Commit 0c73722a authored by Jeromy's avatar Jeromy
Browse files

vendor in notifier

parent d4b42f8e
# goprocess/periodic - periodic process creation
- goprocess: https://github.com/jbenet/goprocess
- Godoc: https://godoc.org/github.com/jbenet/goprocess/periodic
package periodicproc_test
import (
"fmt"
"time"
goprocess "QmSir6qPL1tjuxd8LkR8VZq6v625ExAUVs2eCLeqQuaPGU/goprocess"
periodicproc "QmSir6qPL1tjuxd8LkR8VZq6v625ExAUVs2eCLeqQuaPGU/goprocess/periodic"
)
func ExampleEvery() {
tock := make(chan struct{})
i := 0
p := periodicproc.Every(time.Second, func(proc goprocess.Process) {
tock <- struct{}{}
fmt.Printf("hello %d\n", i)
i++
})
<-tock
<-tock
<-tock
p.Close()
// Output:
// hello 0
// hello 1
// hello 2
}
func ExampleTick() {
p := periodicproc.Tick(time.Second, func(proc goprocess.Process) {
fmt.Println("tick")
})
<-time.After(3*time.Second + 500*time.Millisecond)
p.Close()
// Output:
// tick
// tick
// tick
}
func ExampleTickGo() {
// with TickGo, execution is not rate limited,
// there can be many in-flight simultaneously
wait := make(chan struct{})
p := periodicproc.TickGo(time.Second, func(proc goprocess.Process) {
fmt.Println("tick")
<-wait
})
<-time.After(3*time.Second + 500*time.Millisecond)
wait <- struct{}{}
wait <- struct{}{}
wait <- struct{}{}
p.Close() // blocks us until all children are closed.
// Output:
// tick
// tick
// tick
}
func ExampleOnSignal() {
sig := make(chan struct{})
p := periodicproc.OnSignal(sig, func(proc goprocess.Process) {
fmt.Println("fire!")
})
sig <- struct{}{}
sig <- struct{}{}
sig <- struct{}{}
p.Close()
// Output:
// fire!
// fire!
// fire!
}
// Package periodic is part of github.com/jbenet/goprocess.
// It provides a simple periodic processor that calls a function
// periodically based on some options.
//
// For example:
//
// // use a time.Duration
// p := periodicproc.Every(time.Second, func(proc goprocess.Process) {
// fmt.Printf("the time is %s and all is well", time.Now())
// })
//
// <-time.After(5*time.Second)
// p.Close()
//
// // use a time.Time channel (like time.Ticker)
// p := periodicproc.Tick(time.Tick(time.Second), func(proc goprocess.Process) {
// fmt.Printf("the time is %s and all is well", time.Now())
// })
//
// <-time.After(5*time.Second)
// p.Close()
//
// // or arbitrary signals
// signal := make(chan struct{})
// p := periodicproc.OnSignal(signal, func(proc goprocess.Process) {
// fmt.Printf("the time is %s and all is well", time.Now())
// })
//
// signal<- struct{}{}
// signal<- struct{}{}
// <-time.After(5 * time.Second)
// signal<- struct{}{}
// p.Close()
//
package periodicproc
import (
"time"
gp "QmSir6qPL1tjuxd8LkR8VZq6v625ExAUVs2eCLeqQuaPGU/goprocess"
)
// Every calls the given ProcessFunc at periodic intervals. Internally, it uses
// <-time.After(interval), so it will have the behavior of waiting _at least_
// interval in between calls. If you'd prefer the time.Ticker behavior, use
// periodicproc.Tick instead.
// This is sequentially rate limited, only one call will be in-flight at a time.
func Every(interval time.Duration, procfunc gp.ProcessFunc) gp.Process {
return gp.Go(func(proc gp.Process) {
for {
select {
case <-time.After(interval):
select {
case <-proc.Go(procfunc).Closed(): // spin it out as a child, and wait till it's done.
case <-proc.Closing(): // we're told to close
return
}
case <-proc.Closing(): // we're told to close
return
}
}
})
}
// EveryGo calls the given ProcessFunc at periodic intervals. Internally, it uses
// <-time.After(interval)
// This is not rate limited, multiple calls could be in-flight at the same time.
func EveryGo(interval time.Duration, procfunc gp.ProcessFunc) gp.Process {
return gp.Go(func(proc gp.Process) {
for {
select {
case <-time.After(interval):
proc.Go(procfunc)
case <-proc.Closing(): // we're told to close
return
}
}
})
}
// Tick constructs a ticker with interval, and calls the given ProcessFunc every
// time the ticker fires.
// This is sequentially rate limited, only one call will be in-flight at a time.
//
// p := periodicproc.Tick(time.Second, func(proc goprocess.Process) {
// fmt.Println("fire!")
// })
//
// <-time.After(3 * time.Second)
// p.Close()
//
// // Output:
// // fire!
// // fire!
// // fire!
func Tick(interval time.Duration, procfunc gp.ProcessFunc) gp.Process {
return gp.Go(func(proc gp.Process) {
ticker := time.NewTicker(interval)
callOnTicker(ticker.C, procfunc)(proc)
ticker.Stop()
})
}
// TickGo constructs a ticker with interval, and calls the given ProcessFunc every
// time the ticker fires.
// This is not rate limited, multiple calls could be in-flight at the same time.
//
// p := periodicproc.TickGo(time.Second, func(proc goprocess.Process) {
// fmt.Println("fire!")
// <-time.After(10 * time.Second) // will not block sequential execution
// })
//
// <-time.After(3 * time.Second)
// p.Close()
//
// // Output:
// // fire!
// // fire!
// // fire!
func TickGo(interval time.Duration, procfunc gp.ProcessFunc) gp.Process {
return gp.Go(func(proc gp.Process) {
ticker := time.NewTicker(interval)
goCallOnTicker(ticker.C, procfunc)(proc)
ticker.Stop()
})
}
// Ticker calls the given ProcessFunc every time the ticker fires.
// This is sequentially rate limited, only one call will be in-flight at a time.
func Ticker(ticker <-chan time.Time, procfunc gp.ProcessFunc) gp.Process {
return gp.Go(callOnTicker(ticker, procfunc))
}
// TickerGo calls the given ProcessFunc every time the ticker fires.
// This is not rate limited, multiple calls could be in-flight at the same time.
func TickerGo(ticker <-chan time.Time, procfunc gp.ProcessFunc) gp.Process {
return gp.Go(goCallOnTicker(ticker, procfunc))
}
func callOnTicker(ticker <-chan time.Time, pf gp.ProcessFunc) gp.ProcessFunc {
return func(proc gp.Process) {
for {
select {
case <-ticker:
select {
case <-proc.Go(pf).Closed(): // spin it out as a child, and wait till it's done.
case <-proc.Closing(): // we're told to close
return
}
case <-proc.Closing(): // we're told to close
return
}
}
}
}
func goCallOnTicker(ticker <-chan time.Time, pf gp.ProcessFunc) gp.ProcessFunc {
return func(proc gp.Process) {
for {
select {
case <-ticker:
proc.Go(pf)
case <-proc.Closing(): // we're told to close
return
}
}
}
}
// OnSignal calls the given ProcessFunc every time the signal fires, and waits for it to exit.
