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// Copyright (C) 2014 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.
package scanner
import (
"errors"
"os"
"path/filepath"
"github.com/syncthing/syncthing/lib/protocol"
"github.com/syncthing/syncthing/lib/sync"
)
// The parallel hasher reads FileInfo structures from the inbox, hashes the
// file to populate the Blocks element and sends it to the outbox. A number of
// workers are used in parallel. The outbox will become closed when the inbox
// is closed and all items handled.
func newParallelHasher(dir string, blockSize, workers int, outbox, inbox chan protocol.FileInfo, counter Counter, done, cancel chan struct{}) {
wg := sync.NewWaitGroup()
wg.Add(workers)
for i := 0; i < workers; i++ {
go func() {
hashFiles(dir, blockSize, outbox, inbox, counter, cancel)
wg.Done()
}()
}
go func() {
wg.Wait()
if done != nil {
close(done)
}
close(outbox)
}()
}
func HashFile(path string, blockSize int, counter Counter) ([]protocol.BlockInfo, error) {
fd, err := os.Open(path)
if err != nil {
l.Debugln("open:", err)
return nil, err
}
defer fd.Close()
// Get the size and modtime of the file before we start hashing it.
fi, err := fd.Stat()
if err != nil {
l.Debugln("stat before:", err)
return nil, err
}
size := fi.Size()
modTime := fi.ModTime()
// Hash the file. This may take a while for large files.
blocks, err := Blocks(fd, blockSize, size, counter)
if err != nil {
l.Debugln("blocks:", err)
return nil, err
}
// Recheck the size and modtime again. If they differ, the file changed
// while we were reading it and our hash results are invalid.
fi, err = fd.Stat()
if err != nil {
l.Debugln("stat after:", err)
return nil, err
}
if size != fi.Size() || !modTime.Equal(fi.ModTime()) {
return nil, errors.New("file changed during hashing")
}
return blocks, nil
}
func hashFiles(dir string, blockSize int, outbox, inbox chan protocol.FileInfo, counter Counter, cancel chan struct{}) {
for {
select {
case f, ok := <-inbox:
if !ok {
return
}
if f.IsDirectory() || f.IsDeleted() {
panic("Bug. Asked to hash a directory or a deleted file.")
}
blocks, err := HashFile(filepath.Join(dir, f.Name), blockSize, counter)
if err != nil {
l.Debugln("hash error:", f.Name, err)
continue
}
f.Blocks = blocks
// The size we saw when initially deciding to hash the file
// might not have been the size it actually had when we hashed
// it. Update the size from the block list.
f.Size = 0
for _, b := range blocks {
f.Size += int64(b.Size)
}
select {
case outbox <- f:
case <-cancel:
return
}
case <-cancel:
return
}
}
}
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