From bc1ef48e5667d945d920ca8da7dd7f799148991d Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Wed, 23 Oct 2019 10:37:04 +0200
Subject: [PATCH] Modules hooks: FLUSHDB event example.

---
 src/module.c            |  2 ++
 src/modules/hellohook.c | 27 +++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/src/module.c b/src/module.c
index f3fe4e9ac..a505a2099 100644
--- a/src/module.c
+++ b/src/module.c
@@ -5870,6 +5870,8 @@ void moduleFireServerEvent(uint64_t eid, int subid, void *data) {
                 modulePopulateClientInfoStructure(&civ1,data,
                                                   el->event.dataver);
                 moduledata = &civ1;
+            } else if (eid == REDISMODULE_EVENT_FLUSHDB) {
+                moduledata = data;
             }
             el->callback(&ctx,el->event,subid,moduledata);
             moduleFreeContext(&ctx);
diff --git a/src/modules/hellohook.c b/src/modules/hellohook.c
index ea0ac517d..2e798f500 100644
--- a/src/modules/hellohook.c
+++ b/src/modules/hellohook.c
@@ -50,6 +50,31 @@ void clientChangeCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub,
         ci->id,ci->addr,ci->port);
 }
 
+void flushdbCallback(RedisModuleCtx *ctx, RedisModuleEvent e, uint64_t sub, void *data)
+{
+    REDISMODULE_NOT_USED(ctx);
+    REDISMODULE_NOT_USED(e);
+
+    RedisModuleFlushInfo *fi = data;
+    if (sub == REDISMODULE_SUBEVENT_FLUSHDB_START) {
+        if (fi->dbnum != -1) {
+            RedisModuleCallReply *reply;
+            reply = RedisModule_Call(ctx,"DBSIZE","");
+            long long numkeys = RedisModule_CallReplyInteger(reply);
+            printf("FLUSHDB event of database %d started (%lld keys in DB)\n",
+                fi->dbnum, numkeys);
+        } else {
+            printf("FLUSHALL event started\n");
+        }
+    } else {
+        if (fi->dbnum != -1) {
+            printf("FLUSHDB event of database %d ended\n",fi->dbnum);
+        } else {
+            printf("FLUSHALL event ended\n");
+        }
+    }
+}
+
 /* 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) {
@@ -61,5 +86,7 @@ int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
 
     RedisModule_SubscribeToServerEvent(ctx,
         RedisModuleEvent_ClientChange, clientChangeCallback);
+    RedisModule_SubscribeToServerEvent(ctx,
+        RedisModuleEvent_FlushDB, flushdbCallback);
     return REDISMODULE_OK;
 }