* First we try to free some memory if possible (if there are volatile
* keys in the dataset). If there are not the only thing we can do
* is returning an error. */
- if (server.maxmemory) freeMemoryIfNeeded();
- if (server.maxmemory && (c->cmd->flags & REDIS_CMD_DENYOOM) &&
- zmalloc_used_memory() > server.maxmemory)
- {
- addReplyError(c,"command not allowed when used memory > 'maxmemory'");
- return REDIS_OK;
+ if (server.maxmemory) {
+ int retval = freeMemoryIfNeeded();
+ if ((c->cmd->flags & REDIS_CMD_DENYOOM) && retval == REDIS_ERR) {
+ addReplyError(c,
+ "command not allowed when used memory > 'maxmemory'");
+ return REDIS_OK;
+ }
}
/* Only allow SUBSCRIBE and UNSUBSCRIBE in the context of Pub/Sub */
/* ============================ Maxmemory directive ======================== */
/* This function gets called when 'maxmemory' is set on the config file to limit
- * the max memory used by the server, and we are out of memory.
- * This function will try to, in order:
+ * the max memory used by the server, before processing a command.
*
- * - Free objects from the free list
- * - Try to remove keys with an EXPIRE set
+ * The goal of the function is to free enough memory to keep Redis under the
+ * configured memory limit.
*
- * It is not possible to free enough memory to reach used-memory < maxmemory
- * the server will start refusing commands that will enlarge even more the
- * memory usage.
+ * The function starts calculating how many bytes should be freed to keep
+ * Redis under the limit, and enters a loop selecting the best keys to
+ * evict accordingly to the configured policy.
+ *
+ * If all the bytes needed to return back under the limit were freed the
+ * function returns REDIS_OK, otherwise REDIS_ERR is returned, and the caller
+ * should block the execution of commands that will result in more memory
+ * used by the server.
*/
-void freeMemoryIfNeeded(void) {
- /* Remove keys accordingly to the active policy as long as we are
- * over the memory limit. */
- if (server.maxmemory_policy == REDIS_MAXMEMORY_NO_EVICTION) return;
+int freeMemoryIfNeeded(void) {
+ size_t mem_used, mem_tofree, mem_freed;
+ int slaves = listLength(server.slaves);
+
+ /* Remove the size of slaves output buffers from the count of used
+ * memory. */
+ mem_used = zmalloc_used_memory();
+ if (slaves) {
+ listIter li;
+ listNode *ln;
+
+ listRewind(server.slaves,&li);
+ while((ln = listNext(&li))) {
+ redisClient *slave = listNodeValue(ln);
+ unsigned long obuf_bytes = getClientOutputBufferMemoryUsage(slave);
+ if (obuf_bytes > mem_used)
+ mem_used = 0;
+ else
+ mem_used -= obuf_bytes;
+ }
+ }
- while (server.maxmemory && zmalloc_used_memory() > server.maxmemory) {
- int j, k, freed = 0;
+ /* Check if we are over the memory limit. */
+ if (mem_used <= server.maxmemory) return REDIS_OK;
+
+ if (server.maxmemory_policy == REDIS_MAXMEMORY_NO_EVICTION)
+ return REDIS_ERR; /* We need to free memory, but policy forbids. */
+
+ /* Compute how much memory we need to free. */
+ mem_tofree = mem_used - server.maxmemory;
+ printf("USED: %zu, TOFREE: %zu\n", mem_used, mem_tofree);
+ mem_freed = 0;
+ while (mem_freed < mem_tofree) {
+ int j, k, keys_freed = 0;
for (j = 0; j < server.dbnum; j++) {
long bestval = 0; /* just to prevent warning */
/* Finally remove the selected key. */
if (bestkey) {
+ long long delta;
+
robj *keyobj = createStringObject(bestkey,sdslen(bestkey));
propagateExpire(db,keyobj);
+ /* We compute the amount of memory freed by dbDelete() alone.
+ * It is possible that actually the memory needed to propagate
+ * the DEL in AOF and replication link is greater than the one
+ * we are freeing removing the key, but we can't account for
+ * that otherwise we would never exit the loop.
+ *
+ * AOF and Output buffer memory will be freed eventually so
+ * we only care about memory used by the key space. */
+ delta = (long long) zmalloc_used_memory();
dbDelete(db,keyobj);
+ delta -= (long long) zmalloc_used_memory();
+ // printf("%lld\n",delta);
+ mem_freed += delta;
server.stat_evictedkeys++;
decrRefCount(keyobj);
- freed++;
+ keys_freed++;
+
+ /* When the memory to free starts to be big enough, we may
+ * start spending so much time here that is impossible to
+ * deliver data to the slaves fast enough, so we force the
+ * transmission here inside the loop. */
+ if (slaves) {
+ listIter li;
+ listNode *ln;
+
+ listRewind(server.slaves,&li);
+ while((ln = listNext(&li))) {
+ redisClient *slave = listNodeValue(ln);
+ int events;
+
+ events = aeGetFileEvents(server.el,slave->fd);
+ printf("EVENTS: %d\n", events);
+ if (events & AE_WRITABLE &&
+ slave->replstate == REDIS_REPL_ONLINE &&
+ listLength(slave->reply))
+ {
+ printf("SLAVE %d -> %d\n",
+ slave->fd, (int) listLength(slave->reply));
+ sendReplyToClient(server.el,slave->fd,slave,0);
+ }
+ }
+ }
}
}
- if (!freed) return; /* nothing to free... */
+ if (!keys_freed) return REDIS_ERR; /* nothing to free... */
}
+ return REDIS_OK;
}
/* =================================== Main! ================================ */
projects / redis.git / commitdiff
