os.fdopen() does not accepts bytes as its second argument which represent the
mode in which the file is to be opened. This patch makes sure unicodes are
passed in py3 by using pycompat.sysstr().
Previously Abort raised during 'getbundle' call poorly reported (HTTP-500 for
http, some scary messages for ssh). Abort error have been properly reported for
"push" for a long time, there is not reason to be different for 'getbundle'. We
properly catch such error and report them back the best way available. For
bundle, we issue a valid bundle2 reply (as expected by the client) with an
'error:abort' part. With bundle1 we do as best as we can depending of http or
ssh.
Changeset a0966f529e1b introduced a config option to have the server deny pull
using bundle1. The original protocol has not really been design to allow that
kind of error reporting so some hack was used. It turned the hack only works on
HTTP and that ssh server hangs forever when this is used. After further
digging, there is no way to report the error in a unified way. Using `ooberror`
freeze ssh and raising 'Abort' makes HTTP return a HTTP-500 without further
details. So with sadness we implement a version that dispatch according to the
protocol used.
Now the error is properly reported, but we still have ungraceful abort after
that. The protocol do not allow anything better to happen using bundle1.
Changeset a0966f529e1b introduced a config option to have the server deny push
using bundle1. The original protocol has not really be design to allow such kind
of error reporting so some hack was used. It turned the hack only works on HTTP
and that ssh wire peer hangs forever when the same hack is used. After further
digging, there is no way to report the error in a unified way. Using 'ooberror'
freeze ssh and raising 'Abort' makes HTTP return a HTTP500 without further
details. So with sadness we implement a version that dispatch according to the
protocol used.
We also add a test for pushing over ssh to make sure we won't regress in the
future. That test show that the hint is missing, this is another bug fixed in
the next changeset.
This commit introduces support for advertising a server's support for
media types and compression formats in accordance with the spec defined
in internals.wireproto.
The bulk of the new code is a helper function in wireproto.py to
obtain a prioritized list of compression engines available to the
wire protocol. While not utilized yet, we implement support
for obtaining the list of compression engines advertised by the
client.
The upcoming HTTP protocol enhancements are a bit lower-level than
existing tests (most existing tests are command centric). So,
this commit establishes a new test file that will be appropriate
for holding tests around the functionality of the HTTP protocol
itself.
Rounding out this change, `hg debuginstall` now prints compression
engines available to the server.
Previously, the capabilities list was protocol agnostic and we
advertised the same capabilities list to all clients, regardless of
transport protocol.
A few capabilities are specific to HTTP. I see no good reason why we
should advertise them to SSH clients. So this patch limits their
advertisement to HTTP clients.
This patch is BC, but SSH clients shouldn't be using the removed
capabilities so there should be no impact.
Almost all sys.stdin/out/err in hgext/ and mercurial/ are replaced by util's.
There are a few exceptions:
- lsprof.py and statprof.py are untouched since they are a kind of vendor
code and they never import mercurial modules right now.
- ui._readline() needs to replace sys.stdin and stdout to pass them to
raw_input(). We'll need another workaround here.
Currently, the "streamres" response type is populated with a generator
of chunks with compression possibly already applied. This puts the onus
on commands to perform chunking and compression. Architecturally, I
think this is the wrong place to perform this work. I think commands
should say "here is the data" and the protocol layer should take care
of encoding the final bytes to put on the wire.
Additionally, upcoming commits will improve wire protocol support for
compression. Having a central place for performing compression in the
protocol transport layer will be easier than having to deal with
compression at the commands layer.
This commit refactors the "streamres" response type to accept either
a generator or an object with "read." Additionally, the type now
accepts a flag indicating whether the response is a "version 1
compressible" response. This basically identifies all commands
currently performing compression. I could have used a special type
for this, but a flag works just as well. The argument name
foreshadows the introduction of wire protocol changes, hence the "v1."
