The current code for generating treemanifest revisions takes the list
of files in the changeset and finds the directories from them. This
does not work for merges, since a merge may pick file A from one side
and file B from another and neither of them would appear in the
changeset's "files" list, but the manifest would still change.
Fix this by instead walking the root manifest log for all needed
revisions, storing all needed file and subdirectory revisions, then
recursively visiting the subdirectories. This also turns out to be
faster: cloning a version of hg core converted to treemanifests went
from ~28s to ~19s (timing somewhat unfair: before this patch, timed
until crash; after this patch, timed until manifests complete).
The new algorithm is used only on treemanifest repos. Although it
works equally well on flat manifests, we leave the iteration over
files in the changeset for flat manifests for now.
This is another step towards making the manifest generation recurse
along the directory trees. The loop over 'tmfnodes' now takes the form
of a queue. At this point, we only add to the queue twice: we add the
root manifests, and, while visiting the root manifest revisions, we
add all subdirectory revisions (for treemanifest repos). Thus, any
iterations over 'tmfnodes' after the first will not add any items and
the "queue" will just keep shrinking.
This is another step towards making the manifest generation recurse
along the directory trees. It makes the two calls to _packmanifests()
more similar.
When verbose logging is one, we report the size in bytes of the
manifest data in the changegroup. For files, we report the size per
file, but I'm not sure we need that level of detail (i.e. size per
directory manifest). Instead, report a single figure for the size of
root manifest plus submanifests.
The next few patches will rewrite the manifest generation code to work
with merges. We will then walk dirlogs recursively. This prepares for
that by moving much of the treemanifest code out of _packmanifests()
and into generatemanifests(). For this to work, it also adds
_manifestsdone() method that returns the "end of manifests" close
chunk for cg3 and an empty string for cg1 and cg2.
In b89de5ee5b31 (changegroup: don't support versions 01 and 02 with
treemanifests, 2016-01-19), I stopped supporting use of cg1 and cg2
with treemanifest repos. What I had not considered was that it's
perfectly safe to pull *to* a treemanifest repo using any changegroup
version. As reported in issue5066, I therefore broke pull from old
repos into a treemanifest repo. It was not covered by the test case,
because that pulled from a local repo while enabling treemanifests,
which enabled treemanifests on the source repo as well. After
switching to pulling via HTTP, it breaks.
Fix by splitting up changegroup.supportedversions() into
supportedincomingversions() and supportedoutgoingversions().
There were two mistakes: one was accidental reuse of the fclnode
variable from the loop gathering file nodes, and the other (masked by
that bug) was not correctly handling deleted directories. Both cases
are now fixed and the test passes.
In a few places (at least repair.py and shelve.py), we want to find
the best changegroup version that we can assume users of the repo will
understand. For example, we choose version 01 by default, but if it's
a generaldelta repo, we expect clients to support version 02 anyway,
so we choose that for new bundles (for e.g. "hg strip"). Let's create
a helper for this functionality in changegroup, so we can reuse it
elsewhere later.
Since it would be terribly expensive to convert between flat manifests
and treemanifests, we have decided to simply not support changegroup
version 01 and 02 with treemanifests. Therefore, let's stop announcing
that we support these versions on treemanifest repos.
Note that this means that older clients that try to clone from a
treemanifest repo will fail. What happens is that the server, after
this patch, finds that there are no common versions and raises
"ValueError: no common changegroup version". This results in "abort:
HTTP Error 500: Internal Server Error" on the client.
Before this patch, it was no better: The server would instead find
that there were directory manifest nodes to put in the changegroup 01
or 02 and raise an AssertionError on changegroup.py#668 (assert not
tmfnodes), which would also appear as a 500 to the client.
changegroup.getchunks() determines the end of the stream by looking
for an empty chunk group (two consecutive empty chunks). It ignores
empty groups in the first two groups. Changegroup 3 introduced an
empty chunk between the manifests and the files, which confuses
getchunks(). Since it comes after the first two, getchunks() will stop
there.
