1 files changed, 118 insertions, 0 deletions
diff --git a/vendor/github.com/nxadm/tail/watch/polling.go b/vendor/github.com/nxadm/tail/watch/polling.go
new file mode 100644
index 000000000..fb1706908
--- /dev/null
+++ b/vendor/github.com/nxadm/tail/watch/polling.go
@@ -0,0 +1,118 @@
+// Copyright (c) 2015 HPE Software Inc. All rights reserved.
+// Copyright (c) 2013 ActiveState Software Inc. All rights reserved.
+
+package watch
+
+import (
+	"os"
+	"runtime"
+	"time"
+
+	"github.com/nxadm/tail/util"
+	"gopkg.in/tomb.v1"
+)
+
+// PollingFileWatcher polls the file for changes.
+type PollingFileWatcher struct {
+	Filename string
+	Size     int64
+}
+
+func NewPollingFileWatcher(filename string) *PollingFileWatcher {
+	fw := &PollingFileWatcher{filename, 0}
+	return fw
+}
+
+var POLL_DURATION time.Duration
+
+func (fw *PollingFileWatcher) BlockUntilExists(t *tomb.Tomb) error {
+	for {
+		if _, err := os.Stat(fw.Filename); err == nil {
+			return nil
+		} else if !os.IsNotExist(err) {
+			return err
+		}
+		select {
+		case <-time.After(POLL_DURATION):
+			continue
+		case <-t.Dying():
+			return tomb.ErrDying
+		}
+	}
+	panic("unreachable")
+}
+
+func (fw *PollingFileWatcher) ChangeEvents(t *tomb.Tomb, pos int64) (*FileChanges, error) {
+	origFi, err := os.Stat(fw.Filename)
+	if err != nil {
+		return nil, err
+	}
+
+	changes := NewFileChanges()
+	var prevModTime time.Time
+
+	// XXX: use tomb.Tomb to cleanly manage these goroutines. replace
+	// the fatal (below) with tomb's Kill.
+
+	fw.Size = pos
+
+	go func() {
+		prevSize := fw.Size
+		for {
+			select {
+			case <-t.Dying():
+				return
+			default:
+			}
+
+			time.Sleep(POLL_DURATION)
+			fi, err := os.Stat(fw.Filename)
+			if err != nil {
+				// Windows cannot delete a file if a handle is still open (tail keeps one open)
+				// so it gives access denied to anything trying to read it until all handles are released.
+				if os.IsNotExist(err) || (runtime.GOOS == "windows" && os.IsPermission(err)) {
+					// File does not exist (has been deleted).
+					changes.NotifyDeleted()
+					return
+				}
+
+				// XXX: report this error back to the user
+				util.Fatal("Failed to stat file %v: %v", fw.Filename, err)
+			}
+
+			// File got moved/renamed?
+			if !os.SameFile(origFi, fi) {
+				changes.NotifyDeleted()
+				return
+			}
+
+			// File got truncated?
+			fw.Size = fi.Size()
+			if prevSize > 0 && prevSize > fw.Size {
+				changes.NotifyTruncated()
+				prevSize = fw.Size
+				continue
+			}
+			// File got bigger?
+			if prevSize > 0 && prevSize < fw.Size {
+				changes.NotifyModified()
+				prevSize = fw.Size
+				continue
+			}
+			prevSize = fw.Size
+
+			// File was appended to (changed)?
+			modTime := fi.ModTime()
+			if modTime != prevModTime {
+				prevModTime = modTime
+				changes.NotifyModified()
+			}
+		}
+	}()
+
+	return changes, nil
+}
+
+func init() {
+	POLL_DURATION = 250 * time.Millisecond
+}