From 9ba5270bdac9ec87ca42b46d12c0e18c9f98909b Mon Sep 17 00:00:00 2001
From: John Sully <john@csquare.ca>
Date: Thu, 18 Jul 2019 22:31:20 -0400
Subject: [PATCH] Subexpire entries should load/save

Former-commit-id: a55d98043655473ecdd53db2927381635eefc0b8
---
 src/rdb.cpp | 47 ++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 36 insertions(+), 11 deletions(-)

diff --git a/src/rdb.cpp b/src/rdb.cpp
index bed797305..97ade6d1f 100644
--- a/src/rdb.cpp
+++ b/src/rdb.cpp
@@ -1066,6 +1066,13 @@ int rdbSaveKeyValuePair(rio *rdb, robj *key, robj *val, expireEntry *pexpire) {
     snprintf(szT, 32, "%" PRIu64, val->mvcc_tstamp);
     if (rdbSaveAuxFieldStrStr(rdb,"mvcc-tstamp", szT) == -1) return -1;
 
+    /* Save type, key, value */
+    if (rdbSaveObjectType(rdb,val) == -1) return -1;
+    if (rdbSaveStringObject(rdb,key) == -1) return -1;
+    if (rdbSaveObject(rdb,val,key) == -1) return -1;
+
+    /* Save expire entry after as it will apply to the previously loaded key */
+    /*  This is because we update the expire datastructure directly without buffering */
     if (pexpire != nullptr)
     {
         for (auto itr : *pexpire)
@@ -1078,10 +1085,6 @@ int rdbSaveKeyValuePair(rio *rdb, robj *key, robj *val, expireEntry *pexpire) {
         }
     }
 
-    /* Save type, key, value */
-    if (rdbSaveObjectType(rdb,val) == -1) return -1;
-    if (rdbSaveStringObject(rdb,key) == -1) return -1;
-    if (rdbSaveObject(rdb,val,key) == -1) return -1;
     return 1;
 }
 
@@ -1919,6 +1922,8 @@ int rdbLoadRio(rio *rdb, rdbSaveInfo *rsi, int loading_aof) {
     long long lru_idle = -1, lfu_freq = -1, expiretime = -1, now = mstime();
     long long lru_clock = 0;
     uint64_t mvcc_tstamp = OBJ_MVCC_INVALID;
+    robj *subexpireKey = nullptr;
+    robj *key = nullptr;
 
     rdb->update_cksum = rdbLoadProgressCallback;
     rdb->max_processing_chunk = g_pserver->loading_process_events_interval_bytes;
@@ -1940,7 +1945,7 @@ int rdbLoadRio(rio *rdb, rdbSaveInfo *rsi, int loading_aof) {
     lru_clock = LRU_CLOCK();
     
     while(1) {
-        robj *key, *val;
+        robj *val;
 
         /* Read type. */
         if ((type = rdbLoadType(rdb)) == -1) goto eoferr;
@@ -2048,6 +2053,18 @@ int rdbLoadRio(rio *rdb, rdbSaveInfo *rsi, int loading_aof) {
             } else if (!strcasecmp(szFromObj(auxkey),"mvcc-tstamp")) {
                 static_assert(sizeof(unsigned long long) == sizeof(uint64_t), "Ensure long long is 64-bits");
                 mvcc_tstamp = strtoull(szFromObj(auxval), nullptr, 10);
+            } else if (!strcasecmp(szFromObj(auxkey), "keydb-subexpire-key")) {
+                subexpireKey = auxval;
+                incrRefCount(subexpireKey);
+            } else if (!strcasecmp(szFromObj(auxkey), "keydb-subexpire-when")) {
+                if (key == nullptr || subexpireKey == nullptr) {
+                    serverLog(LL_WARNING, "Corrupt subexpire entry in RDB skipping.");
+                }
+                else {
+                    setExpire(NULL, db, key, subexpireKey, strtoll(szFromObj(auxval), nullptr, 10));
+                    decrRefCount(subexpireKey);
+                    subexpireKey = nullptr;
+                }
             } else {
                 /* We ignore fields we don't understand, as by AUX field
                  * contract. */
@@ -2089,6 +2106,9 @@ int rdbLoadRio(rio *rdb, rdbSaveInfo *rsi, int loading_aof) {
         }
 
         /* Read key */
+        if (key != nullptr)
+            decrRefCount(key);
+
         if ((key = rdbLoadStringObject(rdb)) == NULL) goto eoferr;
         /* Read value */
         if ((val = rdbLoadObject(type,rdb,key, mvcc_tstamp)) == NULL) goto eoferr;
@@ -2102,7 +2122,7 @@ int rdbLoadRio(rio *rdb, rdbSaveInfo *rsi, int loading_aof) {
             decrRefCount(val);
         } else {
             /* Add the new object in the hash table */
-            int fInserted = dbMerge(db, key, val, rsi->fForceSetKey);
+            int fInserted = dbMerge(db, key, val, rsi->fForceSetKey);   // Note: dbMerge will incrRef
 
             if (fInserted)
             {
@@ -2112,14 +2132,9 @@ int rdbLoadRio(rio *rdb, rdbSaveInfo *rsi, int loading_aof) {
 
                 /* Set usage information (for eviction). */
                 objectSetLRUOrLFU(val,lfu_freq,lru_idle,lru_clock);
-
-                /* Decrement the key refcount since dbMerge() will take its
-                * own reference. */
-                decrRefCount(key);
             }
             else
             {
-                decrRefCount(key);
                 decrRefCount(val);
             }
         }
@@ -2130,6 +2145,16 @@ int rdbLoadRio(rio *rdb, rdbSaveInfo *rsi, int loading_aof) {
         lfu_freq = -1;
         lru_idle = -1;
     }
+
+    if (key != nullptr)
+        decrRefCount(key);
+
+    if (subexpireKey != nullptr)
+    {
+        serverLog(LL_WARNING, "Corrupt subexpire entry in RDB.");
+        decrRefCount(subexpireKey);
+        subexpireKey = nullptr;
+    }
     
     /* Verify the checksum if RDB version is >= 5 */
     if (rdbver >= 5) {