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chromium / chromium / src / 69b378ee1 / . / base / debug / activity_tracker.cc
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// Copyright 2016 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/debug/activity_tracker.h"
#include <algorithm>
#include "base/debug/stack_trace.h"
#include "base/files/file.h"
#include "base/files/file_path.h"
#include "base/files/memory_mapped_file.h"
#include "base/logging.h"
#include "base/memory/ptr_util.h"
#include "base/metrics/field_trial.h"
#include "base/metrics/histogram_macros.h"
#include "base/pending_task.h"
#include "base/process/process.h"
#include "base/process/process_handle.h"
#include "base/stl_util.h"
#include "base/strings/string_util.h"
#include "base/threading/platform_thread.h"
namespace base {
namespace debug {
namespace {
// A number that identifies the memory as having been initialized. It's
// arbitrary but happens to be the first 4 bytes of SHA1(ThreadActivityTracker).
// A version number is added on so that major structure changes won't try to
// read an older version (since the cookie won't match).
const uint32_t kHeaderCookie = 0xC0029B24UL + 2; // v2
// The minimum depth a stack should support.
const int kMinStackDepth = 2;
// The amount of memory set aside for holding arbitrary user data (key/value
// pairs) globally or associated with ActivityData entries.
const size_t kUserDataSize = 1024; // bytes
const size_t kGlobalDataSize = 1024; // bytes
const size_t kMaxUserDataNameLength =
static_cast<size_t>(std::numeric_limits<uint8_t>::max());
union ThreadRef {
int64_t as_id;
#if defined(OS_WIN)
// On Windows, the handle itself is often a pseudo-handle with a common
// value meaning "this thread" and so the thread-id is used. The former
// can be converted to a thread-id with a system call.
PlatformThreadId as_tid;
#elif defined(OS_POSIX)
// On Posix, the handle is always a unique identifier so no conversion
// needs to be done. However, it's value is officially opaque so there
// is no one correct way to convert it to a numerical identifier.
PlatformThreadHandle::Handle as_handle;
#endif
};
// Determines the next aligned index.
size_t RoundUpToAlignment(size_t index, size_t alignment) {
return (index + (alignment - 1)) & (0 - alignment);
}
} // namespace
// It doesn't matter what is contained in this (though it will be all zeros)
// as only the address of it is important.
const ActivityData kNullActivityData = {};
ActivityData ActivityData::ForThread(const PlatformThreadHandle& handle) {
ThreadRef thread_ref;
thread_ref.as_id = 0; // Zero the union in case other is smaller.
#if defined(OS_WIN)
thread_ref.as_tid = ::GetThreadId(handle.platform_handle());
#elif defined(OS_POSIX)
thread_ref.as_handle = handle.platform_handle();
#endif
return ForThread(thread_ref.as_id);
}
ActivityTrackerMemoryAllocator::ActivityTrackerMemoryAllocator(
PersistentMemoryAllocator* allocator,
uint32_t object_type,
uint32_t object_free_type,
size_t object_size,
size_t cache_size,
bool make_iterable)
: allocator_(allocator),
object_type_(object_type),
object_free_type_(object_free_type),
object_size_(object_size),
cache_size_(cache_size),
make_iterable_(make_iterable),
iterator_(allocator),
cache_values_(new Reference[cache_size]),
cache_used_(0) {
DCHECK(allocator);
}
ActivityTrackerMemoryAllocator::~ActivityTrackerMemoryAllocator() {}
ActivityTrackerMemoryAllocator::Reference
ActivityTrackerMemoryAllocator::GetObjectReference() {
// First see if there is a cached value that can be returned. This is much
// faster than searching the memory system for free blocks.
while (cache_used_ > 0) {
Reference cached = cache_values_[--cache_used_];
// Change the type of the cached object to the proper type and return it.
// If the type-change fails that means another thread has taken this from
// under us (via the search below) so ignore it and keep trying.
if (allocator_->ChangeType(cached, object_type_, object_free_type_))
return cached;
}
// Fetch the next "free" object from persistent memory. Rather than restart
// the iterator at the head each time and likely waste time going again
// through objects that aren't relevant, the iterator continues from where
// it last left off and is only reset when the end is reached. If the
// returned reference matches |last|, then it has wrapped without finding
// anything.
const Reference last = iterator_.GetLast();
while (true) {
uint32_t type;
Reference found = iterator_.GetNext(&type);
if (found && type == object_free_type_) {
// Found a free object. Change it to the proper type and return it. If
// the type-change fails that means another thread has taken this from
// under us so ignore it and keep trying.
if (allocator_->ChangeType(found, object_type_, object_free_type_))
return found;
}
if (found == last) {
// Wrapped. No desired object was found.
break;
}
if (!found) {
// Reached end; start over at the beginning.
iterator_.Reset();
}
}
// No free block was found so instead allocate a new one.
