145 lines
3.5 KiB
Go
145 lines
3.5 KiB
Go
// Copyright (C) 2014 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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package scanner
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import (
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"context"
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"errors"
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"github.com/syncthing/syncthing/lib/fs"
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"github.com/syncthing/syncthing/lib/protocol"
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"github.com/syncthing/syncthing/lib/sync"
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)
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// HashFile hashes the files and returns a list of blocks representing the file.
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func HashFile(ctx context.Context, fs fs.Filesystem, path string, blockSize int, counter Counter, useWeakHashes bool) ([]protocol.BlockInfo, error) {
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fd, err := fs.Open(path)
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if err != nil {
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l.Debugln("open:", err)
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return nil, err
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}
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defer fd.Close()
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// Get the size and modtime of the file before we start hashing it.
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fi, err := fd.Stat()
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if err != nil {
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l.Debugln("stat before:", err)
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return nil, err
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}
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size := fi.Size()
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modTime := fi.ModTime()
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// Hash the file. This may take a while for large files.
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blocks, err := Blocks(ctx, fd, blockSize, size, counter, useWeakHashes)
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if err != nil {
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l.Debugln("blocks:", err)
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return nil, err
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}
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// Recheck the size and modtime again. If they differ, the file changed
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// while we were reading it and our hash results are invalid.
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fi, err = fd.Stat()
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if err != nil {
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l.Debugln("stat after:", err)
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return nil, err
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}
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if size != fi.Size() || !modTime.Equal(fi.ModTime()) {
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return nil, errors.New("file changed during hashing")
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}
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return blocks, nil
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}
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// The parallel hasher reads FileInfo structures from the inbox, hashes the
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// file to populate the Blocks element and sends it to the outbox. A number of
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// workers are used in parallel. The outbox will become closed when the inbox
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// is closed and all items handled.
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type parallelHasher struct {
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fs fs.Filesystem
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workers int
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outbox chan<- protocol.FileInfo
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inbox <-chan protocol.FileInfo
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counter Counter
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done chan<- struct{}
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useWeakHashes bool
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wg sync.WaitGroup
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}
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func newParallelHasher(ctx context.Context, fs fs.Filesystem, workers int, outbox chan<- protocol.FileInfo, inbox <-chan protocol.FileInfo, counter Counter, done chan<- struct{}, useWeakHashes bool) {
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ph := ¶llelHasher{
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fs: fs,
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workers: workers,
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outbox: outbox,
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inbox: inbox,
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counter: counter,
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done: done,
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useWeakHashes: useWeakHashes,
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wg: sync.NewWaitGroup(),
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}
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for i := 0; i < workers; i++ {
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ph.wg.Add(1)
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go ph.hashFiles(ctx)
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}
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go ph.closeWhenDone()
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}
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func (ph *parallelHasher) hashFiles(ctx context.Context) {
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defer ph.wg.Done()
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for {
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select {
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case f, ok := <-ph.inbox:
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if !ok {
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return
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}
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if f.IsDirectory() || f.IsDeleted() {
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panic("Bug. Asked to hash a directory or a deleted file.")
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}
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blocks, err := HashFile(ctx, ph.fs, f.Name, f.BlockSize(), ph.counter, ph.useWeakHashes)
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if err != nil {
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l.Debugln("hash error:", f.Name, err)
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continue
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}
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f.Blocks = blocks
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// The size we saw when initially deciding to hash the file
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// might not have been the size it actually had when we hashed
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// it. Update the size from the block list.
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f.Size = 0
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for _, b := range blocks {
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f.Size += int64(b.Size)
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}
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select {
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case ph.outbox <- f:
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case <-ctx.Done():
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return
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}
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case <-ctx.Done():
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return
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}
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}
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}
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func (ph *parallelHasher) closeWhenDone() {
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ph.wg.Wait()
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if ph.done != nil {
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close(ph.done)
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}
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close(ph.outbox)
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}
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