syncthing/model/blockqueue.go
2014-06-01 22:50:14 +02:00

120 lines
2.1 KiB
Go

// Copyright (C) 2014 Jakob Borg and other contributors. All rights reserved.
// Use of this source code is governed by an MIT-style license that can be
// found in the LICENSE file.
package model
import (
"sync"
"github.com/calmh/syncthing/scanner"
)
type bqAdd struct {
file scanner.File
have []scanner.Block
need []scanner.Block
}
type bqBlock struct {
file scanner.File
block scanner.Block // get this block from the network
copy []scanner.Block // copy these blocks from the old version of the file
first bool
last bool
}
type blockQueue struct {
inbox chan bqAdd
outbox chan bqBlock
queued []bqBlock
mut sync.Mutex
}
func newBlockQueue() *blockQueue {
q := &blockQueue{
inbox: make(chan bqAdd),
outbox: make(chan bqBlock),
}
go q.run()
return q
}
func (q *blockQueue) addBlock(a bqAdd) {
q.mut.Lock()
defer q.mut.Unlock()
// If we already have it queued, return
for _, b := range q.queued {
if b.file.Name == a.file.Name {
return
}
}
l := len(a.need)
if len(a.have) > 0 {
// First queue a copy operation
q.queued = append(q.queued, bqBlock{
file: a.file,
copy: a.have,
first: true,
last: l == 0,
})
}
// Queue the needed blocks individually
for i, b := range a.need {
q.queued = append(q.queued, bqBlock{
file: a.file,
block: b,
first: len(a.have) == 0 && i == 0,
last: i == l-1,
})
}
if len(a.need)+len(a.have) == 0 {
// If we didn't have anything to fetch, queue an empty block with the "last" flag set to close the file.
q.queued = append(q.queued, bqBlock{
file: a.file,
last: true,
})
}
}
func (q *blockQueue) run() {
for {
if len(q.queued) == 0 {
q.addBlock(<-q.inbox)
} else {
q.mut.Lock()
next := q.queued[0]
q.mut.Unlock()
select {
case a := <-q.inbox:
q.addBlock(a)
case q.outbox <- next:
q.mut.Lock()
q.queued = q.queued[1:]
q.mut.Unlock()
}
}
}
}
func (q *blockQueue) put(a bqAdd) {
q.inbox <- a
}
func (q *blockQueue) get() bqBlock {
return <-q.outbox
}
func (q *blockQueue) empty() bool {
q.mut.Lock()
defer q.mut.Unlock()
return len(q.queued) == 0
}