Reference allocated = allocator_->Allocate(object_size_, object_type_);
if (allocated && make_iterable_)
allocator_->MakeIterable(allocated);
return allocated;
}
void ActivityTrackerMemoryAllocator::ReleaseObjectReference(Reference ref) {
// Zero the memory so that it is ready for immediate use if needed later.
char* mem_base = allocator_->GetAsObject<char>(ref, object_type_);
DCHECK(mem_base);
memset(mem_base, 0, object_size_);
// Mark object as free.
bool success = allocator_->ChangeType(ref, object_free_type_, object_type_);
DCHECK(success);
// Add this reference to our "free" cache if there is space. If not, the type
// has still been changed to indicate that it is free so this (or another)
// thread can find it, albeit more slowly, using the iteration method above.
if (cache_used_ < cache_size_)
cache_values_[cache_used_++] = ref;
}
// static
void Activity::FillFrom(Activity* activity,
const void* program_counter,
const void* origin,
Type type,
const ActivityData& data) {
activity->time_internal = base::TimeTicks::Now().ToInternalValue();
activity->calling_address = reinterpret_cast<uintptr_t>(program_counter);
activity->origin_address = reinterpret_cast<uintptr_t>(origin);
activity->activity_type = type;
activity->data = data;
#if defined(SYZYASAN)
// Create a stacktrace from the current location and get the addresses.
StackTrace stack_trace;
size_t stack_depth;
const void* const* stack_addrs = stack_trace.Addresses(&stack_depth);
// Copy the stack addresses, ignoring the first one (here).
size_t i;
for (i = 1; i < stack_depth && i < kActivityCallStackSize; ++i) {
activity->call_stack[i - 1] = reinterpret_cast<uintptr_t>(stack_addrs[i]);
}
activity->call_stack[i - 1] = 0;
#else
activity->call_stack[0] = 0;
#endif
}
ActivitySnapshot::ActivitySnapshot() {}
ActivitySnapshot::~ActivitySnapshot() {}
ActivityUserData::ValueInfo::ValueInfo() {}
ActivityUserData::ValueInfo::ValueInfo(ValueInfo&&) = default;
ActivityUserData::ValueInfo::~ValueInfo() {}
ActivityUserData::ActivityUserData(void* memory, size_t size)
: memory_(static_cast<char*>(memory)), available_(size) {}
ActivityUserData::~ActivityUserData() {}
void ActivityUserData::Set(StringPiece name,
ValueType type,
const void* memory,
size_t size) {
DCHECK(thread_checker_.CalledOnValidThread());
DCHECK_GE(std::numeric_limits<uint8_t>::max(), name.length());
size = std::min(std::numeric_limits<uint16_t>::max() - (kMemoryAlignment - 1),
size);
// It's possible that no user data is being stored.
if (!memory_)
return;
// The storage of a name is limited so use that limit during lookup.
if (name.length() > kMaxUserDataNameLength)
name.set(name.data(), kMaxUserDataNameLength);
ValueInfo* info;
auto existing = values_.find(name);
if (existing != values_.end()) {
info = &existing->second;
} else {
// The name size is limited to what can be held in a single byte but
// because there are not alignment constraints on strings, it's set tight
// against the header. Its extent (the reserved space, even if it's not
// all used) is calculated so that, when pressed against the header, the
// following field will be aligned properly.
size_t name_size = name.length();
size_t name_extent =
RoundUpToAlignment(sizeof(Header) + name_size, kMemoryAlignment) -
sizeof(Header);
size_t value_extent = RoundUpToAlignment(size, kMemoryAlignment);
// The "basic size" is the minimum size of the record. It's possible that
// lengthy values will get truncated but there must be at least some bytes
// available.
size_t basic_size = sizeof(Header) + name_extent + kMemoryAlignment;
if (basic_size > available_)
return; // No space to store even the smallest value.
// The "full size" is the size for storing the entire value, truncated
// to the amount of available memory.
size_t full_size =
std::min(sizeof(Header) + name_extent + value_extent, available_);
size = std::min(full_size - sizeof(Header) - name_extent, size);
// Allocate a chunk of memory.
Header* header = reinterpret_cast<Header*>(memory_);
memory_ += full_size;
available_ -= full_size;
// Datafill the header and name records. Memory must be zeroed. The |type|
// is written last, atomically, to release all the other values.
