trace_event/heap_profiler_allocation_context_tracker.h"
#include "base/trace_event/heap_profiler_allocation_register.h"
#include "base/trace_event/heap_profiler_heap_dump_writer.h"
#include "base/trace_event/process_memory_dump.h"
#include "base/trace_event/trace_event_argument.h"
#include "build/build_config.h"

#if defined(OS_MACOSX)
#include <malloc/malloc.h>
#else
#include <malloc.h>
#endif
#if defined(OS_WIN)
#include <windows.h>
#endif

namespace base {
namespace trace_event {

namespace {
#if BUILDFLAG(USE_EXPERIMENTAL_ALLOCATOR_SHIM)

using allocator::AllocatorDispatch;

void* HookAlloc(const AllocatorDispatch* self, size_t size) {
  const AllocatorDispatch* const next = self->next;
  void* ptr = next->alloc_function(next, size);
  if (ptr)
    MallocDumpProvider::GetInstance()->InsertAllocation(ptr, size);
  return ptr;
}

void* HookZeroInitAlloc(const AllocatorDispatch* self, size_t n, size_t size) {
  const AllocatorDispatch* const next = self->next;
  void* ptr = next->alloc_zero_initialized_function(next, n, size);
  if (ptr)
    MallocDumpProvider::GetInstance()->InsertAllocation(ptr, n * size);
  return ptr;
}

void* HookllocAligned(const AllocatorDispatch* self,
                      size_t alignment,
                      size_t size) {
  const AllocatorDispatch* const next = self->next;
  void* ptr = next->alloc_aligned_function(next, alignment, size);
  if (ptr)
    MallocDumpProvider::GetInstance()->InsertAllocation(ptr, size);
  return ptr;
}

void* HookRealloc(const AllocatorDispatch* self, void* address, size_t size) {
  const AllocatorDispatch* const next = self->next;
  void* ptr = next->realloc_function(next, address, size);
  MallocDumpProvider::GetInstance()->RemoveAllocation(address);
  if (size > 0)  // realloc(size == 0) means free().
    MallocDumpProvider::GetInstance()->InsertAllocation(ptr, size);
  return ptr;
}

void HookFree(const AllocatorDispatch* self, void* address) {
  if (address)
    MallocDumpProvider::GetInstance()->RemoveAllocation(address);
  const AllocatorDispatch* const next = self->next;
  next->free_function(next, address);
}

size_t HookGetSizeEstimate(const AllocatorDispatch* self, void* address) {
  const AllocatorDispatch* const next = self->next;
  return next->get_size_estimate_function(next, address);
}

AllocatorDispatch g_allocator_hooks = {
    &HookAlloc,           /* alloc_function */
    &HookZeroInitAlloc,   /* alloc_zero_initialized_function */
    &HookllocAligned,     /* alloc_aligned_function */
    &HookRealloc,         /* realloc_function */
    &HookFree,            /* free_function */
    &HookGetSizeEstimate, /* get_size_estimate_function */
    nullptr,              /* next */
};
#endif  // BUILDFLAG(USE_EXPERIMENTAL_ALLOCATOR_SHIM)

#if defined(OS_WIN)
// A structure containing some information about a given heap.
struct WinHeapInfo {
  HANDLE heap_id;
  size_t committed_size;
  size_t uncommitted_size;
  size_t allocated_size;
  size_t block_count;
};

bool GetHeapInformation(WinHeapInfo* heap_info,
                        const std::set<void*>& block_to_skip) {
  CHECK(::HeapLock(heap_info->heap_id) == TRUE);
  PROCESS_HEAP_ENTRY heap_entry;
  heap_entry.lpData = nullptr;
  // Walk over all the entries in this heap.
  while (::HeapWalk(heap_info->heap_id, &heap_entry) != FALSE) {
    if (block_to_skip.count(heap_entry.lpData) == 1)
      continue;
    if ((heap_entry.wFlags & PROCESS_HEAP_ENTRY_BUSY) != 0) {
      heap_info->allocated_size += heap_entry.cbData;
      heap_info->block_count++;
    } else if ((heap_entry.wFlags & PROCESS_HEAP_REGION) != 0) {
      heap_info->committed_size += heap_entry.Region.dwCommittedSize;
      heap_info->uncommitted_size += heap_entry.Region.dwUnCommittedSize;
    }
  }
  CHECK(::HeapUnlock(heap_info->heap_id) == TRUE);
  return true;
}

void WinHeapMemoryDumpImpl(WinHeapInfo* all_heap_info) {
// This method might be flaky for 2 reasons:
//   - GetProcessHeaps is racy by design. It returns a snapshot of the
//     available heaps, but there's no guarantee that that snapshot remains
//     valid. If a heap disappears between GetProcessHeaps() and HeapWalk()
//     then chaos should be assumed. This flakyness is acceptable for tracing.
//   - The MSDN page for HeapLock says: "If the HeapLock function is called on
//     a heap created with the HEAP_NO_SERIALIZATION flag, the results are
//     undefined."
//   - Note that multiple heaps occur on Windows primarily because system and
//     3rd party DLLs will each create their own private heap. It's possible to
//     retrieve the heap the CRT allocates from and report specifically on that
//     heap. It's interesting to report all heaps, as e.g. loading or invoking
//     on a Windows API may consume memory from a private heap.
#if defined(SYZYASAN)
  if (base::debug::IsBinaryInstrumented())
    return;
#endif

