// Copyright (c) 2014-2015 The Notify Authors. All rights reserved.
// Use of this source code is governed by the MIT license that can be
// found in the LICENSE file.
package notify
import "sync"
// nonrecursiveTree TODO(rjeczalik)
type nonrecursiveTree struct {
rw sync.RWMutex // protects root
root root
w watcher
c chan EventInfo
rec chan EventInfo
}
// newNonrecursiveTree TODO(rjeczalik)
func newNonrecursiveTree(w watcher, c, rec chan EventInfo) *nonrecursiveTree {
if rec == nil {
rec = make(chan EventInfo, buffer)
}
t := &nonrecursiveTree{
root: root{nd: newnode("")},
w: w,
c: c,
rec: rec,
}
go t.dispatch(c)
go t.internal(rec)
return t
}
// dispatch TODO(rjeczalik)
func (t *nonrecursiveTree) dispatch(c <-chan EventInfo) {
for ei := range c {
dbgprintf("dispatching %v on %q", ei.Event(), ei.Path())
go func(ei EventInfo) {
var nd node
var isrec bool
dir, base := split(ei.Path())
fn := func(it node, isbase bool) error {
isrec = isrec || it.Watch.IsRecursive()
if isbase {
nd = it
} else {
it.Watch.Dispatch(ei, recursive)
}
return nil
}
t.rw.RLock()
// Notify recursive watchpoints found on the path.
if err := t.root.WalkPath(dir, fn); err != nil {
dbgprint("dispatch did not reach leaf:", err)
t.rw.RUnlock()
return
}
// Notify parent watchpoint.
nd.Watch.Dispatch(ei, 0)
isrec = isrec || nd.Watch.IsRecursive()
// If leaf watchpoint exists, notify it.
if nd, ok := nd.Child[base]; ok {
isrec = isrec || nd.Watch.IsRecursive()
nd.Watch.Dispatch(ei, 0)
}
t.rw.RUnlock()
// If the event describes newly leaf directory created within
if !isrec || ei.Event() != Create {
return
}
if ok, err := ei.(isDirer).isDir(); !ok || err != nil {
return
}
t.rec <- ei
}(ei)
}
}
// internal TODO(rjeczalik)
func (t *nonrecursiveTree) internal(rec <-chan EventInfo) {
for ei := range rec {
var nd node
var eset = internal
t.rw.Lock()
t.root.WalkPath(ei.Path(), func(it node, _ bool) error {
if e := it.Watch[t.rec]; e != 0 && e > eset {
eset = e
}
nd = it
return nil
})
if eset == internal {
t.rw.Unlock()
continue
}
err := nd.Add(ei.Path()).AddDir(t.recFunc(eset))
t.rw.Unlock()
if err != nil {
dbgprintf("internal(%p) error: %v", rec, err)
}
}
}
// watchAdd TODO(rjeczalik)
func (t *nonrecursiveTree) watchAdd(nd node, c chan<- EventInfo, e Event) eventDiff {
if e&recursive != 0 {
diff := nd.Watch.Add(t.rec, e|Create|omit)
nd.Watch.Add(c, e)
return diff
}
return nd.Watch.Add(c, e)
}
// watchDelMin TODO(rjeczalik)
func (t *nonrecursiveTree) watchDelMin(min Event, nd node, c chan<- EventInfo, e Event) eventDiff {
old, ok := nd.Watch[t.rec]
if ok {
nd.Watch[t.rec] = min
}
diff := nd.Watch.Del(c, e)
if ok {
switch old &^= diff[0] &^ diff[1]; {
case old|internal == internal:
delete(nd.Watch, t.rec)
if set, ok := nd.Watch[nil]; ok && len(nd.Watch) == 1 && set == 0 {
delete(nd.Watch, nil)
}
default:
nd.Watch.Add(t.rec, old|Create)
switch {
case diff == none:
case diff[1]|Create == diff[0]:
diff = none
default:
diff[1] |= Create
}
}
}
return diff
}
// watchDel TODO(rjeczalik)
func (t *nonrecursiveTree) watchDel(nd node, c chan<- EventInfo, e Event) eventDiff {
return t.watchDelMin(0, nd, c, e)
}
// Watch TODO(rjeczalik)
func (t *nonrecursiveTree) Watch(path string, c chan<- EventInfo, events ...Event) error {
if c == nil {
panic("notify: Watch using nil channel")
}
// Expanding with empty event set is a nop.
