From: antirez Date: Mon, 3 Jan 2011 16:18:37 +0000 (+0100) Subject: diskstore more fixes X-Git-Url: https://git.saurik.com/redis.git/commitdiff_plain/5d46e370b7da346801e01066e3ed077069d73d3d diskstore more fixes --- diff --git a/src/db.c b/src/db.c index ae40d204..7d2bf4af 100644 --- a/src/db.c +++ b/src/db.c @@ -6,6 +6,35 @@ * C-level DB API *----------------------------------------------------------------------------*/ +/* Important notes on lookup and disk store. + * + * When disk store is enabled on lookup we can have different cases. + * + * a) The key is in memory: + * - If the key is not in IO_SAVEINPROG state we can access it. + * As if it's just IO_SAVE this means we have the key in the IO queue + * but can't be accessed by the IO thread (it requires to be + * translated into an IO Job by the cache cron function.) + * - If the key is in IO_SAVEINPROG we can't touch the key and have + * to blocking wait completion of operations. + * b) The key is not in memory: + * - If it's marked as non existing on disk as well (negative cache) + * we don't need to perform the disk access. + * - if the key MAY EXIST, but is not in memory, and it is marked as IO_SAVE + * then the key can only be a deleted one. As IO_SAVE keys are never + * evicted (dirty state), so the only possibility is that key was deleted. + * - if the key MAY EXIST we need to blocking load it. + * We check that the key is not in IO_SAVEINPROG state before accessing + * the disk object. If it is in this state, we wait. + */ + +void lookupWaitBusyKey(redisDb *db, robj *key) { + /* FIXME: wait just for this key, not everything */ + waitEmptyIOJobsQueue(); + processAllPendingIOJobs(); + redisAssert((cacheScheduleIOGetFlags(db,key) & REDIS_IO_SAVEINPROG) == 0); +} + robj *lookupKey(redisDb *db, robj *key) { dictEntry *de = dictFind(db->dict,key->ptr); if (de) { @@ -20,11 +49,9 @@ robj *lookupKey(redisDb *db, robj *key) { if (server.ds_enabled && cacheScheduleIOGetFlags(db,key) & REDIS_IO_SAVEINPROG) { - /* There is a save in progress for this object! - * Wait for it to get out. */ - waitEmptyIOJobsQueue(); - processAllPendingIOJobs(); - redisAssert(!(cacheScheduleIOGetFlags(db,key) & REDIS_IO_SAVEINPROG)); + /* Need to wait for the key to get unbusy */ + redisLog(REDIS_WARNING,"Lookup found a key in SAVEINPROG state. Waiting. (Key was in the cache)"); + lookupWaitBusyKey(db,key); } server.stat_keyspace_hits++; return val; @@ -36,16 +63,24 @@ robj *lookupKey(redisDb *db, robj *key) { * enabled we may have this key on disk. If so load it in memory * in a blocking way. */ if (server.ds_enabled && cacheKeyMayExist(db,key)) { - if (cacheScheduleIOGetFlags(db,key) & REDIS_IO_SAVEINPROG) { - /* There is a save in progress for this object! - * Wait for it to get out. */ - waitEmptyIOJobsQueue(); - processAllPendingIOJobs(); - redisAssert((cacheScheduleIOGetFlags(db,key) & REDIS_IO_SAVEINPROG) == 0); + long flags = cacheScheduleIOGetFlags(db,key); + + /* They key is not in cache, but it has a SAVE op in queue? + * The only possibility is that the key was deleted, since + * dirty keys are not evicted. */ + if (flags & REDIS_IO_SAVE) { + server.stat_keyspace_misses++; + return NULL; + } + + /* At this point we need to blocking load the key in memory. + * The first thing we do is waiting here if the key is busy. */ + if (flags & REDIS_IO_SAVEINPROG) { + redisLog(REDIS_WARNING,"Lookup found a key in SAVEINPROG