From 6c83ecbb485dae2468a635469bbec7dba20e2c07 Mon Sep 17 00:00:00 2001
From: John Sully <john@csquare.ca>
Date: Fri, 14 Aug 2020 16:05:39 +0000
Subject: [PATCH] Prehash the tombstone for cleanup

Former-commit-id: c9d97a7c7448fc769486175bea1648589487c87c
---
 src/db.cpp       | 12 ++++++++----
 src/dict.cpp     | 10 +++++-----
 src/dict.h       |  2 +-
 src/lazyfree.cpp |  5 ++++-
 src/snapshot.cpp |  3 ++-
 5 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/src/db.cpp b/src/db.cpp
index b7b36b518..b91041f66 100644
--- a/src/db.cpp
+++ b/src/db.cpp
@@ -422,7 +422,8 @@ bool redisDbPersistentData::syncDelete(robj *key)
             if (itr != nullptr)
             {
                 sds keyTombstone = sdsdup(szFromObj(key));
-                if (dictAdd(m_pdictTombstone, keyTombstone, nullptr) != DICT_OK)
+                uint64_t hash = dictGetHash(m_pdict, keyTombstone);
+                if (dictAdd(m_pdictTombstone, keyTombstone, (void*)hash) != DICT_OK)
                     sdsfree(keyTombstone);
             }
         }
@@ -2290,7 +2291,7 @@ void redisDbPersistentData::initialize()
 {
     m_pdbSnapshot = nullptr;
     m_pdict = dictCreate(&dbDictType,this);
-    m_pdictTombstone = dictCreate(&dbDictType,this);
+    m_pdictTombstone = dictCreate(&dbDictTypeTombstone,this);
     m_setexpire = new(MALLOC_LOCAL) expireset();
     m_fAllChanged = 0;
     m_fTrackingChanges = 0;
@@ -2477,8 +2478,11 @@ void redisDbPersistentData::ensure(const char *sdsKey, dictEntry **pde)
             {
                 dictAdd(m_pdict, keyNew, nullptr);
             }
-            *pde = dictFind(m_pdict, sdsKey);
-            dictAdd(m_pdictTombstone, sdsdupshared(itr.key()), nullptr);
+            uint64_t hash = dictGetHash(m_pdict, sdsKey);
+            dictEntry **deT;
+            dictht *ht;
+            *pde = dictFindWithPrev(m_pdict, sdsKey, hash, &deT, &ht);
+            dictAdd(m_pdictTombstone, sdsdupshared(itr.key()), (void*)hash);
         }
     }
     
diff --git a/src/dict.cpp b/src/dict.cpp
index ef7365fdb..c69c663a4 100644
--- a/src/dict.cpp
+++ b/src/dict.cpp
@@ -326,7 +326,7 @@ int dictRehashMilliseconds(dict *d, int ms) {
 static void _dictRehashStep(dict *d) {
     unsigned long iterators;
     __atomic_load(&d->iterators, &iterators, __ATOMIC_RELAXED);
-    if (iterators == 0) dictRehash(d,1);
+    if (iterators == 0) dictRehash(d,10);
 }
 
 /* Add an element to the target hash table */
@@ -541,14 +541,13 @@ void dictRelease(dict *d)
     zfree(d);
 }
 
-dictEntry *dictFindWithPrev(dict *d, const void *key, dictEntry ***dePrevPtr, dictht **pht)
+dictEntry *dictFindWithPrev(dict *d, const void *key, uint64_t h, dictEntry ***dePrevPtr, dictht **pht)
 {
     dictEntry *he;
-    uint64_t h, idx, table;
+    uint64_t idx, table;
 
     if (dictSize(d) == 0) return NULL; /* dict is empty */
     if (dictIsRehashing(d)) _dictRehashStep(d);
-    h = dictHashKey(d, key);
     for (table = 0; table <= 1; table++) {
         *pht = d->ht + table;
         idx = h & d->ht[table].sizemask;
@@ -570,7 +569,8 @@ dictEntry *dictFind(dict *d, const void *key)
 {
     dictEntry **deT;
     dictht *ht;
-    return dictFindWithPrev(d, key, &deT, &ht);
+    uint64_t h = dictHashKey(d, key);
+    return dictFindWithPrev(d, key, h, &deT, &ht);
 }
 
 void *dictFetchValue(dict *d, const void *key) {
diff --git a/src/dict.h b/src/dict.h
index c9118d35f..77ab832db 100644
--- a/src/dict.h
+++ b/src/dict.h
@@ -167,7 +167,7 @@ dictEntry *dictUnlink(dict *ht, const void *key);
 void dictFreeUnlinkedEntry(dict *d, dictEntry *he);
 void dictRelease(dict *d);
 dictEntry * dictFind(dict *d, const void *key);
-dictEntry * dictFindWithPrev(dict *d, const void *key, dictEntry ***dePrevPtr, dictht **ht);
+dictEntry * dictFindWithPrev(dict *d, const void *key, uint64_t h, dictEntry ***dePrevPtr, dictht **ht);
 void *dictFetchValue(dict *d, const void *key);
 int dictResize(dict *d);
 dictIterator *dictGetIterator(dict *d);
diff --git a/src/lazyfree.cpp b/src/lazyfree.cpp
index 1ee49103a..b5f341ed3 100644
--- a/src/lazyfree.cpp
+++ b/src/lazyfree.cpp
@@ -62,7 +62,10 @@ bool redisDbPersistentData::asyncDelete(robj *key) {
     dictEntry *de = dictUnlink(m_pdict,ptrFromObj(key));
     if (de) {
         if (m_pdbSnapshot != nullptr && m_pdbSnapshot->find_cached_threadsafe(szFromObj(key)) != nullptr)
-            dictAdd(m_pdictTombstone, sdsdup((sds)dictGetKey(de)), nullptr);
+        {
+            uint64_t hash = dictGetHash(m_pdict, szFromObj(key));
+            dictAdd(m_pdictTombstone, sdsdup((sds)dictGetKey(de)), (void*)hash);
+        }
 
         robj *val = (robj*)dictGetVal(de);
         if (val->FExpires())
diff --git a/src/snapshot.cpp b/src/snapshot.cpp
index 0ad1b5282..8dd4db367 100644
--- a/src/snapshot.cpp
+++ b/src/snapshot.cpp
@@ -70,6 +70,7 @@ const redisDbPersistentDataSnapshot *redisDbPersistentData::createSnapshot(uint6
 
     auto spdb = std::unique_ptr<redisDbPersistentDataSnapshot>(new (MALLOC_LOCAL) redisDbPersistentDataSnapshot());
     
+    dictRehashMilliseconds(m_pdict, 50);   // Give us the best chance at a fast cleanup
     spdb->m_fAllChanged = false;
     spdb->m_fTrackingChanges = 0;
     spdb->m_pdict = m_pdict;
@@ -303,7 +304,7 @@ void redisDbPersistentData::endSnapshot(const redisDbPersistentDataSnapshot *psn
     {
         dictEntry **dePrev;
         dictht *ht;
-        dictEntry *deSnapshot = dictFindWithPrev(m_spdbSnapshotHOLDER->m_pdict, dictGetKey(de), &dePrev, &ht);
+        dictEntry *deSnapshot = dictFindWithPrev(m_spdbSnapshotHOLDER->m_pdict, dictGetKey(de), (uint64_t)dictGetVal(de), &dePrev, &ht);
         if (deSnapshot == nullptr && m_spdbSnapshotHOLDER->m_pdbSnapshot)
         {
             // The tombstone is for a grand child, propogate it (or possibly in the storage provider - but an extra tombstone won't hurt)