Open Source Continuous File Synchronization
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Jakob Borg 8fc2dfad0c
lib/db: Deduplicate block lists in database (fixes #5898) (#6283)
* lib/db: Deduplicate block lists in database (fixes #5898)

This moves the block list in the database out from being just a field on
the FileInfo to being an object of its own. When putting a FileInfo we
marshal the block list separately and store it keyed by the sha256 of
the marshalled block list. When getting, if we are not doing a
"truncated" get, we do an extra read and unmarshal for the block list.

Old block lists are cleared out by a periodic GC sweep. The alternative
would be to use refcounting, but:

- There is a larger risk of getting that wrong and either dropping a
  block list in error or keeping them around forever.

- It's tricky with our current database, as we don't have dirty reads.
  This means that if we update two FileInfos with identical block lists in
  the same transaction we can't just do read/modify/write for the ref
  counters as we wouldn't see our own first update. See above about
  tracking this and risks about getting it wrong.

GC uses a bloom filter for keys to avoid heavy RAM usage. GC can't run
concurrently with FileInfo updates so there is a new lock around those
operation at the lowlevel.

The end result is a much more compact database, especially for setups
with many peers where files get duplicated many times.

This is per-key-class stats for a large database I'm currently working
with, under the current schema:

```
 0x00:  9138161 items, 870876 KB keys + 7397482 KB data, 95 B +  809 B avg, 1637651 B max
 0x01:   185656 items,  10388 KB keys + 1790909 KB data, 55 B + 9646 B avg,  924525 B max
 0x02:   916890 items,  84795 KB keys +    3667 KB data, 92 B +    4 B avg,     192 B max
 0x03:      384 items,     27 KB keys +       5 KB data, 72 B +   15 B avg,      87 B max
 0x04:     1109 items,     17 KB keys +      17 KB data, 15 B +   15 B avg,      69 B max
 0x06:      383 items,      3 KB keys +       0 KB data,  9 B +    2 B avg,      18 B max
 0x07:      510 items,      4 KB keys +      12 KB data,  9 B +   24 B avg,      41 B max
 0x08:     1349 items,     12 KB keys +      10 KB data,  9 B +    8 B avg,      17 B max
 0x09:      194 items,      0 KB keys +     123 KB data,  5 B +  634 B avg,   11484 B max
 0x0a:        3 items,      0 KB keys +       0 KB data, 14 B +    7 B avg,      30 B max
 0x0b:   181836 items,   2363 KB keys +   10694 KB data, 13 B +   58 B avg,     173 B max
 Total 10426475 items, 968490 KB keys + 9202925 KB data.
```

Note 7.4 GB of data in class 00, total size 9.2 GB. After running the
migration we get this instead:

```
 0x00:  9138161 items, 870876 KB keys + 2611392 KB data, 95 B +  285 B avg,    4788 B max
 0x01:   185656 items,  10388 KB keys + 1790909 KB data, 55 B + 9646 B avg,  924525 B max
 0x02:   916890 items,  84795 KB keys +    3667 KB data, 92 B +    4 B avg,     192 B max
 0x03:      384 items,     27 KB keys +       5 KB data, 72 B +   15 B avg,      87 B max
 0x04:     1109 items,     17 KB keys +      17 KB data, 15 B +   15 B avg,      69 B max
 0x06:      383 items,      3 KB keys +       0 KB data,  9 B +    2 B avg,      18 B max
 0x07:      510 items,      4 KB keys +      12 KB data,  9 B +   24 B avg,      41 B max
 0x09:      194 items,      0 KB keys +     123 KB data,  5 B +  634 B avg,   11484 B max
 0x0a:        3 items,      0 KB keys +       0 KB data, 14 B +   17 B avg,      51 B max
 0x0b:   181836 items,   2363 KB keys +   10694 KB data, 13 B +   58 B avg,     173 B max
 0x0d:    44282 items,   1461 KB keys +   61081 KB data, 33 B + 1379 B avg, 1637399 B max
 Total 10469408 items, 969939 KB keys + 4477905 KB data.
```

Class 00 is now down to 2.6 GB, with just 61 MB added in class 0d.

There will be some additional reads in some cases which theoretically
hurts performance, but this will be more than compensated for by smaller
writes and better compaction.

On my own home setup which just has three devices and a handful of
folders the difference is smaller in absolute numbers of course, but
still less than half the old size:

```
 0x00:  297122 items,  20894 KB keys + 306860 KB data, 70 B + 1032 B avg, 103237 B max
 0x01:  115299 items,   7738 KB keys +  17542 KB data, 67 B +  152 B avg,    419 B max
 0x02: 1430537 items, 121223 KB keys +   5722 KB data, 84 B +    4 B avg,    253 B max
 ...
 Total 1947412 items, 151268 KB keys + 337485 KB data.
```

to:

```
 0x00:  297122 items,  20894 KB keys +  37038 KB data, 70 B +  124 B avg,    520 B max
 0x01:  115299 items,   7738 KB keys +  17542 KB data, 67 B +  152 B avg,    419 B max
 0x02: 1430537 items, 121223 KB keys +   5722 KB data, 84 B +    4 B avg,    253 B max
 ...
 0x0d:   18041 items,    595 KB keys +  71964 KB data, 33 B + 3988 B avg, 101109 B max
 Total 1965447 items, 151863 KB keys + 139628 KB data.
```

