blob: 99b787f4a8010f364a8d95af7c7713eea562c972 [file] [log] [blame]
/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "perfetto/base/metatrace.h"
#include <fcntl.h>
#include <stdlib.h>
#include "perfetto/base/build_config.h"
#include "perfetto/base/file_utils.h"
#include "perfetto/base/time.h"
#if PERFETTO_BUILDFLAG(PERFETTO_OS_WIN)
#include <corecrt_io.h>
#endif
namespace perfetto {
namespace base {
namespace {
int MaybeOpenTraceFile() {
static const char* tracing_path = getenv("PERFETTO_METATRACE_FILE");
if (tracing_path == nullptr)
return -1;
static int fd = open(tracing_path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
return fd;
}
} // namespace
constexpr uint32_t MetaTrace::kMainThreadCpu;
void MetaTrace::WriteEvent(char type, const char* evt_name, size_t cpu) {
int fd = MaybeOpenTraceFile();
if (fd == -1)
return;
// The JSON event format expects both "pid" and "tid" fields to create
// per-process tracks. Here what we really want to achieve is having one track
// per cpu. So we just pretend that each CPU is its own process with
// pid == tid == cpu.
char json[256];
int len = sprintf(json,
"{\"ts\": %f, \"cat\": \"PERF\", \"ph\": \"%c\", \"name\": "
"\"%s\", \"pid\": %zu, \"tid\": %zu},\n",
GetWallTimeNs().count() / 1000.0, type, evt_name, cpu, cpu);
ignore_result(WriteAll(fd, json, static_cast<size_t>(len)));
}
} // namespace base
} // namespace perfetto