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Diffstat (limited to 'vendor/github.com/nxadm/tail/watch/polling.go')
-rw-r--r--vendor/github.com/nxadm/tail/watch/polling.go118
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
+}