Removed channel awareness from keep.GetServerContents().

diff --git a/services/datamanager/keep/keep.go b/services/datamanager/keep/keep.go
index b9e6df03b0994f7e47279c1209883f05c3ab6c8a..de4cbd407e247ab5cffae30bb0648fdd5e3d88b7 100644 (file)
--- a/services/datamanager/keep/keep.go
+++ b/services/datamanager/keep/keep.go
@@ -188,7 +188,17 @@ func GetKeepServers(params GetKeepServersParams) (results ReadServers) {
        // Send off all the index requests concurrently
        responseChan := make(chan ServerResponse)
        for _, keepServer := range sdkResponse.KeepServers {
-               go GetServerContents(params.Logger, keepServer, client, responseChan)
+               // The above keepsServer variable is reused for each iteration, so
+               // it would be shared across all goroutines. This would result in
+               // us querying one server n times instead of n different servers
+               // as we intended. To avoid this we add it as an explicit
+               // parameter which gets copied. This bug and solution is described
+               // in https://golang.org/doc/effective_go.html#channels
+               go func(keepServer ServerAddress) {
+                       responseChan <- GetServerContents(params.Logger,
+                               keepServer,
+                               client)
+               }(keepServer)
        }
 
        results.ServerToContents = make(map[ServerAddress]ServerContents)
@@ -218,8 +228,7 @@ func GetKeepServers(params GetKeepServersParams) (results ReadServers) {
 // understand functions.
 func GetServerContents(arvLogger *logger.Logger,
        keepServer ServerAddress,
-       client http.Client,
-       responseChan chan<- ServerResponse) {
+       client http.Client) (response ServerResponse) {
        // Create and send request.
        url := fmt.Sprintf("http://%s:%d/index", keepServer.Host, keepServer.Port)
        log.Println("About to fetch keep server contents from " + url)
@@ -243,7 +252,6 @@ func GetServerContents(arvLogger *logger.Logger,
                        resp.StatusCode, url, resp.Status)
        }
 
-       response := ServerResponse{}
        response.Address = keepServer
        response.Contents.BlockDigestToInfo =
                make(map[blockdigest.BlockDigest]BlockInfo)
@@ -291,7 +299,7 @@ func GetServerContents(arvLogger *logger.Logger,
                        numSizeDisagreements)
        }
        resp.Body.Close()
-       responseChan <- response
+       return
 }
 
 func parseBlockInfoFromIndexLine(indexLine string) (blockInfo BlockInfo, err error) {