forked from basho/riak-go-client
/
queue.go
102 lines (91 loc) · 1.72 KB
/
queue.go
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package riak
import "sync"
type queue struct {
queueSize uint16
queueChan chan interface{}
sync.RWMutex
}
func newQueue(queueSize uint16) *queue {
if queueSize == 0 {
panic("[queue] size must be greater than zero!")
}
return &queue{
queueSize: queueSize,
queueChan: make(chan interface{}, queueSize),
}
}
func (q *queue) enqueue(v interface{}) error {
if v == nil {
panic("attempt to enqueue nil value")
}
q.Lock()
defer q.Unlock()
return q._do_enqueue(v)
}
func (q *queue) _do_enqueue(v interface{}) error {
if len(q.queueChan) == int(q.queueSize) {
return newClientError("attempt to enqueue when queue is full", nil)
}
q.queueChan <- v
return nil
}
func (q *queue) dequeue() (interface{}, error) {
q.Lock()
defer q.Unlock()
return q._do_dequeue()
}
func (q *queue) _do_dequeue() (interface{}, error) {
select {
case v, ok := <-q.queueChan:
if !ok {
return nil, newClientError("attempt to dequeue from closed queue", nil)
}
return v, nil
default:
return nil, nil
}
}
func (q *queue) iterate(f func(interface{}) (bool, bool)) error {
q.Lock()
defer q.Unlock()
count := uint16(len(q.queueChan))
if count == 0 {
return nil
}
c := uint16(0)
for {
c++
v, err := q._do_dequeue()
if err != nil {
return err
}
// NB: v may be nil if queue is currently empty
brk, re_queue := f(v)
if re_queue && v != nil {
err = q._do_enqueue(v)
if err != nil {
return err
}
}
if brk {
break
}
if c == count {
break
}
}
return nil
}
func (q *queue) isEmpty() bool {
q.RLock()
defer q.RUnlock()
return len(q.queueChan) == 0
}
func (q *queue) count() uint16 {
q.RLock()
defer q.RUnlock()
return uint16(len(q.queueChan))
}
func (q *queue) destroy() {
close(q.queueChan)
}