// Protocol Buffers - Google's data interchange format

// Copyright 2008 Google Inc.  All rights reserved.

// https://developers.google.com/protocol-buffers/

//

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

//

//     * Redistributions of source code must retain the above copyright

// notice, this list of conditions and the following disclaimer.

//     * Redistributions in binary form must reproduce the above

// copyright notice, this list of conditions and the following disclaimer

// in the documentation and/or other materials provided with the

// distribution.

//     * Neither the name of Google Inc. nor the names of its

// contributors may be used to endorse or promote products derived from

// this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef GOOGLE_PROTOBUF_SRC_GOOGLE_PROTOBUF_ARENAZ_SAMPLER_H__

#define GOOGLE_PROTOBUF_SRC_GOOGLE_PROTOBUF_ARENAZ_SAMPLER_H__

#include <atomic>

#include <cstddef>

#include <cstdint>

// Must be included last.

#include <google/protobuf/port_def.inc>

namespace google {

namespace protobuf {

namespace internal {

#if defined(PROTOBUF_ARENAZ_SAMPLE)

struct ThreadSafeArenaStats;

void RecordResetSlow(ThreadSafeArenaStats* info);

void RecordAllocateSlow(ThreadSafeArenaStats* info, size_t requested,

                        size_t allocated, size_t wasted);

// Stores information about a sampled thread safe arena.  All mutations to this

// *must* be made through `Record*` functions below.  All reads from this *must*

// only occur in the callback to `ThreadSafeArenazSampler::Iterate`.

struct ThreadSafeArenaStats

    : public absl::profiling_internal::Sample<ThreadSafeArenaStats> {

  // Constructs the object but does not fill in any fields.

  ThreadSafeArenaStats();

  ~ThreadSafeArenaStats();

  // Puts the object into a clean state, fills in the logically `const` members,

  // blocking for any readers that are currently sampling the object.

  void PrepareForSampling() ABSL_EXCLUSIVE_LOCKS_REQUIRED(init_mu);

  // These fields are mutated by the various Record* APIs and need to be

  // thread-safe.

  std::atomic<int> num_allocations;

  std::atomic<int> num_resets;

  std::atomic<size_t> bytes_requested;

  std::atomic<size_t> bytes_allocated;

  std::atomic<size_t> bytes_wasted;

  // Records the largest size an arena ever had.  Maintained across resets.

  std::atomic<size_t> max_bytes_allocated;

  // Bit i when set to 1 indicates that a thread with tid % 63 = i accessed the

  // underlying arena.  The field is maintained across resets.

  std::atomic<uint64_t> thread_ids;

  // All of the fields below are set by `PrepareForSampling`, they must not

  // be mutated in `Record*` functions.  They are logically `const` in that

  // sense. These are guarded by init_mu, but that is not externalized to

  // clients, who can only read them during

  // `ThreadSafeArenazSampler::Iterate` which will hold the lock.

  static constexpr int kMaxStackDepth = 64;

  int32_t depth;

  void* stack[kMaxStackDepth];

  static void RecordAllocateStats(ThreadSafeArenaStats* info, size_t requested,

                                  size_t allocated, size_t wasted) {

    if (PROTOBUF_PREDICT_TRUE(info == nullptr)) return;

    RecordAllocateSlow(info, requested, allocated, wasted);

  }

};

ThreadSafeArenaStats* SampleSlow(int64_t* next_sample);

void UnsampleSlow(ThreadSafeArenaStats* info);

class ThreadSafeArenaStatsHandle {

 public:

  explicit ThreadSafeArenaStatsHandle() = default;

  explicit ThreadSafeArenaStatsHandle(ThreadSafeArenaStats* info)

      : info_(info) {}

  ~ThreadSafeArenaStatsHandle() {

    if (PROTOBUF_PREDICT_TRUE(info_ == nullptr)) return;

    UnsampleSlow(info_);

  }

  ThreadSafeArenaStatsHandle(ThreadSafeArenaStatsHandle&& other) noexcept

      : info_(absl::exchange(other.info_, nullptr)) {}

  ThreadSafeArenaStatsHandle& operator=(

      ThreadSafeArenaStatsHandle&& other) noexcept {

    if (PROTOBUF_PREDICT_FALSE(info_ != nullptr)) {

      UnsampleSlow(info_);

    }

    info_ = absl::exchange(other.info_, nullptr);

    return *this;

  }

  void RecordReset() {

    if (PROTOBUF_PREDICT_TRUE(info_ == nullptr)) return;

    RecordResetSlow(info_);

  }

  ThreadSafeArenaStats* MutableStats() { return info_; }

  friend void swap(ThreadSafeArenaStatsHandle& lhs,

                   ThreadSafeArenaStatsHandle& rhs) {

    std::swap(lhs.info_, rhs.info_);

  }

  friend class ThreadSafeArenaStatsHandlePeer;

 private:

  ThreadSafeArenaStats* info_ = nullptr;

};

using ThreadSafeArenazSampler =

    ::absl::profiling_internal::SampleRecorder<ThreadSafeArenaStats>;

extern PROTOBUF_THREAD_LOCAL int64_t global_next_sample;

// Returns an RAII sampling handle that manages registration and unregistation

// with the global sampler.

inline ThreadSafeArenaStatsHandle Sample() {

  if (PROTOBUF_PREDICT_TRUE(--global_next_sample > 0)) {

    return ThreadSafeArenaStatsHandle(nullptr);

  }

  return ThreadSafeArenaStatsHandle(SampleSlow(&global_next_sample));

}

#else

struct ThreadSafeArenaStats {

  static void RecordAllocateStats(ThreadSafeArenaStats*, size_t /*requested*/,

                                  size_t /*allocated*/, size_t /*wasted*/) {}

};

ThreadSafeArenaStats* SampleSlow(int64_t* next_sample);

void UnsampleSlow(ThreadSafeArenaStats* info);

class ThreadSafeArenaStatsHandle {

 public:

  explicit ThreadSafeArenaStatsHandle() = default;

  explicit ThreadSafeArenaStatsHandle(ThreadSafeArenaStats*) {}

  void RecordReset() {}

  ThreadSafeArenaStats* MutableStats() { return nullptr; }

  friend void swap(ThreadSafeArenaStatsHandle&, ThreadSafeArenaStatsHandle&) {}

 private:

  friend class ThreadSafeArenaStatsHandlePeer;

};

class ThreadSafeArenazSampler {

 public:

  void Unregister(ThreadSafeArenaStats*) {}

  void SetMaxSamples(int32_t) {}

};

// Returns an RAII sampling handle that manages registration and unregistation

// with the global sampler.

inline ThreadSafeArenaStatsHandle Sample() {

  return ThreadSafeArenaStatsHandle(nullptr);

}

#endif  // defined(PROTOBUF_ARENAZ_SAMPLE)

// Returns a global Sampler.

ThreadSafeArenazSampler& GlobalThreadSafeArenazSampler();

// Enables or disables sampling for thread safe arenas.

void SetThreadSafeArenazEnabled(bool enabled);

// Sets the rate at which thread safe arena will be sampled.

void SetThreadSafeArenazSampleParameter(int32_t rate);

// Sets a soft max for the number of samples that will be kept.

void SetThreadSafeArenazMaxSamples(int32_t max);

// Sets the current value for when arenas should be next sampled.

void SetThreadSafeArenazGlobalNextSample(int64_t next_sample);

}  // namespace internal

}  // namespace protobuf

}  // namespace google

#include <google/protobuf/port_undef.inc>

#endif  // GOOGLE_PROTOBUF_SRC_PROTOBUF_ARENAZ_SAMPLER_H__