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/*
* Copyright (c) 2012 The WebRTC 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 in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "webrtc/base/event_tracer.h"
#include <inttypes.h>
#include <string>
#include <vector>
#include "webrtc/base/checks.h"
#include "webrtc/base/criticalsection.h"
#include "webrtc/base/event.h"
#include "webrtc/base/logging.h"
#include "webrtc/base/platform_thread.h"
#include "webrtc/base/stringutils.h"
#include "webrtc/base/timeutils.h"
#include "webrtc/base/trace_event.h"
// This is a guesstimate that should be enough in most cases.
static const size_t kEventLoggerArgsStrBufferInitialSize = 256;
static const size_t kTraceArgBufferLength = 32;
namespace webrtc {
namespace {
GetCategoryEnabledPtr g_get_category_enabled_ptr = nullptr;
AddTraceEventPtr g_add_trace_event_ptr = nullptr;
} // namespace
void SetupEventTracer(GetCategoryEnabledPtr get_category_enabled_ptr,
AddTraceEventPtr add_trace_event_ptr) {
g_get_category_enabled_ptr = get_category_enabled_ptr;
g_add_trace_event_ptr = add_trace_event_ptr;
}
const unsigned char* EventTracer::GetCategoryEnabled(const char* name) {
if (g_get_category_enabled_ptr)
return g_get_category_enabled_ptr(name);
// A string with null terminator means category is disabled.
return reinterpret_cast<const unsigned char*>("\0");
}
// Arguments to this function (phase, etc.) are as defined in
// webrtc/base/trace_event.h.
void EventTracer::AddTraceEvent(char phase,
const unsigned char* category_enabled,
const char* name,
unsigned long long id,
int num_args,
const char** arg_names,
const unsigned char* arg_types,
const unsigned long long* arg_values,
unsigned char flags) {
if (g_add_trace_event_ptr) {
g_add_trace_event_ptr(phase,
category_enabled,
name,
id,
num_args,
arg_names,
arg_types,
arg_values,
flags);
}
}
} // namespace webrtc
namespace rtc {
namespace tracing {
namespace {
static bool EventTracingThreadFunc(void* params);
// Atomic-int fast path for avoiding logging when disabled.
static volatile int g_event_logging_active = 0;
// TODO(pbos): Log metadata for all threads, etc.
class EventLogger final {
public:
EventLogger()
: logging_thread_(EventTracingThreadFunc, this, "EventTracingThread"),
shutdown_event_(false, false) {}
~EventLogger() { RTC_DCHECK(thread_checker_.CalledOnValidThread()); }
void AddTraceEvent(const char* name,
const unsigned char* category_enabled,
char phase,
int num_args,
const char** arg_names,
const unsigned char* arg_types,
const unsigned long long* arg_values,
uint64_t timestamp,
int pid,
rtc::PlatformThreadId thread_id) {
std::vector<TraceArg> args(num_args);
for (int i = 0; i < num_args; ++i) {
TraceArg& arg = args[i];
arg.name = arg_names[i];
arg.type = arg_types[i];
arg.value.as_uint = arg_values[i];
// Value is a pointer to a temporary string, so we have to make a copy.
if (arg.type == TRACE_VALUE_TYPE_COPY_STRING) {
// Space for the string and for the terminating null character.
size_t str_length = strlen(arg.value.as_string) + 1;
char* str_copy = new char[str_length];
memcpy(str_copy, arg.value.as_string, str_length);
arg.value.as_string = str_copy;
}
}
rtc::CritScope lock(&crit_);
trace_events_.push_back(
{name, category_enabled, phase, args, timestamp, 1, thread_id});
}
// The TraceEvent format is documented here:
// https://docs.google.com/document/d/1CvAClvFfyA5R-PhYUmn5OOQtYMH4h6I0nSsKchNAySU/preview
void Log() {
RTC_DCHECK(output_file_);
static const int kLoggingIntervalMs = 100;
fprintf(output_file_, "{ \"traceEvents\": [\n");
bool has_logged_event = false;
while (true) {
bool shutting_down = shutdown_event_.Wait(kLoggingIntervalMs);
std::vector<TraceEvent> events;
{
rtc::CritScope lock(&crit_);
trace_events_.swap(events);
}
std::string args_str;
args_str.reserve(kEventLoggerArgsStrBufferInitialSize);
for (TraceEvent& e : events) {
args_str.clear();
if (!e.args.empty()) {
args_str += ", \"args\": {";
bool is_first_argument = true;
for (TraceArg& arg : e.args) {
if (!is_first_argument)
args_str += ",";
is_first_argument = false;
args_str += " \"";
args_str += arg.name;
args_str += "\": ";
args_str += TraceArgValueAsString(arg);
// Delete our copy of the string.