The code for chunking and compressing has been moved to the output
generation function for each protocol transport. Some code has been
inlined, resulting in the deletion of now unused methods.
Currently, the "getbundle" wire protocol command obtains a generator of
data, converts it to a util.chunkbuffer, then converts it back to a
generator via the protocol's groupchunks() implementation. For the SSH
protocol, groupchunks() simply reads 4kb chunks then write()s the
data to a file descriptor. For the HTTP protocol, groupchunks() reads
32kb chunks, feeds those into a zlib compressor, emits compressed data
as it is available, and that is sent to the WSGI layer, where it is
likely turned into HTTP chunked transfer chunks as is or further
buffered and turned into a larger chunk.
For both the SSH and HTTP protocols, there is inefficiency from using
util.chunkbuffer.
For SSH, emitting consistent 4kb chunks sounds nice. However, the file
descriptor it is writing to is almost certainly buffered. That means
that a Python .write() probably doesn't translate into exactly what is
written to the I/O layer.
For HTTP, we're going through an intermediate layer to zlib compress
data. So all util.chunkbuffer is doing is ensuring that the chunks we
feed into the zlib compressor are of uniform size. This means more CPU
time in Python buffering and emitting chunks in util.chunkbuffer but
fewer function calls to zlib.
This patch introduces and implements a new wire protocol abstract
method: compresschunks(). It is like groupchunks() except it operates
on a generator instead of something with a .read(). The SSH
implementation simply proxies chunks. The HTTP implementation uses
zlib compression.
To avoid duplicate code, the HTTP groupchunks() has been reimplemented
in terms of compresschunks().
To prove this all works, the "getbundle" wire protocol command has been
switched to compresschunks(). This removes the util.chunkbuffer from
that command. Now, data essentially streams straight from the
changegroup emitter to the wire, possibly through a zlib compressor.
Generators all the way, baby.
There were slim to no performance changes on the server as measured
with the mozilla-central repository. This is likely because CPU
time is dominated by reading revlogs, producing the changegroup, and
zlib compressing the output stream. Still, this brings us a little
closer to our ideal of using generators everywhere.
Currently, exchange.getbundle() returns either a cg1unpacker or a
util.chunkbuffer (in the case of bundle2). This is kinda OK, as
both expose a .read() to consumers. However, localpeer.getbundle()
has code inferring what the response type is based on arguments and
converts the util.chunkbuffer returned in the bundle2 case to a
bundle2.unbundle20 instance. This is a sign that the API for
exchange.getbundle() is not ideal because it doesn't consistently
return an "unbundler" instance.
In addition, unbundlers mask the fact that there is an underlying
generator of changegroup data. In both cg1 and bundle2, this generator
is being fed into a util.chunkbuffer so it can be re-exposed as a
file object.
util.chunkbuffer is a nice abstraction. However, it should only be
used "at the edges." This is because keeping data as a generator is
more efficient than converting it to a chunkbuffer, especially if we
convert that chunkbuffer back to a generator (as is the case in some
code paths currently).
This patch refactors exchange.getbundle() into
exchange.getbundlechunks(). The new API returns an iterator of chunks
instead of a file-like object.
Callers of exchange.getbundle() have been updated to use the new API.
There is a minor change of behavior in test-getbundle.t. This is
because `hg debuggetbundle` isn't defining bundlecaps. As a result,
a cg1 data stream and unpacker is being produced. This is getting fed
into a new bundle20 instance via bundle2.writebundle(), which uses
a backchannel mechanism between changegroup generation to add the
"nbchanges" part parameter. I never liked this backchannel mechanism
and I plan to remove it someday. `hg bundle` still produces the
"nbchanges" part parameter, so there should be no user-visible
change of behavior. I consider this "regression" a bug in
`hg debuggetbundle`. And that bug is captured by an existing
"TODO" in the code to use bundle2 capabilities.
groupchunks() is a generic "turn a file object into a generator"
function. It isn't limited to changegroups. Rename the argument
and update the docstring to reflect this.