* wip

* wip

* wip

* wip
2020-01-24 08:35:44 +01:00
.github github: bump Syncthing version to v1... (#6191) 2019-11-26 08:25:50 +00:00
assets assets, gui: Losslessly compress all JPG, PNG, and PDF images (#6265) 2020-01-16 13:52:43 +01:00
cmd lib/db: Deduplicate block lists in database (fixes #5898) (#6283) 2020-01-24 08:35:44 +01:00
etc cmd/syncthing: Always use monitor process (fixes #4774, fixes #5786) (#6278) 2020-01-20 09:07:46 +01:00
gui gui, man, authors: Update docs, translations, and contributors 2020-01-22 07:45:33 +01:00
lib lib/db: Deduplicate block lists in database (fixes #5898) (#6283) 2020-01-24 08:35:44 +01:00
man gui, man, authors: Update docs, translations, and contributors 2020-01-22 07:45:33 +01:00
meta authors: Enable auto updates (#5074) 2018-07-23 17:41:59 +02:00
script docker: Fix HOME setting (fixes #6234) (#6235) 2019-12-22 17:50:16 +01:00
test test: Get integration tests up to speed (config, build and test fixes) (#5962) 2019-08-20 10:17:11 +02:00
.codecov.yml build: Add option to get test coverage (#5539) 2019-02-14 22:38:47 +00:00
.gitattributes lib/protocol: Revert protobuf encoder changes in v0.14.17 (fixes #3855) 2017-01-01 17:19:00 +00:00
.gitignore all: Become a Go module (fixes #5148) (#5384) 2018-12-18 12:36:38 +01:00
.golangci.yml golangci: Skip godox 2019-12-18 11:33:36 +01:00
AUTHORS gui, man, authors: Update docs, translations, and contributors 2020-01-22 07:45:33 +01:00
build.go build: Generalize code signing 2019-12-03 08:37:43 +01:00
build.sh authors: Enable auto updates (#5074) 2018-07-23 17:41:59 +02:00
CONDUCT.md conduct: Upgrade to Contributor Covenant 2018-06-20 23:53:06 +02:00
CONTRIBUTING.md all: Update docs.s.n links to use https 2016-10-27 17:02:19 +00:00
Dockerfile docker: Add stdiscosrv and strelaysrv Dockerfiles (#6143) 2019-11-11 09:37:08 +01:00
Dockerfile.stdiscosrv docker: Add stdiscosrv and strelaysrv Dockerfiles (#6143) 2019-11-11 09:37:08 +01:00
Dockerfile.strelaysrv docker: Add stdiscosrv and strelaysrv Dockerfiles (#6143) 2019-11-11 09:37:08 +01:00
go.mod lib/db: Deduplicate block lists in database (fixes #5898) (#6283) 2020-01-24 08:35:44 +01:00
go.sum lib/db: Deduplicate block lists in database (fixes #5898) (#6283) 2020-01-24 08:35:44 +01:00
GOALS.md goals: Typo 2017-12-12 08:12:30 +00:00
LICENSE all: Update license url to https (ref #3976) 2017-02-09 08:04:16 +01:00
README-Docker.md docker: Make it easy to disable the GUI, document it (#6021) 2019-09-22 11:33:29 +01:00
README.md readme: Fix broken link to README-Docker.md (#6025) 2019-09-23 13:28:42 +09:00
snapcraft.yaml.template snapcraft: Add desktop plug (#6069) 2019-10-08 18:20:51 +01:00

Syncthing


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Goals

Syncthing is a continuous file synchronization program. It synchronizes files between two or more computers. We strive to fulfill the goals below. The goals are listed in order of importance, the most important one being the first. This is the summary version of the goal list - for more commentary, see the full Goals document.

Syncthing should be:

  1. Safe From Data Loss

    Protecting the user's data is paramount. We take every reasonable precaution to avoid corrupting the user's files.

  2. Secure Against Attackers

    Again, protecting the user's data is paramount. Regardless of our other goals we must never allow the user's data to be susceptible to eavesdropping or modification by unauthorized parties.

  3. Easy to Use

    Syncthing should be approachable, understandable and inclusive.

  4. Automatic

    User interaction should be required only when absolutely necessary.

  5. Universally Available

    Syncthing should run on every common computer. We are mindful that the latest technology is not always available to any given individual.

  6. For Individuals

    Syncthing is primarily about empowering the individual user with safe, secure and easy to use file synchronization.

  7. Everything Else

    There are many things we care about that don't make it on to the list. It is fine to optimize for these values, as long as they are not in conflict with the stated goals above.

Getting Started

Take a look at the getting started guide.

There are a few examples for keeping Syncthing running in the background on your system in the etc directory. There are also several GUI implementations for Windows, Mac and Linux.

Docker

To run Syncthing in Docker, see the Docker README.

Vote on features/bugs

We'd like to encourage you to vote on issues that matter to you. This helps the team understand what are the biggest pain points for our users, and could potentially influence what is being worked on next.

Getting in Touch

The first and best point of contact is the Forum. There is also an IRC channel, #syncthing on freenode (with a web client), for talking directly to developers and users. If you've found something that is clearly a bug, feel free to report it in the GitHub issue tracker.

Building

Building Syncthing from source is easy, and there's a guide that describes it for both Unix and Windows systems.

Signed Releases

As of v0.10.15 and onwards release binaries are GPG signed with the key D26E6ED000654A3E, available from https://syncthing.net/security.html and most key servers.

There is also a built in automatic upgrade mechanism (disabled in some distribution channels) which uses a compiled in ECDSA signature. macOS binaries are also properly code signed.

Documentation

Please see the Syncthing documentation site.

All code is licensed under the MPLv2 License.