The error message is not displayed to the use, but this mirrors the
behavior when a regular get from a special remote fails. At least now
there is not a protocol error.
Now that storeKey can have a different object file passed to it, this
complication is not needed. This avoids a lot of strange situations,
and will also be needed if streaming is eventually supported.
Still needs some work.
The reason that the waitv is necessary is because without it,
runNet loops back around and reads the next protocol message. But it's
not finished reading the whole bytestring yet, and so it reads some part
of it.
Working, but lots of room for improvement...
Without streaming, so there is a delay before download begins as the
file is retreived from the special remote.
And when resuming it retrieves the whole file from the special remote
*again*.
Also, if the special remote throws an exception, currently it
shows as "protocol error".
This makes eg git-annex get default to using the cluster rather than an
arbitrary node, which is better UI.
The actual cost of accessing a proxied node vs using the cluster is
basically the same. But using the cluster allows smarter load-balancing
to be done on the cluster.
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...
The VIA extension is still needed to avoid some extra work and ugly
messages, but this is enough that it actually works.
This filters out the RemoteSides that are a proxied connection via a
remote gateway to the cluster.
The VIA extension will not filter those out, but will send VIA to them
on connect, which will cause the ones that are accessed via the listed
gateways to be filtered out.
Walking a tightrope between security and convenience here, because
git-annex-shell needs to only proxy for things when there has been
an explicit, local action to configure them.
In this case, the user has to have run `git-annex extendcluster`,
which now sets annex-cluster-gateway on the remote.
Note that any repositories that the gateway is recorded to
proxy for will be proxied onward. This is not limited to cluster nodes,
because checking the node log would not add any security; someone could
add any uuid to it. The gateway of course then does its own
checking to determine if it will allow proxying for the remote.
Rejected the idea of automatically instantiating remotes for proxies-of-proxies.
That needs cycle protection, while the current behavior, which happened
for free, is that running git-annex updateproxy on the proxy can be used
to configure it, but only for topologies that actually exist.
The problem with that idea is that the cluster's proxy is necessarily a
remote, and necessarily one that we'll want to sync with, since the git
repository is stored there. So when its preferred content wants a file,
and the cluster does too, the file will get uploaded to it as well as to
the cluster. With fanout, the upload to the cluster will populate the
proxy as well, avoiding a second upload. But only if the file is sent to
the cluster first. If it's sent to the proxy first, there will be two
uploads.
Another, lesser problem is that a repository can proxy for more than one
cluster. So when does it make sense to drop content from the repository?
It could be done when dropping from one cluster, but what of the other
one?
This complication was not necessary anyway. Instead, if it's desirable
to have some content accessed from close to the proxy, one of the
cluster nodes can just be put on the same filesystem as it. That will be
just as fast as storing the content on the proxy.
Except when no nodes want a file, it has to be stored somewhere, so
store it on all. Which is not really desirable, but neither is having to
pick one.
ProtoAssociatedFile deserialization is rather broken, and this could
possibly affect preferred content expressions that match on filenames.
The inability to roundtrip whitespace like tabs and newlines through is
not a problem because preferred content expressions can't be written
that match on whitespace such as a tab. For example:
joey@darkstar:~/tmp/bench/z>git-annex wanted origin-node2 'exclude=*CTRL-VTab*'
wanted origin-node2
git-annex: Parse error: Parse failure: near "*"
But, the filtering of control characters could perhaps be a problem. I think
that filtering is now obsolete, git-annex has comprehensive filtering of
control characters when displaying filenames, that happens at a higher level.
However, I don't want to risk a security hole so am leaving in that filtering
in ProtoAssociatedFile deserialization for now.
Avoid `git-annex sync --content` etc from operating on cluster nodes by default
since syncing with a cluster implicitly syncs with its nodes. This avoids a
lot of unncessary work when a cluster has a lot of nodes just in checking
if each node's preferred content is satisfied. And it avoids content
being sent to nodes individually, so instead syncing with clusters always
fanout uploads to nodes.
