initial changes needed to turn the current VM code into a cache system. Tons of work to do still.

src/diskstore.c

@@ -16,8 +16,17 @@
  * directory will contain in the average 15258 entires, that is ok with
  * most filesystems implementation.
  *
- * The actaul implementation of this disk store is highly related to the
+ * Note that since Redis supports multiple databases, the actual key name
- * filesystem implementation. This implementation may be replaced by
+ * is:
+ *
+ *  /0b/ee/<dbid>_0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33
+ *
+ *  so for instance if the key is inside DB 0:
+ *
+ *  /0b/ee/0_0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33
+ *
+ * The actaul implementation of this disk store is highly dependant to the
+ * filesystem implementation itself. This implementation may be replaced by
  * a B+TREE implementation in future implementations.
  *
  * Data ok every key is serialized using the same format used for .rdb
@@ -68,7 +77,7 @@
 int dsOpen(void) {
     struct stat sb;
     int retval;
-    char *path = server.diskstore_path;
+    char *path = server.ds_path;
 
     if ((retval = stat(path,&sb) == -1) && errno != ENOENT) {
         redisLog(REDIS_WARNING, "Error opening disk store at %s: %s",

src/networking.c

@@ -167,7 +167,7 @@ void _addReplyStringToList(redisClient *c, char *s, size_t len) {
 
 void addReply(redisClient *c, robj *obj) {
     if (_installWriteEvent(c) != REDIS_OK) return;
-    redisAssert(!server.vm_enabled || obj->storage == REDIS_VM_MEMORY);
+    redisAssert(!server.ds_enabled || obj->storage == REDIS_VM_MEMORY);
 
     /* This is an important place where we can avoid copy-on-write
      * when there is a saving child running, avoiding touching the
@@ -460,7 +460,7 @@ void freeClient(redisClient *c) {
     /* Remove from the list of clients waiting for swapped keys, or ready
      * to be restarted, but not yet woken up again. */
     if (c->flags & REDIS_IO_WAIT) {
-        redisAssert(server.vm_enabled);
+        redisAssert(server.ds_enabled);
         if (listLength(c->io_keys) == 0) {
             ln = listSearchKey(server.io_ready_clients,c);
 
@@ -474,7 +474,7 @@ void freeClient(redisClient *c) {
                 dontWaitForSwappedKey(c,ln->value);
             }
         }
-        server.vm_blocked_clients--;
+        server.cache_blocked_clients--;
     }
     listRelease(c->io_keys);
     /* Master/slave cleanup.

src/redis.c

@@ -618,27 +618,12 @@ int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
      * in order to guarantee a strict consistency. */
     if (server.masterhost == NULL) activeExpireCycle();
 
-    /* Swap a few keys on disk if we are over the memory limit and VM
+    /* Remove a few cached objects from memory if we are over the
-     * is enbled. Try to free objects from the free list first. */
+     * configured memory limit */
-    if (vmCanSwapOut()) {
+    while (server.ds_enabled && zmalloc_used_memory() >
-        while (server.vm_enabled && zmalloc_used_memory() >
+            server.cache_max_memory)
-                server.vm_max_memory)
+    {
-        {
+        cacheFreeOneEntry();
-            int retval = (server.vm_max_threads == 0) ?
-                        vmSwapOneObjectBlocking() :
-                        vmSwapOneObjectThreaded();
-            if (retval == REDIS_ERR && !(loops % 300) &&
-                zmalloc_used_memory() >
-                (server.vm_max_memory+server.vm_max_memory/10))
-            {
-                redisLog(REDIS_WARNING,"WARNING: vm-max-memory limit exceeded by more than 10%% but unable to swap more objects out!");
-            }
-            /* Note that when using threade I/O we free just one object,
-             * because anyway when the I/O thread in charge to swap this
-             * object out will finish, the handler of completed jobs
-             * will try to swap more objects if we are still out of memory. */
-            if (retval == REDIS_ERR || server.vm_max_threads > 0) break;
-        }
     }
 
