The proxy always checks the protocol version of a remote before talking
to it in a version-specific way, so the protocol version in the ProxyParams
is the client's protocol version. The remote will always be at the same or
an older protocol version than the client.
Note that in relayDATAFinish, when the client is at protocol version 0,
the remote must thus be as well, and that's why its version is not
checked in the case for that.
With that clarified, it's evident that, in P2P.Http.State, there's no
need to look at the proxied remote's protocol version at all.
For clusters, the timestamps have to be translated, since each node can
have its own idea about what time it is. To translate a timestamp, the
proxy remembers what time it asked the node for a timestamp in
GETTIMESTAMP, and applies the delta as an offset in REMOVE-BEFORE.
This does mean that a remove from a cluster has to call GETTIMESTAMP on
every node before dropping from nodes. Not very efficient. Although
currently it tries to drop from every single node anyway, which is also
not very efficient.
I thought about caching the GETTIMESTAMP from the nodes on the first
call. That would improve efficiency. But, since monotonic clocks on
!Linux don't advance when the computer is suspended, consider what might
happen if one node was suspended for a while, then came back. Its
monotonic timestamp would end up behind where the proxying expects it to
be. Would that result in removing when it shouldn't, or refusing to
remove when it should? Have not thought it through. Either way, a
cluster behaving strangly for an extended period of time because one
of its nodes was briefly asleep doesn't seem like good behavior.
This will allow having an internal thread speaking P2P protocol,
which will be needed to support proxying to external special remotes.
No serialization is done on the internal P2P protocol of course.
When a ByteString is being exchanged, it may or may not be exactly
the length indicated by DATA. While that has to be carefully managed
for the serialized P2P protocol, here it would require buffering the
whole lazy bytestring in memory to check its length when sending,
so it's better to do length checks on the receiving side.
Before it was using a node that might have had a higher cost.
Also threw in a random selection from amoung the low cost nodes. Of
course this is a poor excuse for load balancing, but it's better than
nothing. Most of the time...
Client side support for SUCCESS-PLUS and ALREADY-HAVE-PLUS
is complete, when a PUT stores to additional repositories
than the expected on, the location log is updated with the
additional UUIDs that contain the content.
Started implementing PUT fanout to multiple remotes for clusters.
It is untested, and I fear fencepost errors in the relative
offset calculations. And it is missing proxying for the protocol
after DATA.
Support selecting what remote to proxy for each top-level P2P protocol
message.
This only needs to be extended now to support fanout to multiple
nodes for PUT and REMOVE, and with a remote that fails for
LOCKCONTENT and UNLOCKCONTENT.
But a good first step would be to implement CHECKPRESENT and GET for
clusters. Both should select a node that actually does have the content.
That will allow a cluster to work for GET even when location tracking is
out of date.
Works down to P2P protocol.
The question now is, how to handle protocol version negotiation for
clusters? Connecting to each node to find their protocol versions and
using the lowest would be too expensive with a lot of nodes. So it seems
that the cluster needs to pick its own protocol version to use with the
client.
Then it can either negotiate that same version with the nodes when
it comes time to use them, or it can translate between multiple protocol
versions. That seems complicated. Thinking it would be ok to refuse to
use a node if it is not able to negotiate the same protocol version with
it as with the client. That will mean that sometimes need nodes to be
upgraded when upgrading the cluster's proxy. But protocol versions
rarely change.
For eg, upload fanout.
Delay connecting to a remote until it's needed. When there are many
proxied remotes, it would not do for the proxy to connect to each of
them on startup; that could take a long time.
This does mean a redundant write to the git-annex branch. But,
it means that two clients can be using the same proxy, and after
one sends a file to a proxied remote, the other only has to pull from
the proxy to learn about that. It does not need to pull from every
remote behind the proxy (which it couldn't do anyway as git repo
access is not currently proxied).
