* lib/model, cmd/syncthing: Wait for folder restarts to complete (fixes#5233)
This is the somewhat ugly - but on the other hand clear - fix for what
is really a somewhat thorny issue. To avoid zombie folder runners a new
mutex is introduced that protects the RestartFolder operation. I hate
adding more mutexes but the alternatives I can think of are worse.
The other part of it is that the POST /rest/system/config operation now
waits for the config commit to complete. The point of this is that until
the commit has completed we should not accept another config commit. If
we did, we could end up with two separate RestartFolders queued in the
background. While they are both correct, and will run without
interfering with each other, we can't guarantee the order in which they
will run. Thus it could happen that the newer config got committed
first, and the older config commited after that, leaving us with the
wrong config running.
* test
* wip
* hax
* hax
* unflake test
* per folder mutexes
* paranoia
* race
The problem here is that we would update the sequence index before
updating the FileInfos, which would result in a high sequence number
pointing to a low-sequence FileInfo. The index sender would pick up the
high sequence number, send the old file, and think everything was good.
On the receiving side the old file is a no-op and ignored. The file
remains out of sync until another update for it happens.
This fixes that by correcting the order of operations in the database
update: first we remove old sequence index entries, then we update the
FileInfos (which now don't have anything pointing to them) and then we
add the sequence indexes (which the index sender can see).
The other option is to add "proper" transactions where required at the
database layer. I actually have a branch for that, but it's literally
thousands of lines of diff and I'm putting that off for another day as
this solves the problem...
The problem here is that we would update the sequence index before
updating the FileInfos, which would result in a high sequence number
pointing to a low-sequence FileInfo. The index sender would pick up the
high sequence number, send the old file, and think everything was good.
On the receiving side the old file is a no-op and ignored. The file
remains out of sync until another update for it happens.
This fixes that by correcting the order of operations in the database
update: first we remove old sequence index entries, then we update the
FileInfos (which now don't have anything pointing to them) and then we
add the sequence indexes (which the index sender can see).
The other option is to add "proper" transactions where required at the
database layer. I actually have a branch for that, but it's literally
thousands of lines of diff and I'm putting that off for another day as
this solves the problem...
This removes the out of disk space check from CheckHealth. The disk space is now
only checked if there are files to pull, in which case pulling those files is
stopped, but everything else (dirs, links, deletes) keeps running -> can recover
disk space through pulling.
Adds a receive only folder type that does not send changes, and where the user can optionally revert local changes. Also changes some of the icons to make the three folder types distinguishable.
This is an improvement of PR #4493 and related to (and maybe fixing) #4961
and #4475. Maybe fixing, because there is no clear reproducer for that
problem.
The previous PR added a mechanism to resurrect missing parent directories,
if there is a valid child file to be pulled. The same mechanism does not
exist for dirs and symlinks, even though a missing parent can happen for
those items as well. Therefore this PR extends the resurrection to all types
of pulled items.
In addition I moved the IsDeleted branch while iterating over
processDirectly to the existing IsDeleted branch in the WithNeed iteration.
This saves one pointless assignment and IsDeleted query. Also
We have the invalid bit to indicate that a file isn't good. That's enough for remote devices. For ourselves, it would be good to know sometimes why the file isn't good - because it's an unsupported type, because it matches an ignore pattern, or because we detected the data is bad and we need to rescan it.
Or, and this is the main future reason for the PR, because it's a change detected on a receive only device. We will want something like the invalid flag for those changes, but marking them as invalid today means the scanner will rehash them. Hence something more fine grained is required.
This introduces a LocalFlags fields to the FileInfo where we can stash things that we care about locally. For example,
FlagLocalUnsupported = 1 << 0 // The kind is unsupported, e.g. symlinks on Windows
FlagLocalIgnored = 1 << 1 // Matches local ignore patterns
FlagLocalMustRescan = 1 << 2 // Doesn't match content on disk, must be rechecked fully
The LocalFlags fields isn't sent over the wire; instead the Invalid attribute is calculated based on the flags at index sending time. It's on the FileInfo anyway because that's what we serialize to database etc.