DCHECK_EQ(END_OF_VALUES, header->type.load(std::memory_order_relaxed));
DCHECK_EQ(0, header->value_size.load(std::memory_order_relaxed));
header->name_size = static_cast<uint8_t>(name_size);
header->record_size = full_size;
char* name_memory = reinterpret_cast<char*>(header) + sizeof(Header);
void* value_memory =
reinterpret_cast<char*>(header) + sizeof(Header) + name_extent;
memcpy(name_memory, name.data(), name_size);
header->type.store(type, std::memory_order_release);
// Create an entry in |values_| so that this field can be found and changed
// later on without having to allocate new entries.
StringPiece persistent_name(name_memory, name_size);
auto inserted =
values_.insert(std::make_pair(persistent_name, ValueInfo()));
DCHECK(inserted.second); // True if inserted, false if existed.
info = &inserted.first->second;
info->name = persistent_name;
info->memory = value_memory;
info->size_ptr = &header->value_size;
info->extent = full_size - sizeof(Header) - name_extent;
info->type = type;
}
// Copy the value data to storage. The |size| is written last, atomically, to
// release the copied data. Until then, a parallel reader will just ignore
// records with a zero size.
DCHECK_EQ(type, info->type);
size = std::min(size, info->extent);
info->size_ptr->store(0, std::memory_order_seq_cst);
memcpy(info->memory, memory, size);
info->size_ptr->store(size, std::memory_order_release);
}
void ActivityUserData::SetReference(StringPiece name,
ValueType type,
const void* memory,
size_t size) {
ReferenceRecord rec;
rec.address = reinterpret_cast<uintptr_t>(memory);
rec.size = size;
Set(name, type, &rec, sizeof(rec));
}
// This information is kept for every thread that is tracked. It is filled
// the very first time the thread is seen. All fields must be of exact sizes
// so there is no issue moving between 32 and 64-bit builds.
struct ThreadActivityTracker::Header {
// This unique number indicates a valid initialization of the memory.
std::atomic<uint32_t> cookie;
uint32_t reserved; // pad out to 64 bits
// The process-id and thread-id (thread_ref.as_id) to which this data belongs.
// These identifiers are not guaranteed to mean anything but are unique, in
// combination, among all active trackers. It would be nice to always have
// the process_id be a 64-bit value but the necessity of having it atomic
// (for the memory barriers it provides) limits it to the natural word size
// of the machine.
#ifdef ARCH_CPU_64_BITS
std::atomic<int64_t> process_id;
#else
std::atomic<int32_t> process_id;
int32_t process_id_padding;
#endif
ThreadRef thread_ref;
// The start-time and start-ticks when the data was created. Each activity
// record has a |time_internal| value that can be converted to a "wall time"
// with these two values.
int64_t start_time;
int64_t start_ticks;
// The number of Activity slots in the data.
uint32_t stack_slots;
// The current depth of the stack. This may be greater than the number of
// slots. If the depth exceeds the number of slots, the newest entries
// won't be recorded.
std::atomic<uint32_t> current_depth;
// A memory location used to indicate if changes have been made to the stack
// that would invalidate an in-progress read of its contents. The active
// tracker will zero the value whenever something gets popped from the
// stack. A monitoring tracker can write a non-zero value here, copy the
// stack contents, and read the value to know, if it is still non-zero, that
// the contents didn't change while being copied. This can handle concurrent
// snapshot operations only if each snapshot writes a different bit (which
// is not the current implementation so no parallel snapshots allowed).
std::atomic<uint32_t> stack_unchanged;
// The name of the thread (up to a maximum length). Dynamic-length names
// are not practical since the memory has to come from the same persistent
// allocator that holds this structure and to which this object has no
// reference.
char thread_name[32];
};
ThreadActivityTracker::ScopedActivity::ScopedActivity(
ThreadActivityTracker* tracker,
const void* program_counter,
const void* origin,
Activity::Type type,
const ActivityData& data)
: tracker_(tracker) {
if (tracker_)
activity_id_ = tracker_->PushActivity(program_counter, origin, type, data);
}
ThreadActivityTracker::ScopedActivity::~ScopedActivity() {
if (tracker_)
tracker_->PopActivity(activity_id_);
}
void ThreadActivityTracker::ScopedActivity::ChangeTypeAndData(
Activity::Type type,
const ActivityData& data) {
if (tracker_)
tracker_->ChangeActivity(activity_id_, type, data);
}
ActivityUserData& ThreadActivityTracker::ScopedActivity::user_data() {
if (!user_data_) {
if (tracker_)
user_data_ = tracker_->GetUserData(activity_id_);
else
user_data_ = MakeUnique<ActivityUserData>(nullptr, 0);
}
return *user_data_;
}
ThreadActivityTracker::ThreadActivityTracker(void* base, size_t size)
: header_(static_cast<Header*>(base)),
stack_(reinterpret_cast<Activity*>(reinterpret_cast<char*>(base) +
sizeof(Header))),
stack_slots_(
static_cast<uint32_t>((size - sizeof(Header)) / sizeof(Activity))) {
DCHECK(thread_checker_.CalledOnValidThread());
// Verify the parameters but fail gracefully if they're not valid so that
// production code based on external inputs will not crash. IsValid() will
// return false in this case.
if (!base ||
// Ensure there is enough space for the header and at least a few records.
size < sizeof(Header) + kMinStackDepth * sizeof(Activity) ||
// Ensure that the |stack_slots_| calculation didn't overflow.