Anyway, the overhead of this in git-annex branch writes is no worse
than eg, sending a file to a repository where git-annex assistant
is running, which then sends the file on to a remote, and updates
the git-annex branch then. Indeed, when the assistant also drops
the local copy, that results in more writes to the git-annex branch.
This just happened to work correctly. Rather surprisingly. It turns out
that openP2PSshConnection actually also supports local git remotes,
by just running git-annex-shell with the path to the remote.
Renamed "P2PSsh" to "P2PShell" to make this clear.
Still need to implement GET and PUT, and will implement CONNECT and
NOTIFYCHANGE for completeness.
All ServerMode checking is implemented for the proxy.
There are two possible approaches for how the proxy sends back messages
from the remote to the client. One would be to have a background thread
that reads messages and sends them back as they come in. The other,
which is being implemented so far, is to read messages from the remote
at points where it is expected to send them, and relay back to the
client before reading the next message from the client. At this point,
I'm unsure which approach would be better.
The need for proxynoresponse to be used by UNLOCKCONTENT, for example,
builds protocol knowledge into the proxy which it would not need with
the other method.
connRepo is only used when relaying git upload-pack and receive-pack.
That's only supposed to be used when git-annex-remotedaemon is serving
git-remote-tor-annex connections over tor. But, it was always set, and
so could be used in other places possibly.
Fixed by making connRepo optional in the P2P protocol interface.
In Command.EnableTor, it's not needed, because it only speaks the
protocol in order to check that it's able to connect back to itself via
the hidden service. So changed that to pass Nothing rather than the git
repo.
In Remote.Helper.Ssh, it's connecting to git-annex-shell p2pstdio,
so is making the requests, so will never need connRepo.
In git-annex-shell p2pstdio, it was accepting git upload-pack and
receive-pack requests over the P2P protocol, even though nothing sent
them. This is arguably a security hole, particularly if the user has
set environment variables like GIT_ANNEX_SHELL_LIMITED to prevent
git push/pull via git-annex-shell.
The hoped for optimisation of CommandStart with -J did not materialize.
In fact, not runnign CommandStart in parallel is slower than -J3.
So, CommandStart are still run in parallel.
(The actual bad performance I've been seeing with -J in my big repo
has to do with building the remoteList.)
But, this is still progress toward making -J faster, because it gets rid
of the onlyActionOn roadblock in the way of making CommandCleanup jobs
run separate from CommandPerform jobs.
Added OnlyActionOn constructor for ActionItem which fixes the
onlyActionOn breakage in the last commit.
Made CustomOutput include an ActionItem, so even things using it can
specify OnlyActionOn.
In Command.Move and Command.Sync, there were CommandStarts that used
includeCommandAction, so output messages, which is no longer allowed.
Fixed by using startingCustomOutput, but that's still not quite right,
since it prevents message display for the includeCommandAction run
inside it too.
The goal is to be able to run CommandStart in the main thread when -J is
used, rather than unncessarily passing it off to a worker thread, which
incurs overhead that is signficant when the CommandStart is going to
quickly decide to stop.
To do that, the message it displays needs to be displayed in the worker
thread, after the CommandStart has run.
Also, the change will mean that CommandStart will no longer necessarily
run with the same Annex state as CommandPerform. While its docs already
said it should avoid modifying Annex state, I audited all the
CommandStart code as part of the conversion. (Note that CommandSeek
already sometimes runs with a different Annex state, and that has not been
a source of any problems, so I am not too worried that this change will
lead to breakage going forward.)
The only modification of Annex state I found was it calling
allowMessages in some Commands that default to noMessages. Dealt with
that by adding a startCustomOutput and a startingUsualMessages.
This lets a command start with noMessages and then select the output it
wants for each CommandStart.
One bit of breakage: onlyActionOn has been removed from commands that used it.
The plan is that, since a StartMessage contains an ActionItem,
when a Key can be extracted from that, the parallel job runner can
run onlyActionOn' automatically. Then commands won't need to worry about
this detail. Future work.