// This is sequentially rate limited, only one call will be in-flight at a time.
//
// sig := make(chan struct{})
// p := periodicproc.OnSignal(sig, func(proc goprocess.Process) {
// fmt.Println("fire!")
// <-time.After(time.Second) // delays sequential execution by 1 second
// })
//
// sig<- struct{}
// sig<- struct{}
// sig<- struct{}
//
// // Output:
// // fire!
// // fire!
// // fire!
func OnSignal(sig <-chan struct{}, procfunc gp.ProcessFunc) gp.Process {
return gp.Go(func(proc gp.Process) {
for {
select {
case <-sig:
select {
case <-proc.Go(procfunc).Closed(): // spin it out as a child, and wait till it's done.
case <-proc.Closing(): // we're told to close
return
}
case <-proc.Closing(): // we're told to close
return
}
}
})
}
// OnSignalGo calls the given ProcessFunc every time the signal fires.
// This is not rate limited, multiple calls could be in-flight at the same time.
//
// sig := make(chan struct{})
// p := periodicproc.OnSignalGo(sig, func(proc goprocess.Process) {
// fmt.Println("fire!")
// <-time.After(time.Second) // wont block execution
// })
//
// sig<- struct{}
// sig<- struct{}
// sig<- struct{}
//
// // Output:
// // fire!
// // fire!
// // fire!
func OnSignalGo(sig <-chan struct{}, procfunc gp.ProcessFunc) gp.Process {
return gp.Go(func(proc gp.Process) {
for {
select {
case <-sig:
proc.Go(procfunc)
case <-proc.Closing(): // we're told to close
return
}
}
})
}
package periodicproc
import (
"testing"
"time"
gp "QmSir6qPL1tjuxd8LkR8VZq6v625ExAUVs2eCLeqQuaPGU/goprocess"
ci "github.com/jbenet/go-cienv"
)
var (
grace = time.Millisecond * 5
interval = time.Millisecond * 10
timeout = time.Second * 5
)
func init() {
if ci.IsRunning() {
grace = time.Millisecond * 500
interval = time.Millisecond * 1000
timeout = time.Second * 15
}
}
func between(min, diff, max time.Duration) bool {
return min <= diff && diff <= max
}
func testBetween(t *testing.T, min, diff, max time.Duration) {
if !between(min, diff, max) {
t.Error("time diff incorrect:", min, diff, max)
}
}
type intervalFunc func(times chan<- time.Time, wait <-chan struct{}) (proc gp.Process)
func testSeq(t *testing.T, toTest intervalFunc) {
t.Parallel()
last := time.Now()
times := make(chan time.Time, 10)
p := toTest(times, nil)
for i := 0; i < 5; i++ {
next := <-times
testBetween(t, interval-grace, next.Sub(last), interval+grace)
last = next
}
go p.Close()
select {
case <-p.Closed():
case <-time.After(timeout):
t.Error("proc failed to close")
}
}
func testSeqWait(t *testing.T, toTest intervalFunc) {
t.Parallel()
last := time.Now()
times := make(chan time.Time, 10)
wait := make(chan struct{})
p := toTest(times, wait)
for i := 0; i < 5; i++ {
next := <-times
testBetween(t, interval-grace, next.Sub(last), interval+grace)
<-time.After(interval * 2) // make it wait.
last = time.Now() // make it now (sequential)
wait <- struct{}{} // release it.
}
go p.Close()
select {
case <-p.Closed():
case <-time.After(timeout):
t.Error("proc failed to close")
}
}
func testSeqNoWait(t *testing.T, toTest intervalFunc) {
t.Parallel()
last := time.Now()
times := make(chan time.Time, 10)
wait := make(chan struct{})
p := toTest(times, wait)
for i := 0; i < 5; i++ {
next := <-times
testBetween(t, 0, next.Sub(last), interval+grace) // min of 0
<-time.After(interval * 2) // make it wait.
last = time.Now() // make it now (sequential)
wait <- struct{}{} // release it.
}
go p.Close()
end:
select {
case wait <- struct{}{}: // drain any extras.
goto end
case <-p.Closed():
case <-time.After(timeout):
t.Error("proc failed to close")
}
}
func testParallel(t *testing.T, toTest intervalFunc) {
t.Parallel()
last := time.Now()
times := make(chan time.Time, 10)
wait := make(chan struct{})
p := toTest(times, wait)
for i := 0; i < 5; i++ {
next := <-times
testBetween(t, interval-grace, next.Sub(last), interval+grace)
last = next
<-time.After(interval * 2) // make it wait.
wait <- struct{}{} // release it.
}
go p.Close()
end:
select {
case wait <- struct{}{}: // drain any extras.
goto end
case <-p.Closed():
case <-time.After(timeout):
t.Error("proc failed to close")
}
}
func TestEverySeq(t *testing.T) {
testSeq(t, func(times chan<- time.Time, wait <-chan struct{}) (proc gp.Process) {
return Every(interval, func(proc gp.Process) {
times <- time.Now()
})
})
}
func TestEverySeqWait(t *testing.T) {
testSeqWait(t, func(times chan<- time.Time, wait <-chan struct{}) (proc gp.Process) {
return Every(interval, func(proc gp.Process) {
times <- time.Now()
select {
case <-wait:
case <-proc.Closing():
}
})
})
}
func TestEveryGoSeq(t *testing.T) {
testSeq(t, func(times chan<- time.Time, wait <-chan struct{}) (proc gp.Process) {
return EveryGo(interval, func(proc gp.Process) {
times <- time.Now()
})
})
}
func TestEveryGoSeqParallel(t *testing.T) {
testParallel(t, func(times chan<- time.Time, wait <-chan struct{}) (proc gp.Process) {
return EveryGo(interval, func(proc gp.Process) {
times <- time.Now()
select {
case <-wait:
case <-proc.Closing():
}
})
})
}
func TestTickSeq(t *testing.T) {
testSeq(t, func(times chan<- time.Time, wait <-chan struct{}) (proc gp.Process) {
return Tick(interval, func(proc gp.Process) {
times <- time.Now()
})
})
}
func TestTickSeqNoWait(t *testing.T) {
testSeqNoWait(t, func(times chan<- time.Time, wait <-chan struct{}) (proc gp.Process) {
return Tick(interval, func(proc gp.Process) {
times <- time.Now()
select {
case <-wait:
case <-proc.Closing():
}
})
})
}
func TestTickGoSeq(t *testing.T) {
testSeq(t, func(times chan<- time.Time, wait <-chan struct{}) (proc gp.Process) {
return TickGo(interval, func(proc gp.Process) {
times <- time.Now()
})
})
}
func TestTickGoSeqParallel(t *testing.T) {
testParallel(t, func(times chan<- time.Time, wait <-chan struct{}) (proc gp.Process) {
return TickGo(interval, func(proc gp.Process) {
times <- time.Now()
select {
case <-wait:
case <-proc.Closing():
}
})
})
}
func TestTickerSeq(t *testing.T) {
testSeq(t, func(times chan<- time.Time, wait <-chan struct{}) (proc gp.Process) {
return Ticker(time.Tick(interval), func(proc gp.Process) {
times <- time.Now()
})
})
}
func TestTickerSeqNoWait(t *testing.T) {
testSeqNoWait(t, func(times chan<- time.Time, wait <-chan struct{}) (proc gp.Process) {
return Ticker(time.Tick(interval), func(proc gp.Process) {
times <- time.Now()
select {
case <-wait:
case <-proc.Closing():
}
})
})
}
func TestTickerGoSeq(t *testing.T) {
testSeq(t, func(times chan<- time.Time, wait <-chan struct{}) (proc gp.Process) {
return TickerGo(time.Tick(interval), func(proc gp.Process) {
times <- time.Now()
})
})
}
func TestTickerGoParallel(t *testing.T) {
testParallel(t, func(times chan<- time.Time, wait <-chan struct{}) (proc gp.Process) {
return TickerGo(time.Tick(interval), func(proc gp.Process) {
times <- time.Now()
select {
case <-wait:
case <-proc.Closing():
}
})
})
}
# goprocess/ratelimit - ratelimit children creation
- goprocess: https://github.com/jbenet/goprocess
- Godoc: https://godoc.org/github.com/jbenet/goprocess/ratelimit
// Package ratelimit is part of github.com/jbenet/goprocess.