(size - sizeof(Header)) / sizeof(Activity) >
std::numeric_limits<uint32_t>::max()) {
NOTREACHED();
return;
}
// Ensure that the thread reference doesn't exceed the size of the ID number.
// This won't compile at the global scope because Header is a private struct.
static_assert(
sizeof(header_->thread_ref) == sizeof(header_->thread_ref.as_id),
"PlatformThreadHandle::Handle is too big to hold in 64-bit ID");
// Ensure that the alignment of Activity.data is properly aligned to a
// 64-bit boundary so there are no interoperability-issues across cpu
// architectures.
static_assert(offsetof(Activity, data) % sizeof(uint64_t) == 0,
"ActivityData.data is not 64-bit aligned");
// Provided memory should either be completely initialized or all zeros.
if (header_->cookie.load(std::memory_order_relaxed) == 0) {
// This is a new file. Double-check other fields and then initialize.
DCHECK_EQ(0, header_->process_id.load(std::memory_order_relaxed));
DCHECK_EQ(0, header_->thread_ref.as_id);
DCHECK_EQ(0, header_->start_time);
DCHECK_EQ(0, header_->start_ticks);
DCHECK_EQ(0U, header_->stack_slots);
DCHECK_EQ(0U, header_->current_depth.load(std::memory_order_relaxed));
DCHECK_EQ(0U, header_->stack_unchanged.load(std::memory_order_relaxed));
DCHECK_EQ(0, stack_[0].time_internal);
DCHECK_EQ(0U, stack_[0].origin_address);
DCHECK_EQ(0U, stack_[0].call_stack[0]);
DCHECK_EQ(0U, stack_[0].data.task.sequence_id);
#if defined(OS_WIN)
header_->thread_ref.as_tid = PlatformThread::CurrentId();
#elif defined(OS_POSIX)
header_->thread_ref.as_handle =
PlatformThread::CurrentHandle().platform_handle();
#endif
header_->process_id.store(GetCurrentProcId(), std::memory_order_relaxed);
header_->start_time = base::Time::Now().ToInternalValue();
header_->start_ticks = base::TimeTicks::Now().ToInternalValue();
header_->stack_slots = stack_slots_;
strlcpy(header_->thread_name, PlatformThread::GetName(),
sizeof(header_->thread_name));
// This is done last so as to guarantee that everything above is "released"
// by the time this value gets written.
header_->cookie.store(kHeaderCookie, std::memory_order_release);
valid_ = true;
DCHECK(IsValid());
} else {
// This is a file with existing data. Perform basic consistency checks.
valid_ = true;
valid_ = IsValid();
}
}
ThreadActivityTracker::~ThreadActivityTracker() {}
ThreadActivityTracker::ActivityId ThreadActivityTracker::PushActivity(
const void* program_counter,
const void* origin,
Activity::Type type,
const ActivityData& data) {
// A thread-checker creates a lock to check the thread-id which means
// re-entry into this code if lock acquisitions are being tracked.
DCHECK(type == Activity::ACT_LOCK_ACQUIRE ||
thread_checker_.CalledOnValidThread());
// Get the current depth of the stack. No access to other memory guarded
// by this variable is done here so a "relaxed" load is acceptable.
uint32_t depth = header_->current_depth.load(std::memory_order_relaxed);
// Handle the case where the stack depth has exceeded the storage capacity.
// Extra entries will be lost leaving only the base of the stack.
if (depth >= stack_slots_) {
// Since no other threads modify the data, no compare/exchange is needed.
// Since no other memory is being modified, a "relaxed" store is acceptable.
header_->current_depth.store(depth + 1, std::memory_order_relaxed);
return depth;
}
// Get a pointer to the next activity and load it. No atomicity is required
// here because the memory is known only to this thread. It will be made
// known to other threads once the depth is incremented.