Otherwise, this was a fairly straightforward process of making each
CommandStart compile again. Hopefully other behavior changes were mostly
avoided.
In a few cases, a command had a CommandStart that called a CommandPerform
that then called showStart multiple times. I have collapsed those
down to a single start action. The main command to perhaps suffer from it
is Command.Direct, which used to show a start for each file, and no
longer does.
Another minor behavior change is that some commands used showStart
before, but had an associated file and a Key available, so were changed
to ShowStart with an ActionItemAssociatedFile. That will not change the
normal output or behavior, but --json output will now include the key.
This should not break it for anyone using a real json parser.
This does not change the overall license of the git-annex program, which
was already AGPL due to a number of sources files being AGPL already.
Legally speaking, I'm adding a new license under which these files are
now available; I already released their current contents under the GPL
license. Now they're dual licensed GPL and AGPL. However, I intend
for all my future changes to these files to only be released under the
AGPL license, and I won't be tracking the dual licensing status, so I'm
simply changing the license statement to say it's AGPL.
(In some cases, others wrote parts of the code of a file and released it
under the GPL; but in all cases I have contributed a significant portion
of the code in each file and it's that code that is getting the AGPL
license; the GPL license of other contributors allows combining with
AGPL code.)
Same goal as b18fb1e343 but without
breaking backwards compatability. Just return IO exceptions when running
the P2P protocol, so that git-annex-shell can detect eof and avoid the
ugly message.
This commit was sponsored by Ethan Aubin.
Makes it allow writes, but not deletion of annexed content. Note that
securing pushes to the git repository is left up to the user.
This commit was sponsored by Jack Hill on Patreon.
Unfortunately ReceiveMessage didn't handle unknown messages the way it
was documented to; client sending VERSION would cause the server to
return an ERROR and hang up. Fixed that, but old releases of git-annex
use the P2P protocol for tor and will still have that behavior.
So, version is not negotiated for Remote.P2P connections, only for
Remote.Git connections, which will support VERSION from their first
release. There will need to be a later flag day to change Remote.P2P;
left a commented out line that is the only thing that will need to be
changed then.
Version 1 of the P2P protocol is not implemented yet, but updated
the docs for the DATA change that will be allowed by that version.
This commit was sponsored by Jeff Goeke-Smith on Patreon.
Not yet used for everything else, but this is enough to
verify that it works, and do some benchmarking.
Some bugfixes included, which got it working. Also fallback to old
actions has been verified to work correctly.
Benchmarked dropping one thousand files from a ssh remote on localhost.
Using the old git-annex 40.867 seconds.
With the P2P protocol 9.905 seconds!
This commit was sponsored by Jochen Bartl on Patreon.
Much like Remote.P2P, there's a pool of connections to a peer, in order
to support concurrent operations.
Deals with old git-annex-ssh on the remote that does not support p2pstdio,
by only trying once to use it, and remembering if it's not supported.
Made p2pstdio send an AUTH_SUCCESS with its uuid, which serves the dual
purposes of something to detect to see that the connection is working,
and a way to verify that it's connected to the right uuid.
(There's a redundant uuid check since the uuid field is sent
by git_annex_shell, but I anticipate that being removed later when
the legacy git-annex-shell stuff gets removed.)
Not entirely happy with Remote.Git.runSsh's behavior
when the proto action fails. Running the fallback will work ok, but what
will we do when the fallbacks later get removed? It might be better to
try to reconnect, in case the connection got closed.
This commit was sponsored by Boyd Stephen Smith Jr. on Patreon.
Not yet used by git-annex, but this will allow faster transfers etc than
using individual ssh connections and rsync.
Not called git-annex-shell p2p, because git-annex p2p does something
else and I don't want two subcommands with the same name between the two
for sanity reasons.
This commit was sponsored by Øyvind Andersen Holm.