Fix by rewriting getchunks so it first counts two groups (empty or
not) and then keeps antostarts counting empty groups. With this counting,
changegroup 1 and 2 have exactly one empty group after the first two
groups, while changegroup 3 has two (one for directories and one for
files).
It's a little hard to test this at this point, but I have verified
that this patch fixes narrowhg (which was broken before this
patch). Also, future patches will fix "hg strip" with treemanifests,
and once that's done, getchunks() will be tested through tests of "hg
strip".
By putting the treemanifest code in _unpackmanifests(),
_addchangegroupfiles() will only be about files again, and we get a
nice symmetry between _packmanifests() and _unpackmanifest(). The
immediate benefit to me is that remotefilelog should not need to be
updated to work with treemanifests. It should also make
server.validate and progress output easier to get right. Probably
bundlerepo too.
Remotefilelog overrides changegroup._addchangegroupfiles(), assuming
it is about files, which seems like a natural assumption. However, in
changegroup3, directory manifests are sent in the files section of the
changegroup. These naturally make remotefilelog unhappy.
The fact that the directories are not separated from the files
(although they do come before the files) also makes server.validate
harder to implement. Since we read one chunk at a time from the steam,
once we have found a file (non-directory) entry in the stream, we
would have to push the read data back into the stream, or otherwise
refactor the code. It will be easier if we add an empty chunk after
all directory manifests.
This change adds that empty chunk, although we don't yet take
advantage of it on the reading side. We will soon move the tree
manifest stuff out of _addchangegroupfiles() and into
_unpackmanifests().
In order to give us the freedom to change the changegroup3 format,
let's hide it behind an experimental config. Since it is required by
treemanifests, that will override the cg3 config.
Sometimes a txnclose or changegroup hook wants to iterate through all
the changesets in transaction: in that situation usually the revset
`$HG_NODE:` is used to select the revisions. Unfortunately this revset
sometimes may contain too many changesets because we don't have the
write lock while the hook runs newer changes may be added to
repository in the meantime.
That's why there is a need for extra variable carrying the information about
the last change in the transaction.
By adding a mandatory 'treemanifest' parameter in the bundle2 part, we
make it possible for the recipient to set repo requirements before the
manifest revlog is accessed.
I'm not entirely happy with using a trailing / on a "file" entry for
transferring a treemanifest. We've discussed putting some flags on
each file header[0], but I'm unconvinced that's actually any better:
if we were going to add another feature to the cg format we'd still be
doing a version bump anyway to cg4, so I'm inclined to not spend time
coming up with a more sophisticated format until we actually know what
the next feature we want to stuff in a changegroup will be.
Test changes outside test-treemanifest.t are only due to the new CG3
bundlecap showing up in the wire protocol.
Many thanks to adgar@google.com and martinvonz@google.com for helping
me with various odd corners of the changegroup and treemanifest API.
0: It's not hard refactoring, nor is it a lot of work. I'm just
disinclined to do speculative work when it's not clear what the
customer would actually be.
In the fastpathlinkrev case, lookupmflinknode was a very complicated
way of saying mfs.__getitem__, so let's just get that case out of our
way so it's easier to understand what's going on.
The old code gathered the list of all files that changed anywhere in
history and then gathered changed file nodes by walking the entirety
of each manifest to be sent in order to gather changed file
nodes. That's going to be unfortunate for narrowhg, and it's already
inefficient for medium-to-large repositories.
Timings for bundle --all on my hg repo, tested with hgperf:
Before:
! wall 23.442445 comb 23.440000 user 23.250000 sys 0.190000 (best of 3)
After:
! wall 20.272187 comb 20.270000 user 20.190000 sys 0.080000 (best of 3)
An upcoming change for exchanging treemanifest data will need to
update the repository capabilities, which we should only do if the
repository was empty before we started applying this changegroup. In
the future we will probably need a strategy for upgrading to
treemanifest in requires during a pull (I'm assuming at some point
we'll make it possible to have a flag day to enable treemanifests on
an existing history.)