Activity::FillFrom(&stack_[depth], program_counter, origin, type, data);
// Save the incremented depth. Because this guards |activity| memory filled
// above that may be read by another thread once the recorded depth changes,
// a "release" store is required.
header_->current_depth.store(depth + 1, std::memory_order_release);
// The current depth is used as the activity ID because it simply identifies
// an entry. Once an entry is pop'd, it's okay to reuse the ID.
return depth;
}
void ThreadActivityTracker::ChangeActivity(ActivityId id,
Activity::Type type,
const ActivityData& data) {
DCHECK(thread_checker_.CalledOnValidThread());
DCHECK(type != Activity::ACT_NULL || &data != &kNullActivityData);
DCHECK_LT(id, header_->current_depth.load(std::memory_order_acquire));
// Update the information if it is being recorded (i.e. within slot limit).
if (id < stack_slots_) {
Activity* activity = &stack_[id];
if (type != Activity::ACT_NULL) {
DCHECK_EQ(activity->activity_type & Activity::ACT_CATEGORY_MASK,
type & Activity::ACT_CATEGORY_MASK);
activity->activity_type = type;
}
if (&data != &kNullActivityData)
activity->data = data;
}
}
void ThreadActivityTracker::PopActivity(ActivityId id) {
// Do an atomic decrement of the depth. No changes to stack entries guarded
// by this variable are done here so a "relaxed" operation is acceptable.
// |depth| will receive the value BEFORE it was modified which means the
// return value must also be decremented. The slot will be "free" after
// this call but since only a single thread can access this object, the
// data will remain valid until this method returns or calls outside.
uint32_t depth =
header_->current_depth.fetch_sub(1, std::memory_order_relaxed) - 1;
// Validate that everything is running correctly.
DCHECK_EQ(id, depth);
// A thread-checker creates a lock to check the thread-id which means
// re-entry into this code if lock acquisitions are being tracked.
DCHECK(stack_[depth].activity_type == Activity::ACT_LOCK_ACQUIRE ||
thread_checker_.CalledOnValidThread());
// Check if there was any user-data memory. It isn't free'd until later
// because the call to release it can push something on the stack.
PersistentMemoryAllocator::Reference user_data = stack_[depth].user_data;
stack_[depth].user_data = 0;
// The stack has shrunk meaning that some other thread trying to copy the
// contents for reporting purposes could get bad data. That thread would
// have written a non-zero value into |stack_unchanged|; clearing it here
// will let that thread detect that something did change. This needs to
// happen after the atomic |depth| operation above so a "release" store
// is required.
header_->stack_unchanged.store(0, std::memory_order_release);
// Release resources located above. All stack processing is done so it's
// safe if some outside code does another push.
if (user_data)
GlobalActivityTracker::Get()->ReleaseUserDataMemory(&user_data);
}
std::unique_ptr<ActivityUserData> ThreadActivityTracker::GetUserData(
ActivityId id) {
// User-data is only stored for activities actually held in the stack.
if (id < stack_slots_) {
void* memory =
GlobalActivityTracker::Get()->GetUserDataMemory(&stack_[id].user_data);
if (memory)
return MakeUnique<ActivityUserData>(memory, kUserDataSize);
}
// Return a dummy object that will still accept (but ignore) Set() calls.
return MakeUnique<ActivityUserData>(nullptr, 0);
}
bool ThreadActivityTracker::IsValid() const {
if (header_->cookie.load(std::memory_order_acquire) != kHeaderCookie ||
header_->process_id.load(std::memory_order_relaxed) == 0 ||
header_->thread_ref.as_id == 0 ||
header_->start_time == 0 ||
header_->start_ticks == 0 ||
header_->stack_slots != stack_slots_ ||
header_->thread_name[sizeof(header_->thread_name) - 1] != '\0') {
return false;
}
return valid_;
}
bool ThreadActivityTracker::Snapshot(ActivitySnapshot* output_snapshot) const {
DCHECK(output_snapshot);
// There is no "called on valid thread" check for this method as it can be
// called from other threads or even other processes. It is also the reason
// why atomic operations must be used in certain places above.
// It's possible for the data to change while reading it in such a way that it
// invalidates the read. Make several attempts but don't try forever.
const int kMaxAttempts = 10;
uint32_t depth;
// Stop here if the data isn't valid.
if (!IsValid())
return false;
// Allocate the maximum size for the stack so it doesn't have to be done
// during the time-sensitive snapshot operation. It is shrunk once the
// actual size is known.
output_snapshot->activity_stack.reserve(stack_slots_);
for (int attempt = 0; attempt < kMaxAttempts; ++attempt) {
// Remember the process and thread IDs to ensure they aren't replaced
// during the snapshot operation. Use "acquire" to ensure that all the
// non-atomic fields of the structure are valid (at least at the current
// moment in time).
const int64_t starting_process_id =
header_->process_id.load(std::memory_order_acquire);
const int64_t starting_thread_id = header_->thread_ref.as_id;
// Write a non-zero value to |stack_unchanged| so it's possible to detect
// at the end that nothing has changed since copying the data began. A
// "cst" operation is required to ensure it occurs before everything else.
