rpc/v2: optionally passing context argument to rpc v2 api methods

This commit is contained in:
zsfelfoldi 2015-12-09 18:28:07 +01:00
parent fa187a366d
commit f3aac71fad
8 changed files with 1122 additions and 18 deletions

4
Godeps/Godeps.json generated
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@ -101,6 +101,10 @@
"ImportPath": "golang.org/x/crypto/scrypt",
"Rev": "4ed45ec682102c643324fae5dff8dab085b6c300"
},
{
"ImportPath": "golang.org/x/net/context",
"Rev": "e0403b4e005737430c05a57aac078479844f919c"
},
{
"ImportPath": "golang.org/x/net/html",
"Rev": "e0403b4e005737430c05a57aac078479844f919c"

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// 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 "golang.org/x/net/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's 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)
}

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// 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: 13,
},
{
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 + timeout/10):
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)
}

View File

@ -0,0 +1,26 @@
// 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_test
import (
"fmt"
"time"
"golang.org/x/net/context"
)
func ExampleWithTimeout() {
// Pass a context with a timeout to tell a blocking function that it
// should abandon its work after the timeout elapses.
ctx, _ := context.WithTimeout(context.Background(), 100*time.Millisecond)
select {
case <-time.After(200 * time.Millisecond):
fmt.Println("overslept")
case <-ctx.Done():
fmt.Println(ctx.Err()) // prints "context deadline exceeded"
}
// Output:
// context deadline exceeded
}

View File

@ -25,6 +25,7 @@ import (
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"golang.org/x/net/context"
)
// NewServer will create a new server instance with no registered handlers.
@ -120,6 +121,9 @@ func (s *Server) ServeCodec(codec ServerCodec) {
codec.Close()
}()
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
for {
reqs, batch, err := s.readRequest(codec)
if err != nil {
@ -129,9 +133,9 @@ func (s *Server) ServeCodec(codec ServerCodec) {
}
if batch {
go s.execBatch(codec, reqs)
go s.execBatch(ctx, codec, reqs)
} else {
go s.exec(codec, reqs[0])
go s.exec(ctx, codec, reqs[0])
}
}
}
@ -220,7 +224,7 @@ func (s *Server) unsubscribe(subid string) bool {
}
// handle executes a request and returns the response from the callback.
func (s *Server) handle(codec ServerCodec, req *serverRequest) interface{} {
func (s *Server) handle(ctx context.Context, codec ServerCodec, req *serverRequest) interface{} {
if req.err != nil {
return codec.CreateErrorResponse(&req.id, req.err)
}
@ -255,6 +259,9 @@ func (s *Server) handle(codec ServerCodec, req *serverRequest) interface{} {
}
arguments := []reflect.Value{req.callb.rcvr}
if req.callb.hasCtx {
arguments = append(arguments, reflect.ValueOf(ctx))
}
if len(req.args) > 0 {
arguments = append(arguments, req.args...)
}
@ -277,12 +284,12 @@ func (s *Server) handle(codec ServerCodec, req *serverRequest) interface{} {
}
// exec executes the given request and writes the result back using the codec.
func (s *Server) exec(codec ServerCodec, req *serverRequest) {
func (s *Server) exec(ctx context.Context, codec ServerCodec, req *serverRequest) {
var response interface{}
if req.err != nil {
response = codec.CreateErrorResponse(&req.id, req.err)
} else {
response = s.handle(codec, req)
response = s.handle(ctx, codec, req)
}
if err := codec.Write(response); err != nil {
@ -293,13 +300,13 @@ func (s *Server) exec(codec ServerCodec, req *serverRequest) {
// execBatch executes the given requests and writes the result back using the codec. It will only write the response
// back when the last request is processed.
func (s *Server) execBatch(codec ServerCodec, requests []*serverRequest) {
func (s *Server) execBatch(ctx context.Context, codec ServerCodec, requests []*serverRequest) {
responses := make([]interface{}, len(requests))
for i, req := range requests {
if req.err != nil {
responses[i] = codec.CreateErrorResponse(&req.id, req.err)
} else {
responses[i] = s.handle(codec, req)
responses[i] = s.handle(ctx, codec, req)
}
}