if len(events) == 0 {
return nil
}
path, isrec, err := cleanpath(path)
if err != nil {
return err
}
eset := joinevents(events)
t.rw.Lock()
defer t.rw.Unlock()
nd := t.root.Add(path)
if isrec {
return t.watchrec(nd, c, eset|recursive)
}
return t.watch(nd, c, eset)
}
func (t *nonrecursiveTree) watch(nd node, c chan<- EventInfo, e Event) (err error) {
diff := nd.Watch.Add(c, e)
switch {
case diff == none:
return nil
case diff[1] == 0:
// TODO(rjeczalik): cleanup this panic after implementation is stable
panic("eset is empty: " + nd.Name)
case diff[0] == 0:
err = t.w.Watch(nd.Name, diff[1])
default:
err = t.w.Rewatch(nd.Name, diff[0], diff[1])
}
if err != nil {
nd.Watch.Del(c, diff.Event())
return err
}
return nil
}
func (t *nonrecursiveTree) recFunc(e Event) walkFunc {
return func(nd node) error {
switch diff := nd.Watch.Add(t.rec, e|omit|Create); {
case diff == none:
case diff[1] == 0:
// TODO(rjeczalik): cleanup this panic after implementation is stable
panic("eset is empty: " + nd.Name)
case diff[0] == 0:
t.w.Watch(nd.Name, diff[1])
default:
t.w.Rewatch(nd.Name, diff[0], diff[1])
}
return nil
}
}
func (t *nonrecursiveTree) watchrec(nd node, c chan<- EventInfo, e Event) error {
var traverse func(walkFunc) error
// Non-recursive tree listens on Create event for every recursive
// watchpoint in order to automagically set a watch for every
// created directory.
switch diff := nd.Watch.dryAdd(t.rec, e|Create); {
case diff == none:
t.watchAdd(nd, c, e)
nd.Watch.Add(t.rec, e|omit|Create)
return nil
case diff[1] == 0:
// TODO(rjeczalik): cleanup this panic after implementation is stable
panic("eset is empty: " + nd.Name)
case diff[0] == 0:
// TODO(rjeczalik): BFS into directories and skip subtree as soon as first
// recursive watchpoint is encountered.
traverse = nd.AddDir
default:
traverse = nd.Walk
}
// TODO(rjeczalik): account every path that failed to be (re)watched
// and retry.
if err := traverse(t.recFunc(e)); err != nil {
return err
}
t.watchAdd(nd, c, e)
return nil
}
type walkWatchpointFunc func(Event, node) error
func (t *nonrecursiveTree) walkWatchpoint(nd node, fn walkWatchpointFunc) error {
type minode struct {
min Event
nd node
}
mnd := minode{nd: nd}
stack := []minode{mnd}
Traverse:
for n := len(stack); n != 0; n = len(stack) {
mnd, stack = stack[n-1], stack[:n-1]
// There must be no recursive watchpoints if the node has no watchpoints
// itself (every node in subtree rooted at recursive watchpoints must
// have at least nil (total) and t.rec watchpoints).
if len(mnd.nd.Watch) != 0 {
switch err := fn(mnd.min, mnd.nd); err {
case nil:
case errSkip:
continue Traverse
default:
return err
}
}
for _, nd := range mnd.nd.Child {
stack = append(stack, minode{mnd.nd.Watch[t.rec], nd})
}
}
return nil
}
// Stop TODO(rjeczalik)
func (t *nonrecursiveTree) Stop(c chan<- EventInfo) {
fn := func(min Event, nd node) error {
// TODO(rjeczalik): aggregate watcher errors and retry; in worst case
// forward to the user.
switch diff := t.watchDelMin(min, nd, c, all); {
case diff == none:
return nil
case diff[1] == 0:
t.w.Unwatch(nd.Name)
default:
t.w.Rewatch(nd.Name, diff[0], diff[1])
}
return nil
}
t.rw.Lock()
err := t.walkWatchpoint(t.root.nd, fn) // TODO(rjeczalik): store max root per c
t.rw.Unlock()
dbgprintf("Stop(%p) error: %v\n", c, err)
}
// Close TODO(rjeczalik)
func (t *nonrecursiveTree) Close() error {
err := t.w.Close()
close(t.c)
return err
}