The actual Invalid flag should after this just be considered when building the global state and figuring out availability for remote devices. It is not used for local file index entries.
To optimize WithNeed, which is called for the local device whenever an index
update is received. No tracking for remote devices to conserve db space, as
WithNeed is only queried for completion.
I'm trying to slowly clean this up a bit, and moving functionality out
into the folder types and having those methods not reach into model is
part of it. That can mean takign some odd arguments in the meantime,
some of those should probably become interfaces or properties on folder
in the long term.
The functionality was anyway mostly implemented there and not isolated
in the folderScanner type. The attempt to refactor it out in the other
direction wouldn't work given that the event loop and stuff is on
`folder`.
To newer names better reflecting their types and yet sorting together
with folder.go. Doing it now without asking because there are no open
PRs that will get killed by it, and to avoid bikeshedding the names.
The actual pull method (which is really the only thing that differs
between them) is now an interface member which gets overridden by the
subclass.
"Subclass?!" Well, this is dynamic dispatch with overriding, I guess.
Instead of walking and unmarshalling the entire db and sorting the resulting
file infos by sequence, add store device keys by sequence number in the
database. Thus only the required file infos need be unmarshalled and are already
sorted by index.
Bumping the limit to 2 * the max block size (16 MiB) is a slight
increase compared to previously. Nonetheless I think it's good to allow
us to queue one request and have one on the way in, or conversely have
one large block on the way in and be able to ask for smaller blocks from
others at the same time.
Unignored files are marked as conflicting while scanning, which is then resolved
in the subsequent pull. Automatically reconciles needed items on send-only
folders, if they do not actually differ except for internal metadata.
This doesn't happen today, but it might in the future if the block size
were increased or made variable and we were talking to a client from the
future.
When scanner.Walk detects a change, it now returns the new file info as well as the old file info. It also finds deleted and ignored files while scanning.
Also directory deletions are now always committed to db after their children to prevent temporary failure on remote due to non-empty directory.
Since #4340 pulls aren't happening every 10s anymore and may be delayed up to 1h.
This means that no folder error event reaches the web UI for a long time, thus no
failed items will show up for a long time. Now errors are populated when the
web UI is opened.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4650
LGTM: AudriusButkevicius
This no longer pokes at model internals, and only touches the config.
As a result, model handles this in CommitConfiguration, which restarts
the folders if things change, which repopulate m.folderDevice, m.deviceFolder
and other interal mappings.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4639
Also attempt to handle this nicer by ignoring the truncate failure when
it doesn't matter, and recover by deleting the temp file when it does.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4594
This keeps the data we need about sequence numbers and object counts
persistently in the database. The sizeTracker is expanded into a
metadataTracker than handled multiple folders, and the Counts struct is
made protobuf serializable. It gains a Sequence field to assist in
tracking that as well, and a collection of Counts become a CountsSet
(for serialization purposes).
The initial database scan is also a consistency check of the global
entries. This shouldn't strictly be necessary. Nonetheless I added a
created timestamp to the metadata and set a variable to compare against
that. When the time since the metadata creation is old enough, we drop
the metadata and rebuild from scratch like we used to, while also
consistency checking.
A new environment variable STCHECKDBEVERY can override this interval,
and for example be set to zero to force the check immediately.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4547
LGTM: imsodin
Fix the folder restart behavior (ignore Label), improve the API for that
(imho).
Also removes the tab switch animation in the settings modal, because
annoying.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4577
This should address issue as described in https://forum.syncthing.net/t/stun-nig-party-with-paused-devices/10942/13
Essentially the model and the connection service goes out of sync in terms of thinking if we are connected or not.
Resort to model as being the ultimate source of truth.