// Using "cst" memory ordering is relatively expensive but this is only
// done during analysis so doesn't directly affect the worker threads.
header_->stack_unchanged.store(1, std::memory_order_seq_cst);
// Fetching the current depth also "acquires" the contents of the stack.
depth = header_->current_depth.load(std::memory_order_acquire);
uint32_t count = std::min(depth, stack_slots_);
output_snapshot->activity_stack.resize(count);
if (count > 0) {
// Copy the existing contents. Memcpy is used for speed.
memcpy(&output_snapshot->activity_stack[0], stack_,
count * sizeof(Activity));
}
// Retry if something changed during the copy. A "cst" operation ensures
// it must happen after all the above operations.
if (!header_->stack_unchanged.load(std::memory_order_seq_cst))
continue;
// Stack copied. Record it's full depth.
output_snapshot->activity_stack_depth = depth;
// TODO(bcwhite): Snapshot other things here.
// Get the general thread information. Loading of "process_id" is guaranteed
// to be last so that it's possible to detect below if any content has
// changed while reading it. It's technically possible for a thread to end,
// have its data cleared, a new thread get created with the same IDs, and
// it perform an action which starts tracking all in the time since the
// ID reads above but the chance is so unlikely that it's not worth the
// effort and complexity of protecting against it (perhaps with an
// "unchanged" field like is done for the stack).
output_snapshot->thread_name =
std::string(header_->thread_name, sizeof(header_->thread_name) - 1);
output_snapshot->thread_id = header_->thread_ref.as_id;
output_snapshot->process_id =
header_->process_id.load(std::memory_order_seq_cst);
// All characters of the thread-name buffer were copied so as to not break
// if the trailing NUL were missing. Now limit the length if the actual
// name is shorter.
output_snapshot->thread_name.resize(
strlen(output_snapshot->thread_name.c_str()));
// If the process or thread ID has changed then the tracker has exited and
// the memory reused by a new one. Try again.
if (output_snapshot->process_id != starting_process_id ||
output_snapshot->thread_id != starting_thread_id) {
continue;
}
// Only successful if the data is still valid once everything is done since
// it's possible for the thread to end somewhere in the middle and all its
// values become garbage.
if (!IsValid())
return false;
// Change all the timestamps in the activities from "ticks" to "wall" time.
const Time start_time = Time::FromInternalValue(header_->start_time);
const int64_t start_ticks = header_->start_ticks;
for (Activity& activity : output_snapshot->activity_stack) {
activity.time_internal =
(start_time +
TimeDelta::FromInternalValue(activity.time_internal - start_ticks))
.ToInternalValue();
}
// Success!
return true;
}
// Too many attempts.
return false;
}
// static
size_t ThreadActivityTracker::SizeForStackDepth(int stack_depth) {
return static_cast<size_t>(stack_depth) * sizeof(Activity) + sizeof(Header);
}
GlobalActivityTracker* GlobalActivityTracker::g_tracker_ = nullptr;
GlobalActivityTracker::ManagedActivityTracker::ManagedActivityTracker(
PersistentMemoryAllocator::Reference mem_reference,
void* base,
size_t size)
: ThreadActivityTracker(base, size),
mem_reference_(mem_reference),
mem_base_(base) {}
GlobalActivityTracker::ManagedActivityTracker::~ManagedActivityTracker() {
// The global |g_tracker_| must point to the owner of this class since all
// objects of this type must be destructed before |g_tracker_| can be changed
// (something that only occurs in tests).
DCHECK(g_tracker_);
g_tracker_->ReturnTrackerMemory(this);
}
void GlobalActivityTracker::CreateWithAllocator(
std::unique_ptr<PersistentMemoryAllocator> allocator,
int stack_depth) {
// There's no need to do anything with the result. It is self-managing.