     /* Replication cron function -- used to reconnect to master and
@@ -656,8 +641,8 @@ void beforeSleep(struct aeEventLoop *eventLoop) {
     listNode *ln;
     redisClient *c;
 
-    /* Awake clients that got all the swapped keys they requested */
+    /* Awake clients that got all the on disk keys they requested */
-    if (server.vm_enabled && listLength(server.io_ready_clients)) {
+    if (server.ds_enabled && listLength(server.io_ready_clients)) {
         listIter li;
 
         listRewind(server.io_ready_clients,&li);
@@ -668,7 +653,7 @@ void beforeSleep(struct aeEventLoop *eventLoop) {
             /* Resume the client. */
             listDelNode(server.io_ready_clients,ln);
             c->flags &= (~REDIS_IO_WAIT);
-            server.vm_blocked_clients--;
+            server.cache_blocked_clients--;
             aeCreateFileEvent(server.el, c->fd, AE_READABLE,
                 readQueryFromClient, c);
             cmd = lookupCommand(c->argv[0]->ptr);
@@ -787,13 +772,10 @@ void initServerConfig() {
     server.maxmemory = 0;
     server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_LRU;
     server.maxmemory_samples = 3;
-    server.vm_enabled = 0;
+    server.ds_enabled = 0;
-    server.vm_swap_file = zstrdup("/tmp/redis-%p.vm");
+    server.ds_path = zstrdup("/tmp/redis.ds");
-    server.vm_page_size = 256;          /* 256 bytes per page */
+    server.cache_max_memory = 64LL*1024*1024; /* 64 MB of RAM */
-    server.vm_pages = 1024*1024*100;    /* 104 millions of pages */
+    server.cache_blocked_clients = 0;
-    server.vm_max_memory = 1024LL*1024*1024*1; /* 1 GB of RAM */
-    server.vm_max_threads = 4;
-    server.vm_blocked_clients = 0;
     server.hash_max_zipmap_entries = REDIS_HASH_MAX_ZIPMAP_ENTRIES;
     server.hash_max_zipmap_value = REDIS_HASH_MAX_ZIPMAP_VALUE;
     server.list_max_ziplist_entries = REDIS_LIST_MAX_ZIPLIST_ENTRIES;
@@ -873,7 +855,7 @@ void initServer() {
         server.db[j].expires = dictCreate(&keyptrDictType,NULL);
         server.db[j].blocking_keys = dictCreate(&keylistDictType,NULL);
         server.db[j].watched_keys = dictCreate(&keylistDictType,NULL);
-        if (server.vm_enabled)
+        if (server.ds_enabled)
             server.db[j].io_keys = dictCreate(&keylistDictType,NULL);
         server.db[j].id = j;
     }
@@ -911,7 +893,7 @@ void initServer() {
         }
     }
 
