84 lines
1.5 KiB
Go
84 lines
1.5 KiB
Go
package jounce
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import (
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"gopkg.in/irc.v3"
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)
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// Ring implements a single producer, multiple consumer ring buffer. The ring
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// buffer size is fixed. The ring buffer is stored in memory.
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type Ring struct {
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buffer []*irc.Message
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cap, cur uint64
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consumers map[string]*RingConsumer
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}
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func NewRing(capacity int) *Ring {
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return &Ring{
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buffer: make([]*irc.Message, capacity),
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cap: uint64(capacity),
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consumers: make(map[string]*RingConsumer),
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}
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}
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func (r *Ring) Produce(msg *irc.Message) {
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i := int(r.cur % r.cap)
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r.buffer[i] = msg
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r.cur++
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}
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func (r *Ring) Consumer(name string) *RingConsumer {
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consumer, ok := r.consumers[name]
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if ok {
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return consumer
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}
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consumer = &RingConsumer{
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ring: r,
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cur: r.cur,
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}
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r.consumers[name] = consumer
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return consumer
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}
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type RingConsumer struct {
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ring *Ring
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cur uint64
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}
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func (rc *RingConsumer) Diff() uint64 {
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if rc.cur > rc.ring.cur {
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panic("jounce: consumer cursor greater than producer cursor")
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}
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return rc.ring.cur - rc.cur
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}
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func (rc *RingConsumer) Peek() *irc.Message {
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diff := rc.Diff()
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if diff == 0 {
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return nil
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}
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if diff > rc.ring.cap {
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// Consumer drops diff - cap entries
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rc.cur = rc.ring.cur - rc.ring.cap
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}
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i := int(rc.cur % rc.ring.cap)
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msg := rc.ring.buffer[i]
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if msg == nil {
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panic("jounce: unexpected nil ring buffer entry")
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}
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return msg
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}
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func (rc *RingConsumer) Consume() *irc.Message {
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msg := rc.Peek()
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if msg != nil {
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rc.cur++
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}
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return msg
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}
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func (rc *RingConsumer) Reset() {
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rc.cur = rc.ring.cur
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}
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