GlobalActivityTracker* global_tracker =
new GlobalActivityTracker(std::move(allocator), stack_depth);
// Create a tracker for this thread since it is known.
global_tracker->CreateTrackerForCurrentThread();
}
#if !defined(OS_NACL)
// static
void GlobalActivityTracker::CreateWithFile(const FilePath& file_path,
size_t size,
uint64_t id,
StringPiece name,
int stack_depth) {
DCHECK(!file_path.empty());
DCHECK_GE(static_cast<uint64_t>(std::numeric_limits<int64_t>::max()), size);
// Create and map the file into memory and make it globally available.
std::unique_ptr<MemoryMappedFile> mapped_file(new MemoryMappedFile());
bool success =
mapped_file->Initialize(File(file_path,
File::FLAG_CREATE_ALWAYS | File::FLAG_READ |
File::FLAG_WRITE | File::FLAG_SHARE_DELETE),
{0, static_cast<int64_t>(size)},
MemoryMappedFile::READ_WRITE_EXTEND);
DCHECK(success);
CreateWithAllocator(MakeUnique<FilePersistentMemoryAllocator>(
std::move(mapped_file), size, id, name, false),
stack_depth);
}
#endif // !defined(OS_NACL)
// static
void GlobalActivityTracker::CreateWithLocalMemory(size_t size,
uint64_t id,
StringPiece name,
int stack_depth) {
CreateWithAllocator(
MakeUnique<LocalPersistentMemoryAllocator>(size, id, name), stack_depth);
}
ThreadActivityTracker* GlobalActivityTracker::CreateTrackerForCurrentThread() {
DCHECK(!this_thread_tracker_.Get());
PersistentMemoryAllocator::Reference mem_reference;
{
base::AutoLock autolock(thread_tracker_allocator_lock_);
mem_reference = thread_tracker_allocator_.GetObjectReference();
}
if (!mem_reference) {
// Failure. This shouldn't happen. But be graceful if it does, probably
// because the underlying allocator wasn't given enough memory to satisfy
// to all possible requests.
NOTREACHED();
// Report the thread-count at which the allocator was full so that the
// failure can be seen and underlying memory resized appropriately.
UMA_HISTOGRAM_COUNTS_1000(
"ActivityTracker.ThreadTrackers.MemLimitTrackerCount",
thread_tracker_count_.load(std::memory_order_relaxed));
// Return null, just as if tracking wasn't enabled.
return nullptr;
}
// Convert the memory block found above into an actual memory address.
DCHECK(mem_reference);
void* mem_base =
allocator_->GetAsObject<char>(mem_reference, kTypeIdActivityTracker);
DCHECK(mem_base);
DCHECK_LE(stack_memory_size_, allocator_->GetAllocSize(mem_reference));
// Create a tracker with the acquired memory and set it as the tracker
// for this particular thread in thread-local-storage.
ManagedActivityTracker* tracker =
new ManagedActivityTracker(mem_reference, mem_base, stack_memory_size_);
DCHECK(tracker->IsValid());
this_thread_tracker_.Set(tracker);
int old_count = thread_tracker_count_.fetch_add(1, std::memory_order_relaxed);
UMA_HISTOGRAM_ENUMERATION("ActivityTracker.ThreadTrackers.Count",
old_count + 1, kMaxThreadCount);
return tracker;
}
void GlobalActivityTracker::ReleaseTrackerForCurrentThreadForTesting() {
ThreadActivityTracker* tracker =
reinterpret_cast<ThreadActivityTracker*>(this_thread_tracker_.Get());
if (tracker)
delete tracker;
}
void* GlobalActivityTracker::GetUserDataMemory(
PersistentMemoryAllocator::Reference* reference) {
if (!*reference) {
base::AutoLock autolock(user_data_allocator_lock_);
*reference = user_data_allocator_.GetObjectReference();
if (!*reference)
return nullptr;
}
void* memory =
allocator_->GetAsObject<char>(*reference, kTypeIdUserDataRecord);
DCHECK(memory);
return memory;
}
void GlobalActivityTracker::ReleaseUserDataMemory(
PersistentMemoryAllocator::Reference* reference) {
DCHECK(*reference);
base::AutoLock autolock(user_data_allocator_lock_);
user_data_allocator_.ReleaseObjectReference(*reference);
*reference = PersistentMemoryAllocator::kReferenceNull;
}
GlobalActivityTracker::GlobalActivityTracker(
std::unique_ptr<PersistentMemoryAllocator> allocator,
int stack_depth)
: allocator_(std::move(allocator)),
stack_memory_size_(ThreadActivityTracker::SizeForStackDepth(stack_depth)),
this_thread_tracker_(&OnTLSDestroy),
thread_tracker_count_(0),
thread_tracker_allocator_(allocator_.get(),
kTypeIdActivityTracker,
kTypeIdActivityTrackerFree,
stack_memory_size_,
kCachedThreadMemories,
/*make_iterable=*/true),
user_data_allocator_(allocator_.get(),
kTypeIdUserDataRecord,
kTypeIdUserDataRecordFree,
kUserDataSize,
kCachedUserDataMemories,
/*make_iterable=*/false),
user_data_(
allocator_->GetAsObject<char>(
allocator_->Allocate(kGlobalDataSize, kTypeIdGlobalDataRecord),
kTypeIdGlobalDataRecord),
kGlobalDataSize) {
// Ensure the passed memory is valid and empty (iterator finds nothing).
uint32_t type;
DCHECK(!PersistentMemoryAllocator::Iterator(allocator_.get()).GetNext(&type));
// Ensure that there is no other global object and then make this one such.
