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// Copyright 2016 the V8 project 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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "include/libplatform/v8-tracing.h"
#include "src/base/atomicops.h"
#include "src/base/platform/mutex.h"
#include "src/base/platform/time.h"
#ifdef V8_USE_PERFETTO
#include "base/trace_event/common/trace_event_common.h"
#include "perfetto/trace/chrome/chrome_trace_event.pbzero.h"
#include "perfetto/trace/trace_packet.pbzero.h"
#include "perfetto/tracing.h"
#include "src/base/platform/platform.h"
#include "src/base/platform/semaphore.h"
#include "src/libplatform/tracing/json-trace-event-listener.h"
#endif // V8_USE_PERFETTO
#ifdef V8_USE_PERFETTO
class V8DataSource : public perfetto::DataSource<V8DataSource> {
public:
void OnSetup(const SetupArgs&) override {}
void OnStart(const StartArgs&) override {}
void OnStop(const StopArgs&) override {}
};
PERFETTO_DEFINE_DATA_SOURCE_STATIC_MEMBERS(V8DataSource);
#endif // V8_USE_PERFETTO
namespace v8 {
namespace platform {
namespace tracing {
static const size_t kMaxCategoryGroups = 200;
// Parallel arrays g_category_groups and g_category_group_enabled are separate
// so that a pointer to a member of g_category_group_enabled can be easily
// converted to an index into g_category_groups. This allows macros to deal
// only with char enabled pointers from g_category_group_enabled, and we can
// convert internally to determine the category name from the char enabled
// pointer.
const char* g_category_groups[kMaxCategoryGroups] = {
"toplevel",
"tracing categories exhausted; must increase kMaxCategoryGroups",
"__metadata"};
// The enabled flag is char instead of bool so that the API can be used from C.
unsigned char g_category_group_enabled[kMaxCategoryGroups] = {0};
// Indexes here have to match the g_category_groups array indexes above.
const int g_category_categories_exhausted = 1;
// Metadata category not used in V8.
// const int g_category_metadata = 2;
const int g_num_builtin_categories = 3;
// Skip default categories.
v8::base::AtomicWord g_category_index = g_num_builtin_categories;
TracingController::TracingController() = default;
TracingController::~TracingController() {
StopTracing();
{
// Free memory for category group names allocated via strdup.
base::MutexGuard lock(mutex_.get());
for (size_t i = g_category_index - 1; i >= g_num_builtin_categories; --i) {
const char* group = g_category_groups[i];
g_category_groups[i] = nullptr;
free(const_cast<char*>(group));
}
g_category_index = g_num_builtin_categories;
}
}
void TracingController::Initialize(TraceBuffer* trace_buffer) {
trace_buffer_.reset(trace_buffer);
mutex_.reset(new base::Mutex());
}
#ifdef V8_USE_PERFETTO
void TracingController::InitializeForPerfetto(std::ostream* output_stream) {
output_stream_ = output_stream;
DCHECK_NOT_NULL(output_stream);
DCHECK(output_stream->good());
mutex_.reset(new base::Mutex());
}
void TracingController::SetTraceEventListenerForTesting(
TraceEventListener* listener) {
listener_for_testing_ = listener;
}
#endif
int64_t TracingController::CurrentTimestampMicroseconds() {
return base::TimeTicks::HighResolutionNow().ToInternalValue();
}
int64_t TracingController::CurrentCpuTimestampMicroseconds() {
return base::ThreadTicks::Now().ToInternalValue();
}
namespace {
#ifdef V8_USE_PERFETTO
void AddArgsToTraceProto(
::perfetto::protos::pbzero::ChromeTraceEvent* event, int num_args,
const char** arg_names, const uint8_t* arg_types,
const uint64_t* arg_values,
std::unique_ptr<v8::ConvertableToTraceFormat>* arg_convertables) {
for (int i = 0; i < num_args; i++) {
::perfetto::protos::pbzero::ChromeTraceEvent_Arg* arg = event->add_args();
// TODO(petermarshall): Set name_index instead if need be.
arg->set_name(arg_names[i]);
TraceObject::ArgValue arg_value;
arg_value.as_uint = arg_values[i];
switch (arg_types[i]) {
case TRACE_VALUE_TYPE_CONVERTABLE: {
// TODO(petermarshall): Support AppendToProto for Convertables.