  // Retrieves the number of heaps in the current process.
  DWORD number_of_heaps = ::GetProcessHeaps(0, NULL);

  // Try to retrieve a handle to all the heaps owned by this process. Returns
  // false if the number of heaps has changed.
  //
  // This is inherently racy as is, but it's not something that we observe a lot
  // in Chrome, the heaps tend to be created at startup only.
  std::unique_ptr<HANDLE[]> all_heaps(new HANDLE[number_of_heaps]);
  if (::GetProcessHeaps(number_of_heaps, all_heaps.get()) != number_of_heaps)
    return;

  // Skip the pointer to the heap array to avoid accounting the memory used by
  // this dump provider.
  std::set<void*> block_to_skip;
  block_to_skip.insert(all_heaps.get());

  // Retrieves some metrics about each heap.
  for (size_t i = 0; i < number_of_heaps; ++i) {
    WinHeapInfo heap_info = {0};
    heap_info.heap_id = all_heaps[i];
    GetHeapInformation(&heap_info, block_to_skip);

    all_heap_info->allocated_size += heap_info.allocated_size;
    all_heap_info->committed_size += heap_info.committed_size;
    all_heap_info->uncommitted_size += heap_info.uncommitted_size;
    all_heap_info->block_count += heap_info.block_count;
  }
}
#endif  // defined(OS_WIN)
}  // namespace

// static
const char MallocDumpProvider::kAllocatedObjects[] = "malloc/allocated_objects";

// static
MallocDumpProvider* MallocDumpProvider::GetInstance() {
  return Singleton<MallocDumpProvider,
                   LeakySingletonTraits<MallocDumpProvider>>::get();
}

MallocDumpProvider::MallocDumpProvider()
    : heap_profiler_enabled_(false), tid_dumping_heap_(kInvalidThreadId) {}

MallocDumpProvider::~MallocDumpProvider() {}

// Called at trace dump point time. Creates a snapshot the memory counters for
// the current process.
bool MallocDumpProvider::OnMemoryDump(const MemoryDumpArgs& args,
                                      ProcessMemoryDump* pmd) {
  size_t total_virtual_size = 0;
  size_t resident_size = 0;
  size_t allocated_objects_size = 0;
  size_t allocated_objects_count = 0;
#if defined(USE_TCMALLOC)
  bool res =
      allocator::GetNumericProperty("generic.heap_size", &total_virtual_size);
  DCHECK(res);
  res = allocator::GetNumericProperty("generic.total_physical_bytes",
                                      &resident_size);
  DCHECK(res);
  res = allocator::GetNumericProperty("generic.current_allocated_bytes",
                                      &allocated_objects_size);
  DCHECK(res);
#elif defined(OS_MACOSX) || defined(OS_IOS)
  malloc_statistics_t stats = {0};
  malloc_zone_statistics(nullptr, &stats);
  total_virtual_size = stats.size_allocated;
  allocated_objects_size = stats.size_in_use;

  // The resident size is approximated to the max size in use, which would count
  // the total size of all regions other than the free bytes at the end of each
  // region. In each allocation region the allocations are rounded off to a
  // fixed quantum, so the excess region will not be resident.
  // See crrev.com/1531463004 for detailed explanation.
  resident_size = stats.max_size_in_use;
#elif defined(OS_WIN)
  WinHeapInfo all_heap_info = {};
  WinHeapMemoryDumpImpl(&all_heap_info);
  total_virtual_size =
      all_heap_info.committed_size + all_heap_info.uncommitted_size;
  // Resident size is approximated with committed heap size. Note that it is
  // possible to do this with better accuracy on windows by intersecting the
  // working set with the virtual memory ranges occuipied by the heap. It's not
  // clear that this is worth it, as it's fairly expensive to do.
  resident_size = all_heap_info.committed_size;
  allocated_objects_size = all_heap_info.allocated_size;
  allocated_objects_count = all_heap_info.block_count;
#else
  struct mallinfo info = mallinfo();
  DCHECK_GE(info.arena + info.hblkhd, info.uordblks);

  // In case of Android's jemalloc |arena| is 0 and the outer pages size is
  // reported by |hblkhd|. In case of dlmalloc the total is given by
  // |arena| + |hblkhd|. For more details see link: http://goo.gl/fMR8lF.
  total_virtual_size = info.arena + info.hblkhd;
  resident_size = info.uordblks;

  // Total allocated space is given by |uordblks|.
  allocated_objects_size = info.uordblks;
#endif

