3 * Copyright (c) 1996 Regents of the University of Michigan.
6 * Redistribution and use in source and binary forms are permitted
7 * provided that this notice is preserved and that due credit is given
8 * to the University of Michigan at Ann Arbor. The name of the University
9 * may not be used to endorse or promote products derived from this
10 * software without specific prior written permission. This software
11 * is provided ``as is'' without express or implied warranty.
15 * rq.c - routines used to manage the queue of replication entries.
16 * An Rq (Replication queue) struct contains a linked list of Re
17 * (Replication entry) structures.
19 * Routines wishing to access the replication queue should do so through
20 * the Rq struct's member functions, e.g. rq->rq_gethead() and friends.
21 * For example, Re structs should be added to the queue by calling
22 * the rq_add() member function.
24 * Access to the queue is serialized by a mutex. Member functions which do
25 * not do their own locking should only be called after locking the queue
26 * using the rq_lock() member function. The queue should be unlocked with
27 * the rq_unlock() member function.
29 * Note that some member functions handle their own locking internally.
30 * Callers should not lock the queue before calling these functions.
31 * See the comment block for each function below.
39 #include <ac/stdlib.h>
40 #include <ac/string.h>
41 #include <ac/unistd.h> /* get ftruncate() */
48 * Lock the replication queue.
55 return( ldap_pvt_thread_mutex_lock( &rq->rq_mutex ));
60 * Unlock the replication queue.
67 return( ldap_pvt_thread_mutex_unlock( &rq->rq_mutex ));
73 * Return the head of the queue. Callers should lock the queue before
74 * calling this routine.
81 return( rq == NULL ? NULL : rq->rq_head );
86 * Return the next item in the queue. Callers should lock the queue before
87 * calling this routine.
97 return( re->re_getnext( re ));
103 * Delete the item at the head of the list. The queue should be locked
104 * by the caller before calling this routine.
118 savedhead = rq->rq_head;
119 if ( savedhead == NULL ) {
123 if ( savedhead->re_getrefcnt( savedhead ) != 0 ) {
124 Debug( LDAP_DEBUG_ANY, "Warning: attempt to delete when refcnt != 0\n",
129 rq->rq_head = rq->rq_head->re_getnext( rq->rq_head );
130 rc = savedhead->re_free( savedhead );
131 rq->rq_nre--; /* decrement count of Re's in queue */
137 * Add an entry to the tail of the replication queue. Locking is handled
138 * internally. When items are added to the queue, this routine wakes
139 * up any threads which are waiting for more work by signaling on the
140 * rq->rq_more condition variable.
154 /* Create a new Re */
155 if ( Re_init( &re ) < 0 ) {
160 /* parse buf and fill in the re struct */
161 if ( re->re_parse( re, buf ) < 0 ) {
167 /* Insert into queue */
168 if ( rq->rq_head == NULL ) {
173 rq->rq_tail->re_next = re;
176 /* set the sequence number */
178 if ( !wasempty && !strcmp(rq->rq_tail->re_timestamp, re->re_timestamp )) {
180 * Our new re has the same timestamp as the tail's timestamp.
181 * Increment the seq number in the tail and use it as our seq number.
183 re->re_seq = rq->rq_tail->re_seq + 1;
187 /* Increment count of items in queue */
189 /* wake up any threads waiting for more work */
190 ldap_pvt_thread_cond_broadcast( &rq->rq_more );
192 /* ... and unlock the queue */
200 * Garbage-collect the replication queue. Locking is handled internally.
208 Debug( LDAP_DEBUG_ANY, "Rq_gc: rq is NULL!\n", 0, 0, 0 );
212 while (( rq->rq_head != NULL ) &&
213 ( rq->rq_head->re_getrefcnt( rq->rq_head ) == 0 )) {
214 rq->rq_delhead( rq );
215 rq->rq_ndel++; /* increment count of deleted entries */
223 * For debugging: dump the contents of the replication queue to a file.
224 * Locking is handled internally.
235 Debug( LDAP_DEBUG_ANY, "Rq_dump: rq is NULL!\n", 0, 0, 0 );
239 if (( fp = fopen( SLURPD_DUMPFILE, "w" )) == NULL ) {
240 Debug( LDAP_DEBUG_ANY, "Rq_dump: cannot open \"%s\" for write\n",
241 SLURPD_DUMPFILE, 0, 0 );
246 for ( re = rq->rq_gethead( rq ); re != NULL; re = rq->rq_getnext( re )) {
247 re->re_dump( re, fp );
256 * Write the contents of a replication queue to a file. Returns zero if
257 * successful, -1 if not. Handles queue locking internally. Callers should
258 * provide an open file pointer, which should refer to a locked file.
273 Debug( LDAP_DEBUG_ARGS, "re-write on-disk replication log\n",
278 fseek( fp, 0L, SEEK_SET ); /* Go to beginning of file */
281 for ( re = rq->rq_gethead( rq ); re != NULL; re = rq->rq_getnext( re )) {
282 if ( re->re_write( NULL, re, fp ) < 0 ) {
289 sglob->srpos = ftell( fp ); /* update replog file position */
290 /* and truncate to correct len */
291 if ( ftruncate( fileno( fp ), sglob->srpos ) < 0 ) {
292 Debug( LDAP_DEBUG_ANY, "Error truncating replication log: %s\n",
293 sys_errlist[ errno ], 0, 0 );
295 rq->rq_ndel = 0; /* reset count of deleted re's */
297 rq->rq_lasttrim = now; /* reset last trim time */
304 * Check to see if the private slurpd replication log needs trimming.
305 * The current criteria are:
306 * - The last trim was more than 5 minutes ago, *and*
307 * - We've finished with at least 50 replication log entries since the
308 * last time we re-wrote the replication log.
310 * Return 1 if replogfile should be trimmed, 0 if not.
311 * Any different policy should be implemented by replacing this function.
329 if ( now > ( rq->rq_lasttrim + TRIMCHECK_INTERVAL )) {
330 rc = ( rq->rq_ndel >= 50 );
340 * Return counts of Re structs in the queue.
356 if ( type == RQ_COUNT_ALL ) {
359 for ( re = rq->rq_gethead( rq ); re != NULL;
360 re = rq->rq_getnext( re )) {
361 if ( type == RQ_COUNT_NZRC ) {
362 if ( re->re_getrefcnt( re ) > 1 ) {
374 * Allocate and initialize an Rq object.
381 /* Instantiate the struct */
382 (*rq) = (Rq *) malloc( sizeof( Rq ));
387 /* Fill in all the function pointers */
388 (*rq)->rq_gethead = Rq_gethead;
389 (*rq)->rq_getnext = Rq_getnext;
390 (*rq)->rq_delhead = Rq_delhead;
391 (*rq)->rq_add = Rq_add;
392 (*rq)->rq_gc = Rq_gc;
393 (*rq)->rq_lock = Rq_lock;
394 (*rq)->rq_unlock = Rq_unlock;
395 (*rq)->rq_dump = Rq_dump;
396 (*rq)->rq_needtrim = Rq_needtrim;
397 (*rq)->rq_write = Rq_write;
398 (*rq)->rq_getcount = Rq_getcount;
400 /* Initialize private data */
401 ldap_pvt_thread_mutex_init( &((*rq)->rq_mutex) );
402 ldap_pvt_thread_cond_init( &((*rq)->rq_more) );
403 (*rq)->rq_head = NULL;
404 (*rq)->rq_tail = NULL;
407 (*rq)->rq_lasttrim = (time_t) 0L;