std::string json_value;
arg_convertables[i]->AppendAsTraceFormat(&json_value);
arg->set_json_value(json_value.c_str());
break;
}
case TRACE_VALUE_TYPE_BOOL:
arg->set_bool_value(arg_value.as_bool);
break;
case TRACE_VALUE_TYPE_UINT:
arg->set_uint_value(arg_value.as_uint);
break;
case TRACE_VALUE_TYPE_INT:
arg->set_int_value(arg_value.as_int);
break;
case TRACE_VALUE_TYPE_DOUBLE:
arg->set_double_value(arg_value.as_double);
break;
case TRACE_VALUE_TYPE_POINTER:
arg->set_pointer_value(arg_value.as_uint);
break;
// There is no difference between copy strings and regular strings for
// Perfetto; the set_string_value(const char*) API will copy the string
// into the protobuf by default.
case TRACE_VALUE_TYPE_COPY_STRING:
case TRACE_VALUE_TYPE_STRING:
arg->set_string_value(arg_value.as_string);
break;
default:
UNREACHABLE();
}
}
}
#endif // V8_USE_PERFETTO
} // namespace
uint64_t TracingController::AddTraceEvent(
char phase, const uint8_t* category_enabled_flag, const char* name,
const char* scope, uint64_t id, uint64_t bind_id, int num_args,
const char** arg_names, const uint8_t* arg_types,
const uint64_t* arg_values,
std::unique_ptr<v8::ConvertableToTraceFormat>* arg_convertables,
unsigned int flags) {
int64_t now_us = CurrentTimestampMicroseconds();
return AddTraceEventWithTimestamp(
phase, category_enabled_flag, name, scope, id, bind_id, num_args,
arg_names, arg_types, arg_values, arg_convertables, flags, now_us);
}
uint64_t TracingController::AddTraceEventWithTimestamp(
char phase, const uint8_t* category_enabled_flag, const char* name,
const char* scope, uint64_t id, uint64_t bind_id, int num_args,
const char** arg_names, const uint8_t* arg_types,
const uint64_t* arg_values,
std::unique_ptr<v8::ConvertableToTraceFormat>* arg_convertables,
unsigned int flags, int64_t timestamp) {
int64_t cpu_now_us = CurrentCpuTimestampMicroseconds();
#ifdef V8_USE_PERFETTO
// Don't use COMPLETE events with perfetto - instead transform them into
// BEGIN/END pairs. This avoids the need for a thread-local stack of pending
// trace events as perfetto does not support handles into the trace buffer.
if (phase == TRACE_EVENT_PHASE_COMPLETE) phase = TRACE_EVENT_PHASE_BEGIN;
V8DataSource::Trace([&](V8DataSource::TraceContext ctx) {
auto packet = ctx.NewTracePacket();
auto* trace_event_bundle = packet->set_chrome_events();
auto* trace_event = trace_event_bundle->add_trace_events();
trace_event->set_name(name);
trace_event->set_timestamp(timestamp);
trace_event->set_phase(phase);
trace_event->set_thread_id(base::OS::GetCurrentThreadId());
trace_event->set_duration(0);
trace_event->set_thread_duration(0);
if (scope) trace_event->set_scope(scope);
trace_event->set_id(id);
trace_event->set_flags(flags);
if (category_enabled_flag) {
const char* category_group_name =
GetCategoryGroupName(category_enabled_flag);
DCHECK_NOT_NULL(category_group_name);
trace_event->set_category_group_name(category_group_name);
}
trace_event->set_process_id(base::OS::GetCurrentProcessId());
trace_event->set_thread_timestamp(cpu_now_us);
trace_event->set_bind_id(bind_id);
AddArgsToTraceProto(trace_event, num_args, arg_names, arg_types,
arg_values, arg_convertables);
});
return 0;
#else
uint64_t handle = 0;
if (recording_.load(std::memory_order_acquire)) {
TraceObject* trace_object = trace_buffer_->AddTraceEvent(&handle);
if (trace_object) {
{
base::MutexGuard lock(mutex_.get());
trace_object->Initialize(phase, category_enabled_flag, name, scope, id,
bind_id, num_args, arg_names, arg_types,
arg_values, arg_convertables, flags, timestamp,
cpu_now_us);
}
}
}
return handle;
#endif // V8_USE_PERFETTO