// It provides a simple process that ratelimits child creation.
// This is done internally with a channel/semaphore.
// So the call `RateLimiter.LimitedGo` may block until another
// child is Closed().
package ratelimit
import (
process "QmSir6qPL1tjuxd8LkR8VZq6v625ExAUVs2eCLeqQuaPGU/goprocess"
)
// RateLimiter limits the spawning of children. It does so
// with an internal semaphore. Note that Go will continue
// to be the unlimited process.Process.Go, and ONLY the
// added function `RateLimiter.LimitedGo` will honor the
// limit. This is to improve readability and avoid confusion
// for the reader, particularly if code changes over time.
type RateLimiter struct {
process.Process
limiter chan struct{}
}
func NewRateLimiter(parent process.Process, limit int) *RateLimiter {
proc := process.WithParent(parent)
return &RateLimiter{Process: proc, limiter: LimitChan(limit)}
}
// LimitedGo creates a new process, adds it as a child, and spawns the
// ProcessFunc f in its own goroutine, but may block according to the
// internal rate limit. It is equivalent to:
//
// func(f process.ProcessFunc) {
// <-limitch
// p.Go(func (child process.Process) {
// f(child)
// f.Close() // make sure its children close too!
// limitch<- struct{}{}
// })
/// }
//
// It is useful to construct simple asynchronous workers, children of p,
// and rate limit their creation, to avoid spinning up too many, too fast.
// This is great for providing backpressure to producers.
func (rl *RateLimiter) LimitedGo(f process.ProcessFunc) {
<-rl.limiter
p := rl.Go(f)
// this <-closed() is here because the child may have spawned
// children of its own, and our rate limiter should capture that.
go func() {
<-p.Closed()
rl.limiter <- struct{}{}
}()
}
// LimitChan returns a rate-limiting channel. it is the usual, simple,
// golang-idiomatic rate-limiting semaphore. This function merely
// initializes it with certain buffer size, and sends that many values,
// so it is ready to be used.
func LimitChan(limit int) chan struct{} {
limitch := make(chan struct{}, limit)
for i := 0; i < limit; i++ {
limitch <- struct{}{}
}
return limitch
}
package ratelimit
import (
"testing"
"time"
process "QmSir6qPL1tjuxd8LkR8VZq6v625ExAUVs2eCLeqQuaPGU/goprocess"
)
func TestRateLimitLimitedGoBlocks(t *testing.T) {
numChildren := 6
t.Logf("create a rate limiter with limit of %d", numChildren/2)
rl := NewRateLimiter(process.Background(), numChildren/2)
doneSpawning := make(chan struct{})
childClosing := make(chan struct{})
t.Log("spawn 6 children with LimitedGo.")
go func() {
for i := 0; i < numChildren; i++ {
rl.LimitedGo(func(child process.Process) {
// hang until we drain childClosing
childClosing <- struct{}{}
})
t.Logf("spawned %d", i)
}
close(doneSpawning)
}()
t.Log("should have blocked.")
select {
case <-doneSpawning:
t.Error("did not block")
case <-time.After(time.Millisecond): // for scheduler
t.Log("blocked")
}
t.Logf("drain %d children so they close", numChildren/2)
for i := 0; i < numChildren/2; i++ {
t.Logf("closing %d", i)
<-childClosing // consume child cloing
t.Logf("closed %d", i)
}
t.Log("should be done spawning.")
select {
case <-doneSpawning:
case <-time.After(100 * time.Millisecond): // for scheduler
t.Error("still blocked...")
}
t.Logf("drain %d children so they close", numChildren/2)
for i := 0; i < numChildren/2; i++ {
<-childClosing
t.Logf("closed %d", i)
}
rl.Close() // ensure everyone's closed.
}
func TestRateLimitGoDoesntBlock(t *testing.T) {
numChildren := 6
t.Logf("create a rate limiter with limit of %d", numChildren/2)
rl := NewRateLimiter(process.Background(), numChildren/2)
doneSpawning := make(chan struct{})
childClosing := make(chan struct{})
t.Log("spawn 6 children with usual Process.Go.")
go func() {
for i := 0; i < numChildren; i++ {
rl.Go(func(child process.Process) {
// hang until we drain childClosing
childClosing <- struct{}{}
})
t.Logf("spawned %d", i)
}
close(doneSpawning)
}()
t.Log("should not have blocked.")
select {
case <-doneSpawning:
t.Log("did not block")
case <-time.After(100 * time.Millisecond): // for scheduler
t.Error("process.Go blocked. it should not.")
}
t.Log("drain children so they close")
for i := 0; i < numChildren; i++ {
<-childClosing
t.Logf("closed %d", i)
}
rl.Close() // ensure everyone's closed.
}
...@@ -6,8 +6,8 @@ package notifier ...@@ -6,8 +6,8 @@ package notifier
import ( import (
"sync" "sync"
process "github.com/jbenet/goprocess" process "QmSir6qPL1tjuxd8LkR8VZq6v625ExAUVs2eCLeqQuaPGU/goprocess"
ratelimit "github.com/jbenet/goprocess/ratelimit" ratelimit "QmSir6qPL1tjuxd8LkR8VZq6v625ExAUVs2eCLeqQuaPGU/goprocess/ratelimit"
) )
// Notifiee is a generic interface. Clients implement // Notifiee is a generic interface. Clients implement
......