if (arg.type == TRACE_VALUE_TYPE_COPY_STRING) {
delete[] arg.value.as_string;
arg.value.as_string = nullptr;
}
}
args_str += " }";
}
fprintf(output_file_,
"%s{ \"name\": \"%s\""
", \"cat\": \"%s\""
", \"ph\": \"%c\""
", \"ts\": %" PRIu64
", \"pid\": %d"
#if defined(WEBRTC_WIN)
", \"tid\": %lu"
#else
", \"tid\": %d"
#endif // defined(WEBRTC_WIN)
"%s"
"}\n",
has_logged_event ? "," : " ", e.name, e.category_enabled,
e.phase, e.timestamp, e.pid, e.tid, args_str.c_str());
has_logged_event = true;
}
if (shutting_down)
break;
}
fprintf(output_file_, "]}\n");
if (output_file_owned_)
fclose(output_file_);
output_file_ = nullptr;
}
void Start(FILE* file, bool owned) {
RTC_DCHECK(thread_checker_.CalledOnValidThread());
RTC_DCHECK(file);
RTC_DCHECK(!output_file_);
output_file_ = file;
output_file_owned_ = owned;
{
rtc::CritScope lock(&crit_);
// Since the atomic fast-path for adding events to the queue can be
// bypassed while the logging thread is shutting down there may be some
// stale events in the queue, hence the vector needs to be cleared to not
// log events from a previous logging session (which may be days old).
trace_events_.clear();
}
// Enable event logging (fast-path). This should be disabled since starting
// shouldn't be done twice.
RTC_CHECK_EQ(0,
rtc::AtomicOps::CompareAndSwap(&g_event_logging_active, 0, 1));
// Finally start, everything should be set up now.
logging_thread_.Start();
TRACE_EVENT_INSTANT0("webrtc", "EventLogger::Start");
logging_thread_.SetPriority(kLowPriority);
}
void Stop() {
RTC_DCHECK(thread_checker_.CalledOnValidThread());
TRACE_EVENT_INSTANT0("webrtc", "EventLogger::Stop");
// Try to stop. Abort if we're not currently logging.
if (rtc::AtomicOps::CompareAndSwap(&g_event_logging_active, 1, 0) == 0)
return;
// Wake up logging thread to finish writing.
shutdown_event_.Set();
// Join the logging thread.
logging_thread_.Stop();
}
private:
struct TraceArg {
const char* name;
unsigned char type;
// Copied from webrtc/base/trace_event.h TraceValueUnion.
union TraceArgValue {
bool as_bool;
unsigned long long as_uint;
long long as_int;
double as_double;
const void* as_pointer;
const char* as_string;
} value;
// Assert that the size of the union is equal to the size of the as_uint
// field since we are assigning to arbitrary types using it.
static_assert(sizeof(TraceArgValue) == sizeof(unsigned long long),
"Size of TraceArg value union is not equal to the size of "
"the uint field of that union.");
};
struct TraceEvent {
const char* name;
const unsigned char* category_enabled;
char phase;
std::vector<TraceArg> args;
uint64_t timestamp;
int pid;
rtc::PlatformThreadId tid;
};
static std::string TraceArgValueAsString(TraceArg arg) {
std::string output;
if (arg.type == TRACE_VALUE_TYPE_STRING ||
arg.type == TRACE_VALUE_TYPE_COPY_STRING) {
// Space for every character to be an espaced character + two for
// quatation marks.