This variable has been unused since 4e11f86d8ce7, which was over
2 years ago. gboptsmap should be used instead.
Marking as API because this could break extensions.
Clients escape both argument names and values when using the
batch command. Yet the server was only unescaping argument values.
Fortunately we don't have any argument names that need escaped. But
that isn't an excuse to lack symmetry in the code.
Since the server wasn't properly unescaping argument names, this
means we can never introduce an argument to a batchable command that
needs escaped because an old server wouldn't properly decode its name.
So we've introduced an assertion to detect the accidental introduction
of this in the future. Of course, we could introduce a server
capability that says the server knows how to decode argument names and
allow special argument names to go through. But until there is a need
for it (which I doubt there will be), we shouldn't bother with adding
an unused capability.
Both wireproto.py and sshpeer.py had code for producing the value to
the "cmds" argument used by the "batch" command. This patch extracts
that code to a standalone function and uses it.
As part of teaching Mozilla's replication extension to better handle
repositories with obsolescence data, I encountered a few scenarios
where I wanted built-in wire protocol commands from replication clients
to operate on unfiltered repositories so they could have access to
obsolete changesets.
While the undocumented "web.view" config option provides a mechanism
to choose what filter/view hgweb operates on, this doesn't apply
to wire protocol commands because wireproto.dispatch() is always
operating on the "served" repo.
This patch extracts the line for obtaining the repo that
wireproto commands operate on to its own function so extensions
can monkeypatch it to e.g. return an unfiltered repo.
I stopped short of exposing a config option because I view the use
case for changing this as a niche feature, best left to the domain
of extensions.
All versions of Python we support or hope to support make the hash
functions available in the same way under the same name, so we may as
well drop the util forwards.
Now that batch can be used by remotefilelog, the quadratic string
copying this was doing was actually disastrous. In my local testing,
fetching a 56 meg file used to take 3 minutes, and now takes only a
few seconds.
writebundle() writes a bundle2 bundle or a plain changegroup1. Imagine
away the "2" in "bundle2.py" for a moment and this change should makes
sense. The bundle wraps the changegroup, so it makes sense that it
knows about it. Another sign that this is correct is that the delayed
import of bundle2 in changegroup goes away.
I'll leave it for another time to remove the "2" in "bundle2.py"
(alternatively, extract a new bundle.py from it).
narrowhg (for its narrow spec) and remotefilelog (for its large batch
requests) would like to be able to make requests with argument sets so
absurdly large that they blow out total request size limit on some
http servers. As a workaround, support stuffing args at the start
of the POST body.
We will probably want to leave this behavior off by default in servers
forever, because it makes the old "POSTs are only for writes"
assumption wrong, which might break some of the simpler authentication
configurations.
Unfortunately, the ssh and http implementations are slightly different
due to differences in their _callstream implementations, which
prevents ssh from behaving streamily. We should probably introduce a
new batch command that can stream results over ssh at some point in
the near future.
The streamy behavior of batch over http(s) is an enormous win for
remotefilelog over http: in my testing, it's saving about 40% on file
fetches with a cold cache against a server on localhost.
This is very much like ordinary batch(), but it will let me add a mode
for batch where we have pathologically large requests which are then
handled streamily. This will be a significant improvement for things
like remotefilelog, which may want to request thousands of entities at
once.
I recently implemented the server.bundle1* options to control whether
bundle1 exchange is allowed.
After thinking about Mozilla's strategy for handling generaldelta
rollout a bit more, I think server operators need an additional
lever: disable bundle1 if and only if the repo is generaldelta.
bundle1 exchange for non-generaldelta repos will not have the potential
for CPU explosion that generaldelta repos do. Therefore, it makes sense
for server operators to continue to allow bundle1 exchange for
non-generaldelta repos without having to set a per-repo hgrc option
to change the policy depending on whether the repo is generaldelta.
