+#include "redis.h"
+
+/* ================================ MULTI/EXEC ============================== */
+
+/* Client state initialization for MULTI/EXEC */
+void initClientMultiState(redisClient *c) {
+ c->mstate.commands = NULL;
+ c->mstate.count = 0;
+}
+
+/* Release all the resources associated with MULTI/EXEC state */
+void freeClientMultiState(redisClient *c) {
+ int j;
+
+ for (j = 0; j < c->mstate.count; j++) {
+ int i;
+ multiCmd *mc = c->mstate.commands+j;
+
+ for (i = 0; i < mc->argc; i++)
+ decrRefCount(mc->argv[i]);
+ zfree(mc->argv);
+ }
+ zfree(c->mstate.commands);
+}
+
+/* Add a new command into the MULTI commands queue */
+void queueMultiCommand(redisClient *c, struct redisCommand *cmd) {
+ multiCmd *mc;
+ int j;
+
+ c->mstate.commands = zrealloc(c->mstate.commands,
+ sizeof(multiCmd)*(c->mstate.count+1));
+ mc = c->mstate.commands+c->mstate.count;
+ mc->cmd = cmd;
+ mc->argc = c->argc;
+ mc->argv = zmalloc(sizeof(robj*)*c->argc);
+ memcpy(mc->argv,c->argv,sizeof(robj*)*c->argc);
+ for (j = 0; j < c->argc; j++)
+ incrRefCount(mc->argv[j]);
+ c->mstate.count++;
+}
+
+void multiCommand(redisClient *c) {
+ if (c->flags & REDIS_MULTI) {
+ addReplySds(c,sdsnew("-ERR MULTI calls can not be nested\r\n"));
+ return;
+ }
+ c->flags |= REDIS_MULTI;
+ addReply(c,shared.ok);
+}
+
+void discardCommand(redisClient *c) {
+ if (!(c->flags & REDIS_MULTI)) {
+ addReplySds(c,sdsnew("-ERR DISCARD without MULTI\r\n"));
+ return;
+ }
+
+ freeClientMultiState(c);
+ initClientMultiState(c);
+ c->flags &= (~REDIS_MULTI);
+ unwatchAllKeys(c);
+ addReply(c,shared.ok);
+}
+
+/* Send a MULTI command to all the slaves and AOF file. Check the execCommand
+ * implememntation for more information. */
+void execCommandReplicateMulti(redisClient *c) {
+ struct redisCommand *cmd;
+ robj *multistring = createStringObject("MULTI",5);
+
+ cmd = lookupCommand("multi");
+ if (server.appendonly)
+ feedAppendOnlyFile(cmd,c->db->id,&multistring,1);
+ if (listLength(server.slaves))
+ replicationFeedSlaves(server.slaves,c->db->id,&multistring,1);
+ decrRefCount(multistring);
+}
+
+void execCommand(redisClient *c) {
+ int j;
+ robj **orig_argv;
+ int orig_argc;
+
+ if (!(c->flags & REDIS_MULTI)) {
+ addReplySds(c,sdsnew("-ERR EXEC without MULTI\r\n"));
+ return;
+ }
+
+ /* Check if we need to abort the EXEC if some WATCHed key was touched.
+ * A failed EXEC will return a multi bulk nil object. */
+ if (c->flags & REDIS_DIRTY_CAS) {
+ freeClientMultiState(c);
+ initClientMultiState(c);
+ c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS);
+ unwatchAllKeys(c);
+ addReply(c,shared.nullmultibulk);
+ return;
+ }
+
+ /* Replicate a MULTI request now that we are sure the block is executed.
+ * This way we'll deliver the MULTI/..../EXEC block as a whole and
+ * both the AOF and the replication link will have the same consistency
+ * and atomicity guarantees. */
+ execCommandReplicateMulti(c);
+
+ /* Exec all the queued commands */
+ unwatchAllKeys(c); /* Unwatch ASAP otherwise we'll waste CPU cycles */
+ orig_argv = c->argv;
+ orig_argc = c->argc;
+ addReplySds(c,sdscatprintf(sdsempty(),"*%d\r\n",c->mstate.count));
+ for (j = 0; j < c->mstate.count; j++) {
+ c->argc = c->mstate.commands[j].argc;
+ c->argv = c->mstate.commands[j].argv;
+ call(c,c->mstate.commands[j].cmd);
+ }
+ c->argv = orig_argv;
+ c->argc = orig_argc;
+ freeClientMultiState(c);
+ initClientMultiState(c);
+ c->flags &= ~(REDIS_MULTI|REDIS_DIRTY_CAS);
+ /* Make sure the EXEC command is always replicated / AOF, since we
+ * always send the MULTI command (we can't know beforehand if the
+ * next operations will contain at least a modification to the DB). */
+ server.dirty++;
+}
+
+/* ===================== WATCH (CAS alike for MULTI/EXEC) ===================
+ *
+ * The implementation uses a per-DB hash table mapping keys to list of clients
+ * WATCHing those keys, so that given a key that is going to be modified
+ * we can mark all the associated clients as dirty.
