ff5f50c52c
Update to current version of Go library. Update testsuite for removed types. * go-lang.c (go_langhook_init): Omit float_type_size when calling go_create_gogo. * go-c.h: Update declaration of go_create_gogo. From-SVN: r169098
152 lines
3.8 KiB
Go
152 lines
3.8 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package time
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import (
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"os"
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"syscall"
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"sync"
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"container/heap"
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)
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// The event type represents a single After or AfterFunc event.
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type event struct {
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t int64 // The absolute time that the event should fire.
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f func(int64) // The function to call when the event fires.
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sleeping bool // A sleeper is sleeping for this event.
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}
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type eventHeap []*event
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var events eventHeap
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var eventMutex sync.Mutex
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func init() {
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events.Push(&event{1 << 62, nil, true}) // sentinel
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}
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// Sleep pauses the current goroutine for at least ns nanoseconds.
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// Higher resolution sleeping may be provided by syscall.Nanosleep
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// on some operating systems.
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func Sleep(ns int64) os.Error {
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_, err := sleep(Nanoseconds(), ns)
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return err
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}
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// sleep takes the current time and a duration,
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// pauses for at least ns nanoseconds, and
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// returns the current time and an error.
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func sleep(t, ns int64) (int64, os.Error) {
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// TODO(cw): use monotonic-time once it's available
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end := t + ns
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for t < end {
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errno := syscall.Sleep(end - t)
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if errno != 0 && errno != syscall.EINTR {
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return 0, os.NewSyscallError("sleep", errno)
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}
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t = Nanoseconds()
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}
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return t, nil
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}
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// After waits at least ns nanoseconds before sending the current time
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// on the returned channel.
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func After(ns int64) <-chan int64 {
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c := make(chan int64, 1)
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after(ns, func(t int64) { c <- t })
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return c
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}
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// AfterFunc waits at least ns nanoseconds before calling f
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// in its own goroutine.
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func AfterFunc(ns int64, f func()) {
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after(ns, func(_ int64) {
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go f()
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})
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}
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// after is the implementation of After and AfterFunc.
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// When the current time is after ns, it calls f with the current time.
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// It assumes that f will not block.
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func after(ns int64, f func(int64)) {
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t := Nanoseconds() + ns
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eventMutex.Lock()
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t0 := events[0].t
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heap.Push(events, &event{t, f, false})
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if t < t0 {
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go sleeper()
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}
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eventMutex.Unlock()
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}
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// sleeper continually looks at the earliest event in the queue, marks it
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// as sleeping, waits until it happens, then removes any events
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// in the queue that are due. It stops when it finds an event that is
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// already marked as sleeping. When an event is inserted before the first item,
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// a new sleeper is started.
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//
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// Scheduling vagaries mean that sleepers may not wake up in
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// exactly the order of the events that they are waiting for,
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// but this does not matter as long as there are at least as
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// many sleepers as events marked sleeping (invariant). This ensures that
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// there is always a sleeper to service the remaining events.
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//
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// A sleeper will remove at least the event it has been waiting for
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// unless the event has already been removed by another sleeper. Both
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// cases preserve the invariant described above.
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func sleeper() {
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eventMutex.Lock()
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e := events[0]
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for !e.sleeping {
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t := Nanoseconds()
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if dt := e.t - t; dt > 0 {
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e.sleeping = true
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eventMutex.Unlock()
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if nt, err := sleep(t, dt); err != nil {
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// If sleep has encountered an error,
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// there's not much we can do. We pretend
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// that time really has advanced by the required
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// amount and lie to the rest of the system.
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t = e.t
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} else {
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t = nt
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}
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eventMutex.Lock()
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e = events[0]
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}
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for t >= e.t {
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e.f(t)
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heap.Pop(events)
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e = events[0]
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}
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}
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eventMutex.Unlock()
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}
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func (eventHeap) Len() int {
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return len(events)
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}
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func (eventHeap) Less(i, j int) bool {
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return events[i].t < events[j].t
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}
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func (eventHeap) Swap(i, j int) {
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events[i], events[j] = events[j], events[i]
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}
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func (eventHeap) Push(x interface{}) {
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events = append(events, x.(*event))
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}
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func (eventHeap) Pop() interface{} {
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// TODO: possibly shrink array.
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n := len(events) - 1
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e := events[n]
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events[n] = nil
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events = events[0:n]
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return e
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}
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