state. Waiting (while force loading)."); + lookupWaitBusyKey(db,key); } - redisLog(REDIS_DEBUG,"Force loading key %s via lookup", - key->ptr); + redisLog(REDIS_DEBUG,"Force loading key %s via lookup", key->ptr); val = dsGet(db,key,&expire); if (val) { int retval = dbAdd(db,key,val); @@ -53,6 +88,8 @@ robj *lookupKey(redisDb *db, robj *key) { if (expire != -1) setExpire(db,key,expire); server.stat_keyspace_hits++; return val; + } else { + cacheSetKeyDoesNotExist(db,key); } } server.stat_keyspace_misses++; diff --git a/src/dscache.c b/src/dscache.c index 6bfcac1d..3a06b03e 100644 --- a/src/dscache.c +++ b/src/dscache.c @@ -348,6 +348,20 @@ void vmThreadedIOCompletedJob(aeEventLoop *el, int fd, void *privdata, incrRefCount(j->val); if (j->expire != -1) setExpire(j->db,j->key,j->expire); } + } else { + /* Key not found on disk. If it is also not in memory + * as a cached object, nor there is a job writing it + * in background, we are sure the key does not exist + * currently. + * + * So we set a negative cache entry avoiding that the + * resumed client will block load what does not exist... */ + if (dictFind(j->db->dict,j->key) == NULL && + (cacheScheduleIOGetFlags(j->db,j->key) & + (REDIS_IO_SAVE|REDIS_IO_SAVEINPROG)) == 0) + { + cacheSetKeyDoesNotExist(j->db,j->key); + } } cacheScheduleIODelFlag(j->db,j->key,REDIS_IO_LOADINPROG); handleClientsBlockedOnSwappedKey(j->db,j->key); @@ -469,7 +483,8 @@ void waitEmptyIOJobsQueue(void) { redisLog(REDIS_DEBUG,"waitEmptyIOJobsQueue: new %d, processing %d", listLength(server.io_newjobs), listLength(server.io_processing)); - /* + + /* FIXME: signal or not? if (listLength(server.io_newjobs)) { pthread_cond_signal(&server.io_condvar); } @@ -483,8 +498,12 @@ void waitEmptyIOJobsQueue(void) { if (io_processed_len) { vmThreadedIOCompletedJob(NULL,server.io_ready_pipe_read, (void*)0xdeadbeef,0); + /* FIXME: probably wiser to drop this sleeps. Anyway + * the contention on the IO thread will avoid we to loop + * too fast here. */ usleep(1000); /* 1 millisecond */ } else { + /* FIXME: same as fixme above. */ usleep(10000); /* 10 milliseconds */ } } diff --git a/tests/assets/default.conf b/tests/assets/default.conf index 8113e157..04233284 100644 --- a/tests/assets/default.conf +++ b/tests/assets/default.conf @@ -86,7 +86,7 @@ dbfilename dump.rdb # Also the Append Only File will be created inside this directory. # # Note that you must specify a directory here, not a file name. -dir ./test/tmp +dir /tmp ################################# REPLICATION ################################# diff --git a/tests/support/server.tcl b/tests/support/server.tcl index 4f48d22d..ad711e6e 100644 --- a/tests/support/server.tcl +++ b/tests/support/server.tcl @@ -177,6 +177,9 @@ proc start_server {options {code undefined}} { if {$::valgrind} { exec valgrind --suppressions=src/valgrind.sup src/redis-server $config_file > $stdout 2> $stderr & } else { + if {$::verbose} { + puts "Logging on $stdout / $stderr" + } exec src/redis-server $config_file > $stdout 2> $stderr & } diff --git a/tests/test_helper.tcl b/tests/test_helper.tcl index 2b7a8957..8ab2f6e4 100644 --- a/tests/test_helper.tcl +++ b/tests/test_helper.tcl @@ -13,7 +13,7 @@ set ::host 127.0.0.1 set ::port 16379 set ::traceleaks 0 set ::valgrind 0 -set ::verbose 0 +set ::verbose 1 set ::denytags {} set ::allowtags {} set ::external 0; # If "1" this means, we are running against external instance