-    if (server.vm_enabled) vmInit();
+    if (server.ds_enabled) dsInit();
 }
 
 /* Populates the Redis Command Table starting from the hard coded list
@@ -1050,8 +1032,8 @@ int processCommand(redisClient *c) {
         queueMultiCommand(c,cmd);
         addReply(c,shared.queued);
     } else {
-        if (server.vm_enabled && server.vm_max_threads > 0 &&
+        if (server.ds_enabled && blockClientOnSwappedKeys(c,cmd))
-            blockClientOnSwappedKeys(c,cmd)) return REDIS_ERR;
+            return REDIS_ERR;
         call(c,cmd);
     }
     return REDIS_OK;
@@ -1072,7 +1054,6 @@ int prepareForShutdown() {
     if (server.appendonly) {
         /* Append only file: fsync() the AOF and exit */
         aof_fsync(server.appendfd);
-        if (server.vm_enabled) unlink(server.vm_swap_file);
     } else if (server.saveparamslen > 0) {
         /* Snapshotting. Perform a SYNC SAVE and exit */
         if (rdbSave(server.dbfilename) != REDIS_OK) {
@@ -1185,7 +1166,7 @@ sds genRedisInfoString(void) {
         "hash_max_zipmap_value:%zu\r\n"
         "pubsub_channels:%ld\r\n"
         "pubsub_patterns:%u\r\n"
-        "vm_enabled:%d\r\n"
+        "ds_enabled:%d\r\n"
         "role:%s\r\n"
         ,REDIS_VERSION,
         redisGitSHA1(),
@@ -1228,7 +1209,7 @@ sds genRedisInfoString(void) {
         server.hash_max_zipmap_value,
         dictSize(server.pubsub_channels),
         listLength(server.pubsub_patterns),
-        server.vm_enabled != 0,
+        server.ds_enabled != 0,
         server.masterhost == NULL ? "master" : "slave"
     );
     if (server.masterhost) {
@@ -1255,33 +1236,13 @@ sds genRedisInfoString(void) {
             );
         }
     }
-    if (server.vm_enabled) {
+    if (server.ds_enabled) {
         lockThreadedIO();
         info = sdscatprintf(info,
-            "vm_conf_max_memory:%llu\r\n"
+            "cache_max_memory:%llu\r\n"
-            "vm_conf_page_size:%llu\r\n"
+            "cache_blocked_clients:%lu\r\n"
-            "vm_conf_pages:%llu\r\n"
+            ,(unsigned long long) server.cache_max_memory,
-            "vm_stats_used_pages:%llu\r\n"
+            (unsigned long) server.cache_blocked_clients
-            "vm_stats_swapped_objects:%llu\r\n"
-            "vm_stats_swappin_count:%llu\r\n"
-            "vm_stats_swappout_count:%llu\r\n"
-            "vm_stats_io_newjobs_len:%lu\r\n"
-            "vm_stats_io_processing_len:%lu\r\n"
-            "vm_stats_io_processed_len:%lu\r\n"
-            "vm_stats_io_active_threads:%lu\r\n"
-            "vm_stats_blocked_clients:%lu\r\n"
-            ,(unsigned long long) server.vm_max_memory,
-            (unsigned long long) server.vm_page_size,
-            (unsigned long long) server.vm_pages,
-            (unsigned long long) server.vm_stats_used_pages,
-            (unsigned long long) server.vm_stats_swapped_objects,
-            (unsigned long long) server.vm_stats_swapins,
-            (unsigned long long) server.vm_stats_swapouts,
-            (unsigned long) listLength(server.io_newjobs),
-            (unsigned long) listLength(server.io_processing),
-            (unsigned long) listLength(server.io_processed),
-            (unsigned long) server.io_active_threads,
-            (unsigned long) server.vm_blocked_clients
         );
         unlockThreadedIO();
     }

src/redis.h

@@ -440,7 +440,7 @@ struct redisServer {
     int maxmemory_samples;
     /* Blocked clients */
     unsigned int bpop_blocked_clients;
-    unsigned int vm_blocked_clients;
+    unsigned int cache_blocked_clients;
     list *unblocked_clients;
     /* Sort parameters - qsort_r() is only available under BSD so we
      * have to take this state global, in order to pass it to sortCompare() */
@@ -448,11 +448,9 @@ struct redisServer {
     int sort_alpha;
     int sort_bypattern;
     /* Virtual memory configuration */
-    int vm_enabled;
+    int ds_enabled; /* backend disk in redis.conf */
-    char *vm_swap_file;
+    char *ds_path;  /* location of the disk store on disk */
-    off_t vm_page_size;
+    unsigned long long cache_max_memory;
-    off_t vm_pages;
-    unsigned long long vm_max_memory;
     /* Zip structure config */
     size_t hash_max_zipmap_entries;
     size_t hash_max_zipmap_value;