I can't immediately pin down how this happens, yet some ideas.
ConfigSaved happens in separate routine, so it's possbile that we have some sort of device removed yet connection comes in parallel kind of thing.
However, in this case the connection exists in the model, and does not exist in the connection service and the only way for the connection to be removed
in the connection service is device removal from the config.
Given the subject, this might also be related to the device being paused.
Also, adds more info to the logs
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4533
We need to reset prevSeq so that we force a full check when someone
reconnects - the sequence number may not have changed due to the
reconnect. (This is a regression; we did this before f6ea2a7.)
Also add an optimization: we schedule a pull after scanning, but there
is no need to do so if no changes were detected. This matters now
because the scheduled pull actually traverses the database which is
expensive.
This, however, makes the pull not happen on initial scan if there were
no changes during the initial scan. Compensate by always scheduling a
pull after initial scan in the rwfolder itself.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4508
LGTM: imsodin, AudriusButkevicius
Diff is large due to comment reformatting and indentation but all it
does is wrap the file mtime/size/permissions check in an "if
stat.IsRegular()".
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4507
This removes a significant, complex chunk of database code. The
"replace" operation walked both the old and new in lockstep and made the
relevant changes to make the new situation correct. But since delta
indexes we pretty much never need this - we just used replace to drop
the existing data and start over.
This makes that explicit and removes the complexity.
(This is one of those things that would be annoying to make case
insensitive, while the actual "drop and then insert" that we do is
easier.)
This is fairly well unit tested...
The one change to the tests is to cover the fact that previously replace
with something identical didn't bump the sequence number, while
obviously removing everything and re-inserting does. This is not
behavior we depend on anywhere.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4500
LGTM: imsodin, AudriusButkevicius
The folder marker conversion forgot to hide the .stfolder. This adds
that, for those who have not yet been converted.
Also adds Hide() calls to the folder start, to mend historical
unhidedness. (I'm sure this will upset someone who is manually managing
their .stignores in the other direction...)
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4384
Currently all errors during pulling and the first of these errors again on
finishing are logged to info. Besides that the errors logged when finishing
are stored in f.errors. This PR moves all logging during pulling to the debug
channel (they might still be relevant in some obscure debugging case) and
uses the stored errors to log the main error per fail when all pulling
iterations are done and failed.
Additional instead of trying 11 times it now only tries 3 times.
This is the first part of what is discussed here:
https://forum.syncthing.net/t/reduce-verboseness-of-puller/10261
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4338
Prior to this, the following is possible:
- Create a symlink "foo -> /somewhere", it gets synced
- Delete "foo", it gets versioned
- Create "foo/bar", it gets synced
- Delete "foo/bar", it gets versioned in "/somewhere/bar"
With this change, versioners should never version symlinks.
This solves the erratic test failures on model.TestIgnores by ensuring
that the ignore patterns are reloaded even in the face of unchanged
timestamps.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4208
The folder already knew how to stop properly, but the fs.Walk() didn't
and can potentially take a very long time. This adds context support to
Walk and the underlying scanning stuff, and passes in an appropriate
context from above. The stop channel in model.folder is replaced with a
context for this purpose.
To test I added an infiniteFS that represents a large amount of data
(not actually infinite, but close) and verify that walking it is
properly stopped. For that to be implemented smoothly I moved out the
Walk function to it's own type, as typically the implementer of a new
filesystem type might not need or want to reimplement Walk.
It's somewhat tricky to test that this actually works properly on the
actual sendReceiveFolder and so on, as those are started from inside the
model and the filesystem isn't easily pluggable etc. Instead I've tested
that part manually by adding a huge folder and verifying that pause,
resume and reconfig do the right things by looking at debug output.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4117
Harmonize how we use batches in the model, using ProtoSize() to judge
the actual weight of the entire batch instead of estimating. Use smaller
batches in the block map - I think we might have though that batch.Len()
in the leveldb was the batch size in bytes, but it's actually number of
operations.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4114
The mechanism to disallow manual scans before the initial scan completed
(#3996) , had the side effect, that if the initial scan failed, no further
scans are allowed. So this marks the initial scan as finished regardless of
whether it succeeded or not.