+ *
+ * Also every client contains a list of WATCHed keys so that's possible to
+ * un-watch such keys when the client is freed or when UNWATCH is called. */
+
+/* In the client->watched_keys list we need to use watchedKey structures
+ * as in order to identify a key in Redis we need both the key name and the
+ * DB */
+typedef struct watchedKey {
+ robj *key;
+ redisDb *db;
+} watchedKey;
+
+/* Watch for the specified key */
+void watchForKey(redisClient *c, robj *key) {
+ list *clients = NULL;
+ listIter li;
+ listNode *ln;
+ watchedKey *wk;
+
+ /* Check if we are already watching for this key */
+ listRewind(c->watched_keys,&li);
+ while((ln = listNext(&li))) {
+ wk = listNodeValue(ln);
+ if (wk->db == c->db && equalStringObjects(key,wk->key))
+ return; /* Key already watched */
+ }
+ /* This key is not already watched in this DB. Let's add it */
+ clients = dictFetchValue(c->db->watched_keys,key);
+ if (!clients) {
+ clients = listCreate();
+ dictAdd(c->db->watched_keys,key,clients);
+ incrRefCount(key);
+ }
+ listAddNodeTail(clients,c);
+ /* Add the new key to the lits of keys watched by this client */
+ wk = zmalloc(sizeof(*wk));
+ wk->key = key;
+ wk->db = c->db;
+ incrRefCount(key);
+ listAddNodeTail(c->watched_keys,wk);
+}
+
+/* Unwatch all the keys watched by this client. To clean the EXEC dirty
+ * flag is up to the caller. */
+void unwatchAllKeys(redisClient *c) {
+ listIter li;
+ listNode *ln;
+
+ if (listLength(c->watched_keys) == 0) return;
+ listRewind(c->watched_keys,&li);
+ while((ln = listNext(&li))) {
+ list *clients;
+ watchedKey *wk;
+
+ /* Lookup the watched key -> clients list and remove the client
+ * from the list */
+ wk = listNodeValue(ln);
+ clients = dictFetchValue(wk->db->watched_keys, wk->key);
+ redisAssert(clients != NULL);
+ listDelNode(clients,listSearchKey(clients,c));
+ /* Kill the entry at all if this was the only client */
+ if (listLength(clients) == 0)
+ dictDelete(wk->db->watched_keys, wk->key);
+ /* Remove this watched key from the client->watched list */
+ listDelNode(c->watched_keys,ln);
+ decrRefCount(wk->key);
+ zfree(wk);
+ }
+}
+
+/* "Touch" a key, so that if this key is being WATCHed by some client the
+ * next EXEC will fail. */
+void touchWatchedKey(redisDb *db, robj *key) {
+ list *clients;
+ listIter li;
+ listNode *ln;
+
+ if (dictSize(db->watched_keys) == 0) return;
+ clients = dictFetchValue(db->watched_keys, key);
+ if (!clients) return;
+
+ /* Mark all the clients watching this key as REDIS_DIRTY_CAS */
+ /* Check if we are already watching for this key */
+ listRewind(clients,&li);
+ while((ln = listNext(&li))) {
+ redisClient *c = listNodeValue(ln);
+
+ c->flags |= REDIS_DIRTY_CAS;
+ }
+}
+
+/* On FLUSHDB or FLUSHALL all the watched keys that are present before the
+ * flush but will be deleted as effect of the flushing operation should
+ * be touched. "dbid" is the DB that's getting the flush. -1 if it is
+ * a FLUSHALL operation (all the DBs flushed). */
+void touchWatchedKeysOnFlush(int dbid) {
+ listIter li1, li2;
+ listNode *ln;
+
+ /* For every client, check all the waited keys */
+ listRewind(server.clients,&li1);
+ while((ln = listNext(&li1))) {
+ redisClient *c = listNodeValue(ln);
+ listRewind(c->watched_keys,&li2);
+ while((ln = listNext(&li2))) {
+ watchedKey *wk = listNodeValue(ln);
+
+ /* For every watched key matching the specified DB, if the
+ * key exists, mark the client as dirty, as the key will be
+ * removed. */
+ if (dbid == -1 || wk->db->id == dbid) {
+ if (dictFind(wk->db->dict, wk->key->ptr) != NULL)
+ c->flags |= REDIS_DIRTY_CAS;
+ }
+ }
+ }
+}
+
+void watchCommand(redisClient *c) {
+ int j;
+
+ if (c->flags & REDIS_MULTI) {
+ addReplySds(c,sdsnew("-ERR WATCH inside MULTI is not allowed\r\n"));
+ return;
+ }
+ for (j = 1; j < c->argc; j++)
+ watchForKey(c,c->argv[j]);
+ addReply(c,shared.ok);
+}
+
+void unwatchCommand(redisClient *c) {
+ unwatchAllKeys(c);
+ c->flags &= (~REDIS_DIRTY_CAS);
+ addReply(c,shared.ok);
+}
projects / redis.git / blobdiff