create merge virtual repo task pool (#473)

* create merge virtual repo task pool

* use for range

fileserver/virtual_repo.go

@@ -15,6 +15,26 @@ import (
 	"github.com/haiwen/seafile-server/fileserver/repomgr"
 )
 
+const mergeVirtualRepoWorkerNumber = 5
+
+var mergeVirtualRepoTasks = make(chan string, 100)
+
+func virtualRepoInit() {
+	go createMergeVirtualRepoTaskPool(mergeVirtualRepoWorkerNumber)
+}
+
+func createMergeVirtualRepoTaskPool(n int) {
+	for i := 0; i < n; i++ {
+		go mergeVirtualRepoWorker()
+	}
+}
+
+func mergeVirtualRepoWorker() {
+	for repoID := range mergeVirtualRepoTasks {
+		mergeVirtualRepo(repoID, "")
+	}
+}
+
 func mergeVirtualRepo(repoID, excludeRepo string) {
 	virtual, err := repomgr.IsVirtualRepo(repoID)
 	if err != nil {