View File

@ -6,6 +6,8 @@ import (
"reflect"
"testing"
"time"
"golang.org/x/net/context"
)
type Service struct{}
@ -27,6 +29,10 @@ func (s *Service) Echo(str string, i int, args *Args) Result {
return Result{str, i, args}
}
func (s *Service) EchoWithCtx(ctx context.Context, str string, i int, args *Args) Result {
return Result{str, i, args}
}
func (s *Service) Rets() (string, error) {
return "", nil
}
@ -64,8 +70,8 @@ func TestServerRegisterName(t *testing.T) {
t.Fatalf("Expected service calc to be registered")
}
if len(svc.callbacks) != 3 {
t.Errorf("Expected 3 callbacks for service 'calc', got %d", len(svc.callbacks))
if len(svc.callbacks) != 4 {
t.Errorf("Expected 4 callbacks for service 'calc', got %d", len(svc.callbacks))
}
if len(svc.subscriptions) != 1 {
@ -217,3 +223,33 @@ func TestServerMethodExecution(t *testing.T) {
t.Fatalf("expected %s, got %s\n", expected, codec.output)
}
}
func TestServerMethodWithCtx(t *testing.T) {
server := NewServer()
service := new(Service)
if err := server.RegisterName("test", service); err != nil {
t.Fatalf("%v", err)
}
id := int64(12345)
req := jsonRequest{
Method: "echoWithCtx",
Version: "2.0",
Id: &id,
}
args := []interface{}{"string arg", 1122, &Args{"qwerty"}}
req.Payload, _ = json.Marshal(&args)
input, _ := json.Marshal(&req)
codec := &ServerTestCodec{input: input, closer: make(chan interface{})}
go server.ServeCodec(codec)
<-codec.closer
expected := `{"jsonrpc":"2.0","id":12345,"result":{"String":"string arg","Int":1122,"Args":{"S":"qwerty"}}}`
if expected != codec.output {
t.Fatalf("expected %s, got %s\n", expected, codec.output)
}
}

View File

@ -22,7 +22,6 @@ import (
"math/big"
"reflect"
"strings"
"sync"
"github.com/ethereum/go-ethereum/event"
@ -41,6 +40,7 @@ type callback struct {
rcvr reflect.Value // receiver of method
method reflect.Method // callback
argTypes []reflect.Type // input argument types
hasCtx bool // method's first argument is a context (not included in argTypes)
errPos int // err return idx, of -1 when method cannot return error
isSubscribe bool // indication if the callback is a subscription
}

View File

@ -24,6 +24,8 @@ import (
"reflect"
"unicode"
"unicode/utf8"
"golang.org/x/net/context"
)
// Is this an exported - upper case - name?
@ -107,6 +109,8 @@ func isBlockNumber(t reflect.Type) bool {
return t == blockNumberType
}
var contextType = reflect.TypeOf(new(context.Context)).Elem()
// suitableCallbacks iterates over the methods of the given type. It will determine if a method satisfies the criteria
// for a RPC callback or a subscription callback and adds it to the collection of callbacks or subscriptions. See server
// documentation for a summary of these criteria.
@ -129,12 +133,19 @@ METHODS:
h.method = method
h.errPos = -1
firstArg := 1
numIn := mtype.NumIn()
if numIn >= 2 && mtype.In(1) == contextType {
h.hasCtx = true
firstArg = 2
}
if h.isSubscribe {
h.argTypes = make([]reflect.Type, mtype.NumIn()-1) // skip rcvr type
for i := 1; i < mtype.NumIn(); i++ {
h.argTypes = make([]reflect.Type, numIn-firstArg) // skip rcvr type
for i := firstArg; i < numIn; i++ {
argType := mtype.In(i)
if isExportedOrBuiltinType(argType) {
h.argTypes[i-1] = argType
h.argTypes[i-firstArg] = argType
} else {
continue METHODS
}
@ -144,17 +155,15 @@ METHODS:
continue METHODS
}
numIn := mtype.NumIn()
// determine method arguments, ignore first arg since it's the receiver type
// Arguments must be exported or builtin types
h.argTypes = make([]reflect.Type, numIn-1)
for i := 1; i < numIn; i++ {
h.argTypes = make([]reflect.Type, numIn-firstArg)
for i := firstArg; i < numIn; i++ {
argType := mtype.In(i)
if !isExportedOrBuiltinType(argType) {
continue METHODS
}
h.argTypes[i-1] = argType
h.argTypes[i-firstArg] = argType
}
// check that all returned values are exported or builtin types