Add support to notify modules of keys loaded by flash on startup (#536)

runtest-moduleapi

@@ -37,5 +37,6 @@ $TCLSH tests/test_helper.tcl \
 --single unit/moduleapi/hash \
 --single unit/moduleapi/zset \
 --single unit/moduleapi/stream \
+--single unit/moduleapi/load \
 --config server-threads 3 \
 "${@}"

src/db.cpp

@@ -2607,6 +2607,14 @@ void clusterStorageLoadCallback(const char *rgchkey, size_t cch, void *)
     slotToKeyUpdateKeyCore(rgchkey, cch, true /*add*/);
 }
 
+void moduleLoadCallback(const char * rgchKey, size_t cchKey, void *data) {
+    if (g_pserver->cluster_enabled) {
+        clusterStorageLoadCallback(rgchKey, cchKey, data);
+    }
+    robj *keyobj = createEmbeddedStringObject(rgchKey, cchKey);
+    moduleNotifyKeyspaceEvent(NOTIFY_LOADED, "loaded", keyobj, *(int *)data);
+}
+
 void redisDb::initialize(int id)
 {
     redisDbPersistentData::initialize();
@@ -2625,8 +2633,8 @@ void redisDb::storageProviderInitialize()
 {
     if (g_pserver->m_pstorageFactory != nullptr)
     {
-        IStorageFactory::key_load_iterator itr = (g_pserver->cluster_enabled) ? clusterStorageLoadCallback : nullptr;
-        this->setStorageProvider(StorageCache::create(g_pserver->m_pstorageFactory, id, itr, nullptr));
+        IStorageFactory::key_load_iterator itr = moduleLoadCallback;
+        this->setStorageProvider(StorageCache::create(g_pserver->m_pstorageFactory, id, itr, &id));
     }
 }
 

src/redismodule.h

@@ -326,6 +326,7 @@ static const RedisModuleEvent
 #define REDISMODULE_SUBEVENT_LOADING_ENDED 3
 #define REDISMODULE_SUBEVENT_LOADING_FAILED 4
 #define _REDISMODULE_SUBEVENT_LOADING_NEXT 5
+#define REDISMODULE_SUBEVENT_LOADING_FLASH_START 6
 
 #define REDISMODULE_SUBEVENT_CLIENT_CHANGE_CONNECTED 0
 #define REDISMODULE_SUBEVENT_CLIENT_CHANGE_DISCONNECTED 1

src/server.cpp

@@ -4068,12 +4068,6 @@ void initServer(void) {
         }
     }
 
-    /* We have to initialize storage providers after the cluster has been initialized */
-    for (int idb = 0; idb < cserver.dbnum; ++idb)
-    {
-        g_pserver->db[idb]->storageProviderInitialize();
-    }
-
     saveMasterStatusToStorage(false); // eliminate the repl-offset field
     
     /* Initialize ACL default password if it exists */
@@ -4086,6 +4080,15 @@ void initServer(void) {
  * Thread Local Storage initialization collides with dlopen call.
  * see: https://sourceware.org/bugzilla/show_bug.cgi?id=19329 */
 void InitServerLast() {
+
+    /* We have to initialize storage providers after the cluster has been initialized */
+    moduleFireServerEvent(REDISMODULE_EVENT_LOADING, REDISMODULE_SUBEVENT_LOADING_FLASH_START, NULL);
+    for (int idb = 0; idb < cserver.dbnum; ++idb)
+    {
+        g_pserver->db[idb]->storageProviderInitialize();
+    }
+    moduleFireServerEvent(REDISMODULE_EVENT_LOADING, REDISMODULE_SUBEVENT_LOADING_ENDED, NULL);
+
     bioInit();
     set_jemalloc_bg_thread(cserver.jemalloc_bg_thread);
     g_pserver->initial_memory_usage = zmalloc_used_memory();

tests/modules/Makefile

@@ -39,7 +39,8 @@ TEST_MODULES = \
     defragtest.so \
     hash.so \
     zset.so \
-    stream.so
+    stream.so \
+    load.so
 