DCHECK(!g_tracker_);
g_tracker_ = this;
}
GlobalActivityTracker::~GlobalActivityTracker() {
DCHECK_EQ(g_tracker_, this);
DCHECK_EQ(0, thread_tracker_count_.load(std::memory_order_relaxed));
g_tracker_ = nullptr;
}
void GlobalActivityTracker::ReturnTrackerMemory(
ManagedActivityTracker* tracker) {
PersistentMemoryAllocator::Reference mem_reference = tracker->mem_reference_;
void* mem_base = tracker->mem_base_;
DCHECK(mem_reference);
DCHECK(mem_base);
// Remove the destructed tracker from the set of known ones.
DCHECK_LE(1, thread_tracker_count_.load(std::memory_order_relaxed));
thread_tracker_count_.fetch_sub(1, std::memory_order_relaxed);
// Release this memory for re-use at a later time.
base::AutoLock autolock(thread_tracker_allocator_lock_);
thread_tracker_allocator_.ReleaseObjectReference(mem_reference);
}
// static
void GlobalActivityTracker::OnTLSDestroy(void* value) {
delete reinterpret_cast<ManagedActivityTracker*>(value);
}
ScopedActivity::ScopedActivity(const void* program_counter,
uint8_t action,
uint32_t id,
int32_t info)
: GlobalActivityTracker::ScopedThreadActivity(
program_counter,
nullptr,
static_cast<Activity::Type>(Activity::ACT_GENERIC | action),
ActivityData::ForGeneric(id, info),
/*lock_allowed=*/true),
id_(id) {
// The action must not affect the category bits of the activity type.
DCHECK_EQ(0, action & Activity::ACT_CATEGORY_MASK);
}
void ScopedActivity::ChangeAction(uint8_t action) {
DCHECK_EQ(0, action & Activity::ACT_CATEGORY_MASK);
ChangeTypeAndData(static_cast<Activity::Type>(Activity::ACT_GENERIC | action),
kNullActivityData);
}
void ScopedActivity::ChangeInfo(int32_t info) {
ChangeTypeAndData(Activity::ACT_NULL, ActivityData::ForGeneric(id_, info));
}
void ScopedActivity::ChangeActionAndInfo(uint8_t action, int32_t info) {
DCHECK_EQ(0, action & Activity::ACT_CATEGORY_MASK);
ChangeTypeAndData(static_cast<Activity::Type>(Activity::ACT_GENERIC | action),
ActivityData::ForGeneric(id_, info));
}
ScopedTaskRunActivity::ScopedTaskRunActivity(
const void* program_counter,
const base::PendingTask& task)
: GlobalActivityTracker::ScopedThreadActivity(
program_counter,
task.posted_from.program_counter(),
Activity::ACT_TASK_RUN,
ActivityData::ForTask(task.sequence_num),
/*lock_allowed=*/true) {}
ScopedLockAcquireActivity::ScopedLockAcquireActivity(
const void* program_counter,
const base::internal::LockImpl* lock)
: GlobalActivityTracker::ScopedThreadActivity(
program_counter,
nullptr,
Activity::ACT_LOCK_ACQUIRE,
ActivityData::ForLock(lock),
/*lock_allowed=*/false) {}
ScopedEventWaitActivity::ScopedEventWaitActivity(
const void* program_counter,
const base::WaitableEvent* event)
: GlobalActivityTracker::ScopedThreadActivity(
program_counter,
nullptr,
Activity::ACT_EVENT_WAIT,
ActivityData::ForEvent(event),
/*lock_allowed=*/true) {}
ScopedThreadJoinActivity::ScopedThreadJoinActivity(
const void* program_counter,
const base::PlatformThreadHandle* thread)
: GlobalActivityTracker::ScopedThreadActivity(
program_counter,
nullptr,
Activity::ACT_THREAD_JOIN,
ActivityData::ForThread(*thread),
/*lock_allowed=*/true) {}
#if !defined(OS_NACL) && !defined(OS_IOS)
ScopedProcessWaitActivity::ScopedProcessWaitActivity(
const void* program_counter,
const base::Process* process)
: GlobalActivityTracker::ScopedThreadActivity(
program_counter,
nullptr,
Activity::ACT_PROCESS_WAIT,
ActivityData::ForProcess(process->Pid()),
/*lock_allowed=*/true) {}
#endif
} // namespace debug
} // namespace base