components/metrics: Add runtime memory leak detector

third_party/tcmalloc/chromium/src/leak_detector.cc

+// Copyright (c) 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.
+
+// ---
+// Author: Simon Que
+
+#include <unistd.h>
+#include <link.h>
+
+#include "base/basictypes.h"
+#include "base/custom_allocator.h"
+#include "base/googleinit.h"
+#include "base/logging.h"
+#include "base/spinlock.h"
+#include <gperftools/malloc_extension.h>
+#include <gperftools/malloc_hook.h>
+#include "leak_detector_impl.h"
+#include "tcmalloc_guard.h"
+
+DEFINE_int32(sampling_factor,
+             EnvToInt("LEAK_DETECTOR_SAMPLING_FACTOR", 1),
+             "Used for sampling allocs and frees. Randomly samples "
+             "|sampling_factor|/256 of the pointers being allocated and "
+             "freed.");
+DEFINE_int32(stack_depth,
+             EnvToInt("LEAK_DETECTOR_STACK_DEPTH", 4),
+             "The number of call stack levels to unwind when profiling "
+             "allocations by call stack.");
+DEFINE_uint64(dump_interval_bytes,
+              EnvToInt("LEAK_DETECTOR_DUMP_INTERVAL_KB", 32768) * 1024,
+              "Dump allocation stats and check for memory leaks after this "
+              "many bytes have been allocated since the last dump/check. Does "
+              "not get affected by sampling.");
+DEFINE_bool(dump_leak_analysis,
+            EnvToInt("LEAK_DETECTOR_VERBOSE", false),
+            "Dump all leak analysis data, not just suspected leak reports.");
+
+DEFINE_int32(size_suspicion_threshold,
+             EnvToInt("LEAK_DETECTOR_SIZE_SUSPICION_THRESHOLD", 4),
+             "The number of times an allocation size must be suspected as a "
+             "leak before it gets reported.");
+DEFINE_int32(call_stack_suspicion_threshold,
+             EnvToInt("LEAK_DETECTOR_CALL_STACK_SUSPICION_THRESHOLD", 4),
+             "The number of times a call stack for a particular allocation "
+             "size must be suspected as a leak before it gets reported.");
+
+namespace leak_detector {
+
+namespace {
+
+// We strip out different number of stack frames in debug mode
+// because less inlining happens in that case
+#ifdef NDEBUG
+static const int kStripFrames = 2;
+#else
+static const int kStripFrames = 3;
+#endif
+
+// Use a simple spinlock for locking. Don't use a mutex, which can call malloc
+// and cause infinite recursion.
+SpinLock heap_lock(SpinLock::LINKER_INITIALIZED);
+
+// For storing the address range of the Chrome binary in memory.
+struct MappingInfo {
+  uint64 addr;
+  uint64 size;
+} chrome_mapping;
+
+// For making allocations within the leak detector that it should not track.
+LowLevelAlloc::Arena *leak_detector_arena;
+
+// Points to the active instance of the leak detector.
+// Modify this only when locked.
+LeakDetectorImpl* leak_detector = NULL;
+
+// Keep track of the total number of bytes allocated.
+// TODO(sque): This might render LeakDetectorImpl::stats redundant.
+// Modify this only when locked.
+uint64 total_alloc_size = 0;
+
+// Keep track of the total alloc size when the last dump occurred.
+// Modify this only when locked.
+uint64 last_alloc_dump_size = 0;
+
+// Dump allocation stats and check for leaks after |FLAGS_dump_interval_bytes|
+// have been allocated since the last time that was done. Should be called with
+// a lock since it modifies the global variable |last_alloc_dump_size|.
+inline void MaybeDumpStatsAndCheckForLeaks() {
+  if (total_alloc_size > last_alloc_dump_size + FLAGS_dump_interval_bytes) {
+    leak_detector->DumpStats();
+    last_alloc_dump_size = total_alloc_size;
+    leak_detector->TestForLeaks();
+  }
+}
+
+// Convert a pointer to a hash value. Returns only the upper eight bits.
+inline unsigned int PointerToHash(const void* ptr) {
+  // The input data is the pointer address, not the location in memory pointed
+  // to by the pointer.
+  const uint64_t kMultiplier = 0x9ddfea08eb382d69ULL;
+  uint64_t value = reinterpret_cast<uint64_t>(ptr) * kMultiplier;
+  return value >> 56;
+}
+
+// Uses PointerToHash() to pseudorandomly sample |ptr|.
+inline bool ShouldSample(const void* ptr) {
+  return PointerToHash(ptr) < FLAGS_sampling_factor;
+}
+
+// Allocation/deallocation hooks for MallocHook.
+void NewHook(const void* ptr, size_t size) {
+  {
+    SpinLockHolder l(&heap_lock);
+    total_alloc_size += size;
+  }
+
+  if (!ShouldSample(ptr) || !ptr || !leak_detector)
+    return;
+
+  // Take the stack trace outside the critical section.
+  // leak_detector->ShouldGetStackTraceForSize() is const; there is no need for
+  // a lock.
