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

   $id$ */

/* System */
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/uio.h>

/* Libowfat */
#include "byte.h"
#include "io.h"
#include "uint32.h"

/* Opentracker */
#include "trackerlogic.h"
#include "ot_mutex.h"
#include "ot_stats.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];
static size_t    g_torrent_count;

/* Self pipe from opentracker.c */
extern int g_self_pipe[2];

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

ot_vector *mutex_bucket_lock_by_hash( ot_hash hash ) {
  return mutex_bucket_lock( uint32_read_big( (char*)hash ) >> OT_BUCKET_COUNT_SHIFT );
}

void mutex_bucket_unlock( int bucket, int delta_torrentcount ) {
  pthread_mutex_unlock(bucket_mutex + bucket);
  g_torrent_count += delta_torrentcount;
}

void mutex_bucket_unlock_by_hash( ot_hash hash, int delta_torrentcount ) {
  mutex_bucket_unlock( uint32_read_big( (char*)hash ) >> OT_BUCKET_COUNT_SHIFT, delta_torrentcount );
}

size_t mutex_get_torrent_count( ) {
  return g_torrent_count;
}

/* TaskQueue Magic */

struct ot_task {
  ot_taskid       taskid;
  ot_tasktype     tasktype;
  int64           sock;
  int             iovec_entries;
  struct iovec   *iovec;
  struct ot_task *next;
};

static ot_taskid next_free_taskid = 1;
static struct ot_task *tasklist;
static pthread_mutex_t tasklist_mutex;
static pthread_cond_t tasklist_being_filled;

int mutex_workqueue_pushtask( int64 sock, ot_tasktype tasktype ) {
  struct ot_task ** tmptask, * task;

  task = malloc(sizeof( struct ot_task));
  if( !task )
    return -1;

  task->taskid        = 0;
  task->tasktype      = tasktype;
  task->sock          = sock;
  task->iovec_entries = 0;
  task->iovec         = NULL;
  task->next          = 0;

  /* Want exclusive access to tasklist */
  pthread_mutex_lock( &tasklist_mutex );

  /* Skip to end of list */
  tmptask = &tasklist;
  while( *tmptask )
    tmptask = &(*tmptask)->next;
  *tmptask = task;

  /* Inform waiting workers and release lock */
  pthread_cond_broadcast( &tasklist_being_filled );
  pthread_mutex_unlock( &tasklist_mutex );
  return 0;
}

void mutex_workqueue_canceltask( int64 sock ) {
  struct ot_task ** task;

  /* Want exclusive access to tasklist */
  pthread_mutex_lock( &tasklist_mutex );

  for (task = &tasklist; *task; task = &((*task)->next))
    if ((*task)->sock == sock) {
      struct iovec *iovec = (*task)->iovec;
      struct ot_task *ptask = *task;
      int i;

      /* Free task's iovec */
      for( i=0; i<(*task)->iovec_entries; ++i )
        free( iovec[i].iov_base );

      *task = (*task)->next;
      free( ptask );
      break;
    }

  /* Release lock */
  pthread_mutex_unlock( &tasklist_mutex );
}

ot_taskid mutex_workqueue_poptask( ot_tasktype *tasktype ) {
  struct ot_task * task;
  ot_taskid taskid = 0;

  /* Want exclusive access to tasklist */
  pthread_mutex_lock( &tasklist_mutex );

  while( !taskid ) {
    /* Skip to the first unassigned task this worker wants to do */
    for (task = tasklist; task; task = task->next)
      if (!task->taskid && ( TASK_CLASS_MASK & task->tasktype ) == *tasktype) {
        /* If we found an outstanding task, assign a taskid to it
           and leave the loop */
        task->taskid = taskid = ++next_free_taskid;
        *tasktype = task->tasktype;
        break;
      }

    /* Wait until the next task is being fed */
    if (!taskid)
      pthread_cond_wait( &tasklist_being_filled, &tasklist_mutex );
  }

  /* Release lock */
  pthread_mutex_unlock( &tasklist_mutex );

  return taskid;
}

void mutex_workqueue_pushsuccess( ot_taskid taskid ) {
  struct ot_task ** task;

  /* Want exclusive access to tasklist */
  pthread_mutex_lock( &tasklist_mutex );

  for (task = &tasklist; *task; task = &((*task)->next))
    if ((*task)->taskid == taskid) {
      struct ot_task *ptask = *task;
      *task = (*task)->next;
      free( ptask );
      break;
    }

  /* Release lock */
  pthread_mutex_unlock( &tasklist_mutex );
}

int mutex_workqueue_pushresult( ot_taskid taskid, int iovec_entries, struct iovec *iovec ) {
  struct ot_task * task;
  const char byte = 'o';

  /* Want exclusive access to tasklist */
  pthread_mutex_lock( &tasklist_mutex );

  for (task = tasklist; task; task = task->next)
    if (task->taskid == taskid) {
      task->iovec_entries = iovec_entries;
      task->iovec         = iovec;
      task->tasktype      = TASK_DONE;
      break;
    }

  /* Release lock */
  pthread_mutex_unlock( &tasklist_mutex );

  io_trywrite( g_self_pipe[1], &byte, 1 );

  /* Indicate whether the worker has to throw away results */
  return task ? 0 : -1;
}

int64 mutex_workqueue_popresult( int *iovec_entries, struct iovec ** iovec ) {
  struct ot_task ** task;
  int64 sock = -1;

  /* Want exclusive access to tasklist */
  pthread_mutex_lock( &tasklist_mutex );

  for (task = &tasklist; *task; task = &((*task)->next))
    if ((*task)->tasktype == TASK_DONE) {
      struct ot_task *ptask = *task;

      *iovec_entries = (*task)->iovec_entries;
      *iovec         = (*task)->iovec;
      sock           = (*task)->sock;

      *task = (*task)->next;
      free( ptask );
      break;
    }

  /* Release lock */
  pthread_mutex_unlock( &tasklist_mutex );
  return sock;
}

void mutex_init( ) {
  int i;
  pthread_mutex_init(&tasklist_mutex, NULL);
  pthread_cond_init (&tasklist_being_filled, NULL);
  for (i=0; i < OT_BUCKET_COUNT; ++i)
      pthread_mutex_init(bucket_mutex + i, NULL);
  byte_zero( all_torrents, sizeof( all_torrents ) );
}

void mutex_deinit( ) {
  int i;
  for (i=0; i < OT_BUCKET_COUNT; ++i)
      pthread_mutex_destroy(bucket_mutex + i);
  pthread_mutex_destroy(&tasklist_mutex);
  pthread_cond_destroy(&tasklist_being_filled);
  byte_zero( all_torrents, sizeof( all_torrents ) );
}

const char *g_version_mutex_c = "$Source$: $Revision$\n";