1// Copyright 2016 The go-ethereum Authors 2// This file is part of the go-ethereum library. 3// 4// The go-ethereum library is free software: you can redistribute it and/or modify 5// it under the terms of the GNU Lesser General Public License as published by 6// the Free Software Foundation, either version 3 of the License, or 7// (at your option) any later version. 8// 9// The go-ethereum library is distributed in the hope that it will be useful, 10// but WITHOUT ANY WARRANTY; without even the implied warranty of 11// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12// GNU Lesser General Public License for more details. 13// 14// You should have received a copy of the GNU Lesser General Public License 15// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17// Package mclock is a wrapper for a monotonic clock source 18package mclock 19 20import ( 21 "time" 22 23 _ "unsafe" // for go:linkname 24) 25 26//go:noescape 27//go:linkname nanotime runtime.nanotime 28func nanotime() int64 29 30// AbsTime represents absolute monotonic time. 31type AbsTime int64 32 33// Now returns the current absolute monotonic time. 34func Now() AbsTime { 35 return AbsTime(nanotime()) 36} 37 38// Add returns t + d as absolute time. 39func (t AbsTime) Add(d time.Duration) AbsTime { 40 return t + AbsTime(d) 41} 42 43// Sub returns t - t2 as a duration. 44func (t AbsTime) Sub(t2 AbsTime) time.Duration { 45 return time.Duration(t - t2) 46} 47 48// The Clock interface makes it possible to replace the monotonic system clock with 49// a simulated clock. 50type Clock interface { 51 Now() AbsTime 52 Sleep(time.Duration) 53 NewTimer(time.Duration) ChanTimer 54 After(time.Duration) <-chan AbsTime 55 AfterFunc(d time.Duration, f func()) Timer 56} 57 58// Timer is a cancellable event created by AfterFunc. 59type Timer interface { 60 // Stop cancels the timer. It returns false if the timer has already 61 // expired or been stopped. 62 Stop() bool 63} 64 65// ChanTimer is a cancellable event created by NewTimer. 66type ChanTimer interface { 67 Timer 68 69 // The channel returned by C receives a value when the timer expires. 70 C() <-chan AbsTime 71 // Reset reschedules the timer with a new timeout. 72 // It should be invoked only on stopped or expired timers with drained channels. 73 Reset(time.Duration) 74} 75 76// System implements Clock using the system clock. 77type System struct{} 78 79// Now returns the current monotonic time. 80func (c System) Now() AbsTime { 81 return Now() 82} 83 84// Sleep blocks for the given duration. 85func (c System) Sleep(d time.Duration) { 86 time.Sleep(d) 87} 88 89// NewTimer creates a timer which can be rescheduled. 90func (c System) NewTimer(d time.Duration) ChanTimer { 91 ch := make(chan AbsTime, 1) 92 t := time.AfterFunc(d, func() { 93 // This send is non-blocking because that's how time.Timer 94 // behaves. It doesn't matter in the happy case, but does 95 // when Reset is misused. 96 select { 97 case ch <- c.Now(): 98 default: 99 } 100 }) 101 return &systemTimer{t, ch} 102} 103 104// After returns a channel which receives the current time after d has elapsed. 105func (c System) After(d time.Duration) <-chan AbsTime { 106 ch := make(chan AbsTime, 1) 107 time.AfterFunc(d, func() { ch <- c.Now() }) 108 return ch 109} 110 111// AfterFunc runs f on a new goroutine after the duration has elapsed. 112func (c System) AfterFunc(d time.Duration, f func()) Timer { 113 return time.AfterFunc(d, f) 114} 115 116type systemTimer struct { 117 *time.Timer 118 ch <-chan AbsTime 119} 120 121func (st *systemTimer) Reset(d time.Duration) { 122 st.Timer.Reset(d) 123} 124 125func (st *systemTimer) C() <-chan AbsTime { 126 return st.ch 127} 128