eth/fetcher: fix a closure data race

karalabe · karalabe · commit 3ce17d2862e8 · 2015-06-22T20:13:18.000+03:00
diff --git a/eth/fetcher/fetcher.go b/eth/fetcher/fetcher.go
@@ -281,12 +281,13 @@ func (f *Fetcher) loop() {
 
 					glog.V(logger.Detail).Infof("Peer %s: fetching %s", peer, list)
 				}
-				hashes := hashes // closure!
+				// Create a closure of the fetch and schedule in on a new thread
+				fetcher, hashes := f.fetching[hashes[0]].fetch, hashes
 				go func() {
 					if f.fetchingHook != nil {
 						f.fetchingHook(hashes)
 					}
-					f.fetching[hashes[0]].fetch(hashes)
+					fetcher(hashes)
 				}()
 			}
 			// Schedule the next fetch if blocks are still pending

Original file line number	Diff line number	Diff line change
`@@ -281,12 +281,13 @@ func (f *Fetcher) loop() {`
`281`	`281`
`282`	`282`	`glog.V(logger.Detail).Infof("Peer %s: fetching %s", peer, list)`
`283`	`283`	`}`
`284`		`- hashes := hashes // closure!`
	`284`	`+ // Create a closure of the fetch and schedule in on a new thread`
	`285`	`+ fetcher, hashes := f.fetching[hashes[0]].fetch, hashes`
`285`	`286`	`go func() {`
`286`	`287`	`if f.fetchingHook != nil {`
`287`	`288`	`f.fetchingHook(hashes)`
`288`	`289`	`}`
`289`		`- f.fetching[hashes[0]].fetch(hashes)`
	`290`	`+ fetcher(hashes)`
`290`	`291`	`}()`
`291`	`292`	`}`
`292`	`293`	`// Schedule the next fetch if blocks are still pending`