There was also redundant code in rofolder and a pointless check for folder
health in scanSubsIfHealthy (happens in internalScanFolderSubdirs as well).
This also moves logging from folder.go to ro/rw-folder.go to include the
information about whether it is send-only or send-receive
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4104
This deprecates the current minDiskFreePct setting and introduces
minDiskFree. The latter is, in it's serialized form, a string with a
unit. We accept percentages ("2.35%") and absolute values ("250 k", "12.5
Gi"). Common suffixes are understood. The config editor lets the user
enter the string, and validates it.
We still default to "1 %", but the user can change that to an absolute
value at will.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4087
LGTM: AudriusButkevicius, imsodin
This adds a new config AllowedNetworks per device, which when set should
contain a list of network prefixes (192.168.0.0/126 etc) that are
allowed for the given device. The connection service will not attempt
connections to addresses outside of the given networks and incoming
connections will be rejected as well.
I've added the config to the normal device editor and shown it (when
set) in the device summary on the main screen.
There's a unit test for the IsAllowedNetwork method, I've done some
manual sanity testing on top of that.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4073
One more step on the path of the great refactoring. Touches rwfolder a
little bit since it uses the Lstat from fs as well, but mostly this is
just on the scanner as rwfolder is scheduled for a later refactor.
There are a couple of usages of fs.DefaultFilesystem that will in the
end become a filesystem injected from the top, but that comes later.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4070
LGTM: AudriusButkevicius, imsodin
Adds a unit test to ensure we don't scan symlinks on Windows. For the
rwfolder, trusts that the logic in the invalid check is correct and that
the check is actually called from the need loop.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4042
Basically, if we don't care about the sync status of the file we should
not tag someone else out of sync because they don't have the latest
version. This solves *my* "Syncing - 100%" scenario at least.
The reason this happens seems to be like this, in my situation. I have
three devices, connected in a "line": A-B-C. A is a Mac and litters
.DS_Store files everywhere. I've ignored these, but some escaped into
the folders before I did so. I've also ignored them on B and C but at
different stages. B was flagging C as out of sync, because at the point
the ignores were introduced C had a lower version of .DS_Store than A.
Now none of them are sending updates about it any more since it's
ignored...
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3981
After this change,
- Symlinks on Windows are always unsupported. Sorry.
- Symlinks are always enabled on other platforms. They are just a small
file like anything else. There is no need to special case them. If you
don't want to sync some symlinks, ignore them.
- The protocol doesn't differentiate between different "types" of
symlinks. If that distinction ever does become relevant the individual
devices can figure it out by looking at the destination when they
create the link.
It's backwards compatible in that all the old symlink types are still
understood to be symlinks, and the new SYMLINK type is equivalent to the
old SYMLINK_UNKNOWN which was always a valid way to do it.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3962
LGTM: AudriusButkevicius
Syncthing adds some hidden files when a folder is added, but there is currently
no equivalent cleanup procedure. This change is conservative as not to
accidentally cause data loss.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3874
Since we anyway need the folderConfig for this I'm skipping the copying
of all it's attributes that rwfolder did and just keeping the original
around instead.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3825
Instead, trust (and test) that the temp file has appropriate permissions
from the start. The only place where this changes our behavior is for
ignores which go from 0644 to 0600. I'm OK with that.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3756
This makes the device ID a real type that can be used in the protobuf
schema. That avoids the juggling back and forth from []byte in a bunch
of places and simplifies the code.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3695
When files that were previously marked as deleted became ignored, we
used to do nothing at all. This changes that behavior to set the Invalid
bit (that we should rename to Ignored). This then becomes an update to
other devices that they should not trust our knowledge about the file in
question.
