From 48acb8e4233f92bc4db07fc70815b09f0f917515 Mon Sep 17 00:00:00 2001
From: DreamPiggy <lizhuoli1126@126.com>
Date: Mon, 4 Jun 2018 20:16:27 +0800
Subject: [PATCH] Fix that the downloader operation may not call the completion
 block in race condition, which the operation we get is finished but not been
 removed from the operation array.

---
 SDWebImage/SDWebImageDownloader.m | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/SDWebImage/SDWebImageDownloader.m b/SDWebImage/SDWebImageDownloader.m
index f775a249..76291a17 100644
--- a/SDWebImage/SDWebImageDownloader.m
+++ b/SDWebImage/SDWebImageDownloader.m
@@ -275,7 +275,8 @@
     
     LOCK(self.operationsLock);
     SDWebImageDownloaderOperation *operation = [self.URLOperations objectForKey:url];
-    if (!operation) {
+    // There is a case that the operation may be marked as finished, but not been removed from `self.URLOperations`.
+    if (!operation || operation.isFinished) {
         operation = createCallback();
         __weak typeof(self) wself = self;
         operation.completionBlock = ^{