The previous changeset is a simpler way of fixing issue4934 without changing the
spirit of the code. We can remove the dual call to 'delayupdate' but we keep the
tests to show that the issue is still fixed.
The 'prechangegroup' interfere with 'delayupdate' logic because it trigger the
one time call of 'changelog._writepending' (see issure4934). There is no reason
not to call that hook before setting up 'delayupdate' so we move the call a bit
earlier to avoid interference.
The try finally is here to ensure we release the just-created transaction.
Therefore we should not do half a dozen operations before actually entry the try
scope.
We need to call delayupdate again after writing to the changelog.
Otherwise the prechangegroup hook consumes the delayupdate subscription and
future hooks don't see the pending changes (see issue 4934 for more details).
Adds a test that triggers the prechangegroup hook before the pretxnchangegroup
hook and verifies that the output of pretxnchangegroup doesn't change.
This patch centralizes passing HG_PENDING to external hook process
into '_exthook()'. To make in-memory changes visible to external hook
process, this patch does:
- write (or schedule to write) in-memory dirstate changes, and
- set HG_PENDING environment variable, if:
- a transaction is running, and
- there are in-memory changes to be visible
This patch tests some commands with some hooks, because transaction
activity of a same hook differs from each other ("---": "not tested").
======== ========= ========= ============
command preupdate precommit pretxncommit
======== ========= ========= ============
unshelve o --- ---
backout x --- ---
import --- o o
qrefresh --- x o
======== ========= ========= ============
Each hooks are examined separately to prevent in-memory changes from
being visible to external process accidentally by side effect of hooks
previously invoked.
I'm about to add a cg3, and it seems prudent to annotate what formats
support what features. It strikes me that we may want to consider
moving to a more feature-oriented model in the future, but we'll see
how that looks in a little while I guess.
I'm not sure what to do abstraction-wise here. It might be more
sensible to make a memoryrepo that could apply a bundle in-memory and
then we could make the changegroup data be strictly an applyable
stream, but that's an idea for Later.
The current setup requires to pass both a packer and, optionally, the version
of the unpacker. This is confusing and error prone as the two value cannot
mismatch. Instead, we simply grab the version from the packer. This fixes a bug
where requesting a cg2 from 'hg bundle' were reported as changegroup 1.
I should have caught that in the initial changeset but I missed it somehow.
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 current writebundle function do two things:
- taking a changegroup-packer instance and storing it into a valid bundle with
proper header.
- creating a temporary or requested file to store that bundle
We would like to make it easier to forward bundle stream directly from a remote
peer to a file, so we split the two logic to be able to skip the one about
building a valid bundle (the remote is already sending one).
For some obscure reasons (probably upsetting a Greek goddess),
getchangegroup did not had a 'version' argument to control the changegroup
version. We fixes this to allow cg02 to be used with 'hg bundle' in the future.
For some obscure reasons (probably upsetting a Greek goddess),
getlocalchangegroup did not have a 'version' argument to control the
changegroup version. We fix this to allow cg02 to be used with 'hg
bundle' in the future.
Bundle2 compression is more complex than the bundle1 one. Therefore it
is handled by the bundler itself. Moreover, on-disk bundle2 will
probably have a large number of flavors so simply adding a new "format"
for it does not seems the way to go.
This will be used in the next changeset to compress bundle2 strip backup.
For "space saving", bundle1 "strip" the first two bytes of the BZ stream since
they always are 'BZ'. So the current code boostrap the uncompressor with 'BZ'.
This hack is impractical in more generic case so we move it in a dedicated
"decompression".
Before this patch, addchangegroup() would walk the changelog and compute
the set of seen files between applying changesets and applying
manifests. When cloning large repositories such as mozilla-central,
this consumed a non-trivial amount of time. On my MBP, this walk takes
~10s. On a dainty EC2 instance, this was measured to take ~125s! On the
latter machine, this delay was enough for the Mercurial server to
disconnect the client, thinking it had timed out, thus causing a clone
to abort.
