src/trace_processor/file_reader.cc

/*
 * 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 "src/trace_processor/file_reader.h"

#include <fcntl.h>
#include <sys/stat.h>

namespace perfetto {
namespace trace_processor {

FileReader::FileReader(const char* path, bool print_progress) {
  fd_.reset(open(path, O_RDONLY));
  if (!fd_)
    PERFETTO_FATAL("Could not open %s", path);
  struct stat stat_buf {};
  PERFETTO_CHECK(fstat(*fd_, &stat_buf) == 0);
  file_size_ = static_cast<uint64_t>(stat_buf.st_size);
  print_progress_ = print_progress;
}

FileReader::~FileReader() = default;

uint32_t FileReader::Read(uint64_t offset, uint32_t len, uint8_t* dst) {
  ssize_t res = pread(*fd_, dst, len, static_cast<off_t>(offset));
  uint64_t size_read = offset + static_cast<uint64_t>(res);
  if (print_progress_ && (!res || size_read >= last_progress_bytes_ + 1E8)) {
    last_progress_bytes_ = size_read;
    double progress = size_read * 100.0 / file_size_;
    fprintf(stderr, "\rReading trace: %.2f%% %.1f MB / %.1f MB", progress,
            size_read / 1E6, file_size_ / 1E6);
    fflush(stderr);
    if (size_read == file_size_)
      fprintf(stderr, "\r%80s\r", "");
  }
  return res > 0 ? static_cast<uint32_t>(res) : 0;
}

}  // namespace trace_processor
}  // namespace perfetto