mapcache_lock_result mapcache_locker_disk_aquire_lock(mapcache_context *ctx, mapcache_locker *self, char *resource, void **lock) {
char *lockname, errmsg[120];
mapcache_locker_disk *ldisk;
apr_file_t *lockfile;
apr_status_t rv;
assert(self->type == MAPCACHE_LOCKER_DISK);
ldisk = (mapcache_locker_disk*)self;
*lock = NULL; /*unused*/
lockname = lock_filename_for_resource(ctx,ldisk,resource);
/* create the lockfile */
rv = apr_file_open(&lockfile,lockname,APR_WRITE|APR_CREATE|APR_EXCL|APR_XTHREAD,APR_OS_DEFAULT,ctx->pool);
/* if the file already exists, wait for it to disappear */
/* TODO: check the lock isn't stale (i.e. too old) */
if( rv != APR_SUCCESS ) {
if( !APR_STATUS_IS_EEXIST(rv) ) {
ctx->set_error(ctx, 500, "failed to create lockfile %s: %s", lockname, apr_strerror(rv,errmsg,120));
return MAPCACHE_LOCK_NOENT;
}
return MAPCACHE_LOCK_LOCKED;
} else {
/* we acquired the lock */
char *pid_s;
pid_t pid;
apr_size_t pid_s_len;
pid = getpid();
pid_s = apr_psprintf(ctx->pool,"%"APR_PID_T_FMT,pid);
pid_s_len = strlen(pid_s);
apr_file_write(lockfile,pid_s,&pid_s_len);
apr_file_close(lockfile);
return MAPCACHE_LOCK_AQUIRED;
}
}
int mapcache_lock_or_wait_for_resource(mapcache_context *ctx, char *resource)
{
char *lockname = lock_filename_for_resource(ctx,resource);
apr_file_t *lockfile;
apr_status_t rv;
/* create the lockfile */
rv = apr_file_open(&lockfile,lockname,APR_WRITE|APR_CREATE|APR_EXCL|APR_XTHREAD,APR_OS_DEFAULT,ctx->pool);
/* if the file already exists, wait for it to disappear */
/* TODO: check the lock isn't stale (i.e. too old) */
if( rv != APR_SUCCESS ) {
apr_finfo_t info;
rv = apr_stat(&info,lockname,0,ctx->pool);
#ifdef DEBUG
if(!APR_STATUS_IS_ENOENT(rv)) {
ctx->log(ctx, MAPCACHE_DEBUG, "waiting on resource lock %s", resource);
}
#endif
while(!APR_STATUS_IS_ENOENT(rv)) {
/* sleep for the configured number of micro-seconds (default is 1/100th of a second) */
apr_sleep(ctx->config->lock_retry_interval);
rv = apr_stat(&info,lockname,0,ctx->pool);
}
return MAPCACHE_FALSE;
} else {
/* we acquired the lock */
apr_file_close(lockfile);
return MAPCACHE_TRUE;
}
}
mapcache_lock_result mapcache_locker_disk_ping_lock(mapcache_context *ctx, mapcache_locker *self, char *resource, void *lock) {
apr_finfo_t info;
apr_status_t rv;
char *lockname;
mapcache_locker_disk *ldisk = (mapcache_locker_disk*)self;
lockname = lock_filename_for_resource(ctx,ldisk,resource);
rv = apr_stat(&info,lockname,0,ctx->pool);
if(APR_STATUS_IS_ENOENT(rv)) {
return MAPCACHE_LOCK_NOENT;
} else {
return MAPCACHE_LOCK_LOCKED;
}
}
void mapcache_locker_disk_release_lock(mapcache_context *ctx, mapcache_locker *self, char *resource, void *lock)
{
mapcache_locker_disk *ld = (mapcache_locker_disk*)self;
char *lockname = lock_filename_for_resource(ctx,ld,resource);
apr_file_remove(lockname,ctx->pool);
}
void mapcache_unlock_resource(mapcache_context *ctx, char *resource)
{
char *lockname = lock_filename_for_resource(ctx,resource);
apr_file_remove(lockname,ctx->pool);
}