This patch enables the changelog to compute the set of changed files as
new revisions are added. By doing so, we:
* avoid a potentially heavy computation between changelog and manifest
processing by spreading the computation across all changelog additions
* avoid extra reads from the changelog by operating on the data as it is
added
The downside of this is that the add revision callback does result in
extra I/O. Before, we would perform a flush (and subsequent read to
construct the full revision) when new delta chains were created. For
changelogs, this is typically every 2-4 revisions. Using the callback
guarantees there will be a flush after every added revision *and* an
open + read of the changelog to obtain the full revision in order to
read the added files. So, this increases the frequency of these
operations by the average chain length. In the future, the revlog
should be smart enough to know how to read revisions that haven't been
flushed yet, thus eliminating this extra I/O.
On my MBP, the total CPU times for an `hg unbundle` with a local
mozilla-central gzip bundle containing 251,934 changesets and 211,065
files did not have a statistically significant change with this patch,
holding steady around 360s. So, the increased revlog flushing did not
have an effect.
With this patch, there is no longer a visible pause between applying
changeset and manifest data. Before, it sure felt like Mercurial was
lethargic making this transition. Now, the transition is nearly
instantaneous, giving the impression that Mercurial is faster. Of course,
eliminating this pause means that the potential for network disconnect due
to channel inactivity during the changelog walk is eliminated as well.
And that is the impetus behind this change.
The computation of roots was buggy, any ancestor of a bundled merge which was
also a descendant of the parents of a bundled revision were included as part of
the bundle. We fix it and add a test for strip (which revealed the problem).
Check the test for a practical usecase.
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 .`.
This eliminates the following test failure on Windows, as well as a similar one
in evolve's test-wireproto.t. See the previous patch for details on the
problem.
--- e:/Projects/hg/tests/test-init.t
+++ e:/Projects/hg/tests/test-init.t.err
@@ -216,10 +216,10 @@
* test 0:08b9e9f63b32
$ hg clone -e "python \"$TESTDIR/dummyssh\"" local ssh://user@dummy/remote-bookmarks
searching for changes
+ exporting bookmark test
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
- exporting bookmark test
$ hg -R remote-bookmarks bookmarks
test 0:08b9e9f63b32
It is finally time to freeze the bundle2 format! To do so we:
- rename HG2Y to HG20,
- drop "b2x:" prefix from all part names,
- rename capability to "bundle2-exp" to "bundle2"
- rename the hook flag from 'bundle2-exp' to 'bundle2'
'repo' is a very confusing name to use for 'self', especially when
it's not a repo. Also drop repo.ui member (a.k.a. self.ui) now that
'self' doesn't shadow outer 'repo' variable.
To ensure that exchanged deltas in the presence of censored revisions can
always be applied to the recipient repository, the deltas must replace the
entire base text. To make this restriction reasonably enforceable, the delta
must do so with a single patch operation.
For background and broader design of the censorship feature, see:
http://mercurial.selenic.com/wiki/CensorPlan
To ensure interoperability when clones disagree about which file nodes are
censored, a restriction is made on deltas based on censored nodes. Any such
delta must replace the full text of the base in a single patch.
If the recipient of a delta considers the base to be censored and the delta
is not in the expected form, the recipient must reject it, as it can't know
if the source has also censored the base.
For background and broader design of the censorship feature, see:
http://mercurial.selenic.com/wiki/CensorPlan
This diff adds support to writebundle to generate a bundle2 wrapper; upcoming
diffs will add an option to write a v2 changegroup part instead of v1 in these
bundles.
The next diff will add support for writing bundle2 files to writebundle, but
the bundle2 generator wants access to a ui object. This changes the signature
and callsites to pass one in.
This is kind of similar to the debugbundle command but gives summarized actual
uncompressed number of bytes when creating the bundle. The numbers are as
usable as the bundle format is efficient. Hopefully bundle2 will make it a
better indicator of actual entropy.
