fs: make syncCopyMove use context for go routine cancellation

fs/sync.go

@@ -3,13 +3,13 @@
 package fs
 
 import (
-	"context"
 	"fmt"
 	"sort"
 	"sync"
 	"time"
 
 	"github.com/pkg/errors"
+	"golang.org/x/net/context"
 )
 
 var oldSyncMethod = BoolP("old-sync-method", "", false, "Deprecated - use --fast-list instead")
@@ -22,6 +22,8 @@ type syncCopyMove struct {
 	DoMove     bool
 	dir        string
 	// internal state
+	ctx            context.Context     // internal context for controlling go-routines
+	cancel         func()              // cancel the context
 	noTraverse     bool                // if set don't trafevers the dst
 	deletersWg     sync.WaitGroup      // for delete before go routine
 	deleteFilesCh  chan Object         // channel to receive deletes if delete before
@@ -34,7 +36,6 @@ type syncCopyMove struct {
 	dstFilesResult chan error          // error result of dst listing
 	dstEmptyDirsMu sync.Mutex          // protect dstEmptyDirs
 	dstEmptyDirs   []DirEntry          // potentially empty directories
-	abort          chan struct{}       // signal to abort the copiers
 	checkerWg      sync.WaitGroup      // wait for checkers
 	toBeChecked    ObjectPairChan      // checkers channel
 	transfersWg    sync.WaitGroup      // wait for transfers
@@ -66,7 +67,6 @@ func newSyncCopyMove(fdst, fsrc Fs, deleteMode DeleteMode, DoMove bool) (*syncCo
 		srcFilesResult: make(chan error, 1),
 		dstFilesResult: make(chan error, 1),
 		noTraverse:     Config.NoTraverse,
-		abort:          make(chan struct{}),
 		toBeChecked:    make(ObjectPairChan, Config.Transfers),
 		toBeUploaded:   make(ObjectPairChan, Config.Transfers),
 		deleteFilesCh:  make(chan Object, Config.Checkers),
@@ -75,6 +75,7 @@ func newSyncCopyMove(fdst, fsrc Fs, deleteMode DeleteMode, DoMove bool) (*syncCo
 		toBeRenamed:    make(ObjectPairChan, Config.Transfers),
 		trackRenamesCh: make(chan Object, Config.Checkers),
 	}
+	s.ctx, s.cancel = context.WithCancel(context.Background())
 	if s.noTraverse && s.deleteMode != DeleteModeOff {
 		Errorf(nil, "Ignoring --no-traverse with sync")
 		s.noTraverse = false
@@ -124,10 +125,10 @@ func newSyncCopyMove(fdst, fsrc Fs, deleteMode DeleteMode, DoMove bool) (*syncCo
 	return s, nil
 }
 
-// Check to see if have set the abort flag
+// Check to see if the context has been cancelled
 func (s *syncCopyMove) aborting() bool {
 	select {
-	case <-s.abort:
+	case <-s.ctx.Done():
 		return true
 	default:
 	}
@@ -144,7 +145,7 @@ outer:
 		}
 		select {
 		case out <- o:
-		case <-s.abort:
+		case <-s.ctx.Done():
 			break outer
 		}
 	}
@@ -218,7 +219,7 @@ func (s *syncCopyMove) processError(err error) {
 	switch {
 	case IsFatalError(err):
 		if !s.aborting() {
-			close(s.abort)
+			s.cancel()
 		}
 		s.fatalErr = err
 	case IsNoRetryError(err):
@@ -287,7 +288,7 @@ func (s *syncCopyMove) pairChecker(in ObjectPairChan, out ObjectPairChan, wg *sy
 				}
 			}
 			Stats.DoneChecking(src.Remote())
-		case <-s.abort:
+		case <-s.ctx.Done():
 			return
 		}
 	}
@@ -311,7 +312,7 @@ func (s *syncCopyMove) pairRenamer(in ObjectPairChan, out ObjectPairChan, wg *sy
 				// pass on if not renamed
 				out <- pair
 			}
-		case <-s.abort:
+		case <-s.ctx.Done():
 			return
 		}
 	}
@@ -339,7 +340,7 @@ func (s *syncCopyMove) pairCopyOrMove(in ObjectPairChan, fdst Fs, wg *sync.WaitG
 			}
 			s.processError(err)
 			Stats.DoneTransferring(src.Remote(), err == nil)
-		case <-s.abort:
+		case <-s.ctx.Done():
 			return
 		}
 	}
@@ -650,8 +651,8 @@ func (s *syncCopyMove) run() error {
 
 	s.startTrackRenames()
 
-	ctx := context.Background()
+	// set up a march over fdst and fsrc
-	m := newMarch(ctx, s.fdst, s.fsrc, s.dir, s)
+	m := newMarch(s.ctx, s.fdst, s.fsrc, s.dir, s)
 	m.run()
 
 	s.stopTrackRenames()