cache.c

bind 9.3结合mysql数据库

		cleaner->cleaning_interval = 0; /* Initially turned off. */
		result = isc_timer_create(timermgr, isc_timertype_inactive,
					   NULL, NULL,
					   cleaner->task,
					   cleaning_timer_action, cleaner,
					   &cleaner->cleaning_timer);
		if (result != ISC_R_SUCCESS) {
			UNEXPECTED_ERROR(__FILE__, __LINE__,
					 "isc_timer_create() failed: %s",
					 dns_result_totext(result));
			result = ISC_R_UNEXPECTED;
			goto cleanup;
		}

		cleaner->resched_event =
			isc_event_allocate(cache->mctx, cleaner,
					   DNS_EVENT_CACHECLEAN,
					   incremental_cleaning_action,
					   cleaner, sizeof(isc_event_t));
		if (cleaner->resched_event == NULL) {
			result = ISC_R_NOMEMORY;
			goto cleanup;
		}
		
		cleaner->overmem_event =
			isc_event_allocate(cache->mctx, cleaner,
					   DNS_EVENT_CACHEOVERMEM,
					   overmem_cleaning_action,
					   cleaner, sizeof(isc_event_t));
		if (cleaner->overmem_event == NULL) {
			result = ISC_R_NOMEMORY;
			goto cleanup;
		}
	}

	return (ISC_R_SUCCESS);

 cleanup:
	if (cleaner->overmem_event != NULL)
		isc_event_free(&cleaner->overmem_event);
	if (cleaner->resched_event != NULL)
		isc_event_free(&cleaner->resched_event);
	if (cleaner->cleaning_timer != NULL)
		isc_timer_detach(&cleaner->cleaning_timer);
	if (cleaner->task != NULL)
		isc_task_detach(&cleaner->task);
	DESTROYLOCK(&cleaner->lock);
 fail:
	return (result);
}

static void
begin_cleaning(cache_cleaner_t *cleaner) {
	isc_result_t result;

	REQUIRE(CLEANER_IDLE(cleaner));

	/*
	 * Create an iterator and position it at the beginning of the cache.
	 */
	result = dns_db_createiterator(cleaner->cache->db, ISC_FALSE,
				       &cleaner->iterator);
	if (result != ISC_R_SUCCESS)
		isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
			      DNS_LOGMODULE_CACHE, ISC_LOG_WARNING,
			      "cache cleaner could not create "
			      "iterator: %s", isc_result_totext(result));
	else {
		dns_dbiterator_setcleanmode(cleaner->iterator, ISC_TRUE);
		result = dns_dbiterator_first(cleaner->iterator);
	}

	if (result != ISC_R_SUCCESS) {
		/*
		 * If the result is ISC_R_NOMORE, the database is empty,
		 * so there is nothing to be cleaned.
		 */
		if (result != ISC_R_NOMORE)
			UNEXPECTED_ERROR(__FILE__, __LINE__,
					 "cache cleaner: "
					 "dns_dbiterator_first() failed: %s",
					 dns_result_totext(result));

		if (cleaner->iterator != NULL)
			dns_dbiterator_destroy(&cleaner->iterator);
	} else {
		/*
		 * Pause the iterator to free its lock.
		 */
		result = dns_dbiterator_pause(cleaner->iterator);
		RUNTIME_CHECK(result == ISC_R_SUCCESS);

		isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
			      DNS_LOGMODULE_CACHE, ISC_LOG_DEBUG(1),
			      "begin cache cleaning, mem inuse %lu",
		            (unsigned long)isc_mem_inuse(cleaner->cache->mctx));
		cleaner->state = cleaner_s_busy;
		isc_task_send(cleaner->task, &cleaner->resched_event);
	}

	return;
}

static void
end_cleaning(cache_cleaner_t *cleaner, isc_event_t *event) {
	REQUIRE(CLEANER_BUSY(cleaner));
	REQUIRE(event != NULL);

	dns_dbiterator_destroy(&cleaner->iterator);

	dns_cache_setcleaninginterval(cleaner->cache,
				      cleaner->cleaning_interval);

	isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE, DNS_LOGMODULE_CACHE,
		      ISC_LOG_DEBUG(1), "end cache cleaning, mem inuse %lu",
		      (unsigned long)isc_mem_inuse(cleaner->cache->mctx));

	cleaner->state = cleaner_s_idle;
	cleaner->resched_event = event;
}

/*
 * This is run once for every cache-cleaning-interval as defined in named.conf.
 */
static void
cleaning_timer_action(isc_task_t *task, isc_event_t *event) {
	cache_cleaner_t *cleaner = event->ev_arg;

