/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
   It is considered beerware. Prost. Skol. Cheers or whatever.

   $id$ */

/* System */
#include <arpa/inet.h>
#include <pthread.h>
#include <stdatomic.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/uio.h>


/* Opentracker */
#include "ot_iovec.h"
#include "ot_mutex.h"
#include "ot_stats.h"
#include "trackerlogic.h"

/* #define MTX_DBG( STRING ) fprintf( stderr, STRING ) */
#define MTX_DBG(STRING)

/* Our global all torrents list */
static ot_vector       all_torrents[OT_BUCKET_COUNT];
static pthread_mutex_t bucket_mutex[OT_BUCKET_COUNT];
/* Every bucket's unlock adjusts this, and a bucket lock only keeps other
   threads out of that one bucket, so the counter needs its own protection */
static _Atomic size_t  g_torrent_count;

/* Self pipe from opentracker.c */

ot_vector *mutex_bucket_lock(int bucket) {
  pthread_mutex_lock(bucket_mutex + bucket);
  return all_torrents + bucket;
}

/* Torrents are spread over buckets by the first four bytes of their info_hash,
   which may sit at any alignment, hence the memcpy */
static int bucket_from_hash(ot_hash const hash) {
  uint32_t bucket;
  memcpy(&bucket, hash, sizeof(bucket));
  return ntohl(bucket) >> OT_BUCKET_COUNT_SHIFT;
}

ot_vector *mutex_bucket_lock_by_hash(ot_hash const hash) { return mutex_bucket_lock(bucket_from_hash(hash)); }

void mutex_bucket_unlock(int bucket, int delta_torrentcount) {
  pthread_mutex_unlock(bucket_mutex + bucket);
  if (delta_torrentcount)
    atomic_fetch_add_explicit(&g_torrent_count, (size_t)delta_torrentcount, memory_order_relaxed);
}

void mutex_bucket_unlock_by_hash(ot_hash const hash, int delta_torrentcount) {
  mutex_bucket_unlock(bucket_from_hash(hash), delta_torrentcount);
}

size_t mutex_get_torrent_count(void) { return atomic_load_explicit(&g_torrent_count, memory_order_relaxed); }

void mutex_init(void) {
  size_t i;
  for (i = 0; i < OT_BUCKET_COUNT; ++i)
    pthread_mutex_init(bucket_mutex + i, NULL);
  memset(all_torrents, 0, sizeof(all_torrents));
}

/* Let every worker parked on the queue see that the tracker is stopping */
void mutex_deinit(void) {
  size_t i;
  for (i = 0; i < OT_BUCKET_COUNT; ++i)
    pthread_mutex_destroy(bucket_mutex + i);
  memset(all_torrents, 0, sizeof(all_torrents));
}