}
void TracingController::UpdateTraceEventDuration(
const uint8_t* category_enabled_flag, const char* name, uint64_t handle) {
int64_t now_us = CurrentTimestampMicroseconds();
int64_t cpu_now_us = CurrentCpuTimestampMicroseconds();
#ifdef V8_USE_PERFETTO
V8DataSource::Trace([&](V8DataSource::TraceContext ctx) {
auto packet = ctx.NewTracePacket();
auto* trace_event_bundle = packet->set_chrome_events();
auto* trace_event = trace_event_bundle->add_trace_events();
trace_event->set_phase(TRACE_EVENT_PHASE_END);
trace_event->set_thread_id(base::OS::GetCurrentThreadId());
trace_event->set_timestamp(now_us);
trace_event->set_process_id(base::OS::GetCurrentProcessId());
trace_event->set_thread_timestamp(cpu_now_us);
});
#else
TraceObject* trace_object = trace_buffer_->GetEventByHandle(handle);
if (!trace_object) return;
trace_object->UpdateDuration(now_us, cpu_now_us);
#endif // V8_USE_PERFETTO
}
const char* TracingController::GetCategoryGroupName(
const uint8_t* category_group_enabled) {
// Calculate the index of the category group by finding
// category_group_enabled in g_category_group_enabled array.
uintptr_t category_begin =
reinterpret_cast<uintptr_t>(g_category_group_enabled);
uintptr_t category_ptr = reinterpret_cast<uintptr_t>(category_group_enabled);
// Check for out of bounds category pointers.
DCHECK(category_ptr >= category_begin &&
category_ptr < reinterpret_cast<uintptr_t>(g_category_group_enabled +
kMaxCategoryGroups));
uintptr_t category_index =
(category_ptr - category_begin) / sizeof(g_category_group_enabled[0]);
return g_category_groups[category_index];
}
void TracingController::StartTracing(TraceConfig* trace_config) {
#ifdef V8_USE_PERFETTO
DCHECK_NOT_NULL(output_stream_);
DCHECK(output_stream_->good());
json_listener_ = base::make_unique<JSONTraceEventListener>(output_stream_);
// TODO(petermarshall): Set other the params for the config.
::perfetto::TraceConfig perfetto_trace_config;
perfetto_trace_config.add_buffers()->set_size_kb(4096);
auto* ds_config = perfetto_trace_config.add_data_sources()->mutable_config();
ds_config->set_name("v8.trace_events");
perfetto::DataSourceDescriptor dsd;
dsd.set_name("v8.trace_events");
bool registered = V8DataSource::Register(dsd);
CHECK(registered);
tracing_session_ =
perfetto::Tracing::NewTrace(perfetto::BackendType::kUnspecifiedBackend);
tracing_session_->Setup(perfetto_trace_config);
tracing_session_->StartBlocking();
#endif // V8_USE_PERFETTO
trace_config_.reset(trace_config);
std::unordered_set<v8::TracingController::TraceStateObserver*> observers_copy;
{
base::MutexGuard lock(mutex_.get());
recording_.store(true, std::memory_order_release);
UpdateCategoryGroupEnabledFlags();
observers_copy = observers_;
}
for (auto o : observers_copy) {
o->OnTraceEnabled();
}
}
void TracingController::StopTracing() {
bool expected = true;
if (!recording_.compare_exchange_strong(expected, false)) {
return;
}
UpdateCategoryGroupEnabledFlags();
std::unordered_set<v8::TracingController::TraceStateObserver*> observers_copy;
{
base::MutexGuard lock(mutex_.get());
observers_copy = observers_;
}
for (auto o : observers_copy) {
o->OnTraceDisabled();
}
#ifdef V8_USE_PERFETTO
// Emit a fake trace event from the main thread. The final trace event is
// sometimes skipped because perfetto can't guarantee that the caller is
// totally finished writing to it without synchronization. To avoid the
// situation where we lose the last trace event, add a fake one here that will
// be sacrificed.
// TODO(petermarshall): Use the Client API to flush here rather than this
// workaround when that becomes available.