output.reserve(strlen(arg.value.as_string) * 2 + 2);
output += '\"';
const char* c = arg.value.as_string;
do {
if (*c == '"' || *c == '\\') {
output += '\\';
output += *c;
} else {
output += *c;
}
} while (*++c);
output += '\"';
} else {
output.resize(kTraceArgBufferLength);
size_t print_length = 0;
switch (arg.type) {
case TRACE_VALUE_TYPE_BOOL:
if (arg.value.as_bool) {
strcpy(&output[0], "true");
print_length = 4;
} else {
strcpy(&output[0], "false");
print_length = 5;
}
break;
case TRACE_VALUE_TYPE_UINT:
print_length = sprintfn(&output[0], kTraceArgBufferLength, "%llu",
arg.value.as_uint);
break;
case TRACE_VALUE_TYPE_INT:
print_length = sprintfn(&output[0], kTraceArgBufferLength, "%lld",
arg.value.as_int);
break;
case TRACE_VALUE_TYPE_DOUBLE:
print_length = sprintfn(&output[0], kTraceArgBufferLength, "%f",
arg.value.as_double);
break;
case TRACE_VALUE_TYPE_POINTER:
print_length = sprintfn(&output[0], kTraceArgBufferLength, "\"%p\"",
arg.value.as_pointer);
break;
}
size_t output_length = print_length < kTraceArgBufferLength
? print_length
: kTraceArgBufferLength - 1;
// This will hopefully be very close to nop. On most implementations, it
// just writes null byte and sets the length field of the string.
output.resize(output_length);
}
return output;
}
rtc::CriticalSection crit_;
std::vector<TraceEvent> trace_events_ GUARDED_BY(crit_);
rtc::PlatformThread logging_thread_;
rtc::Event shutdown_event_;
rtc::ThreadChecker thread_checker_;
FILE* output_file_ = nullptr;
bool output_file_owned_ = false;
};
static bool EventTracingThreadFunc(void* params) {
static_cast<EventLogger*>(params)->Log();
// False indicates that the thread function has done its job and doesn't need
// to be restarted again. Log() runs its own internal loop.
return false;
}
static EventLogger* volatile g_event_logger = nullptr;
static const char* const kDisabledTracePrefix = TRACE_DISABLED_BY_DEFAULT("");
const unsigned char* InternalGetCategoryEnabled(const char* name) {
const char* prefix_ptr = &kDisabledTracePrefix[0];
const char* name_ptr = name;
// Check whether name contains the default-disabled prefix.
while (*prefix_ptr == *name_ptr && *prefix_ptr != '\0') {
++prefix_ptr;
++name_ptr;
}
return reinterpret_cast<const unsigned char*>(*prefix_ptr == '\0' ? ""
: name);
}
void InternalAddTraceEvent(char phase,
const unsigned char* category_enabled,
const char* name,
unsigned long long id,
int num_args,
const char** arg_names,
const unsigned char* arg_types,
const unsigned long long* arg_values,
unsigned char flags) {
// Fast path for when event tracing is inactive.
if (rtc::AtomicOps::AcquireLoad(&g_event_logging_active) == 0)
return;
g_event_logger->AddTraceEvent(name, category_enabled, phase, num_args,
arg_names, arg_types, arg_values,
rtc::TimeMicros(), 1, rtc::CurrentThreadId());
}
} // namespace
void SetupInternalTracer() {
RTC_CHECK(rtc::AtomicOps::CompareAndSwapPtr(
&g_event_logger, static_cast<EventLogger*>(nullptr),
new EventLogger()) == nullptr);
webrtc::SetupEventTracer(InternalGetCategoryEnabled, InternalAddTraceEvent);
}
void StartInternalCaptureToFile(FILE* file) {
g_event_logger->Start(file, false);
}
bool StartInternalCapture(const char* filename) {
FILE* file = fopen(filename, "w");
if (!file) {
LOG(LS_ERROR) << "Failed to open trace file '" << filename
<< "' for writing.";
return false;
}
g_event_logger->Start(file, true);
return true;
}
void StopInternalCapture() {
g_event_logger->Stop();
}
void ShutdownInternalTracer() {
StopInternalCapture();
EventLogger* old_logger = rtc::AtomicOps::AcquireLoadPtr(&g_event_logger);
RTC_DCHECK(old_logger);
RTC_CHECK(rtc::AtomicOps::CompareAndSwapPtr(
&g_event_logger, old_logger,
static_cast<EventLogger*>(nullptr)) == old_logger);
delete old_logger;
webrtc::SetupEventTracer(nullptr, nullptr);
}
} // namespace tracing
} // namespace rtc