ParallelProcessDirectoryStructure

need to use this for simpler parallel processing

weed/filer/meta_replay.go

@@ -2,6 +2,7 @@ package filer
 
 import (
 	"context"
+	"sync"
 
 	"github.com/seaweedfs/seaweedfs/weed/glog"
 	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
@@ -35,3 +36,40 @@ func Replay(filerStore FilerStore, resp *filer_pb.SubscribeMetadataResponse) err
 
 	return nil
 }
+
+
+// ParallelProcessDirectoryStructure processes each entry in parallel, and also ensure parent directories are processed first.
+// This also assumes the parent directories are in the entryChan already.
+func ParallelProcessDirectoryStructure(entryChan chan *Entry, concurrency int, eachEntryFn func(entry *Entry)(error)) (firstErr error) {
+
+	executors := util.NewLimitedConcurrentExecutor(concurrency)
+
+	var wg sync.WaitGroup
+	for entry := range entryChan {
+		wg.Add(1)
+		if entry.IsDirectory() {
+			func() {
+				defer wg.Done()
+				if err := eachEntryFn(entry); err != nil {
+					if firstErr == nil {
+						firstErr = err
+					}
+				}
+			}()
+		} else {
+			executors.Execute(func() {
+				defer wg.Done()
+				if err := eachEntryFn(entry); err != nil {
+					if firstErr == nil {
+						firstErr = err
+					}
+				}
+			})
+		}
+		if firstErr != nil {
+			break
+		}
+	}
+	wg.Wait()
+	return
+}