src/trace_processor/read_trace.cc

/*
 * Copyright (C) 2019 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/trace_processor/read_trace.h"

#include "perfetto/ext/base/scoped_file.h"
#include "perfetto/trace_processor/trace_processor.h"

#if PERFETTO_BUILDFLAG(PERFETTO_OS_LINUX) || \
    PERFETTO_BUILDFLAG(PERFETTO_OS_MACOSX)
#define PERFETTO_HAS_AIO_H() 1
#else
#define PERFETTO_HAS_AIO_H() 0
#endif

#if PERFETTO_HAS_AIO_H()
#include <aio.h>
#endif

namespace perfetto {
namespace trace_processor {

util::Status ReadTrace(
    TraceProcessor* tp,
    const char* filename,
    const std::function<void(uint64_t parsed_size)>& progress_callback) {
  base::ScopedFile fd(base::OpenFile(filename, O_RDONLY));
  if (!fd)
    return util::ErrStatus("Could not open trace file (path: %s)", filename);

  // 1MB chunk size seems the best tradeoff on a MacBook Pro 2013 - i7 2.8 GHz.
  constexpr size_t kChunkSize = 1024 * 1024;
  uint64_t file_size = 0;

#if PERFETTO_HAS_AIO_H()
  // Load the trace in chunks using async IO. We create a simple pipeline where,
  // at each iteration, we parse the current chunk and asynchronously start
  // reading the next chunk.
  struct aiocb cb {};
  cb.aio_nbytes = kChunkSize;
  cb.aio_fildes = *fd;

  std::unique_ptr<uint8_t[]> aio_buf(new uint8_t[kChunkSize]);
#if defined(MEMORY_SANITIZER)
  // Just initialize the memory to make the memory sanitizer happy as it
  // cannot track aio calls below.
  memset(aio_buf.get(), 0, kChunkSize);
#endif  // defined(MEMORY_SANITIZER)
  cb.aio_buf = aio_buf.get();

  PERFETTO_CHECK(aio_read(&cb) == 0);
  struct aiocb* aio_list[1] = {&cb};

  for (int i = 0;; i++) {
    if (progress_callback && i % 128 == 0)
      progress_callback(file_size);

    // Block waiting for the pending read to complete.
    PERFETTO_CHECK(aio_suspend(aio_list, 1, nullptr) == 0);
    auto rsize = aio_return(&cb);
    if (rsize <= 0)
      break;
    file_size += static_cast<uint64_t>(rsize);

    // Take ownership of the completed buffer and enqueue a new async read
    // with a fresh buffer.
    std::unique_ptr<uint8_t[]> buf(std::move(aio_buf));
    aio_buf.reset(new uint8_t[kChunkSize]);
#if defined(MEMORY_SANITIZER)
    // Just initialize the memory to make the memory sanitizer happy as it
    // cannot track aio calls below.
    memset(aio_buf.get(), 0, kChunkSize);
#endif  // defined(MEMORY_SANITIZER)
    cb.aio_buf = aio_buf.get();
    cb.aio_offset += rsize;
    PERFETTO_CHECK(aio_read(&cb) == 0);

    // Parse the completed buffer while the async read is in-flight.
    util::Status status = tp->Parse(std::move(buf), static_cast<size_t>(rsize));
    if (PERFETTO_UNLIKELY(!status.ok()))
      return status;
  }
#else   // PERFETTO_HAS_AIO_H()
  // Load the trace in chunks using ordinary read().
  // This version is used on Windows, since there's no aio library.
  for (int i = 0;; i++) {
    if (progress_callback && i % 128 == 0)
      progress_callback(file_size);

    std::unique_ptr<uint8_t[]> buf(new uint8_t[kChunkSize]);
    auto rsize = read(*fd, buf.get(), kChunkSize);
    if (rsize <= 0)
      break;
    file_size += static_cast<uint64_t>(rsize);

    util::Status status = tp->Parse(std::move(buf), static_cast<size_t>(rsize));
    if (PERFETTO_UNLIKELY(!status.ok()))
      return status;
  }
#endif  // PERFETTO_HAS_AIO_H()

  tp->NotifyEndOfFile();
  tp->SetCurrentTraceName(filename);

  if (progress_callback)
    progress_callback(file_size);
  return util::OkStatus();
}

}  // namespace trace_processor
}  // namespace perfetto