Read this diff without whitespace...
Tested by
- creating a bunch of files on s1
- letting them sync to s2
- shutting down s2
- deleting the files on s1 and rescanning
- adding the files to .stignore on s1 and rescanning
- starting up s2 and letting it sync
- observing the files are not deleted on s2, and it considers itself up
to date.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3557
We used to consider deleted files & directories 128 bytes large. After
the delta indexes change a bug slipped in where deleted files would be
weighted according to their old non-deleted size. Both ways are
incorrect (but the latest change made it worse), as if there are more
files deleted than remaining data in the repo the needSize can be
greater than the globalSize, resulting in a negative completion
percentage.
This change makes it so that deleted items are zero bytes large, which
makes more sense. Instead we expose the number of files that we need to
delete as a separate field in the Completion() result, and hack the
percentage down to 95% complete if it was 100% complete but we need to
delete files. This latter part is sort of ugly, but necessary to give
the user some sort of feedback.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3556
We previously set the mtime on the temp file, and then renamed it to the
real path. Unfortunately that means we'd save the real timestamp under
the under the temp name ".syncthing.foo.tmp" when the actual file that
we will look up on the next scan is "foo". This moves the Chtimes later,
ensuring that it gets recorded correctly under the right name.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3519
These are no longer required with Go 1.7. Change made by removing the
functions, doing a global s/osutil.Remove/os.Remove/.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3514
So there were some issues here. The main problem was that
model.Close(deviceID) was overloaded to mean "the connection was closed
by the protocol layer" and "i want to close this connection". That meant
it could get called twice - once *to* close the connection and then once
more when the connection *was* closed.
After this refactor there is instead a Closed(conn) method that is the
callback. I didn't need to change the parameter in the end, but I think
it's clearer what it means when it takes the connection that was closed
instead of a device ID. To close a connection, the new close(deviceID)
method is used instead, which only closes the underlying connection and
leaves the cleanup to the Closed() callback.
I also changed how we do connection switching. Instead of the connection
service calling close and then adding the connection, it just adds the
new connection. The model knows that it already has a connection and
makes sure to close and clean out that one before adding the new
connection.
To make sure to sequence this properly I added a new map of channels
that get created on connection add and closed by Closed(), so that
AddConnection() can do the close and wait for the cleanup to happen
before proceeding.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3490
Furthermore:
1. Cleans configs received, migrates them as we receive them.
2. Clears indexes of devices we no longer share the folder with
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3478
This adds a new nanoseconds field to the FileInfo, populates it during
scans and sets the non-truncated time in Chtimes calls.
The actual file modification time is defined as modified_s seconds +
modified_ns nanoseconds. It's expected that the modified_ns field is <=
1e9 (that is, all whole seconds should go in the modified_s field) but
not really enforced. Given that it's an int32 the timestamp can be
adjusted += ~2.9 seconds by the modified_ns field...
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3431
We could have a file to sync with permissions rw------- but we'd create
the temp file with rw-rw-rw- minus umask, usually rw-r--r--. This
potentially exposes private data while the file is being synced.
Similarly, when ignorePerms was set and we were reusing a temp files we
would set the permissions to rw-r--r-- explicitly, potentially
overriding a strict umask that would otherwise have had the file be
rw-------.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3437
This changes the BEP protocol to use protocol buffer serialization
instead of XDR, and therefore also the database format. The local
discovery protocol is also updated to be protocol buffer format.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3276
LGTM: AudriusButkevicius
This contains the following behavioral changes:
- Duplicate folder IDs is now fatal during startup
- Invalid folder flags in the ClusterConfig is fatal for the connection
(this will go away soon with the proto changes, as we won't have any
unknown flags any more then)
- Empty path is a folder error reported at runtime
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3370
The various path cleaning operations done in in cleanedPath() removes
it, so we make sure it's added again at the end. This makes adding the
slash in prepare() unnecessary, but keep it anyway for display purposes
(people looking at the config).
