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Remove ctxcloser

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License: MIT
Signed-off-by: rht <rhtbot@gmail.com>
This commit is contained in:
rht
2015-06-15 20:00:52 +07:00
parent 224a9eb0b9
commit 5bfd694ca7
1 changed files with 0 additions and 183 deletions
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183
util/ctxcloser/closer.go
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@ -1,183 +0,0 @@
package ctxcloser
import (
"sync"
context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
)
// CloseFunc is a function used to close a ContextCloser
type CloseFunc func() error
var nilCloseFunc = func() error { return nil }
// ContextCloser is an interface for services able to be opened and closed.
// It has a parent Context, and Children. But ContextCloser is not a proper
// "tree" like the Context tree. It is more like a Context-WaitGroup hybrid.
// It models a main object with a few children objects -- and, unlike the
// context -- concerns itself with the parent-child closing semantics:
//
// - Can define a CloseFunc (func() error) to be run at Close time.
// - Children call Children().Add(1) to be waited upon
// - Children can select on <-Closing() to know when they should shut down.
// - Close() will wait until all children call Children().Done()
// - <-Closed() signals when the service is completely closed.
//
// ContextCloser can be embedded into the main object itself. In that case,
// the closeFunc (if a member function) has to be set after the struct
// is intialized:
//
// type service struct {
// ContextCloser
// net.Conn
// }
//
// func (s *service) close() error {
// return s.Conn.Close()
// }
//
// func newService(ctx context.Context, c net.Conn) *service {
// s := &service{c}
// s.ContextCloser = NewContextCloser(ctx, s.close)
// return s
// }
//
type ContextCloser interface {
// Context is the context of this ContextCloser. It is "sort of" a parent.
Context() context.Context
// Children is a sync.Waitgroup for all children goroutines that should
// shut down completely before this service is said to be "closed".
// Follows the semantics of WaitGroup:
//
// Children().Add(1) // add one more dependent child
// Children().Done() // child signals it is done
//
Children() *sync.WaitGroup
// AddCloserChild registers a dependent ContextCloser child. The child will
// be closed when this parent is closed, and waited upon to finish. It is
// the functional equivalent of the following:
//
// go func(parent, child ContextCloser) {
// parent.Children().Add(1) // add one more dependent child
// <-parent.Closing() // wait until parent is closing
// child.Close() // signal child to close
// parent.Children().Done() // child signals it is done
// }(a, b)
//
AddCloserChild(c ContextCloser)
// Close is a method to call when you wish to stop this ContextCloser
Close() error
// Closing is a signal to wait upon, like Context.Done().
// It fires when the object should be closing (but hasn't yet fully closed).
// The primary use case is for child goroutines who need to know when
// they should shut down. (equivalent to Context().Done())
Closing() <-chan struct{}
// Closed is a method to wait upon, like Context.Done().
// It fires when the entire object is fully closed.
// The primary use case is for external listeners who need to know when
// this object is completly done, and all its children closed.
Closed() <-chan struct{}
}
// contextCloser is an OpenCloser with a cancellable context
type contextCloser struct {
ctx context.Context
cancel context.CancelFunc
// called to run the close logic.
closeFunc CloseFunc
// closed is released once the close function is done.
closed chan struct{}
// wait group for child goroutines
children sync.WaitGroup
// sync primitive to ensure the close logic is only called once.
closeOnce sync.Once
// error to return to clients of Close().
closeErr error
}
// NewContextCloser constructs and returns a ContextCloser. It will call
// cf CloseFunc before its Done() Wait signals fire.
func NewContextCloser(ctx context.Context, cf CloseFunc) ContextCloser {
if cf == nil {
cf = nilCloseFunc
}
ctx, cancel := context.WithCancel(ctx)
c := &contextCloser{
ctx: ctx,
cancel: cancel,
closeFunc: cf,
closed: make(chan struct{}),
}
c.Children().Add(1) // we're a child goroutine, to be waited upon.
go c.closeOnContextDone()
return c
}
func (c *contextCloser) Context() context.Context {
return c.ctx
}
func (c *contextCloser) Children() *sync.WaitGroup {
return &c.children
}
func (c *contextCloser) AddCloserChild(child ContextCloser) {
c.children.Add(1)
go func(parent, child ContextCloser) {
<-parent.Closing() // wait until parent is closing
child.Close() // signal child to close
parent.Children().Done() // child signals it is done
}(c, child)
}
// Close is the external close function. it's a wrapper around internalClose
// that waits on Closed()
func (c *contextCloser) Close() error {
c.internalClose()
<-c.Closed() // wait until we're totally done.
return c.closeErr
}
func (c *contextCloser) Closing() <-chan struct{} {
return c.Context().Done()
}
func (c *contextCloser) Closed() <-chan struct{} {
return c.closed
}
func (c *contextCloser) internalClose() {
go c.closeOnce.Do(c.closeLogic)
}
// the _actual_ close process.
func (c *contextCloser) closeLogic() {
// this function should only be called once (hence the sync.Once).
// and it will panic at the bottom (on close(c.closed)) otherwise.
c.cancel() // signal that we're shutting down (Closing)
c.closeErr = c.closeFunc() // actually run the close logic
c.children.Wait() // wait till all children are done.
close(c.closed) // signal that we're shut down (Closed)
}
// if parent context is shut down before we call Close explicitly,
// we need to go through the Close motions anyway. Hence all the sync
// stuff all over the place...
func (c *contextCloser) closeOnContextDone() {
<-c.Context().Done() // wait until parent (context) is done.
c.internalClose()
c.Children().Done()
}