src/profiling/memory/client.h

/*
 * 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.
 */

#ifndef SRC_PROFILING_MEMORY_CLIENT_H_
#define SRC_PROFILING_MEMORY_CLIENT_H_

#include <pthread.h>
#include <stddef.h>

#include <condition_variable>
#include <mutex>
#include <vector>

#include "perfetto/base/unix_socket.h"
#include "src/profiling/memory/wire_protocol.h"

namespace perfetto {
namespace profiling {

class BorrowedSocket;

class SocketPool {
 public:
  friend class BorrowedSocket;
  SocketPool(std::vector<base::UnixSocketRaw> sockets);

  BorrowedSocket Borrow();
  void Shutdown();

 private:
  bool shutdown_ = false;

  void Return(base::UnixSocketRaw);
  std::timed_mutex mutex_;
  std::condition_variable_any cv_;
  std::vector<base::UnixSocketRaw> sockets_;
  size_t available_sockets_;
  size_t dead_sockets_ = 0;
};

// Socket borrowed from a SocketPool. Gets returned once it goes out of scope.
class BorrowedSocket {
 public:
  BorrowedSocket(const BorrowedSocket&) = delete;
  BorrowedSocket& operator=(const BorrowedSocket&) = delete;
  BorrowedSocket(BorrowedSocket&& other) noexcept
      : sock_(std::move(other.sock_)), socket_pool_(other.socket_pool_) {
    other.socket_pool_ = nullptr;
  }

  BorrowedSocket(base::UnixSocketRaw sock, SocketPool* socket_pool)
      : sock_(std::move(sock)), socket_pool_(socket_pool) {}

  ~BorrowedSocket() {
    if (socket_pool_ != nullptr)
      socket_pool_->Return(std::move(sock_));
  }

  base::UnixSocketRaw* operator->() { return &sock_; }
  base::UnixSocketRaw* get() { return &sock_; }
  void Shutdown() { sock_.Shutdown(); }
  explicit operator bool() const { return !!sock_; }

 private:
  base::UnixSocketRaw sock_;
  SocketPool* socket_pool_ = nullptr;
};

// Cache for frees that have been observed. It is infeasible to send every
// free separately, so we batch and send the whole buffer once it is full.
class FreePage {
 public:
  FreePage(uint64_t client_generation) {
    free_page_.client_generation = client_generation;
  }

  // Add address to buffer. Flush if necessary using a socket borrowed from
  // pool.
  // Can be called from any thread. Must not hold mutex_.`
  bool Add(const uint64_t addr, uint64_t sequence_number, SocketPool* pool);

 private:
  // Needs to be called holding mutex_.
  bool FlushLocked(SocketPool* pool);

  FreeMetadata free_page_;
  std::timed_mutex mutex_;
  size_t offset_ = 0;
};

const char* GetThreadStackBase();

// RAII wrapper around pthread_key_t. This is different from a ScopedResource
// because it needs a separate boolean indicating validity.
class PThreadKey {
 public:
  PThreadKey(const PThreadKey&) = delete;
  PThreadKey& operator=(const PThreadKey&) = delete;

  PThreadKey(void (*destructor)(void*)) noexcept
      : valid_(pthread_key_create(&key_, destructor) == 0) {}
  ~PThreadKey() noexcept {
    if (valid_)
      pthread_key_delete(key_);
  }
  bool valid() const { return valid_; }
  pthread_key_t get() const {
    PERFETTO_DCHECK(valid_);
    return key_;
  }

 private:
  pthread_key_t key_;
  bool valid_;
};

constexpr uint32_t kClientSockTimeoutMs = 1000;

// This is created and owned by the malloc hooks.
class Client {
 public:
  Client(std::vector<base::UnixSocketRaw> sockets);
  Client(const std::string& sock_name, size_t conns);
  bool RecordMalloc(uint64_t alloc_size,
                    uint64_t total_size,
                    uint64_t alloc_address);
  bool RecordFree(uint64_t alloc_address);
  bool MaybeSampleAlloc(uint64_t alloc_size,
                        uint64_t alloc_address,
                        void* (*unhooked_malloc)(size_t),
                        void (*unhooked_free)(void*));
  void Shutdown();

  ClientConfiguration client_config_for_testing() { return client_config_; }
  bool inited() { return inited_; }

 private:
  ssize_t ShouldSampleAlloc(uint64_t alloc_size,
                            void* (*unhooked_malloc)(size_t),
                            void (*unhooked_free)(void*));
  const char* GetStackBase();

  static std::atomic<uint64_t> max_generation_;
  const uint64_t generation_;

  std::atomic<bool> inited_{false};
  ClientConfiguration client_config_;
  PThreadKey pthread_key_;
  SocketPool socket_pool_;
  FreePage free_page_;
  const char* main_thread_stack_base_ = nullptr;
  std::atomic<uint64_t> sequence_number_{0};
};

}  // namespace profiling
}  // namespace perfetto

#endif  // SRC_PROFILING_MEMORY_CLIENT_H_