{
"name": "go-notifier",
"author": "whyrusleeping",
"version": "1.0.0",
"gxDependencies": [
{
"name": "goprocess",
"hash": "QmSir6qPL1tjuxd8LkR8VZq6v625ExAUVs2eCLeqQuaPGU",
"version": "1.0.0"
}
],
"language": "go",
"gx": {
"dvcsimport": "github.com/whyrusleeping/go-notifier"
}
}
\ No newline at end of file
...@@ -3,7 +3,7 @@ package log ...@@ -3,7 +3,7 @@ package log
import ( import (
"errors" "errors"
"golang.org/x/net/context" "QmacZi9WygGK7Me8mH53pypyscHzU386aUZXpr28GZgUct/context"
) )
type key int type key int
......
...@@ -3,7 +3,7 @@ package log ...@@ -3,7 +3,7 @@ package log
import ( import (
"testing" "testing"
"golang.org/x/net/context" "QmacZi9WygGK7Me8mH53pypyscHzU386aUZXpr28GZgUct/context"
) )
func TestContextContainsMetadata(t *testing.T) { func TestContextContainsMetadata(t *testing.T) {
......
package log package log
import "golang.org/x/net/context" import "QmacZi9WygGK7Me8mH53pypyscHzU386aUZXpr28GZgUct/context"
func ExampleEventLogger() { func ExampleEventLogger() {
{ {
......
...@@ -5,7 +5,7 @@ import ( ...@@ -5,7 +5,7 @@ import (
"fmt" "fmt"
"time" "time"
context "golang.org/x/net/context" context "QmacZi9WygGK7Me8mH53pypyscHzU386aUZXpr28GZgUct/context"
) )
// StandardLogger provides API compatibility with standard printf loggers // StandardLogger provides API compatibility with standard printf loggers
......
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package context defines the Context type, which carries deadlines,
// cancelation signals, and other request-scoped values across API boundaries
// and between processes.
//
// Incoming requests to a server should create a Context, and outgoing calls to
// servers should accept a Context. The chain of function calls between must
// propagate the Context, optionally replacing it with a modified copy created
// using WithDeadline, WithTimeout, WithCancel, or WithValue.
//
// Programs that use Contexts should follow these rules to keep interfaces
// consistent across packages and enable static analysis tools to check context
// propagation:
//
// Do not store Contexts inside a struct type; instead, pass a Context
// explicitly to each function that needs it. The Context should be the first
// parameter, typically named ctx:
//
// func DoSomething(ctx context.Context, arg Arg) error {
// // ... use ctx ...
// }
//
// Do not pass a nil Context, even if a function permits it. Pass context.TODO
// if you are unsure about which Context to use.
//
// Use context Values only for request-scoped data that transits processes and
// APIs, not for passing optional parameters to functions.
//
// The same Context may be passed to functions running in different goroutines;
// Contexts are safe for simultaneous use by multiple goroutines.
//
// See http://blog.golang.org/context for example code for a server that uses
// Contexts.
package context
import (
"errors"
"fmt"
"sync"
"time"
)
// A Context carries a deadline, a cancelation signal, and other values across
// API boundaries.
//
// Context's methods may be called by multiple goroutines simultaneously.
type Context interface {
// Deadline returns the time when work done on behalf of this context
// should be canceled. Deadline returns ok==false when no deadline is
// set. Successive calls to Deadline return the same results.
Deadline() (deadline time.Time, ok bool)
// Done returns a channel that's closed when work done on behalf of this
// context should be canceled. Done may return nil if this context can
// never be canceled. Successive calls to Done return the same value.
//
// WithCancel arranges for Done to be closed when cancel is called;
// WithDeadline arranges for Done to be closed when the deadline
// expires; WithTimeout arranges for Done to be closed when the timeout
// elapses.
//
// Done is provided for use in select statements:
//
// // Stream generates values with DoSomething and sends them to out
// // until DoSomething returns an error or ctx.Done is closed.
// func Stream(ctx context.Context, out <-chan Value) error {
// for {
// v, err := DoSomething(ctx)
// if err != nil {
// return err
// }
// select {
// case <-ctx.Done():
// return ctx.Err()
// case out <- v:
// }
// }
// }
//
// See http://blog.golang.org/pipelines for more examples of how to use
// a Done channel for cancelation.
Done() <-chan struct{}
// Err returns a non-nil error value after Done is closed. Err returns
// Canceled if the context was canceled or DeadlineExceeded if the
// context's deadline passed. No other values for Err are defined.
// After Done is closed, successive calls to Err return the same value.
Err() error
// Value returns the value associated with this context for key, or nil
// if no value is associated with key. Successive calls to Value with
// the same key returns the same result.
//
// Use context values only for request-scoped data that transits
// processes and API boundaries, not for passing optional parameters to
// functions.
//
// A key identifies a specific value in a Context. Functions that wish
// to store values in Context typically allocate a key in a global
// variable then use that key as the argument to context.WithValue and
// Context.Value. A key can be any type that supports equality;
// packages should define keys as an unexported type to avoid
// collisions.
//
// Packages that define a Context key should provide type-safe accessors
// for the values stores using that key:
//
// // Package user defines a User type that's stored in Contexts.
// package user
//
// import "golang.org/x/net/context"
//
// // User is the type of value stored in the Contexts.
// type User struct {...}
//
// // key is an unexported type for keys defined in this package.
// // This prevents collisions with keys defined in other packages.
// type key int
//
// // userKey is the key for user.User values in Contexts. It is
// // unexported; clients use user.NewContext and user.FromContext
// // instead of using this key directly.
// var userKey key = 0
//
// // NewContext returns a new Context that carries value u.
// func NewContext(ctx context.Context, u *User) context.Context {
// return context.WithValue(ctx, userKey, u)
// }
//
// // FromContext returns the User value stored in ctx, if any.
// func FromContext(ctx context.Context) (*User, bool) {
// u, ok := ctx.Value(userKey).(*User)
// return u, ok
// }
Value(key interface{}) interface{}
}
// Canceled is the error returned by Context.Err when the context is canceled.
var Canceled = errors.New("context canceled")
// DeadlineExceeded is the error returned by Context.Err when the context's
// deadline passes.
var DeadlineExceeded = errors.New("context deadline exceeded")
// An emptyCtx is never canceled, has no values, and has no deadline. It is not
// struct{}, since vars of this type must have distinct addresses.
type emptyCtx int
func (*emptyCtx) Deadline() (deadline time.Time, ok bool) {
return
}
func (*emptyCtx) Done() <-chan struct{} {
return nil
}
func (*emptyCtx) Err() error {
return nil
}
func (*emptyCtx) Value(key interface{}) interface{} {
return nil
}
func (e *emptyCtx) String() string {
switch e {
case background:
return "context.Background"
case todo:
return "context.TODO"
}
return "unknown empty Context"
}
var (
background = new(emptyCtx)
todo = new(emptyCtx)
)
// Background returns a non-nil, empty Context. It is never canceled, has no
// values, and has no deadline. It is typically used by the main function,
// initialization, and tests, and as the top-level Context for incoming
// requests.
func Background() Context {
return background
}
// TODO returns a non-nil, empty Context. Code should use context.TODO when
// it's unclear which Context to use or it is not yet available (because the
// surrounding function has not yet been extended to accept a Context
// parameter). TODO is recognized by static analysis tools that determine
// whether Contexts are propagated correctly in a program.
func TODO() Context {
return todo
}
// A CancelFunc tells an operation to abandon its work.