	UNUSED(task);

	INSIST(task == cleaner->task);
	INSIST(event->ev_type == ISC_TIMEREVENT_TICK);

	isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE, DNS_LOGMODULE_CACHE,
		      ISC_LOG_DEBUG(1), "cache cleaning timer fired, "
		      "cleaner state = %d", cleaner->state);

	if (cleaner->state == cleaner_s_idle)
		begin_cleaning(cleaner);

	isc_event_free(&event);
}

/*
 * This is called when the cache either surpasses its upper limit
 * or shrinks beyond its lower limit.
 */
static void
overmem_cleaning_action(isc_task_t *task, isc_event_t *event) {
	cache_cleaner_t *cleaner = event->ev_arg;
	isc_boolean_t want_cleaning = ISC_FALSE;
	
	UNUSED(task);

	INSIST(task == cleaner->task);
	INSIST(event->ev_type == DNS_EVENT_CACHEOVERMEM);
	INSIST(cleaner->overmem_event == NULL);

	isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE, DNS_LOGMODULE_CACHE,
		      ISC_LOG_DEBUG(1), "overmem_cleaning_action called, "
		      "overmem = %d, state = %d", cleaner->overmem,
		      cleaner->state);

	LOCK(&cleaner->lock);

	if (cleaner->overmem) {
		if (cleaner->state == cleaner_s_idle)
			want_cleaning = ISC_TRUE;
	} else {
		if (cleaner->state == cleaner_s_busy)
			/*
			 * end_cleaning() can't be called here because
			 * then both cleaner->overmem_event and
			 * cleaner->resched_event will point to this
			 * event.  Set the state to done, and then
			 * when the incremental_cleaning_action() event
			 * is posted, it will handle the end_cleaning.
			 */
			cleaner->state = cleaner_s_done;
	}

	cleaner->overmem_event = event;

	UNLOCK(&cleaner->lock);

	if (want_cleaning)
		begin_cleaning(cleaner);
}

/*
 * Do incremental cleaning.
 */
static void
incremental_cleaning_action(isc_task_t *task, isc_event_t *event) {
	cache_cleaner_t *cleaner = event->ev_arg;
	isc_result_t result;
	int n_names;

	UNUSED(task);

	INSIST(task == cleaner->task);
	INSIST(event->ev_type == DNS_EVENT_CACHECLEAN);

	if (cleaner->state == cleaner_s_done) {
		cleaner->state = cleaner_s_busy;
		end_cleaning(cleaner, event);
		return;
	}

	INSIST(CLEANER_BUSY(cleaner));

	n_names = cleaner->increment;

	REQUIRE(DNS_DBITERATOR_VALID(cleaner->iterator));

	while (n_names-- > 0) {
		dns_dbnode_t *node = NULL;

		result = dns_dbiterator_current(cleaner->iterator, &node,
						NULL);
		if (result != ISC_R_SUCCESS) {
			UNEXPECTED_ERROR(__FILE__, __LINE__,
				 "cache cleaner: dns_dbiterator_current() "
				 "failed: %s", dns_result_totext(result));

			end_cleaning(cleaner, event);
			return;
		}

		/*
		 * The node was not needed, but was required by
		 * dns_dbiterator_current().  Give up its reference.
		 */
		dns_db_detachnode(cleaner->cache->db, &node);

