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53 lines
1.6 KiB
53 lines
1.6 KiB
package p2p
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import (
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"sync"
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)
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// default capacity for the size of a queue
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const defaultCapacity uint = 16e6 // ~16MB
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// queue does QoS scheduling for Envelopes, enqueueing and dequeueing according
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// to some policy. Queues are used at contention points, i.e.:
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//
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// - Receiving inbound messages to a single channel from all peers.
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// - Sending outbound messages to a single peer from all channels.
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type queue interface {
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// enqueue returns a channel for submitting envelopes.
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enqueue() chan<- Envelope
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// dequeue returns a channel ordered according to some queueing policy.
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dequeue() <-chan Envelope
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// close closes the queue. After this call enqueue() will block, so the
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// caller must select on closed() as well to avoid blocking forever. The
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// enqueue() and dequeue() channels will not be closed.
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close()
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// closed returns a channel that's closed when the scheduler is closed.
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closed() <-chan struct{}
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}
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// fifoQueue is a simple unbuffered lossless queue that passes messages through
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// in the order they were received, and blocks until message is received.
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type fifoQueue struct {
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queueCh chan Envelope
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closeFn func()
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closeCh <-chan struct{}
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}
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func newFIFOQueue(size int) queue {
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closeCh := make(chan struct{})
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once := &sync.Once{}
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return &fifoQueue{
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queueCh: make(chan Envelope, size),
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closeFn: func() { once.Do(func() { close(closeCh) }) },
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closeCh: closeCh,
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}
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}
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func (q *fifoQueue) enqueue() chan<- Envelope { return q.queueCh }
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func (q *fifoQueue) dequeue() <-chan Envelope { return q.queueCh }
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func (q *fifoQueue) close() { q.closeFn() }
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func (q *fifoQueue) closed() <-chan struct{} { return q.closeCh }
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