// A CancelFunc does not wait for the work to stop.
// After the first call, subsequent calls to a CancelFunc do nothing.
type CancelFunc func()
// WithCancel returns a copy of parent with a new Done channel. The returned
// context's Done channel is closed when the returned cancel function is called
// or when the parent context's Done channel is closed, whichever happens first.
//
// Canceling this context releases resources associated with it, so code should
// call cancel as soon as the operations running in this Context complete.
func WithCancel(parent Context) (ctx Context, cancel CancelFunc) {
c := newCancelCtx(parent)
propagateCancel(parent, &c)
return &c, func() { c.cancel(true, Canceled) }
}
// newCancelCtx returns an initialized cancelCtx.
func newCancelCtx(parent Context) cancelCtx {
return cancelCtx{
Context: parent,
done: make(chan struct{}),
}
}
// propagateCancel arranges for child to be canceled when parent is.
func propagateCancel(parent Context, child canceler) {
if parent.Done() == nil {
return // parent is never canceled
}
if p, ok := parentCancelCtx(parent); ok {
p.mu.Lock()
if p.err != nil {
// parent has already been canceled
child.cancel(false, p.err)
} else {
if p.children == nil {
p.children = make(map[canceler]bool)
}
p.children[child] = true
}
p.mu.Unlock()
} else {
go func() {
select {
case <-parent.Done():
child.cancel(false, parent.Err())
case <-child.Done():
}
}()
}
}
// parentCancelCtx follows a chain of parent references until it finds a
// *cancelCtx. This function understands how each of the concrete types in this
// package represents its parent.
func parentCancelCtx(parent Context) (*cancelCtx, bool) {
for {
switch c := parent.(type) {
case *cancelCtx:
return c, true
case *timerCtx:
return &c.cancelCtx, true
case *valueCtx:
parent = c.Context
default:
return nil, false
}
}
}
// removeChild removes a context from its parent.
func removeChild(parent Context, child canceler) {
p, ok := parentCancelCtx(parent)
if !ok {
return
}
p.mu.Lock()
if p.children != nil {
delete(p.children, child)
}
p.mu.Unlock()
}
// A canceler is a context type that can be canceled directly. The
// implementations are *cancelCtx and *timerCtx.
type canceler interface {
cancel(removeFromParent bool, err error)
Done() <-chan struct{}
}
// A cancelCtx can be canceled. When canceled, it also cancels any children
// that implement canceler.
type cancelCtx struct {
Context
done chan struct{} // closed by the first cancel call.
mu sync.Mutex
children map[canceler]bool // set to nil by the first cancel call
err error // set to non-nil by the first cancel call
}
func (c *cancelCtx) Done() <-chan struct{} {
return c.done
}
func (c *cancelCtx) Err() error {
c.mu.Lock()
defer c.mu.Unlock()
return c.err
}
func (c *cancelCtx) String() string {
return fmt.Sprintf("%v.WithCancel", c.Context)
}
// cancel closes c.done, cancels each of c's children, and, if
// removeFromParent is true, removes c from its parent's children.
func (c *cancelCtx) cancel(removeFromParent bool, err error) {
if err == nil {
panic("context: internal error: missing cancel error")
}
c.mu.Lock()
if c.err != nil {
c.mu.Unlock()
return // already canceled
}
c.err = err
close(c.done)
for child := range c.children {
// NOTE: acquiring the child's lock while holding parent's lock.
child.cancel(false, err)
}
c.children = nil
c.mu.Unlock()
if removeFromParent {
removeChild(c.Context, c)
}
}
// WithDeadline returns a copy of the parent context with the deadline adjusted
// to be no later than d. If the parent's deadline is already earlier than d,
// WithDeadline(parent, d) is semantically equivalent to parent. The returned
// context's Done channel is closed when the deadline expires, when the returned
// cancel function is called, or when the parent context's Done channel is
// closed, whichever happens first.
//
// Canceling this context releases resources associated with it, so code should
// call cancel as soon as the operations running in this Context complete.
func WithDeadline(parent Context, deadline time.Time) (Context, CancelFunc) {
if cur, ok := parent.Deadline(); ok && cur.Before(deadline) {
// The current deadline is already sooner than the new one.
return WithCancel(parent)
}
c := &timerCtx{
cancelCtx: newCancelCtx(parent),
deadline: deadline,
}
propagateCancel(parent, c)
d := deadline.Sub(time.Now())
if d <= 0 {
c.cancel(true, DeadlineExceeded) // deadline has already passed
return c, func() { c.cancel(true, Canceled) }
}
c.mu.Lock()
defer c.mu.Unlock()
if c.err == nil {
c.timer = time.AfterFunc(d, func() {
c.cancel(true, DeadlineExceeded)
})
}
return c, func() { c.cancel(true, Canceled) }
}
// A timerCtx carries a timer and a deadline. It embeds a cancelCtx to
// implement Done and Err. It implements cancel by stopping its timer then
// delegating to cancelCtx.cancel.
type timerCtx struct {
cancelCtx
timer *time.Timer // Under cancelCtx.mu.
deadline time.Time
}
func (c *timerCtx) Deadline() (deadline time.Time, ok bool) {
return c.deadline, true
}
func (c *timerCtx) String() string {
return fmt.Sprintf("%v.WithDeadline(%s [%s])", c.cancelCtx.Context, c.deadline, c.deadline.Sub(time.Now()))
}
func (c *timerCtx) cancel(removeFromParent bool, err error) {
c.cancelCtx.cancel(false, err)
if removeFromParent {
// Remove this timerCtx from its parent cancelCtx's children.
removeChild(c.cancelCtx.Context, c)
}
c.mu.Lock()
if c.timer != nil {
c.timer.Stop()
c.timer = nil
}
c.mu.Unlock()
}
// WithTimeout returns WithDeadline(parent, time.Now().Add(timeout)).
//
// Canceling this context releases resources associated with it, so code should
// call cancel as soon as the operations running in this Context complete:
//
// func slowOperationWithTimeout(ctx context.Context) (Result, error) {
// ctx, cancel := context.WithTimeout(ctx, 100*time.Millisecond)
// defer cancel() // releases resources if slowOperation completes before timeout elapses
// return slowOperation(ctx)
// }
func WithTimeout(parent Context, timeout time.Duration) (Context, CancelFunc) {
return WithDeadline(parent, time.Now().Add(timeout))
}
// WithValue returns a copy of parent in which the value associated with key is
// val.
//
// Use context Values only for request-scoped data that transits processes and
// APIs, not for passing optional parameters to functions.
func WithValue(parent Context, key interface{}, val interface{}) Context {
return &valueCtx{parent, key, val}
}
// A valueCtx carries a key-value pair. It implements Value for that key and
// delegates all other calls to the embedded Context.
type valueCtx struct {
Context
key, val interface{}
}
func (c *valueCtx) String() string {
return fmt.Sprintf("%v.WithValue(%#v, %#v)", c.Context, c.key, c.val)
}
func (c *valueCtx) Value(key interface{}) interface{} {
if c.key == key {
return c.val
}
return c.Context.Value(key)
}
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package context
import (
"fmt"
"math/rand"
"runtime"
"strings"
"sync"
"testing"
"time"
)
// otherContext is a Context that's not one of the types defined in context.go.
