src/traced/probes/process_stats_data_source.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 "process_stats_data_source.h"

#include <utility>

#include "perfetto/trace/ps/process_tree.pbzero.h"
#include "perfetto/trace/trace_packet.pbzero.h"
#include "src/process_stats/file_utils.h"
#include "src/process_stats/procfs_utils.h"

namespace perfetto {

ProcessStatsDataSource::ProcessStatsDataSource(
    TracingSessionID id,
    std::unique_ptr<TraceWriter> writer)
    : session_id_(id), writer_(std::move(writer)), weak_factory_(this) {}

ProcessStatsDataSource::~ProcessStatsDataSource() = default;

base::WeakPtr<ProcessStatsDataSource> ProcessStatsDataSource::GetWeakPtr()
    const {
  return weak_factory_.GetWeakPtr();
}

void ProcessStatsDataSource::WriteAllProcesses() {
  auto trace_packet = writer_->NewTracePacket();
  auto* trace_packet_ptr = &*trace_packet;
  std::set<int32_t>* seen_pids = &seen_pids_;

  file_utils::ForEachPidInProcPath("/proc",
                                   [trace_packet_ptr, seen_pids](int pid) {
                                     // ForEachPid will list all processes and
                                     // threads. Here we want to iterate first
                                     // only by processes (for which pid ==
                                     // thread group id)
                                     if (procfs_utils::ReadTgid(pid) != pid)
                                       return;

                                     WriteProcess(pid, trace_packet_ptr);
                                     seen_pids->insert(pid);
                                   });
}

void ProcessStatsDataSource::OnPids(const std::vector<int32_t>& pids) {
  auto trace_packet = writer_->NewTracePacket();
  for (int32_t pid : pids) {
    auto it_and_inserted = seen_pids_.emplace(pid);
    if (it_and_inserted.second)
      WriteProcess(pid, &*trace_packet);
  }
}

// static
void ProcessStatsDataSource::WriteProcess(
    int32_t pid,
    protos::pbzero::TracePacket* trace_packet) {
  auto* process_tree = trace_packet->set_process_tree();

  std::unique_ptr<ProcessInfo> process = procfs_utils::ReadProcessInfo(pid);
  procfs_utils::ReadProcessThreads(process.get());
  auto* process_writer = process_tree->add_processes();
  process_writer->set_pid(process->pid);
  process_writer->set_ppid(process->ppid);
  for (const auto& field : process->cmdline)
    process_writer->add_cmdline(field.c_str());
  for (auto& thread : process->threads) {
    auto* thread_writer = process_writer->add_threads();
    thread_writer->set_tid(thread.second.tid);
    thread_writer->set_name(thread.second.name);
  }
}

}  // namespace perfetto