210 lines
4.3 KiB
Go
210 lines
4.3 KiB
Go
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// Copyright 2020 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package stack
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import (
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"container/heap"
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"sync"
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"time"
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"github.com/dpjacques/clockwork"
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"gvisor.dev/gvisor/pkg/tcpip"
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)
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type fakeClock struct {
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clock clockwork.FakeClock
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// mu protects the fields below.
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mu sync.RWMutex
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// times is min-heap of times. A heap is used for quick retrieval of the next
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// upcoming time of scheduled work.
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times *timeHeap
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// waitGroups stores one WaitGroup for all work scheduled to execute at the
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// same time via AfterFunc. This allows parallel execution of all functions
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// passed to AfterFunc scheduled for the same time.
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waitGroups map[time.Time]*sync.WaitGroup
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}
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func newFakeClock() *fakeClock {
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return &fakeClock{
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clock: clockwork.NewFakeClock(),
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times: &timeHeap{},
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waitGroups: make(map[time.Time]*sync.WaitGroup),
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}
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}
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var _ tcpip.Clock = (*fakeClock)(nil)
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// NowNanoseconds implements tcpip.Clock.NowNanoseconds.
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func (fc *fakeClock) NowNanoseconds() int64 {
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return fc.clock.Now().UnixNano()
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}
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// NowMonotonic implements tcpip.Clock.NowMonotonic.
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func (fc *fakeClock) NowMonotonic() int64 {
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return fc.NowNanoseconds()
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}
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// AfterFunc implements tcpip.Clock.AfterFunc.
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func (fc *fakeClock) AfterFunc(d time.Duration, f func()) tcpip.Timer {
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until := fc.clock.Now().Add(d)
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wg := fc.addWait(until)
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return &fakeTimer{
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clock: fc,
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until: until,
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timer: fc.clock.AfterFunc(d, func() {
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defer wg.Done()
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f()
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}),
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}
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}
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// addWait adds an additional wait to the WaitGroup for parallel execution of
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// all work scheduled for t. Returns a reference to the WaitGroup modified.
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func (fc *fakeClock) addWait(t time.Time) *sync.WaitGroup {
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fc.mu.RLock()
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wg, ok := fc.waitGroups[t]
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fc.mu.RUnlock()
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if ok {
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wg.Add(1)
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return wg
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}
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fc.mu.Lock()
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heap.Push(fc.times, t)
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fc.mu.Unlock()
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wg = &sync.WaitGroup{}
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wg.Add(1)
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fc.mu.Lock()
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fc.waitGroups[t] = wg
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fc.mu.Unlock()
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return wg
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}
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// removeWait removes a wait from the WaitGroup for parallel execution of all
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// work scheduled for t.
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func (fc *fakeClock) removeWait(t time.Time) {
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fc.mu.RLock()
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defer fc.mu.RUnlock()
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wg := fc.waitGroups[t]
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wg.Done()
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}
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// advance executes all work that have been scheduled to execute within d from
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// the current fake time. Blocks until all work has completed execution.
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func (fc *fakeClock) advance(d time.Duration) {
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// Block until all the work is done
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until := fc.clock.Now().Add(d)
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for {
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fc.mu.Lock()
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if fc.times.Len() == 0 {
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fc.mu.Unlock()
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return
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}
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t := heap.Pop(fc.times).(time.Time)
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if t.After(until) {
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// No work to do
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heap.Push(fc.times, t)
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fc.mu.Unlock()
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return
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}
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fc.mu.Unlock()
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diff := t.Sub(fc.clock.Now())
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fc.clock.Advance(diff)
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fc.mu.RLock()
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wg := fc.waitGroups[t]
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fc.mu.RUnlock()
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wg.Wait()
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fc.mu.Lock()
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delete(fc.waitGroups, t)
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fc.mu.Unlock()
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}
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}
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type fakeTimer struct {
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clock *fakeClock
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timer clockwork.Timer
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mu sync.RWMutex
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until time.Time
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}
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var _ tcpip.Timer = (*fakeTimer)(nil)
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// Reset implements tcpip.Timer.Reset.
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func (ft *fakeTimer) Reset(d time.Duration) {
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if !ft.timer.Reset(d) {
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return
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}
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ft.mu.Lock()
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defer ft.mu.Unlock()
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ft.clock.removeWait(ft.until)
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ft.until = ft.clock.clock.Now().Add(d)
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ft.clock.addWait(ft.until)
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}
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// Stop implements tcpip.Timer.Stop.
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func (ft *fakeTimer) Stop() bool {
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if !ft.timer.Stop() {
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return false
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}
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ft.mu.RLock()
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defer ft.mu.RUnlock()
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ft.clock.removeWait(ft.until)
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return true
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}
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type timeHeap []time.Time
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var _ heap.Interface = (*timeHeap)(nil)
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func (h timeHeap) Len() int {
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return len(h)
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}
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func (h timeHeap) Less(i, j int) bool {
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return h[i].Before(h[j])
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}
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func (h timeHeap) Swap(i, j int) {
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h[i], h[j] = h[j], h[i]
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}
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func (h *timeHeap) Push(x interface{}) {
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*h = append(*h, x.(time.Time))
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}
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func (h *timeHeap) Pop() interface{} {
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last := (*h)[len(*h)-1]
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*h = (*h)[:len(*h)-1]
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return last
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}
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