 
 .PHONY: all

tests/modules/hooks.c

@@ -212,6 +212,7 @@ void loadingCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void
         case REDISMODULE_SUBEVENT_LOADING_RDB_START: keyname = "loading-rdb-start"; break;
         case REDISMODULE_SUBEVENT_LOADING_AOF_START: keyname = "loading-aof-start"; break;
         case REDISMODULE_SUBEVENT_LOADING_REPL_START: keyname = "loading-repl-start"; break;
+        case REDISMODULE_SUBEVENT_LOADING_FLASH_START: keyname = "loading-flash-start"; break;
         case REDISMODULE_SUBEVENT_LOADING_ENDED: keyname = "loading-end"; break;
         case REDISMODULE_SUBEVENT_LOADING_FAILED: keyname = "loading-failed"; break;
     }

tests/modules/load.c

@@ -0,0 +1,94 @@
+/* Server hooks API example
+ *
+ * -----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2019, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#define REDISMODULE_EXPERIMENTAL_API
+#include "redismodule.h"
+
+size_t count, finalCount;
+
+/* Client state change callback. */
+void loadCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data) {
+    REDISMODULE_NOT_USED(ctx);
+    REDISMODULE_NOT_USED(e);
+    REDISMODULE_NOT_USED(data);
+
+    if (sub == REDISMODULE_SUBEVENT_LOADING_FLASH_START || sub == REDISMODULE_SUBEVENT_LOADING_RDB_START || sub == REDISMODULE_SUBEVENT_LOADING_AOF_START || sub == REDISMODULE_SUBEVENT_LOADING_REPL_START) {
+        count = 0;
+        finalCount = 0;
+    } else if (sub == REDISMODULE_SUBEVENT_LOADING_ENDED) {
+        finalCount = count;
+    }
+}
+
+int loadKeyCallback(RedisModuleCtx *ctx, int type,  const char *event, RedisModuleString *key) {
+    REDISMODULE_NOT_USED(ctx);
+    REDISMODULE_NOT_USED(type);
+    REDISMODULE_NOT_USED(event);
+
+    const char *keyname = RedisModule_StringPtrLen(key, NULL);
+
+    RedisModule_Log(ctx, REDISMODULE_LOGLEVEL_NOTICE, "Loaded key: %s", keyname);
+
+    count++;
+    return 0;
+}
+
+int LoadCount_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    RedisModule_AutoMemory(ctx); /* Use automatic memory management. */
+
+    if (argc != 1) return RedisModule_WrongArity(ctx);
+
+    RedisModule_ReplyWithLongLong(ctx, finalCount);
+
+    return REDISMODULE_OK;
+}
+
+/* This function must be present on each Redis module. It is used in order to
+ * register the commands into the Redis server. */
+int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    if (RedisModule_Init(ctx,"load",1,REDISMODULE_APIVER_1)
+        == REDISMODULE_ERR) return REDISMODULE_ERR;
+
+    RedisModule_SubscribeToServerEvent(ctx,
+        RedisModuleEvent_Loading, loadCallback);
+    RedisModule_SubscribeToKeyspaceEvents(ctx,
+        REDISMODULE_NOTIFY_LOADED, loadKeyCallback);
+
+    if (RedisModule_CreateCommand(ctx, "load.count",
+        LoadCount_RedisCommand,"readonly",1,1,1) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
+    return REDISMODULE_OK;
+}

tests/unit/moduleapi/load.tcl

@@ -0,0 +1,15 @@
+set testmodule [file normalize tests/modules/load.so]
+
+if {$::flash_enabled} {
+    start_server [list tags [list "modules"] overrides [list storage-provider {flash ./rocks.db.master} databases 256 loadmodule $testmodule]] {
+        test "Module is notified of keys loaded from flash" {
+            r flushall
+            r set foo bar
+            r set bar foo
+            r set foobar barfoo
+            assert_equal [r load.count] 0
+            r debug reload
+            assert_equal [r load.count] 3
+        }
+    }
+}