The downside is that there are situations where a cluster's preferred content
settings can be met, but those of its nodes are not. Or where a node does not
contain a key, but the cluster does, and there are not enough copies of the key
yet, so it would be desirable the send it there. I think that's an acceptable
tradeoff. These kind of situations are ones where the cluster itself should
probably be responsible for copying content to the node. Which it can do much
less expensively than a client can. Part of the balanced preferred content
design that I will be working on in a couple of months involves rebalancing
clusters, so I expect to revisit this.
The use of annex-sync config does allow running git-annex sync with a specific
node, or nodes, and it will sync with it. And it's also possible to set
annex-sync git configs to make it sync with a node by default. (Although that
will require setting up an explicit git remote for the node rather than relying
on the proxied remote.)
Logs.Cluster.Basic is needed because Remote.Git cannot import Logs.Cluster
due to a cycle. And the Annex.Startup load of clusters happens
too late for Remote.Git to use that. This does mean one redundant load
of the cluster log, though only when there is a proxy.
This makes git-annex sync and similar not treat proxied remotes as git
syncable remotes.
Also, display in git-annex info remote when the remote is proxied.
Loading the remote list a second time was removing all proxied remotes.
That happened because setting up the proxied remote added some config
fields to the in-memory git config, and on the second load, it saw those
configs and decided not to overwrite them with the proxy.
Now on the second load, that still happens. But now, the proxied
git configs are used to generate a remote same as if those configs were
all set. The reason that didn't happen before was twofold,
the gitremotes cache was not dropped, and the remote's url field was not
set correctly.
The problem with the remote's url field is that while it was marked as
proxy inherited, all other proxy inherited fields are annex- configs.
And the code to inherit didn't work for the url field.
Now it all works, but git-annex sync is left running git push/pull on
the proxied remote, which doesn't work. That still needs to be fixed.
Tested it with small chunk sizes (like 2) and resumes that were
eg 1 byte from the end of the file or beginning of file.
Also, git-annex testremote passes now against a cluster!
When the destination does not start with a copy, the cluster has one or
more copies. If more, dropping would reduce the number of copies, so
numcopies must be checked.
Considered checking how many nodes of the cluster contain a copy. If
only 1 node does, it could allow a move without checking numcopies.
The problem with that, though, is that other nodes of the cluster could
have copies that we don't know about. And dropping from a cluster tries
to drop from all nodes, so will drop even from those. So any drop from a
cluster can remove more than 1 copy.
Dropping from a cluster drops from every node of the cluster.
Including nodes that the cluster does not think have the content.
This is different from GET and CHECKPRESENT, which do trust the
cluster's location log. The difference is that removing from a cluster
should make 100% the content is gone from every node. So doing extra
work is ok. Compare with CHECKPRESENT where checking every node could
make it very expensive, and the worst that can happen in a false
negative is extra work being done.
Extended the P2P protocol with FAILURE-PLUS to handle the case where a
drop from one node succeeds, but a drop from another node fails. In that
case the entire cluster drop has failed.
Note that SUCCESS-PLUS is returned when dropping from a proxied remote
that is not a cluster, when the protocol version supports it. This is
because P2P.Proxy does not know when it's proxying for a single node
cluster vs for a remote that is not a cluster.
This is obviously necessary in order for dropping from a cluster to be able to
drop from all nodes.
It also avoids violating numcopies when a cluster node is a special remote.
If it were used in the drop proof, nothing would prevent the cluster from
dropping from it.
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.
This assumes that the proxy for a cluster has up-to-date location
logs. If it didn't, it might proxy the checkpresent to a node that no
longer has the content, while some other node still does, and so
it would incorrectly appear that the cluster no longer contains the
content.
Since cluster UUIDs are not stored to location logs,
git-annex fsck --fast when claiming to fix a location log when
that occurred would not cause any problems. And presumably the location
tracking would later get sorted out.
At least usually, changes to the content of nodes goes via the proxy,
and it will update its location logs, so they will be accurate. However,
if there were multiple proxies to the same cluster, or nodes were
accessed directly (or via proxy to the node and not the cluster),
the proxy's location log could certainly be wrong.
(The location log access for GET has the same issues.)