// This lets us test code paths that differ based on the underlying type of the
// Context.
type otherContext struct {
Context
}
func TestBackground(t *testing.T) {
c := Background()
if c == nil {
t.Fatalf("Background returned nil")
}
select {
case x := <-c.Done():
t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
default:
}
if got, want := fmt.Sprint(c), "context.Background"; got != want {
t.Errorf("Background().String() = %q want %q", got, want)
}
}
func TestTODO(t *testing.T) {
c := TODO()
if c == nil {
t.Fatalf("TODO returned nil")
}
select {
case x := <-c.Done():
t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
default:
}
if got, want := fmt.Sprint(c), "context.TODO"; got != want {
t.Errorf("TODO().String() = %q want %q", got, want)
}
}
func TestWithCancel(t *testing.T) {
c1, cancel := WithCancel(Background())
if got, want := fmt.Sprint(c1), "context.Background.WithCancel"; got != want {
t.Errorf("c1.String() = %q want %q", got, want)
}
o := otherContext{c1}
c2, _ := WithCancel(o)
contexts := []Context{c1, o, c2}
for i, c := range contexts {
if d := c.Done(); d == nil {
t.Errorf("c[%d].Done() == %v want non-nil", i, d)
}
if e := c.Err(); e != nil {
t.Errorf("c[%d].Err() == %v want nil", i, e)
}
select {
case x := <-c.Done():
t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
default:
}
}
cancel()
time.Sleep(100 * time.Millisecond) // let cancelation propagate
for i, c := range contexts {
select {
case <-c.Done():
default:
t.Errorf("<-c[%d].Done() blocked, but shouldn't have", i)
}
if e := c.Err(); e != Canceled {
t.Errorf("c[%d].Err() == %v want %v", i, e, Canceled)
}
}
}
func TestParentFinishesChild(t *testing.T) {
// Context tree:
// parent -> cancelChild
// parent -> valueChild -> timerChild
parent, cancel := WithCancel(Background())
cancelChild, stop := WithCancel(parent)
defer stop()
valueChild := WithValue(parent, "key", "value")
timerChild, stop := WithTimeout(valueChild, 10000*time.Hour)
defer stop()
select {
case x := <-parent.Done():
t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
case x := <-cancelChild.Done():
t.Errorf("<-cancelChild.Done() == %v want nothing (it should block)", x)
case x := <-timerChild.Done():
t.Errorf("<-timerChild.Done() == %v want nothing (it should block)", x)
case x := <-valueChild.Done():
t.Errorf("<-valueChild.Done() == %v want nothing (it should block)", x)
default:
}
// The parent's children should contain the two cancelable children.
pc := parent.(*cancelCtx)
cc := cancelChild.(*cancelCtx)
tc := timerChild.(*timerCtx)
pc.mu.Lock()
if len(pc.children) != 2 || !pc.children[cc] || !pc.children[tc] {
t.Errorf("bad linkage: pc.children = %v, want %v and %v",
pc.children, cc, tc)
}
pc.mu.Unlock()
if p, ok := parentCancelCtx(cc.Context); !ok || p != pc {
t.Errorf("bad linkage: parentCancelCtx(cancelChild.Context) = %v, %v want %v, true", p, ok, pc)
}
if p, ok := parentCancelCtx(tc.Context); !ok || p != pc {
t.Errorf("bad linkage: parentCancelCtx(timerChild.Context) = %v, %v want %v, true", p, ok, pc)
}
cancel()
pc.mu.Lock()
if len(pc.children) != 0 {
t.Errorf("pc.cancel didn't clear pc.children = %v", pc.children)
}
pc.mu.Unlock()
// parent and children should all be finished.
check := func(ctx Context, name string) {
select {
case <-ctx.Done():
default:
t.Errorf("<-%s.Done() blocked, but shouldn't have", name)
}
if e := ctx.Err(); e != Canceled {
t.Errorf("%s.Err() == %v want %v", name, e, Canceled)
}
}
check(parent, "parent")
check(cancelChild, "cancelChild")
check(valueChild, "valueChild")
check(timerChild, "timerChild")
// WithCancel should return a canceled context on a canceled parent.
precanceledChild := WithValue(parent, "key", "value")
select {
case <-precanceledChild.Done():
default:
t.Errorf("<-precanceledChild.Done() blocked, but shouldn't have")
}
if e := precanceledChild.Err(); e != Canceled {
t.Errorf("precanceledChild.Err() == %v want %v", e, Canceled)
}
}
func TestChildFinishesFirst(t *testing.T) {
cancelable, stop := WithCancel(Background())
defer stop()
for _, parent := range []Context{Background(), cancelable} {
child, cancel := WithCancel(parent)
select {
case x := <-parent.Done():
t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
case x := <-child.Done():
t.Errorf("<-child.Done() == %v want nothing (it should block)", x)
default:
}
cc := child.(*cancelCtx)
pc, pcok := parent.(*cancelCtx) // pcok == false when parent == Background()
if p, ok := parentCancelCtx(cc.Context); ok != pcok || (ok && pc != p) {
t.Errorf("bad linkage: parentCancelCtx(cc.Context) = %v, %v want %v, %v", p, ok, pc, pcok)
}
if pcok {
pc.mu.Lock()
if len(pc.children) != 1 || !pc.children[cc] {
t.Errorf("bad linkage: pc.children = %v, cc = %v", pc.children, cc)
}
pc.mu.Unlock()
}
cancel()
if pcok {
pc.mu.Lock()
if len(pc.children) != 0 {
t.Errorf("child's cancel didn't remove self from pc.children = %v", pc.children)
}
pc.mu.Unlock()
}
// child should be finished.
select {
case <-child.Done():
default:
t.Errorf("<-child.Done() blocked, but shouldn't have")
}
if e := child.Err(); e != Canceled {
t.Errorf("child.Err() == %v want %v", e, Canceled)
}
// parent should not be finished.