V8DataSource::Trace([&](V8DataSource::TraceContext ctx) {
auto packet = ctx.NewTracePacket();
});
tracing_session_->StopBlocking();
std::vector<char> trace = tracing_session_->ReadTraceBlocking();
json_listener_->ParseFromArray(trace);
if (listener_for_testing_) listener_for_testing_->ParseFromArray(trace);
json_listener_.reset();
#else
{
base::MutexGuard lock(mutex_.get());
DCHECK(trace_buffer_);
trace_buffer_->Flush();
}
#endif // V8_USE_PERFETTO
}
void TracingController::UpdateCategoryGroupEnabledFlag(size_t category_index) {
unsigned char enabled_flag = 0;
const char* category_group = g_category_groups[category_index];
if (recording_.load(std::memory_order_acquire) &&
trace_config_->IsCategoryGroupEnabled(category_group)) {
enabled_flag |= ENABLED_FOR_RECORDING;
}
// TODO(fmeawad): EventCallback and ETW modes are not yet supported in V8.
// TODO(primiano): this is a temporary workaround for catapult:#2341,
// to guarantee that metadata events are always added even if the category
// filter is "-*". See crbug.com/618054 for more details and long-term fix.
if (recording_.load(std::memory_order_acquire) &&
!strcmp(category_group, "__metadata")) {
enabled_flag |= ENABLED_FOR_RECORDING;
}
base::Relaxed_Store(reinterpret_cast<base::Atomic8*>(
g_category_group_enabled + category_index),
enabled_flag);
}
void TracingController::UpdateCategoryGroupEnabledFlags() {
size_t category_index = base::Acquire_Load(&g_category_index);
for (size_t i = 0; i < category_index; i++) UpdateCategoryGroupEnabledFlag(i);
}
const uint8_t* TracingController::GetCategoryGroupEnabled(
const char* category_group) {
// Check that category group does not contain double quote
DCHECK(!strchr(category_group, '"'));
// The g_category_groups is append only, avoid using a lock for the fast path.
size_t category_index = base::Acquire_Load(&g_category_index);
// Search for pre-existing category group.
for (size_t i = 0; i < category_index; ++i) {
if (strcmp(g_category_groups[i], category_group) == 0) {
return &g_category_group_enabled[i];
}
}
// Slow path. Grab the lock.
base::MutexGuard lock(mutex_.get());
// Check the list again with lock in hand.
unsigned char* category_group_enabled = nullptr;
category_index = base::Acquire_Load(&g_category_index);
for (size_t i = 0; i < category_index; ++i) {
if (strcmp(g_category_groups[i], category_group) == 0) {
return &g_category_group_enabled[i];
}
}
// Create a new category group.
// Check that there is a slot for the new category_group.
DCHECK(category_index < kMaxCategoryGroups);
if (category_index < kMaxCategoryGroups) {
// Don't hold on to the category_group pointer, so that we can create
// category groups with strings not known at compile time (this is
// required by SetWatchEvent).
const char* new_group = strdup(category_group);
g_category_groups[category_index] = new_group;
DCHECK(!g_category_group_enabled[category_index]);
// Note that if both included and excluded patterns in the
// TraceConfig are empty, we exclude nothing,
// thereby enabling this category group.
UpdateCategoryGroupEnabledFlag(category_index);
category_group_enabled = &g_category_group_enabled[category_index];
// Update the max index now.
base::Release_Store(&g_category_index, category_index + 1);
} else {
category_group_enabled =
&g_category_group_enabled[g_category_categories_exhausted];
}
return category_group_enabled;
}
void TracingController::AddTraceStateObserver(
v8::TracingController::TraceStateObserver* observer) {
{
base::MutexGuard lock(mutex_.get());
observers_.insert(observer);
if (!recording_.load(std::memory_order_acquire)) return;
}
// Fire the observer if recording is already in progress.
observer->OnTraceEnabled();
}
void TracingController::RemoveTraceStateObserver(
v8::TracingController::TraceStateObserver* observer) {
base::MutexGuard lock(mutex_.get());
DCHECK(observers_.find(observer) != observers_.end());
observers_.erase(observer);
}
} // namespace tracing
} // namespace platform
} // namespace v8