simpleperf/event_selection_set.h

/*
 * Copyright (C) 2015 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.
 */

#ifndef SIMPLE_PERF_EVENT_SELECTION_SET_H_
#define SIMPLE_PERF_EVENT_SELECTION_SET_H_

#include <functional>
#include <map>
#include <set>
#include <unordered_map>
#include <vector>

#include <android-base/macros.h>

#include "event_attr.h"
#include "event_fd.h"
#include "event_type.h"
#include "perf_event.h"
#include "record.h"

constexpr double DEFAULT_PERIOD_TO_DETECT_CPU_HOTPLUG_EVENTS_IN_SEC = 0.5;
constexpr double DEFAULT_PERIOD_TO_CHECK_MONITORED_TARGETS_IN_SEC = 1;

struct CounterInfo {
  pid_t tid;
  int cpu;
  PerfCounter counter;
};

struct CountersInfo {
  uint32_t group_id;
  std::string event_name;
  std::string event_modifier;
  std::vector<CounterInfo> counters;
};

class IOEventLoop;

// EventSelectionSet helps to monitor events. It is used in following steps:
// 1. Create an EventSelectionSet, and add event types to monitor by calling
//    AddEventType() or AddEventGroup().
// 2. Define how to monitor events by calling SetEnableOnExec(), SampleIdAll(),
//    SetSampleFreq(), etc.
// 3. Start monitoring by calling OpenEventFilesForCpus() or
//    OpenEventFilesForThreadsOnCpus(). If SetEnableOnExec() has been called
//    in step 2, monitor will be delayed until the monitored thread calls
//    exec().
// 4. Read counters by calling ReadCounters(), or read mapped event records
//    by calling MmapEventFiles(), PrepareToReadMmapEventData() and
//    FinishReadMmapEventData().
// 5. Stop monitoring automatically in the destructor of EventSelectionSet by
//    closing perf event files.

class EventSelectionSet {
 public:
  EventSelectionSet(bool for_stat_cmd)
      : for_stat_cmd_(for_stat_cmd), mmap_pages_(0), loop_(nullptr) {}

  bool empty() const { return groups_.empty(); }

  bool AddEventType(const std::string& event_name);
  bool AddEventGroup(const std::vector<std::string>& event_names);
  std::vector<const EventType*> GetTracepointEvents() const;
  std::vector<EventAttrWithId> GetEventAttrWithId() const;

  void SetEnableOnExec(bool enable);
  bool GetEnableOnExec();
  void SampleIdAll();
  void SetSampleFreq(uint64_t sample_freq);
  void SetSamplePeriod(uint64_t sample_period);
  void UseDefaultSampleFreq();
  bool SetBranchSampling(uint64_t branch_sample_type);
  void EnableFpCallChainSampling();
  bool EnableDwarfCallChainSampling(uint32_t dump_stack_size);
  void SetInherit(bool enable);
  bool NeedKernelSymbol() const;

  void AddMonitoredProcesses(const std::set<pid_t>& processes) {
    processes_.insert(processes.begin(), processes.end());
  }

  void AddMonitoredThreads(const std::set<pid_t>& threads) {
    threads_.insert(threads.begin(), threads.end());
  }

  const std::set<pid_t>& GetMonitoredProcesses() const { return processes_; }

  const std::set<pid_t>& GetMonitoredThreads() const { return threads_; }

  bool HasMonitoredTarget() const {
    return !processes_.empty() || !threads_.empty();
  }

  void SetIOEventLoop(IOEventLoop& loop) {
    loop_ = &loop;
  }

  bool OpenEventFiles(const std::vector<int>& on_cpus);
  bool ReadCounters(std::vector<CountersInfo>* counters);
  bool MmapEventFiles(size_t min_mmap_pages, size_t max_mmap_pages);
  bool PrepareToReadMmapEventData(const std::function<bool(Record*)>& callback);
  bool FinishReadMmapEventData();

  // If monitored_cpus is empty, monitor all cpus.
  bool HandleCpuHotplugEvents(const std::vector<int>& monitored_cpus,
                              double check_interval_in_sec =
                                  DEFAULT_PERIOD_TO_DETECT_CPU_HOTPLUG_EVENTS_IN_SEC);

  // Stop profiling if all monitored processes/threads don't exist.
  bool StopWhenNoMoreTargets(double check_interval_in_sec =
                                 DEFAULT_PERIOD_TO_CHECK_MONITORED_TARGETS_IN_SEC);

 private:
  struct EventSelection {
    EventTypeAndModifier event_type_modifier;
    perf_event_attr event_attr;
    std::vector<std::unique_ptr<EventFd>> event_fds;
    // counters for event files closed for cpu hotplug events
    std::vector<CounterInfo> hotplugged_counters;
  };
  typedef std::vector<EventSelection> EventSelectionGroup;

  bool BuildAndCheckEventSelection(const std::string& event_name,
                                   EventSelection* selection);
  void UnionSampleType();
  bool OpenEventFilesOnGroup(EventSelectionGroup& group, pid_t tid, int cpu,
                             std::string* failed_event_type);

  bool MmapEventFiles(size_t mmap_pages, bool report_error);
  bool ReadMmapEventData();

  bool DetectCpuHotplugEvents();
  bool HandleCpuOnlineEvent(int cpu);
  bool HandleCpuOfflineEvent(int cpu);
  bool CreateMappedBufferForCpu(int cpu);
  bool CheckMonitoredTargets();

  const bool for_stat_cmd_;

  std::vector<EventSelectionGroup> groups_;
  std::set<pid_t> processes_;
  std::set<pid_t> threads_;
  size_t mmap_pages_;

  IOEventLoop* loop_;
  std::function<bool(Record*)> record_callback_;

  std::set<int> monitored_cpus_;
  std::vector<int> online_cpus_;

  // Records from all mapped buffers are stored in record_buffer_, each
  // RecordBufferHead manages records read from one mapped buffer. Create
  // record_buffer_heads_ and record_buffer_ here to avoid allocating them
  // from heap each time calling ReadMmapEventData().
  struct RecordBufferHead {
    size_t current_pos;  // current position in record_buffer_
    size_t end_pos;  // end position in record_buffer_
    perf_event_attr* attr;
    uint64_t timestamp;
    std::unique_ptr<Record> r;
  };
  std::vector<RecordBufferHead> record_buffer_heads_;
  std::vector<char> record_buffer_;

  DISALLOW_COPY_AND_ASSIGN(EventSelectionSet);
};

bool IsBranchSamplingSupported();
bool IsDwarfCallChainSamplingSupported();

#endif  // SIMPLE_PERF_EVENT_SELECTION_SET_H_