+  void* stack[FLAGS_stack_depth];
+  int depth = 0;
+  if (leak_detector->ShouldGetStackTraceForSize(size)) {
+    depth = MallocHook::GetCallerStackTrace(
+        stack, FLAGS_stack_depth, kStripFrames + 1);
+  }
+
+  SpinLockHolder l(&heap_lock);
+  leak_detector->RecordAlloc(ptr, size, depth, stack);
+  MaybeDumpStatsAndCheckForLeaks();
+}
+
+void DeleteHook(const void* ptr) {
+  if (!ShouldSample(ptr) || !ptr || !leak_detector)
+    return;
+
+  SpinLockHolder l(&heap_lock);
+  leak_detector->RecordFree(ptr);
+}
+
+// Callback for dl_iterate_phdr() to find the Chrome binary mapping.
+int IterateLoadedObjects(struct dl_phdr_info *info,
+                         size_t /* size */,
+                         void *data) {
+    uint64 base_addr = info->dlpi_addr;
+    if (FLAGS_dump_leak_analysis) {
+      RAW_LOG(0, "%d: name=%s addr=%lx (%d segments)", getpid(),
+              info->dlpi_name, base_addr, info->dlpi_phnum);
+    }
+    for (int i = 0; i < info->dlpi_phnum; i++) {
+      const ElfW(Phdr)& header = info->dlpi_phdr[i];
+      RAW_LOG(0, "%d: \t\t header %2d: type=%x, offset=%lx, vaddr=%lx, "
+              "paddr=%lx, filesz=%lx, memsz=%lx", getpid(), i,
+              header.p_type,
+              header.p_offset,
+              header.p_vaddr,
+              header.p_paddr,
+              header.p_filesz,
+              header.p_memsz);
+      if (header.p_type == SHT_PROGBITS && header.p_offset == 0 && data) {
+        MappingInfo* mapping = static_cast<MappingInfo*>(data);
+        mapping->addr = info->dlpi_addr + header.p_offset;
+        mapping->size = header.p_memsz;
+        if (FLAGS_dump_leak_analysis) {
+          RAW_LOG(0, "%d: Chrome mapped from %lx to %lx", getpid(),
+                  mapping->addr, mapping->addr + mapping->size);
+        }
+        return 1;
+      }
+    }
+    return 0;
+}
+
+}  // namespace
+
+//----------------------------------------------------------------------
+// Starting/stopping
+//----------------------------------------------------------------------
+
+void LeakDetectorStart() {
+  // If the sampling factor is too low, don't bother enabling the leak detector.
+  if (FLAGS_sampling_factor < 1) {
+    RAW_LOG(0, "%d: Not enabling leak detector because sampling_factor = %d",
+            getpid(), FLAGS_sampling_factor);
+    return;
+  }
+
+  // Locate the Chrome binary mapping before doing anything else.
+  dl_iterate_phdr(IterateLoadedObjects, &chrome_mapping);
+
+  SpinLockHolder l(&heap_lock);
+  if (leak_detector)
+    return;
+
+  RAW_LOG(0, "%d: Starting leak detector. Sampling factor: %d", getpid(),
+          FLAGS_sampling_factor);
+
+  // This should be done before the hooks are set up, since it should
+  // call new, and we want that to be accounted for correctly.
+  MallocExtension::Initialize();
+
+  leak_detector_arena =
+      LowLevelAlloc::NewArena(0, LowLevelAlloc::DefaultArena());
+  CustomAllocator::SetArena(leak_detector_arena);
+
+  leak_detector = new(CustomAllocator::Allocate(sizeof(LeakDetectorImpl)))
+      LeakDetectorImpl(chrome_mapping.addr, chrome_mapping.size);
+
+  // We do not reset dump_count so if the user does a sequence of
+  // HeapProfilerStart/HeapProfileStop, we will get a continuous
+  // sequence of profiles.
+
+  // Now set the hooks that capture new/delete and malloc/free.
+  RAW_CHECK(MallocHook::SetNewHook(&NewHook) == NULL, "");
+  RAW_CHECK(MallocHook::SetDeleteHook(&DeleteHook) == NULL, "");
+}
+
+void LeakDetectorStop() {
+  SpinLockHolder l(&heap_lock);
+
+  if (!leak_detector)
+    return;
+
+  // Unset our new/delete hooks, checking they were set:
+  RAW_CHECK(MallocHook::SetNewHook(NULL) == &NewHook, "");
+  RAW_CHECK(MallocHook::SetDeleteHook(NULL) == &DeleteHook, "");
+
+  leak_detector->~LeakDetectorImpl();
+  CustomAllocator::Free(leak_detector, sizeof(LeakDetectorImpl));
+  leak_detector = NULL;
+
+  CustomAllocator::SetArena(NULL);
+  if (!LowLevelAlloc::DeleteArena(leak_detector_arena)) {
+    RAW_LOG(FATAL, "Memory leak in LeakDetector.");
+  }
+}
+
+}  // namespace leak_detector
+
+#if defined(ENABLE_LEAK_DETECTOR)
+
+// We want to make sure tcmalloc is up and running before starting the profiler
+static const TCMallocGuard tcmalloc_initializer;
+REGISTER_MODULE_INITIALIZER(leakdetector, leak_detector::LeakDetectorStart());
+REGISTER_MODULE_DESTRUCTOR(leakdetector, leak_detector::LeakDetectorStop());
+
+#endif  // defined(ENABLE_LEAK_DETECTOR)