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-rw-r--r--mutex.c77
1 files changed, 77 insertions, 0 deletions
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1/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
2 It is considered beerware. Prost. Skol. Cheers or whatever. */
3
4#include <pthread.h>
5#include <stdio.h>
6
7#include "trackerlogic.h"
8#include "mutex.h"
9
10static int bucket_locklist[ OT_MAX_THREADS ];
11static int bucket_locklist_count = 0;
12static pthread_mutex_t bucket_mutex;
13static pthread_cond_t bucket_being_unlocked;
14
15static int bucket_check( int bucket ) {
16 /* C should come with auto-i ;) */
17 int i;
18
19 /* No more space to acquire lock to bucket -- should not happen */
20 if( bucket_locklist_count == OT_MAX_THREADS ) {
21 fprintf( stderr, "More lock requests than mutexes. Consult source code.\n" );
22 return -1;
23 }
24
25 /* See, if bucket is already locked */
26 for( i=0; i<bucket_locklist_count; ++i )
27 if( bucket_locklist[ i ] == bucket )
28 return -1;
29
30 return 0;
31}
32
33static void bucket_push( int bucket ) {
34 bucket_locklist[ bucket_locklist_count++ ] = bucket;
35}
36
37static void bucket_remove( int bucket ) {
38 int i = 0;
39
40 while( ( i < bucket_locklist_count ) && ( bucket_locklist[ i ] != bucket ) )
41 ++i;
42
43 if( i == bucket_locklist_count ) {
44 fprintf( stderr, "Request to unlock bucket that was never lock. Consult source code.\n" );
45 return;
46 }
47
48 for( ; i < bucket_locklist_count - 1; ++i )
49 bucket_locklist[ i ] = bucket_locklist[ i + 1 ];
50
51 --bucket_locklist_count;
52}
53
54void mutex_bucket_lock( int bucket ) {
55 pthread_mutex_lock( &bucket_mutex );
56 while( !bucket_check( bucket ) )
57 pthread_cond_wait( &bucket_being_unlocked, &bucket_mutex );
58 bucket_push( bucket );
59 pthread_mutex_unlock( &bucket_mutex );
60}
61
62void mutex_bucket_unlock( int bucket ) {
63 pthread_mutex_lock( &bucket_mutex );
64 bucket_remove( bucket );
65 pthread_cond_broadcast( &bucket_being_unlocked );
66 pthread_mutex_unlock( &bucket_mutex );
67}
68
69void mutex_init( ) {
70 pthread_mutex_init(&bucket_mutex, NULL);
71 pthread_cond_init (&bucket_being_unlocked, NULL);
72}
73
74void mutex_deinit( ) {
75 pthread_mutex_destroy(&bucket_mutex);
76 pthread_cond_destroy(&bucket_being_unlocked);
77}