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b1c8f88a44
We've had weak/rolling hashing in the code for quite a while. It was a popular request for a while, based on the belief that rsync does this and we should too. However, the benefit is quite small; we save on average about 0.8% of transferred blocks over the population as a whole: <img width="974" alt="Screenshot 2025-03-28 at 17 09 02" src="https://github.com/user-attachments/assets/bbe10dea-f85e-4043-9823-7cef1220b4a2" /> This would be fine if the cost was comparably low, however the downside of attempting rolling hash matching is that we (by default) do a complete file read on the destination in order to look for matches before we starting pulling blocks for the file. For any larger file this means a sometimes long, I/O-intensive pause before the file starts syncing, for usually no benefit. I propose we simply rip off the bandaid and save the effort.
92 lines
1.9 KiB
Go
92 lines
1.9 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 protocol
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import (
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"time"
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)
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type TestModel struct {
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data []byte
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folder string
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name string
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offset int64
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size int32
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hash []byte
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fromTemporary bool
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indexFn func(string, []FileInfo)
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ccFn func(*ClusterConfig)
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closedCh chan struct{}
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closedErr error
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}
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func newTestModel() *TestModel {
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return &TestModel{
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closedCh: make(chan struct{}),
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}
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}
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func (t *TestModel) Index(_ Connection, idx *Index) error {
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if t.indexFn != nil {
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t.indexFn(idx.Folder, idx.Files)
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}
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return nil
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}
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func (*TestModel) IndexUpdate(Connection, *IndexUpdate) error {
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return nil
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}
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func (t *TestModel) Request(_ Connection, req *Request) (RequestResponse, error) {
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t.folder = req.Folder
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t.name = req.Name
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t.offset = req.Offset
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t.size = int32(req.Size)
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t.hash = req.Hash
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t.fromTemporary = req.FromTemporary
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buf := make([]byte, len(t.data))
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copy(buf, t.data)
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return &fakeRequestResponse{buf}, nil
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}
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func (t *TestModel) Closed(_ Connection, err error) {
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t.closedErr = err
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close(t.closedCh)
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}
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func (t *TestModel) ClusterConfig(_ Connection, config *ClusterConfig) error {
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if t.ccFn != nil {
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t.ccFn(config)
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}
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return nil
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}
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func (*TestModel) DownloadProgress(Connection, *DownloadProgress) error {
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return nil
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}
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func (t *TestModel) closedError() error {
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select {
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case <-t.closedCh:
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return t.closedErr
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case <-time.After(1 * time.Second):
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return nil // Timeout
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}
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}
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type fakeRequestResponse struct {
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data []byte
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}
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func (r *fakeRequestResponse) Data() []byte {
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return r.data
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}
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func (*fakeRequestResponse) Close() {}
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func (*fakeRequestResponse) Wait() {}
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