This patch introduces a new set of options to control bundle1 behavior
for generaldelta repos. These options enable server operators to limit
bundle1 restrictions to the class of repos that can be performance
issues. It also allows server operators to tie bundle1 access to store
format. In many server environments (including Mozilla's), legacy repos
will not be generaldelta and new repos will or might be. New repos often
aren't bound by legacy access requirements, so setting a global policy
that disallows access to new/generaldelta repos via bundle1 could be a
reasonable policy in many server environments. This patch makes this
policy very easy to implement (modify global hgrc, add options to
existing generaldelta repos to grandfather them in).
bundle2 is the new and preferred wire protocol format. For various
reasons, server operators may wish to force clients to use it.
One reason is performance. If a repository is stored in generaldelta,
the server must recompute deltas in order to produce the bundle1
changegroup. This can be extremely expensive. For mozilla-central,
bundle generation typically takes a few minutes. However, generating
a non-gd bundle from a generaldelta encoded mozilla-central requires
over 30 minutes of CPU! If a large repository like mozilla-central
were encoded in generaldelta and non-gd clients connected, they could
easily flood a server by cloning.
This patch gives server operators config knobs to control whether
bundle1 is allowed for push and pull operations. The default is to
support legacy bundle1 clients, making this patch backwards compatible.
We want that capability to be stable in our testing. This is currently not an
issue because the set is size 1, but this will be once generaldelta related
data gets in there.
The SSH peer class accesses wireproto.commands[cmd] as part of encoding
command arguments. Previously, the wire protocol command was defined in
the clonebundles extension. If the client didn't have this extension
enabled (which it likely doesn't since it is meant as a server-side
extension), then clients attempting to clone via ssh:// would get a
crash due to a KeyError accessing wireproto.commands['clonebundles']
when cloning from a server that is advertising clone bundles.
Moving the definition of the wire protocol command to wireproto.py makes
this problem go away.
A side effect of this code move is servers will always respond to
"clonebundles" wire protocol command requests. This should be fine: the
server will return an empty response unless a clone bundles manifest
file is present and clients shouldn't call the command unless the server
is advertising the capability, which only happens if the clonebundles
extension is enabled and the manifest file exists.
The client now sends a "cbattempted" boolean flag to the "getbundle"
wire protocol command to tell the server whether a clone bundle was
attempted.
The presence of this flag will enable the server to conditionally emit a
bundle2 "output" part advertising the availability of clone bundles to
compatible clients that don't have it enabled.
The client represents boolean arguments as '0' and '1'.
bool('0') == bool('1') == True, so a simple bool(val) isn't sufficient
for converting the argument back to a bool type.
Currently, "obsmarkers" is the only boolean argument to getbundle.
I /think/ the only place where we currently set the "obsmarkers"
argument is during bundle2 pulls. As a result of this bug, the server
/might/ be sending obsolete markers bundle2 part(s) to clients that
don't request them. That is why I marked this BC.
Surprisingly there was no test fall out from this change. I suspect a
lapse in test coverage.
The home of 'Abort' is 'error' not 'util' however, a lot of code seems to be
confused about that and gives all the credit to 'util' instead of the
hardworking 'error'. In a spirit of equity, we break the cycle of injustice and
give back to 'error' the respect it deserves. And screw that 'util' poser.
For great justice.
The stream clone data over the wire protocol contains a header line
indicating total file count and data size. In bundle2, this metadata can
be captured by a part parameter and doesn't need to be in the body.
In preparation for bundle2, have generatev1() return the raw metadata
and move the header generation to its own function.
We bulk move functions from exchange.py related to streaming clones.
Function names were renamed slightly to drop a component redundant with
the module name. Docstrings and comments referencing old names and
locations were updated accordingly.
This means that users of request batching don't need to worry
themselves with capability checking. Instead, they can just use
batching, and if the remote server doesn't support batching for some
reason the wirepeer code will transparently un-batch the requests.
