95 lines
1.8 KiB
Go
95 lines
1.8 KiB
Go
package main
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import "github.com/calmh/syncthing/scanner"
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type bqAdd struct {
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file scanner.File
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have []scanner.Block
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need []scanner.Block
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}
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type bqBlock struct {
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file scanner.File
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block scanner.Block // get this block from the network
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copy []scanner.Block // copy these blocks from the old version of the file
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last bool
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}
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type blockQueue struct {
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inbox chan bqAdd
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outbox chan bqBlock
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queued []bqBlock
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}
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func newBlockQueue() *blockQueue {
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q := &blockQueue{
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inbox: make(chan bqAdd),
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outbox: make(chan bqBlock),
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}
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go q.run()
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return q
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}
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func (q *blockQueue) addBlock(a bqAdd) {
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// If we already have it queued, return
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for _, b := range q.queued {
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if b.file.Name == a.file.Name {
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return
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}
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}
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if len(a.have) > 0 {
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// First queue a copy operation
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q.queued = append(q.queued, bqBlock{
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file: a.file,
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copy: a.have,
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})
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}
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// Queue the needed blocks individually
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l := len(a.need)
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for i, b := range a.need {
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q.queued = append(q.queued, bqBlock{
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file: a.file,
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block: b,
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last: i == l-1,
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})
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}
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if l == 0 {
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// If we didn't have anything to fetch, queue an empty block with the "last" flag set to close the file.
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q.queued = append(q.queued, bqBlock{
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file: a.file,
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last: true,
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})
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}
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}
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func (q *blockQueue) run() {
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for {
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if len(q.queued) == 0 {
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q.addBlock(<-q.inbox)
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} else {
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next := q.queued[0]
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select {
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case a := <-q.inbox:
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q.addBlock(a)
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case q.outbox <- next:
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q.queued = q.queued[1:]
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}
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}
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}
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}
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func (q *blockQueue) put(a bqAdd) {
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q.inbox <- a
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}
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func (q *blockQueue) get() bqBlock {
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return <-q.outbox
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}
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func (q *blockQueue) empty() bool {
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// There is a race condition here. We're only mostly sure the queue is empty if the expression below is true.
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return len(q.queued) == 0 && len(q.inbox) == 0 && len(q.outbox) == 0
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}
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