From 131a8c9e35c8aa7a0e0a579f85e0ea3e1ae93c57 Mon Sep 17 00:00:00 2001
From: John Sully <john@csquare.ca>
Date: Wed, 24 Mar 2021 19:58:51 +0000
Subject: [PATCH] Fix bug where we skip valid dict elements in dictGetRandomKey

Former-commit-id: 626b56b00824573660af0c47b210fd1e8d2cfeb2
---
 src/dict.cpp | 11 +++++++++--
 src/dict.h   |  1 +
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/dict.cpp b/src/dict.cpp
index c682e2ec9..831a32f8f 100644
--- a/src/dict.cpp
+++ b/src/dict.cpp
@@ -373,6 +373,7 @@ int dictRehash(dict *d, int n) {
 dictAsyncRehashCtl::dictAsyncRehashCtl(struct dict *d, dictAsyncRehashCtl *next) : dict(d), next(next) {
     queue.reserve(c_targetQueueSize);
     __atomic_fetch_add(&d->refcount, 1, __ATOMIC_RELEASE);
+    this->rehashIdxBase = d->rehashidx;
 }
 
 dictAsyncRehashCtl *dictRehashAsyncStart(dict *d, int buckets) {
@@ -931,12 +932,18 @@ dictEntry *dictGetRandomKey(dict *d)
     if (dictSize(d) == 0) return NULL;
     if (dictIsRehashing(d)) _dictRehashStep(d);
     if (dictIsRehashing(d)) {
+        long rehashidx = d->rehashidx;
+        auto async = d->asyncdata;
+        while (async != nullptr) {
+            rehashidx = std::min((long)async->rehashIdxBase, rehashidx);
+            async = async->next;
+        }
         do {
             /* We are sure there are no elements in indexes from 0
              * to rehashidx-1 */
-            h = d->rehashidx + (random() % (d->ht[0].size +
+            h = rehashidx + (random() % (d->ht[0].size +
                                             d->ht[1].size -
-                                            d->rehashidx));
+                                            rehashidx));
             he = (h >= d->ht[0].size) ? d->ht[1].table[h - d->ht[0].size] :
                                       d->ht[0].table[h];
         } while(he == NULL);
diff --git a/src/dict.h b/src/dict.h
index ab57a7d7f..f24108d32 100644
--- a/src/dict.h
+++ b/src/dict.h
@@ -100,6 +100,7 @@ struct dictAsyncRehashCtl {
     struct dict *dict = nullptr;
     std::vector<workItem> queue;
     size_t hashIdx = 0;
+    long rehashIdxBase;
     dictAsyncRehashCtl *next = nullptr;
     std::atomic<bool> done { false };
     std::atomic<bool> abondon { false };