added diskstore.c in Makefile and prototypes in redis.h

src/Makefile

@@ -24,7 +24,7 @@ PREFIX= /usr/local
 INSTALL_BIN= $(PREFIX)/bin
 INSTALL= cp -p
 
-OBJ = adlist.o ae.o anet.o dict.o redis.o sds.o zmalloc.o lzf_c.o lzf_d.o pqsort.o zipmap.o sha1.o ziplist.o release.o networking.o util.o object.o db.o replication.o rdb.o t_string.o t_list.o t_set.o t_zset.o t_hash.o config.o aof.o vm.o pubsub.o multi.o debug.o sort.o intset.o syncio.o
+OBJ = adlist.o ae.o anet.o dict.o redis.o sds.o zmalloc.o lzf_c.o lzf_d.o pqsort.o zipmap.o sha1.o ziplist.o release.o networking.o util.o object.o db.o replication.o rdb.o t_string.o t_list.o t_set.o t_zset.o t_hash.o config.o aof.o dscache.o pubsub.o multi.o debug.o sort.o intset.o syncio.o diskstore.o
 BENCHOBJ = ae.o anet.o redis-benchmark.o sds.o adlist.o zmalloc.o
 CLIOBJ = anet.o sds.o adlist.o redis-cli.o zmalloc.o release.o
 CHECKDUMPOBJ = redis-check-dump.o lzf_c.o lzf_d.o
@@ -50,7 +50,6 @@ ae_select.o: ae_select.c
 anet.o: anet.c fmacros.h anet.h
 aof.o: aof.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
   zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h
-chprgname.o: chprgname.c
 config.o: config.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
   zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h
 db.o: db.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
@@ -58,6 +57,10 @@ db.o: db.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
 debug.o: debug.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
   zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h sha1.h
 dict.o: dict.c fmacros.h dict.h zmalloc.h
+diskstore.o: diskstore.c redis.h fmacros.h config.h ae.h sds.h dict.h \
+  adlist.h zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h
+dscache.o: dscache.c redis.h fmacros.h config.h ae.h sds.h dict.h \
+  adlist.h zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h
 intset.o: intset.c intset.h zmalloc.h
 lzf_c.o: lzf_c.c lzfP.h
 lzf_d.o: lzf_d.c lzfP.h
@@ -72,11 +75,12 @@ pubsub.o: pubsub.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
   zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h
 rdb.o: rdb.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
   zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h lzf.h
-redis-benchmark.o: redis-benchmark.c fmacros.h ae.h anet.h sds.h adlist.h \
-  zmalloc.h
+redis-benchmark.o: redis-benchmark.c fmacros.h ae.h \
+  ../deps/hiredis/hiredis.h sds.h adlist.h zmalloc.h
 redis-check-aof.o: redis-check-aof.c fmacros.h config.h
 redis-check-dump.o: redis-check-dump.c lzf.h
-redis-cli.o: redis-cli.c fmacros.h version.h sds.h adlist.h zmalloc.h
+redis-cli.o: redis-cli.c fmacros.h version.h ../deps/hiredis/hiredis.h \
+  sds.h zmalloc.h ../deps/linenoise/linenoise.h help.h
 redis.o: redis.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
   zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h
 release.o: release.c release.h
@@ -86,7 +90,8 @@ sds.o: sds.c sds.h zmalloc.h
 sha1.o: sha1.c sha1.h
 sort.o: sort.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
   zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h pqsort.h
-syncio.o: syncio.c
+syncio.o: syncio.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
+  zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h
 t_hash.o: t_hash.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
   zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h
 t_list.o: t_list.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
@@ -99,8 +104,6 @@ t_zset.o: t_zset.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
   zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h
 util.o: util.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
   zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h
-vm.o: vm.c redis.h fmacros.h config.h ae.h sds.h dict.h adlist.h \
-  zmalloc.h anet.h zipmap.h ziplist.h intset.h version.h
 ziplist.o: ziplist.c zmalloc.h ziplist.h
 zipmap.o: zipmap.c zmalloc.h
 zmalloc.o: zmalloc.c config.h
@@ -138,7 +141,7 @@ clean:
 	rm -rf $(PRGNAME) $(BENCHPRGNAME) $(CLIPRGNAME) $(CHECKDUMPPRGNAME) $(CHECKAOFPRGNAME) *.o *.gcda *.gcno *.gcov
 