select {
case x := <-parent.Done():
t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
default:
}
if e := parent.Err(); e != nil {
t.Errorf("parent.Err() == %v want nil", e)
}
}
}
func testDeadline(c Context, wait time.Duration, t *testing.T) {
select {
case <-time.After(wait):
t.Fatalf("context should have timed out")
case <-c.Done():
}
if e := c.Err(); e != DeadlineExceeded {
t.Errorf("c.Err() == %v want %v", e, DeadlineExceeded)
}
}
func TestDeadline(t *testing.T) {
c, _ := WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
if got, prefix := fmt.Sprint(c), "context.Background.WithDeadline("; !strings.HasPrefix(got, prefix) {
t.Errorf("c.String() = %q want prefix %q", got, prefix)
}
testDeadline(c, 200*time.Millisecond, t)
c, _ = WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
o := otherContext{c}
testDeadline(o, 200*time.Millisecond, t)
c, _ = WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
o = otherContext{c}
c, _ = WithDeadline(o, time.Now().Add(300*time.Millisecond))
testDeadline(c, 200*time.Millisecond, t)
}
func TestTimeout(t *testing.T) {
c, _ := WithTimeout(Background(), 100*time.Millisecond)
if got, prefix := fmt.Sprint(c), "context.Background.WithDeadline("; !strings.HasPrefix(got, prefix) {
t.Errorf("c.String() = %q want prefix %q", got, prefix)
}
testDeadline(c, 200*time.Millisecond, t)
c, _ = WithTimeout(Background(), 100*time.Millisecond)
o := otherContext{c}
testDeadline(o, 200*time.Millisecond, t)
c, _ = WithTimeout(Background(), 100*time.Millisecond)
o = otherContext{c}
c, _ = WithTimeout(o, 300*time.Millisecond)
testDeadline(c, 200*time.Millisecond, t)
}
func TestCanceledTimeout(t *testing.T) {
c, _ := WithTimeout(Background(), 200*time.Millisecond)
o := otherContext{c}
c, cancel := WithTimeout(o, 400*time.Millisecond)
cancel()
time.Sleep(100 * time.Millisecond) // let cancelation propagate
select {
case <-c.Done():
default:
t.Errorf("<-c.Done() blocked, but shouldn't have")
}
if e := c.Err(); e != Canceled {
t.Errorf("c.Err() == %v want %v", e, Canceled)
}
}
type key1 int
type key2 int
var k1 = key1(1)
var k2 = key2(1) // same int as k1, different type
var k3 = key2(3) // same type as k2, different int
func TestValues(t *testing.T) {
check := func(c Context, nm, v1, v2, v3 string) {
if v, ok := c.Value(k1).(string); ok == (len(v1) == 0) || v != v1 {
t.Errorf(`%s.Value(k1).(string) = %q, %t want %q, %t`, nm, v, ok, v1, len(v1) != 0)
}
if v, ok := c.Value(k2).(string); ok == (len(v2) == 0) || v != v2 {
t.Errorf(`%s.Value(k2).(string) = %q, %t want %q, %t`, nm, v, ok, v2, len(v2) != 0)
}
if v, ok := c.Value(k3).(string); ok == (len(v3) == 0) || v != v3 {
t.Errorf(`%s.Value(k3).(string) = %q, %t want %q, %t`, nm, v, ok, v3, len(v3) != 0)
}
}
c0 := Background()
check(c0, "c0", "", "", "")
c1 := WithValue(Background(), k1, "c1k1")
check(c1, "c1", "c1k1", "", "")
if got, want := fmt.Sprint(c1), `context.Background.WithValue(1, "c1k1")`; got != want {
t.Errorf("c.String() = %q want %q", got, want)
}
c2 := WithValue(c1, k2, "c2k2")
check(c2, "c2", "c1k1", "c2k2", "")
c3 := WithValue(c2, k3, "c3k3")
check(c3, "c2", "c1k1", "c2k2", "c3k3")
c4 := WithValue(c3, k1, nil)
check(c4, "c4", "", "c2k2", "c3k3")
o0 := otherContext{Background()}
check(o0, "o0", "", "", "")
o1 := otherContext{WithValue(Background(), k1, "c1k1")}
check(o1, "o1", "c1k1", "", "")
o2 := WithValue(o1, k2, "o2k2")
check(o2, "o2", "c1k1", "o2k2", "")
o3 := otherContext{c4}
check(o3, "o3", "", "c2k2", "c3k3")
o4 := WithValue(o3, k3, nil)
check(o4, "o4", "", "c2k2", "")
}
func TestAllocs(t *testing.T) {
bg := Background()
for _, test := range []struct {
desc string
f func()
limit float64
gccgoLimit float64
}{
{
desc: "Background()",
f: func() { Background() },
limit: 0,
gccgoLimit: 0,
},
{
desc: fmt.Sprintf("WithValue(bg, %v, nil)", k1),
f: func() {
c := WithValue(bg, k1, nil)
c.Value(k1)
},
limit: 3,
gccgoLimit: 3,
},
{
desc: "WithTimeout(bg, 15*time.Millisecond)",
f: func() {
c, _ := WithTimeout(bg, 15*time.Millisecond)
<-c.Done()
},
limit: 8,
gccgoLimit: 15,
},
{
desc: "WithCancel(bg)",
f: func() {
c, cancel := WithCancel(bg)
cancel()
<-c.Done()
},
limit: 5,
gccgoLimit: 8,
},
{
desc: "WithTimeout(bg, 100*time.Millisecond)",
f: func() {
c, cancel := WithTimeout(bg, 100*time.Millisecond)
cancel()
<-c.Done()
},
limit: 8,
gccgoLimit: 25,
},
} {
limit := test.limit
if runtime.Compiler == "gccgo" {
// gccgo does not yet do escape analysis.
// TOOD(iant): Remove this when gccgo does do escape analysis.
limit = test.gccgoLimit
}
if n := testing.AllocsPerRun(100, test.f); n > limit {
t.Errorf("%s allocs = %f want %d", test.desc, n, int(limit))
}
}
}
func TestSimultaneousCancels(t *testing.T) {
root, cancel := WithCancel(Background())
m := map[Context]CancelFunc{root: cancel}
q := []Context{root}
// Create a tree of contexts.
for len(q) != 0 && len(m) < 100 {
parent := q[0]
q = q[1:]
for i := 0; i < 4; i++ {
ctx, cancel := WithCancel(parent)
m[ctx] = cancel
q = append(q, ctx)
}
}
// Start all the cancels in a random order.
var wg sync.WaitGroup
wg.Add(len(m))
for _, cancel := range m {
go func(cancel CancelFunc) {
cancel()
wg.Done()
}(cancel)
}
// Wait on all the contexts in a random order.
for ctx := range m {
select {
case <-ctx.Done():
case <-time.After(1 * time.Second):
buf := make([]byte, 10<<10)
n := runtime.Stack(buf, true)
t.Fatalf("timed out waiting for <-ctx.Done(); stacks:\n%s", buf[:n])
}
}
// Wait for all the cancel functions to return.
done := make(chan struct{})
go func() {
wg.Wait()
close(done)
}()
select {
case <-done:
case <-time.After(1 * time.Second):
buf := make([]byte, 10<<10)
n := runtime.Stack(buf, true)
t.Fatalf("timed out waiting for cancel functions; stacks:\n%s", buf[:n])
}
}
func TestInterlockedCancels(t *testing.T) {
parent, cancelParent := WithCancel(Background())
child, cancelChild := WithCancel(parent)
go func() {
parent.Done()
cancelChild()
}()
cancelParent()
select {
case <-child.Done():
case <-time.After(1 * time.Second):
buf := make([]byte, 10<<10)
n := runtime.Stack(buf, true)
t.Fatalf("timed out waiting for child.Done(); stacks:\n%s", buf[:n])
}
}
func TestLayersCancel(t *testing.T) {
testLayers(t, time.Now().UnixNano(), false)
}
func TestLayersTimeout(t *testing.T) {
testLayers(t, time.Now().UnixNano(), true)
}
func testLayers(t *testing.T, seed int64, testTimeout bool) {
rand.Seed(seed)
errorf := func(format string, a ...interface{}) {
t.Errorf(fmt.Sprintf("seed=%d: %s", seed, format), a...)
