broadcast

Documentation

Index

• type Broadcast
  • func (c *Broadcast) HoldLock(cb func(broadcast func(), getWaitCh func() <-chan struct{}))
  • func (c *Broadcast) HoldLockMaybeAsync(cb func(broadcast func(), getWaitCh func() <-chan struct{}))
  • func (c *Broadcast) TryHoldLock(cb func(broadcast func(), getWaitCh func() <-chan struct{})) bool
  • func (c *Broadcast) Wait(ctx context.Context, ...) error

Examples

• Broadcast
• Broadcast.Wait

Types

type Broadcast

type Broadcast struct {
	// contains filtered or unexported fields
}

Broadcast implements notifying waiters via a channel.

The zero-value of this struct is valid.

Example

// b guards currValue
var b Broadcast
var currValue int

go func() {
	// 0 to 9 inclusive
	for i := range 10 {
		<-time.After(time.Millisecond * 20)
		b.HoldLock(func(broadcast func(), getWaitCh func() <-chan struct{}) {
			currValue = i
			broadcast()
		})
	}
}()

var waitCh <-chan struct{}
var gotValue int
for {
	b.HoldLock(func(broadcast func(), getWaitCh func() <-chan struct{}) {
		gotValue = currValue
		waitCh = getWaitCh()
	})

	// last value
	if gotValue == 9 {
		// success
		break
	}

	// otherwise keep waiting
	<-waitCh
}

fmt.Printf("waited for value to increment: %v\n", gotValue)

Output:

waited for value to increment: 9

func (*Broadcast) HoldLock

func (c *Broadcast) HoldLock(cb func(broadcast func(), getWaitCh func() <-chan struct{}))

HoldLock locks the mutex and calls the callback.

broadcast closes the wait channel, if any. getWaitCh returns a channel that will be closed when broadcast is called.

func (*Broadcast) HoldLockMaybeAsync

func (c *Broadcast) HoldLockMaybeAsync(cb func(broadcast func(), getWaitCh func() <-chan struct{}))

HoldLockMaybeAsync locks the mutex and calls the callback if possible. If the mutex cannot be locked right now, starts a new Goroutine to wait for it.

func (*Broadcast) TryHoldLock

func (c *Broadcast) TryHoldLock(cb func(broadcast func(), getWaitCh func() <-chan struct{})) bool

TryHoldLock attempts to lock the mutex and call the callback. It returns true if the lock was acquired and the callback was called, false otherwise.

func (*Broadcast) Wait

func (c *Broadcast) Wait(ctx context.Context, cb func(broadcast func(), getWaitCh func() <-chan struct{}) (bool, error)) error

Wait waits for the cb to return true or an error before returning. When the broadcast channel is broadcasted, re-calls cb again to re-check the value. cb is called while the mutex is locked. Returns context.Canceled if ctx is canceled.

Example

// b guards currValue
var b Broadcast
var currValue int

go func() {
	// 0 to 9 inclusive
	for i := range 10 {
		<-time.After(time.Millisecond * 20)
		b.HoldLock(func(broadcast func(), getWaitCh func() <-chan struct{}) {
			currValue = i
			broadcast()
		})
	}
}()

ctx := context.Background()
var gotValue int
err := b.Wait(ctx, func(broadcast func(), getWaitCh func() <-chan struct{}) (bool, error) {
	gotValue = currValue
	return gotValue == 9, nil
})
if err != nil {
	fmt.Printf("failed to wait for value: %v", err.Error())
	return
}

fmt.Printf("waited for value to increment: %v\n", gotValue)

Output:

waited for value to increment: 9