This is useful when accepting pull requests to assess whether the repo size
increase seems reasonable for the diff before pushing stuff upstream, It has
helped me catching large files that should have been committed as largefiles
but was committed as regular files in intermediate changesets.
This output doesn't combine well with debug output so we only enable it when
verbose without debug.
We already have a _repo property on the packer, and we only access the
changelog and manifest revlog in one place, so it's just as easy to
get them from self._repo.
Since we always pass self._reorder to self.group(), let's drop the
parameter and let group() read from self._reorder itself. There are no
other in-tree callers to group().
The difference between reorder=None (bundle.reorder=auto) and
reorder=False is that the generaldelta revlogs get reordered with the
former. In cg2packer, group() we check if the revlog uses generaldelta
and if reorder=None and then convert that to reorder=False. We are
effectively saying that whether or not generaldelta is used, we want
reorder=None to mean reorder=False for changegroup 2. To make this
clearer, check if reorder=None in the constructor and change it to
False there and drop the overriding of group(). Also document the
reason for turning reordering off.
The config option bundle.reorder can be {on,off,auto}, which gets read
into the 'reorder' variable as {True,False,None}. In two places, we
need to decide how to handle the None/auto case. I personally find it
easier to read those expressions when written to explicitly compare to
None.
changegroup.group() and changegroup.generatefiles() both currently
start progress (with topic "bundling"), but changegroup.generate()
closes the topic. Move the closing to the functions that start the
topic, so it's easier to see where the topic is started and closed.
This completes a move that seems to have been started in f8f5836242c6
(bundle-ng: move progress handling out of the linkrev callback,
2013-05-10).
The 'mf' variable is a manifest revlog, not a manifest, so let's
rename it accordingly. We already call the changelog variable 'cl', so
'ml' seems appropriate.
The parameter has been unused since it was introduced in 40209abd6471
(bundle: refactor changegroup prune to be its own function,
2013-05-30), and Durham says it is not used by his extension either.
Previously, if reorder was true during the creation of a changegroup bundle,
it was possible that the manifest and filelogs would be reordered such that the
resulting bundle filelog had a linkrev that pointed to a commit that was not
the earliest instance of the filelog revision. For example:
With commits:
0<-1<---3<-4
\ /
--2<---
if 2 and 3 added the same version of a file, if the manifests of 2 and 3 have
their order reversed, but the changelog did not, it could produce a filelog with
linkrevs 0<-3 instead of 0<-2, which meant if commit 3 was stripped, it would
delete that file data from the repository and commit 2 would be corrupt (as
would any future pulls that tried to build upon that version of the file).
The fix is to make the linkrev fixup smarter. Previously it considered the first
manifest that added a file to be the first commit that added that file, which is
not true. Now, for every file revision we add to the bundle we make sure we
attach it to the earliest applicable linkrev.
Previously, fnodes had a key and empty dict value for every element in
changedfiles. This is somewhat wasteful. Empty dicts in CPython consume
a lot more memory than you would expect - 280 bytes.
On mozilla-central, which has ~190,000 files/fnodes keys, the previous
loop populating fnodes allocated 91,924 KB of memory, most of that for
the empty dicts.
With this patch in place, our peak RSS during mozilla-central clone
drops:
before: 364,356 KB
after: 326,008 KB
delta: -38,348 KB
When combined with the previous patch, total peak RSS decrease is now
190,116 KB.
The contents of fnodes are only accessed once per key. It is wasteful to
cache the value since nobody will use it.
Before this patch, the caching of unused data in fnodes was effectively
causing a memory leak during the file streaming part of bundle creation.
On mozilla-central (which has ~190,000 entries in fnodes), this patch
has a significant impact on RSS at the end of generate():
before: 516,124 KB
after: 364,356 KB
delta: -151,768 KB
The origin of this code can be traced back to 1f567a607f1f and has been
with us since the 2.7 release.
lookupmf() is currently defined earlier than when it is needed. Future
patches further refactoring this code will be easier to read when
lookupmf() is in its new home.