}
const (
timeout = 200 * time.Millisecond
minLayers = 30
)
type value int
var (
vals []*value
cancels []CancelFunc
numTimers int
ctx = Background()
)
for i := 0; i < minLayers || numTimers == 0 || len(cancels) == 0 || len(vals) == 0; i++ {
switch rand.Intn(3) {
case 0:
v := new(value)
ctx = WithValue(ctx, v, v)
vals = append(vals, v)
case 1:
var cancel CancelFunc
ctx, cancel = WithCancel(ctx)
cancels = append(cancels, cancel)
case 2:
var cancel CancelFunc
ctx, cancel = WithTimeout(ctx, timeout)
cancels = append(cancels, cancel)
numTimers++
}
}
checkValues := func(when string) {
for _, key := range vals {
if val := ctx.Value(key).(*value); key != val {
errorf("%s: ctx.Value(%p) = %p want %p", when, key, val, key)
}
}
}
select {
case <-ctx.Done():
errorf("ctx should not be canceled yet")
default:
}
if s, prefix := fmt.Sprint(ctx), "context.Background."; !strings.HasPrefix(s, prefix) {
t.Errorf("ctx.String() = %q want prefix %q", s, prefix)
}
t.Log(ctx)
checkValues("before cancel")
if testTimeout {
select {
case <-ctx.Done():
case <-time.After(timeout + 100*time.Millisecond):
errorf("ctx should have timed out")
}
checkValues("after timeout")
} else {
cancel := cancels[rand.Intn(len(cancels))]
cancel()
select {
case <-ctx.Done():
default:
errorf("ctx should be canceled")
}
checkValues("after cancel")
}
}
func TestCancelRemoves(t *testing.T) {
checkChildren := func(when string, ctx Context, want int) {
if got := len(ctx.(*cancelCtx).children); got != want {
t.Errorf("%s: context has %d children, want %d", when, got, want)
}
}
ctx, _ := WithCancel(Background())
checkChildren("after creation", ctx, 0)
_, cancel := WithCancel(ctx)
checkChildren("with WithCancel child ", ctx, 1)
cancel()
checkChildren("after cancelling WithCancel child", ctx, 0)
ctx, _ = WithCancel(Background())
checkChildren("after creation", ctx, 0)
_, cancel = WithTimeout(ctx, 60*time.Minute)
checkChildren("with WithTimeout child ", ctx, 1)
cancel()
checkChildren("after cancelling WithTimeout child", ctx, 0)
}
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build go1.5
package ctxhttp
import "net/http"
func canceler(client *http.Client, req *http.Request) func() {
ch := make(chan struct{})
req.Cancel = ch
return func() {
close(ch)
}
}
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !go1.5
package ctxhttp
import "net/http"
type requestCanceler interface {
CancelRequest(*http.Request)
}
func canceler(client *http.Client, req *http.Request) func() {
rc, ok := client.Transport.(requestCanceler)
if !ok {
return func() {}
}
return func() {
rc.CancelRequest(req)
}
}
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package ctxhttp provides helper functions for performing context-aware HTTP requests.
package ctxhttp
import (
"io"
"net/http"
"net/url"
"strings"
"QmacZi9WygGK7Me8mH53pypyscHzU386aUZXpr28GZgUct/context"
)
// Do sends an HTTP request with the provided http.Client and returns an HTTP response.
// If the client is nil, http.DefaultClient is used.
// If the context is canceled or times out, ctx.Err() will be returned.
func Do(ctx context.Context, client *http.Client, req *http.Request) (*http.Response, error) {
if client == nil {
client = http.DefaultClient
}
// Request cancelation changed in Go 1.5, see cancelreq.go and cancelreq_go14.go.
cancel := canceler(client, req)
type responseAndError struct {
resp *http.Response
err error
}
result := make(chan responseAndError, 1)
go func() {
resp, err := client.Do(req)
result <- responseAndError{resp, err}
}()
select {
case <-ctx.Done():
cancel()
return nil, ctx.Err()
case r := <-result:
return r.resp, r.err
}
}
// Get issues a GET request via the Do function.
func Get(ctx context.Context, client *http.Client, url string) (*http.Response, error) {
req, err := http.NewRequest("GET", url, nil)
if err != nil {
return nil, err
}
return Do(ctx, client, req)
}
// Head issues a HEAD request via the Do function.
func Head(ctx context.Context, client *http.Client, url string) (*http.Response, error) {
req, err := http.NewRequest("HEAD", url, nil)
if err != nil {
return nil, err
}
return Do(ctx, client, req)
}
// Post issues a POST request via the Do function.
func Post(ctx context.Context, client *http.Client, url string, bodyType string, body io.Reader) (*http.Response, error) {
req, err := http.NewRequest("POST", url, body)
if err != nil {
return nil, err
}
req.Header.Set("Content-Type", bodyType)
return Do(ctx, client, req)
}
// PostForm issues a POST request via the Do function.
func PostForm(ctx context.Context, client *http.Client, url string, data url.Values) (*http.Response, error) {
return Post(ctx, client, url, "application/x-www-form-urlencoded", strings.NewReader(data.Encode()))
}
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ctxhttp
import (
"io/ioutil"
"net/http"
"net/http/httptest"
"testing"
"time"
"QmacZi9WygGK7Me8mH53pypyscHzU386aUZXpr28GZgUct/context"
)
const (
requestDuration = 100 * time.Millisecond
requestBody = "ok"
)
func TestNoTimeout(t *testing.T) {
ctx := context.Background()
resp, err := doRequest(ctx)
if resp == nil || err != nil {
t.Fatalf("error received from client: %v %v", err, resp)
}
}
func TestCancel(t *testing.T) {
ctx, cancel := context.WithCancel(context.Background())
go func() {
time.Sleep(requestDuration / 2)
cancel()
}()
resp, err := doRequest(ctx)
if resp != nil || err == nil {
t.Fatalf("expected error, didn't get one. resp: %v", resp)
}
if err != ctx.Err() {
t.Fatalf("expected error from context but got: %v", err)
}
}
func TestCancelAfterRequest(t *testing.T) {
ctx, cancel := context.WithCancel(context.Background())
resp, err := doRequest(ctx)
// Cancel before reading the body.
// Request.Body should still be readable after the context is canceled.
cancel()
b, err := ioutil.ReadAll(resp.Body)
if err != nil || string(b) != requestBody {
t.Fatalf("could not read body: %q %v", b, err)
}
}
func doRequest(ctx context.Context) (*http.Response, error) {
var okHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
time.Sleep(requestDuration)
w.Write([]byte(requestBody))
})
serv := httptest.NewServer(okHandler)
defer serv.Close()
return Get(ctx, nil, serv.URL)
}
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