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3342
While attempting to fix#2782 I thought the problem was the
CheckFolderHealth method, so I cleaned it up. That turned out not to be
the case, but I think this is better anyhow.
It also moves the "create folder and marker if the folder was empty in
the index" code to StartFolder where I think it makes better sense.
This is covered by a number of existing tests.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3343
This adds a metric for "committed items" to the database instance that I
use in the test code, and a couple of tests that ensure that scans that
don't change anything also don't commit anything.
There was a case in the scanner where we set the invalid bit on files
that are ignored, even though they were already ignored and had the
invalid bit set. I had assumed this would result in an extra database
commit, but it was in fact filtered out by the Set... Anyway, I think we
can save some work on not pushing that change to the Set at all.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3298
This is in preparation for future changes, but also improves the
handling when talking to pre-v0.13 clients. It breaks out the Hello
message and magic from the rest of the protocol implementation, with the
intention that this small part of the protocol will survive future
changes.
To enable this, and future testing, the new ExchangeHello function takes
an interface that can be implemented by future Hello versions and
returns a version indendent result type. It correctly detects pre-v0.13
protocols and returns a "too old" error message which gets logged to the
user at warning level:
[I6KAH] 09:21:36 WARNING: Connecting to [...]:
the remote device speaks an older version of the protocol (v0.12) not
compatible with this version
Conversely, something entirely unknown will generate:
[I6KAH] 09:40:27 WARNING: Connecting to [...]:
the remote device speaks an unknown (newer?) version of the protocol
The intention is that in future iterations the Hello exchange will
succeed on at least one side and ExchangeHello will return the actual
data from the Hello together with ErrTooOld and an even more precise
message can be generated.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3289
Without this the summary service doesn't know to recalculate completion
percentage for remote devices when DownloadProgress messages come in.
That means that completion percentage isn't updated in the GUI while
transfers of large files are ongoing. With this change, it updates
correctly.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3144
I think this better reflects what it means. Also tweaks the verbose
format to be more like our other things and lightly refactors the code
to not have the boolean and include the folder in the event.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3121
The old usage pattern was to create a Walker with a bunch of attributes,
then call Walk() on it and nothing else. This extracts the attributes
into a Config struct and exposes a Walk(cfg Config) method instead, as
there was no reason to expose the state-holding walker type.
Also creates a few no-op implementations of the necessary interfaces
so that we can skip nil checks and simiplify things here and there.
Definitely look at this diff without whitespace.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3060
When doing prefix scans in the database, "foo" should not be considered
a prefix of "foo2". Instead, it should match "foo" exactly and also
strings with the prefix "foo/". This is more restrictive than what the
standard leveldb prefix scan does so we add some code to enforce it.
Also exposes the initialScanCompleted on the rwfolder for testing, and
change it to be a channel (so we can wait for it from another
goroutine). Otherwise we can't be sure when the initial scan has
completed, and we need to wait for that or it might pick up changes
we're doing at an unexpected time.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3067
The VersioningConfig change is because it defaults to nil but gets
deserialized to map[string]string{}. Now prepare() enforces a single
representation of the empty map.
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3065
1. Removes separate relay lists and relay clients/services, just makes it a listen address
2. Easier plugging-in of other transports
3. Allows "hot" disabling and enabling NAT services
4. Allows "hot" listen address changes
5. Changes listen address list with a preferable "default" value just like for discovery
6. Debounces global discovery announcements as external addresses change (which it might alot upon starting)
7. Stops this whole "pick other peers relay by latency". This information is no longer available,
but I don't think it matters as most of the time other peer only has one relay.
8. Rename ListenAddress to ListenAddresses, as well as in javascript land.
9. Stop serializing deprecated values to JSON
GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/2982
