diff options
Diffstat (limited to 'vendor/github.com/rjeczalik/notify/watchpoint.go')
| -rw-r--r-- | vendor/github.com/rjeczalik/notify/watchpoint.go | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/vendor/github.com/rjeczalik/notify/watchpoint.go b/vendor/github.com/rjeczalik/notify/watchpoint.go new file mode 100644 index 000000000..5afc914f4 --- /dev/null +++ b/vendor/github.com/rjeczalik/notify/watchpoint.go @@ -0,0 +1,103 @@ +// 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 + +// EventDiff describes a change to an event set - EventDiff[0] is an old state, +// while EventDiff[1] is a new state. If event set has not changed (old == new), +// functions typically return the None value. +type eventDiff [2]Event + +func (diff eventDiff) Event() Event { + return diff[1] &^ diff[0] +} + +// Watchpoint +// +// The nil key holds total event set - logical sum for all registered events. +// It speeds up computing EventDiff for Add method. +// +// The rec key holds an event set for a watchpoints created by RecursiveWatch +// for a Watcher implementation which is not natively recursive. +type watchpoint map[chan<- EventInfo]Event + +// None is an empty event diff, think null object. +var none eventDiff + +// rec is just a placeholder +var rec = func() (ch chan<- EventInfo) { + ch = make(chan<- EventInfo) + close(ch) + return +}() + +func (wp watchpoint) dryAdd(ch chan<- EventInfo, e Event) eventDiff { + if e &^= internal; wp[ch]&e == e { + return none + } + total := wp[ch] &^ internal + return eventDiff{total, total | e} +} + +// Add assumes neither c nor e are nil or zero values. +func (wp watchpoint) Add(c chan<- EventInfo, e Event) (diff eventDiff) { + wp[c] |= e + diff[0] = wp[nil] + diff[1] = diff[0] | e + wp[nil] = diff[1] &^ omit + // Strip diff from internal events. + diff[0] &^= internal + diff[1] &^= internal + if diff[0] == diff[1] { + return none + } + return +} + +func (wp watchpoint) Del(c chan<- EventInfo, e Event) (diff eventDiff) { + wp[c] &^= e + if wp[c] == 0 { + delete(wp, c) + } + diff[0] = wp[nil] + delete(wp, nil) + if len(wp) != 0 { + // Recalculate total event set. + for _, e := range wp { + diff[1] |= e + } + wp[nil] = diff[1] &^ omit + } + // Strip diff from internal events. + diff[0] &^= internal + diff[1] &^= internal + if diff[0] == diff[1] { + return none + } + return +} + +func (wp watchpoint) Dispatch(ei EventInfo, extra Event) { + e := eventmask(ei, extra) + if !matches(wp[nil], e) { + return + } + for ch, eset := range wp { + if ch != nil && matches(eset, e) { + select { + case ch <- ei: + default: // Drop event if receiver is too slow + dbgprintf("dropped %s on %q: receiver too slow", ei.Event(), ei.Path()) + } + } + } +} + +func (wp watchpoint) Total() Event { + return wp[nil] &^ internal +} + +func (wp watchpoint) IsRecursive() bool { + return wp[nil]&recursive != 0 +} |