Summary: Ref T10860. This doesn't change anything, it just separates all this stuff out of `PhabricatorRepository` since I'm planning to add a bit more state to it and it's already pretty big and fairly separable.
Test Plan: Pulled, pushed, browsed Diffusion.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T10860
Differential Revision: https://secure.phabricator.com/D15790
Summary: Ref T4292. This will let the UI and future `bin/repository` tools give administrators more tools to understand problems when reporting or resolving them.
Test Plan:
- Pushed fully clean repository.
- Pushed previously-pushed repository.
- Forced write to abort, inspected useful information in the database.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T4292
Differential Revision: https://secure.phabricator.com/D15748
Summary:
Ref T4292. Small fixes:
- There was a bug with the //first// write, where we'd write 1 but expect 0. Fix this.
- Narrow the window where we hold the `isWriting` lock: we don't need to wait for the client to finish.
- Release the lock even if something throws.
- Use a more useful variable name.
Test Plan:
- Made new writes to a fresh cluster repository.
- Made sequential writes.
- Made concurrent writes.
- Made good writes and bad writes.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T4292
Differential Revision: https://secure.phabricator.com/D15747
Summary:
Ref T4292. This mostly implements the locking/versioning logic for multi-master repositories. It is only active on Git SSH pathways, and doesn't actually do anything useful yet: it just does bookkeeping so far.
When we read (e.g., `git fetch`) the logic goes like this:
- Get the read lock (unique to device + repository).
- Read all the versions of the repository on every other device.
- If any node has a newer version:
- Fetch the newer version.
- Increment our version to be the same as the version we fetched.
- Release the read lock.
- Actually do the fetch.
This makes sure that any time you do a read, you always read the most recently acknowledged write. You may have to wait for an internal fetch to happen (this isn't actually implemented yet) but the operation will always work like you expect it to.
When we write (e.g., `git push`) the logic goes like this:
- Get the write lock (unique to the repository).
- Do all the read steps so we're up to date.
- Mark a write pending.
- Do the actual write.
- Bump our version and mark our write finished.
- Release the write lock.
This allows you to write to any replica. Again, you might have to wait for a fetch first, but everything will work like you expect.
There's one notable failure mode here: if the network connection between the repository node and the database fails during the write, the write lock might be released even though a write is ongoing.
The "isWriting" column protects against that, by staying locked if we lose our connection to the database. This will currently "freeze" the repository (prevent any new writes) until an administrator can sort things out, since it'd dangerous to continue doing writes (we may lose data).
(Since we won't actually acknowledge the write, I think, we could probably smooth this out a bit and make it self-healing //most// of the time: basically, have the broken node rewind itself by updating from another good node. But that's a little more complex.)
Test Plan:
- Pushed changes to a cluster-mode repository.
- Viewed web interface, saw "writing" flag and version changes.
- Pulled changes.
- Faked various failures, got sensible states.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T4292
Differential Revision: https://secure.phabricator.com/D15688
Summary: Fixes T7034. Like HTTP, proxy requests to the correct host if a repository has an Almanac service host.
Test Plan: Ran VCS requests through the proxy.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T7034
Differential Revision: https://secure.phabricator.com/D11543
Summary:
Ref T7034.
In a cluster environment, when a user connects with a VCS request over SSH (like `git pull`), the receiving server may need to proxy it to a server which can actually satisfy the request.
In order to proxy the request, we need to know which repository the user is interested in accessing.
Split the SSH workflow into two steps:
# First, identify the repository.
# Then, execute the operation.
In the future, this will allow us to put a possible "proxy the whole thing somewhere else" step in the middle, mirroring the behavior of Conduit.
This is trivially easy in `git` and `hg`. Both identify the repository on the commmand line.
This is fiendishly complex in `svn`, for the same reasons that hosting SVN was hard in the first place. Specifically:
- The client doesn't tell us what it's after.
- To get it to tell us, we have to send it a server capabilities string //first//.
- We can't just start an `svnserve` process and read the repository out after a little while, because we may need to proxy the request once we figure out the repository.
- We can't consume the client protocol frame that tells us what the client wants, because when we start the real server request it won't know what the client is after if it never receives that frame.
- On the other hand, we must consume the second copy of the server protocol frame that would be sent to the client, or they'll get two "HELLO" messages and not know what to do.
The approach here is straightforward, but the implementation is not trivial. Roughly:
- Start `svnserve`, read the "hello" frame from it.
- Kill `svnserve`.
- Send the "hello" to the client.
- Wait for the client to send us "I want repository X".
- Save the message it sent us in the "peekBuffer".
- Return "this is a request for repository X", so we can proxy it.
Then, to continue the request:
- Start the real `svnserve`.
- Read the "hello" frame from it and throw it away.
- Write the data in the "peekBuffer" to it, as though we'd just received it from the client.
- State of the world is normal again, so we can continue.
Also fixed some other issues:
- SVN could choke if `repository.default-local-path` contained extra slashes.
- PHP might emit some complaints when executing the commit hook; silence those.
Test Plan: Pushed and pulled repositories in SVN, Mercurial and Git.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T7034
Differential Revision: https://secure.phabricator.com/D11541
Summary: Ref T6822.
Test Plan: `grep`. This method is only called from within `PhutilArgumentWorkflow::__construct`.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: Korvin, epriestley
Maniphest Tasks: T6822
Differential Revision: https://secure.phabricator.com/D11415