This will allow for some slight simplification in a handful of
places. Prior to this change, largefiles would have been silently
broken against a server which did not support batching.
"Real" batching only makes sense for wirepeers, but it greatly
simplifies the clients of peer instances if they can be ignorant to
actual batching capabilities of that peer. By moving the
not-really-batched batching code into peer.peer, all peer instances
now work with the batching API, thus simplifying users.
This leaves a couple of name forwards in wirepeer.py. Originally I had
planned to clean those up, but it kind of unclarifies other bits of
code that want to use batching, so I think it makes sense for the
names to stay exposed by wireproto. Specifically, almost nothing is
currently aware of peer (see largefiles.proto for an example), so
making them be aware of the peer module *and* the wireproto module
seems like some abstraction leakage. I *think* the right long-term fix
would actually be to make wireproto an implementation detail that
clients wouldn't need to know about, but I don't really know what that
would entail at the moment.
As far as I'm aware, no clients of batching in third-party extensions
will need updating, which is nice icing.
This issue appears to be as old as wireproto batching itself: I can
reproduce the failure as far back as 6afda0a50a20 trivially by
rebasing the test changes in this patch, which was back in the 1.9
era. I didn't test before that change, because prior to that the
testfile has a different name and I'm lazy.
Note that the test thought it was checking this case, but it actually
wasn't: it put a literal ; in the arg and response for its greet
command, but the mangle/unmangle step defined in the test meant that
instead of "Fo, =;o" going over the wire, "Gp-!><p" went instead,
which doesn't contain any special characters (those being [.=;]) and
thus not exercising the escaping. The test has been updated to use
pre-unmangled special characters, so the request is now "Fo+<:o",
which mangles to "Gp,=;p". I have confirmed that the test fails
without the adjustment to the escaping rules in wireproto.py.
No existing clients of RPC batching were depending on the old behavior
in any way. The only *actual* users of batchable RPCs in core were:
1) largefiles, wherein it batches up many statlfile calls. It sends
hexlified hashes over the wire and gets a 0, 1, or 2 back as a
response. No risk of special characters.
2) setdiscovery, which was using heads() and known(), both of which
communicate via hexlified nodes. Again, no risk of special characters.
Since the escaping functionality has been completely broken since it
was introduced, we know that it has no users. As such, we can change
the escaping mechanism without having to worry about backwards
compatibility issues.
For the curious, this was detected by chance: it happens that the
lz4-compressed text of a test file for remotefilelog compressed to
something containing a ;, which then caused the failure when I moved
remotefilelog to using batching for file content fetching.
Well-behaved Mercurial clients will respect the httpheader capability by not
sending http headers longer than the given limit in bytes. The limit is
currently hard-coded at 1024 bytes, a safe value for any web server.
Since parsing headers is a notable factor in web server performance, tuning
header size can nontrivially improve performance for request-heavy operations
(eg. obsolete marker negotiation). Exposing the maximum header length limit
as a configuration setting is a simple way to enable such tuning.
Python 2.6 introduced the "except type as instance" syntax, replacing
the "except type, instance" syntax that came before. Python 3 dropped
support for the latter syntax. Since we no longer support Python 2.4 or
2.5, we have no need to continue supporting the "except type, instance".
This patch mass rewrites the exception syntax to be Python 2.6+ and
Python 3 compatible.
This patch was produced by running `2to3 -f except -w -n .`.
The 'bundlecaps' argument is expected to be a set, but 'listkeys' is
expected to be a list where ordering matters. We introduce a new 'scsv'
argument type for the 'set' version and move 'csv' to the 'list'
version.
'test-ssh.t' is changed because this introduced an instability in the order we
were producing listkeys parts.
This is a useful information to have in general and we already have debug
output related to listkeys. I'm planning to play around with massive amount of
phases roots and bookmarks so having this data in debug will be very useful.
This already got me to spot that one of the Logilab's review repo is exchanging
65KB of phases data during each exchanges.