		/*
		 * Step to the next node.
		 */
		result = dns_dbiterator_next(cleaner->iterator);

		if (result != ISC_R_SUCCESS) {
			/*
			 * Either the end was reached (ISC_R_NOMORE) or
			 * some error was signaled.  If the cache is still
			 * overmem and no error was encountered,
			 * keep trying to clean it, otherwise stop cleanng.
			 */
			if (result != ISC_R_NOMORE)
				UNEXPECTED_ERROR(__FILE__, __LINE__,
						 "cache cleaner: "
						 "dns_dbiterator_next() "
						 "failed: %s",
						 dns_result_totext(result));
			else if (cleaner->overmem) {
				result = dns_dbiterator_first(cleaner->
							      iterator);
				if (result == ISC_R_SUCCESS) {
					isc_log_write(dns_lctx,
						      DNS_LOGCATEGORY_DATABASE,
						      DNS_LOGMODULE_CACHE,
						      ISC_LOG_DEBUG(1),
						      "cache cleaner: "
						      "still overmem, "
						      "reset and try again");
					continue;
				}
			}

			end_cleaning(cleaner, event);
			return;
		}
	}

	/*
	 * We have successfully performed a cleaning increment but have
	 * not gone through the entire cache.  Free the iterator locks
	 * and reschedule another batch.  If it fails, just try to continue
	 * anyway.
	 */
	result = dns_dbiterator_pause(cleaner->iterator);
	RUNTIME_CHECK(result == ISC_R_SUCCESS);

	isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE, DNS_LOGMODULE_CACHE,
		      ISC_LOG_DEBUG(1), "cache cleaner: checked %d nodes, "
		      "mem inuse %lu, sleeping", cleaner->increment,
		      (unsigned long)isc_mem_inuse(cleaner->cache->mctx));

	isc_task_send(task, &event);
	INSIST(CLEANER_BUSY(cleaner));
	return;
}

/*
 * Do immediate cleaning.
 */
isc_result_t
dns_cache_clean(dns_cache_t *cache, isc_stdtime_t now) {
	isc_result_t result;
	dns_dbiterator_t *iterator = NULL;

	REQUIRE(VALID_CACHE(cache));

	result = dns_db_createiterator(cache->db, ISC_FALSE, &iterator);
	if (result != ISC_R_SUCCESS)
		return result;

	result = dns_dbiterator_first(iterator);

	while (result == ISC_R_SUCCESS) {
		dns_dbnode_t *node = NULL;
		result = dns_dbiterator_current(iterator, &node,
						(dns_name_t *)NULL);
		if (result != ISC_R_SUCCESS)
			break;

		/*
		 * Check TTLs, mark expired rdatasets stale.
		 */
		result = dns_db_expirenode(cache->db, node, now);
		if (result != ISC_R_SUCCESS) {
			UNEXPECTED_ERROR(__FILE__, __LINE__,
					 "cache cleaner: dns_db_expirenode() "
					 "failed: %s",
					 dns_result_totext(result));
			/*
			 * Continue anyway.
			 */
		}

		/*
		 * This is where the actual freeing takes place.
		 */
		dns_db_detachnode(cache->db, &node);

		result = dns_dbiterator_next(iterator);
	}

	dns_dbiterator_destroy(&iterator);

	if (result == ISC_R_NOMORE)
		result = ISC_R_SUCCESS;

	return (result);
}

static void
water(void *arg, int mark) {
	dns_cache_t *cache = arg;
	isc_boolean_t overmem = ISC_TF(mark == ISC_MEM_HIWATER);

	REQUIRE(VALID_CACHE(cache));

	LOCK(&cache->cleaner.lock);
	
	dns_db_overmem(cache->db, overmem);
	cache->cleaner.overmem = overmem;

	if (cache->cleaner.overmem_event != NULL)
		isc_task_send(cache->cleaner.task,
			      &cache->cleaner.overmem_event);

	UNLOCK(&cache->cleaner.lock);
}

void
dns_cache_setcachesize(dns_cache_t *cache, isc_uint32_t size) {
	isc_uint32_t lowater;
	isc_uint32_t hiwater;

	REQUIRE(VALID_CACHE(cache));

	/*
	 * Impose a minumum cache size; pathological things happen if there
	 * is too little room.
	 */
	if (size != 0 && size < DNS_CACHE_MINSIZE)
		size = DNS_CACHE_MINSIZE;

	hiwater = size - (size >> 3);	/* Approximately 7/8ths. */
	lowater = size - (size >> 2);	/* Approximately 3/4ths. */

	/*
	 * If the cache was overmem and cleaning, but now with the new limits
	 * it is no longer in an overmem condition, then the next
	 * isc_mem_put for cache memory will do the right thing and trigger
	 * water().
	 */

	if (size == 0 || hiwater == 0 || lowater == 0)
		/*
		 * Disable cache memory limiting.
		 */
		isc_mem_setwater(cache->mctx, water, cache, 0, 0);
	else
		/*
		 * Establish new cache memory limits (either for the first
		 * time, or replacing other limits).
		 */
		isc_mem_setwater(cache->mctx, water, cache, hiwater, lowater);
}

