/*
Copyright (c) 2018 Advanced Micro Devices, Inc. All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

#ifndef MEMORY_POOL_H_
#define MEMORY_POOL_H_

#include <pthread.h>
#include <stdlib.h>

#include <atomic>
#include <mutex>

#include "util/exception.h"

#define PTHREAD_CALL(call)                                                                         \
  do {                                                                                             \
    int err = call;                                                                                \
    if (err != 0) {                                                                                \
      errno = err;                                                                                 \
      perror(#call);                                                                               \
      abort();                                                                                     \
    }                                                                                              \
  } while (0)

namespace roctracer {

class MemoryPool {
  public:
  typedef std::mutex mutex_t;

  static void allocator_default(char** ptr, size_t size, void* arg) {
    (void)arg;
    if (*ptr == NULL) {
      *ptr = reinterpret_cast<char*>(malloc(size));
    } else if (size != 0) {
      *ptr = reinterpret_cast<char*>(realloc(*ptr, size));
    } else {
      free(*ptr); 
      *ptr = NULL;
    }
  }

  MemoryPool(const roctracer_properties_t& properties) { 
    // Assigning pool allocator
    alloc_fun_ = allocator_default;
    alloc_arg_ = NULL;
    if (properties.alloc_fun != NULL) {
      alloc_fun_ = properties.alloc_fun;
      alloc_arg_ = properties.alloc_arg;
    }

    // Pool definition
    buffer_size_ = properties.buffer_size;
    const size_t pool_size = 2 * buffer_size_;
    pool_begin_ = NULL;
    alloc_fun_(&pool_begin_, pool_size, alloc_arg_);
    if (pool_begin_ == NULL) EXC_ABORT(ROCTRACER_STATUS_ERROR, "pool allocator failed");
    pool_end_ = pool_begin_ + pool_size;
    buffer_begin_ = pool_begin_;
    buffer_end_ = buffer_begin_ + buffer_size_;
    write_ptr_ = buffer_begin_;

    // Consuming read thread
    read_callback_fun_ = properties.buffer_callback_fun;
    read_callback_arg_ = properties.buffer_callback_arg;
    consumer_arg_.set(this, NULL, NULL, true);
    PTHREAD_CALL(pthread_mutex_init(&read_mutex_, NULL));
    PTHREAD_CALL(pthread_cond_init(&read_cond_, NULL));
    PTHREAD_CALL(pthread_create(&consumer_thread_, NULL, reader_fun, &consumer_arg_));
  }

  ~MemoryPool() {
    Flush();
    PTHREAD_CALL(pthread_cancel(consumer_thread_));
    void *res;
    PTHREAD_CALL(pthread_join(consumer_thread_, &res));
    if (res != PTHREAD_CANCELED) EXC_ABORT(ROCTRACER_STATUS_ERROR, "consumer thread wasn't stopped correctly");
    allocator_default(&pool_begin_, 0, alloc_arg_);
  }

  template <typename Record>
  void Write(const Record& record) {
    std::lock_guard<mutex_t> lock(write_mutex_);
    getRecord<Record>(record);
  }

  void Flush() {
    std::lock_guard<mutex_t> lock(write_mutex_);
    if (write_ptr_ > buffer_begin_) {
      spawn_reader(buffer_begin_, write_ptr_);
      sync_reader(&consumer_arg_);
      buffer_begin_ = (buffer_end_ == pool_end_) ? pool_begin_ : buffer_end_;
      buffer_end_ = buffer_begin_ + buffer_size_;
      write_ptr_ = buffer_begin_;
    }
  }

  private:
  struct consumer_arg_t {
    MemoryPool* obj;
    const char* begin;
    const char* end;
    volatile std::atomic<bool> valid;
    void set(MemoryPool* obj_p, const char* begin_p, const char* end_p, bool valid_p) {
      obj = obj_p;
      begin = begin_p;
      end = end_p;
      valid.store(valid_p);
    }
  };

  template <typename Record>
  Record* getRecord(const Record& init) {
    char* next = write_ptr_ + sizeof(Record);
    if (next > buffer_end_) {
      if (write_ptr_ == buffer_begin_) EXC_ABORT(ROCTRACER_STATUS_ERROR, "buffer size(" << buffer_size_ << ") is less then the record(" << sizeof(Record) << ")");
      spawn_reader(buffer_begin_, write_ptr_);
      buffer_begin_ = (buffer_end_ == pool_end_) ? pool_begin_ : buffer_end_;
      buffer_end_ = buffer_begin_ + buffer_size_;
      write_ptr_ = buffer_begin_;
      next = write_ptr_ + sizeof(Record);
    }

    Record* ptr = reinterpret_cast<Record*>(write_ptr_);
    write_ptr_ = next;

    *ptr = init;
    return ptr;
  }

  static void reset_reader(consumer_arg_t* arg) {
    arg->valid.store(false);
  }

  static void sync_reader(const consumer_arg_t* arg) {
    while(arg->valid.load() == true) PTHREAD_CALL(pthread_yield());
  }

  static void* reader_fun(void* consumer_arg) {
    consumer_arg_t* arg = reinterpret_cast<consumer_arg_t*>(consumer_arg);
    roctracer::MemoryPool* obj = arg->obj;

    reset_reader(arg);

    while (1) {
      PTHREAD_CALL(pthread_mutex_lock(&(obj->read_mutex_)));
      while (arg->valid.load() == false) {
        PTHREAD_CALL(pthread_cond_wait(&(obj->read_cond_), &(obj->read_mutex_)));
      }

      obj->read_callback_fun_(arg->begin, arg->end, obj->read_callback_arg_);
      reset_reader(arg);
      PTHREAD_CALL(pthread_mutex_unlock(&(obj->read_mutex_)));
    }

    return NULL;
  }

  void spawn_reader(const char* data_begin, const char* data_end) {
    sync_reader(&consumer_arg_);
    PTHREAD_CALL(pthread_mutex_lock(&read_mutex_));
    consumer_arg_.set(this, data_begin, data_end, true);
    PTHREAD_CALL(pthread_cond_signal(&read_cond_));
    PTHREAD_CALL(pthread_mutex_unlock(&read_mutex_));
  }

  // pool allocator
  roctracer_allocator_t alloc_fun_;
  void* alloc_arg_;

  // Pool definition
  size_t buffer_size_;
  char* pool_begin_;
  char* pool_end_;
  char* buffer_begin_;
  char* buffer_end_;
  char* write_ptr_;
  mutex_t write_mutex_;

  // Consuming read thread
  roctracer_buffer_callback_t read_callback_fun_;
  void* read_callback_arg_;
  consumer_arg_t consumer_arg_;
  pthread_t consumer_thread_;
  pthread_mutex_t read_mutex_;
  pthread_cond_t read_cond_;
};

}  // namespace roctracer

#endif  // MEMORY_POOL_H_