  MemoryAllocatorDump* outer_dump = pmd->CreateAllocatorDump("malloc");
  outer_dump->AddScalar("virtual_size", MemoryAllocatorDump::kUnitsBytes,
                        total_virtual_size);
  outer_dump->AddScalar(MemoryAllocatorDump::kNameSize,
                        MemoryAllocatorDump::kUnitsBytes, resident_size);

  MemoryAllocatorDump* inner_dump = pmd->CreateAllocatorDump(kAllocatedObjects);
  inner_dump->AddScalar(MemoryAllocatorDump::kNameSize,
                        MemoryAllocatorDump::kUnitsBytes,
                        allocated_objects_size);
  if (allocated_objects_count != 0) {
    inner_dump->AddScalar(MemoryAllocatorDump::kNameObjectCount,
                          MemoryAllocatorDump::kUnitsObjects,
                          allocated_objects_count);
  }

  if (resident_size > allocated_objects_size) {
    // Explicitly specify why is extra memory resident. In tcmalloc it accounts
    // for free lists and caches. In mac and ios it accounts for the
    // fragmentation and metadata.
    MemoryAllocatorDump* other_dump =
        pmd->CreateAllocatorDump("malloc/metadata_fragmentation_caches");
    other_dump->AddScalar(MemoryAllocatorDump::kNameSize,
                          MemoryAllocatorDump::kUnitsBytes,
                          resident_size - allocated_objects_size);
  }

  // Heap profiler dumps.
  if (!heap_profiler_enabled_)
    return true;

  // The dumps of the heap profiler should be created only when heap profiling
  // was enabled (--enable-heap-profiling) AND a DETAILED dump is requested.
  // However, when enabled, the overhead of the heap profiler should be always
  // reported to avoid oscillations of the malloc total in LIGHT dumps.

  tid_dumping_heap_ = PlatformThread::CurrentId();
  // At this point the Insert/RemoveAllocation hooks will ignore this thread.
  // Enclosing all the temporariy data structures in a scope, so that the heap
  // profiler does not see unabalanced malloc/free calls from these containers.
  {
    TraceEventMemoryOverhead overhead;
    hash_map<AllocationContext, AllocationMetrics> metrics_by_context;
    {
      AutoLock lock(allocation_register_lock_);
      if (allocation_register_) {
        if (args.level_of_detail == MemoryDumpLevelOfDetail::DETAILED) {
          for (const auto& alloc_size : *allocation_register_) {
            AllocationMetrics& metrics = metrics_by_context[alloc_size.context];
            metrics.size += alloc_size.size;
            metrics.count++;
          }
        }
        allocation_register_->EstimateTraceMemoryOverhead(&overhead);
      }
    }  // lock(allocation_register_lock_)
    pmd->DumpHeapUsage(metrics_by_context, overhead, "malloc");
  }
  tid_dumping_heap_ = kInvalidThreadId;

  return true;
}

void MallocDumpProvider::OnHeapProfilingEnabled(bool enabled) {
#if BUILDFLAG(USE_EXPERIMENTAL_ALLOCATOR_SHIM)
  if (enabled) {
    {
      AutoLock lock(allocation_register_lock_);
      allocation_register_.reset(new AllocationRegister());
    }
    allocator::InsertAllocatorDispatch(&g_allocator_hooks);
  } else {
    AutoLock lock(allocation_register_lock_);
    allocation_register_.reset();
    // Insert/RemoveAllocation below will no-op if the register is torn down.
    // Once disabled, heap profiling will not re-enabled anymore for the
    // lifetime of the process.
  }
#endif
  heap_profiler_enabled_ = enabled;
}

void MallocDumpProvider::InsertAllocation(void* address, size_t size) {
  // CurrentId() can be a slow operation (crbug.com/497226). This apparently
  // redundant condition short circuits the CurrentID() calls when unnecessary.
  if (tid_dumping_heap_ != kInvalidThreadId &&
      tid_dumping_heap_ == PlatformThread::CurrentId())
    return;

  // AllocationContextTracker will return nullptr when called re-reentrantly.
  // This is the case of GetInstanceForCurrentThread() being called for the
  // first time, which causes a new() inside the tracker which re-enters the
  // heap profiler, in which case we just want to early out.
  auto* tracker = AllocationContextTracker::GetInstanceForCurrentThread();
  if (!tracker)
    return;
  AllocationContext context = tracker->GetContextSnapshot();

  AutoLock lock(allocation_register_lock_);
  if (!allocation_register_)
    return;

  allocation_register_->Insert(address, size, context);
}

void MallocDumpProvider::RemoveAllocation(void* address) {
  // No re-entrancy is expected here as none of the calls below should
  // cause a free()-s (|allocation_register_| does its own heap management).
  if (tid_dumping_heap_ != kInvalidThreadId &&
      tid_dumping_heap_ == PlatformThread::CurrentId())
    return;
  AutoLock lock(allocation_register_lock_);
  if (!allocation_register_)
    return;
  allocation_register_->Remove(address);
}

}  // namespace trace_event
}  // namespace base