/*
 * The cleaner task is shutting down; do the necessary cleanup.
 */
static void
cleaner_shutdown_action(isc_task_t *task, isc_event_t *event) {
	dns_cache_t *cache = event->ev_arg;
	isc_boolean_t should_free = ISC_FALSE;

	UNUSED(task);

	INSIST(task == cache->cleaner.task);
	INSIST(event->ev_type == ISC_TASKEVENT_SHUTDOWN);

	if (CLEANER_BUSY(&cache->cleaner))
		end_cleaning(&cache->cleaner, event);
	else
		isc_event_free(&event);

	LOCK(&cache->lock);

	cache->live_tasks--;
	INSIST(cache->live_tasks == 0);

	if (cache->references == 0)
		should_free = ISC_TRUE;

	/*
	 * By detaching the timer in the context of its task,
	 * we are guaranteed that there will be no further timer
	 * events.
	 */
	if (cache->cleaner.cleaning_timer != NULL)
		isc_timer_detach(&cache->cleaner.cleaning_timer);

	/* Make sure we don't reschedule anymore. */
	(void)isc_task_purge(task, NULL, DNS_EVENT_CACHECLEAN, NULL);

	UNLOCK(&cache->lock);

	if (should_free)
		cache_free(cache);
}

isc_result_t
dns_cache_flush(dns_cache_t *cache) {
	dns_db_t *db = NULL;
	isc_result_t result;

	result = cache_create_db(cache, &db);
	if (result != ISC_R_SUCCESS)
		return (result);

	dns_db_detach(&cache->db);
	cache->db = db;
	return (ISC_R_SUCCESS);
}

isc_result_t
dns_cache_flushname(dns_cache_t *cache, dns_name_t *name) {
	isc_result_t result;
	dns_rdatasetiter_t *iter = NULL;
	dns_dbnode_t *node = NULL;
	dns_db_t *db = NULL;
	
	LOCK(&cache->lock);
	if (cache->db != NULL)
		dns_db_attach(cache->db, &db);
	UNLOCK(&cache->lock);
	if (db == NULL)
		return (ISC_R_SUCCESS);
	result = dns_db_findnode(cache->db, name, ISC_FALSE, &node);
	if (result == ISC_R_NOTFOUND) {
		result = ISC_R_SUCCESS;
		goto cleanup_db;
	}
	if (result != ISC_R_SUCCESS)
		goto cleanup_db;

	result = dns_db_allrdatasets(cache->db, node, NULL,
				     (isc_stdtime_t)0, &iter);
	if (result != ISC_R_SUCCESS)
		goto cleanup_node;

	for (result = dns_rdatasetiter_first(iter);
	     result == ISC_R_SUCCESS;
	     result = dns_rdatasetiter_next(iter))
	{
		dns_rdataset_t rdataset;
		dns_rdataset_init(&rdataset);

		dns_rdatasetiter_current(iter, &rdataset);

		for (result = dns_rdataset_first(&rdataset);
		     result == ISC_R_SUCCESS;
		     result = dns_rdataset_next(&rdataset))
		{
			dns_rdata_t rdata = DNS_RDATA_INIT;
			dns_rdatatype_t covers;

			dns_rdataset_current(&rdataset, &rdata);
			if (rdata.type == dns_rdatatype_rrsig)
				covers = dns_rdata_covers(&rdata);
			else
				covers = 0;
			result = dns_db_deleterdataset(cache->db, node, NULL,
						       rdata.type, covers);
			if (result != ISC_R_SUCCESS &&
			    result != DNS_R_UNCHANGED)
				break;
		}
		dns_rdataset_disassociate(&rdataset);
		if (result != ISC_R_NOMORE)
			break;
	}
	if (result == ISC_R_NOMORE)
		result = ISC_R_SUCCESS;

	dns_rdatasetiter_destroy(&iter);

 cleanup_node:
	dns_db_detachnode(cache->db, &node);

 cleanup_db:
	dns_db_detach(&db);
	return (result);
}