 dep:
-	$(CC) -MM *.c
+	$(CC) -MM *.c -I ../deps/hiredis -I ../deps/linenoise
 
 test: redis-server
 	(cd ..; tclsh8.5 tests/test_helper.tcl --tags "${TAGS}" --file "${FILE}")

src/vm.c → src/dscache.c

@@ -5,6 +5,73 @@
 #include <math.h>
 #include <signal.h>
 
+/* dscache.c - Disk store cache for disk store backend.
+ *
+ * When Redis is configured for using disk as backend instead of memory, the
+ * memory is used as a cache, so that recently accessed keys are taken in
+ * memory for fast read and write operations.
+ *
+ * Modified keys are marked to be flushed on disk, and will be flushed
+ * as long as the maxium configured flush time elapsed.
+ *
+ * This file implements the whole caching subsystem and contains further
+ * documentation. */
+
+/* TODO:
+ *
+ * - The WATCH helper will be used to signal the cache system
+ *   we need to flush a given key/dbid into disk, adding this key/dbid
+ *   pair into a server.ds_cache_dirty linked list AND hash table (so that we
+ *   don't add the same thing multiple times).
+ *
+ * - cron() checks if there are elements on this list. When there are things
+ *   to flush, we create an IO Job for the I/O thread.
+ *   FIXME: how to mark this key as "busy"? With VM we used to change the
+ *   object->storage field, but this time we need this to work with every
+ *   kind of object, including shared ones. One possibility is just killing
+ *   object sharing at all. So let's assume this will be our solution.
+ *
+ *   So we set keys that are in the process of being saved as
+ *   object->storage = REDIS_STORAGE_SAVING;
+ *
+ * - This is what we do on key lookup:
+ *   1) The key already exists in memory. object->storage == REDIS_DS_MEMORY.
+ *      We don't do nothing special, lookup, return value object pointer.
+ *   2) The key is in memory but object->storage == REDIS_DS_SAVING.
+ *      This is an explicit lookup so we have to abort the saving operation.
+ *      We kill the IO Job, set the storage to == REDIS_DB_MEMORY but
+ *      re-queue the object in the server.ds_cache_dirty list.
+ *
+ *      Btw here we need some protection against the problem of continuously
+ *      writing against a value having the effect of this value to be never
+ *      saved on disk. That is, at some point we need to block and write it
+ *      if there is too much delay.
+ *   3) The key is not in memory. We block to load the key from disk.
+ *      Of course the key may not be present at all on the disk store as well,
+ *      in such case we just detect this condition and continue, returning
+ *      NULL from lookup.
+ *
+ * - Preloading of needed keys:
+ *   1) As it was done with VM, also with this new system we try preloading
+ *      keys a client is going to use. We block the client, load keys
+ *      using the I/O thread, unblock the client. Same code as VM more or less.
+ *
+ * - Transfering keys from memory to disk.
+ *   Again while in cron() we detect our memory limit was reached. What we
+ *   do is transfering random keys that are not set as dirty on disk, using
+ *   LRU to select the key.
+ *   If this is not enough to return again under the memory limits we also
+ *   start to flush keys that need to be synched on disk synchronously,
+ *   removing it from the memory.
+ *
+ * - IO thread operations are no longer stopped for sync loading/saving of
+ *   things. When a key is found to be in the process of being saved or
+ *   loaded we simply wait for the IO thread to end its work.
+ *
+ *   Otherwise if there is to load a key without any IO thread operation
+ *   just started it is blocking-loaded in the lookup function.
+ */
+
 /* Virtual Memory is composed mainly of two subsystems:
  * - Blocking Virutal Memory
  * - Threaded Virtual Memory I/O

src/redis.h

@@ -792,7 +792,14 @@ int htNeedsResize(dict *dict);
 void oom(const char *msg);
 void populateCommandTable(void);
 
-/* Virtual Memory */
+/* Disk store */
+int dsOpen(void);
+int dsClose(void);
+int dsSet(redisDb *db, robj *key, robj *val);
+robj *dsGet(redisDb *db, robj *key);
+int dsExists(redisDb *db, robj *key);
+
+/* Disk Store Cache */
 void vmInit(void);
 void vmMarkPagesFree(off_t page, off_t count);
 robj *vmLoadObject(robj *o);