clonebundles: support for seeding clones from pre-generated bundles Cloning can be an expensive operation for servers because the server generates a bundle from existing repository data at request time. For a large repository like mozilla-central, this consumes 4+ minutes of CPU time on the server. It also results in significant network utilization. Multiplied by hundreds or even thousands of clients and the ensuing load can result in difficulties scaling the Mercurial server. Despite generation of bundles being deterministic until the next changeset is added, the generation of bundles to service a clone request is not cached. Each clone thus performs redundant work. This is wasteful. This patch introduces the "clonebundles" extension and related client-side functionality to help alleviate this deficiency. The client-side feature is behind an experimental flag and is not enabled by default. It works as follows: 1) Server operator generates a bundle and makes it available on a server (likely HTTP). 2) Server operator defines the URL of a bundle file in a .hg/clonebundles.manifest file. 3) Client `hg clone`ing sees the server is advertising bundle URLs. 4) Client fetches and applies the advertised bundle. 5) Client performs equivalent of `hg pull` to fetch changes made since the bundle was created. Essentially, the server performs the expensive work of generating a bundle once and all subsequent clones fetch a static file from somewhere. Scaling static file serving is a much more manageable problem than scaling a Python application like Mercurial. Assuming your repository grows less than 1% per day, the end result is 99+% of CPU and network load from clones is eliminated, allowing Mercurial servers to scale more easily. Serving static files also means data can be transferred to clients as fast as they can consume it, rather than as fast as servers can generate it. This makes clones faster. Mozilla has implemented similar functionality of this patch on hg.mozilla.org using a custom extension. We are hosting bundle files in Amazon S3 and CloudFront (a CDN) and have successfully offloaded >1 TB/day in data transfer from hg.mozilla.org, freeing up significant bandwidth and CPU resources. The positive impact has been stellar and I believe it has proved its value to be included in Mercurial core. I feel it is important for the client-side support to be enabled in core by default because it means that clients will get faster, more reliable clones and will enable server operators to reduce load without requiring any client-side configuration changes (assuming clients are up to date, of course). The scope of this feature is narrowly and specifically tailored to cloning, despite "serve pulls from pre-generated bundles" being a valid and useful feature. I would eventually like for Mercurial servers to support transferring *all* repository data via statically hosted files. You could imagine a server that siphons all pushed data to bundle files and instructs clients to apply a stream of bundles to reconstruct all repository data. This feature, while useful and powerful, is significantly more work to implement because it requires the server component have awareness of discovery and a mapping of which changesets are in which files. Full, clone bundles, by contrast, are much simpler. The wire protocol command is named "clonebundles" instead of something more generic like "staticbundles" to leave the door open for a new, more powerful and more generic server-side component with minimal backwards compatibility implications. The name "bundleclone" is used by Mozilla's extension and would cause problems since there are subtle differences in Mozilla's extension. Mozilla's experience with this idea has taught us that some form of "content negotiation" is required. Not all clients will support all bundle formats or even URLs (advanced TLS requirements, etc). To ensure the highest uptake possible, a server needs to advertise multiple versions of bundles and clients need to be able to choose the most appropriate from that list one. The "attributes" in each server-advertised entry facilitate this filtering and sorting. Their use will become apparent in subsequent patches. Initial inspiration and credit for the idea of cloning from static files belongs to Augie Fackler and his "lookaside clone" extension proof of concept.

sslutil: expose attribute indicating whether SNI is supported This will be used so clone bundles can advertise whether URLs require SNI. This will be explained more in a subsequent patch.

resolve: perform all premerges before performing any file merges (BC) Just like the BC to merge before it, this allows for a maximally consistent state before providing any prompts to the user.

test-resolve.t: add some tests for .orig file contents An upcoming patch will touch some code around this area, and I couldn't find any tests related to this.

test-resolve.t: add some output to show order of operations This basically shows the behavior of resolve with multiple files. An upcoming behavior change will cause this output to also change.

merge.mergestate: perform all premerges before any merges (BC) We perform all that we can non-interactively before prompting the user for input via their merge tool. This allows for a maximally consistent state when the user is first prompted. The test output changes indicate the actual behavior change happening.

merge: introduce a preresolve function The section of code that writes out the version of the file cached in the merge state should only be run at preresolve time. This is so that if the premerge keeps around conflict markers, those don't get overwritten before the main merge.

merge.mergestate._resolve: also return completed status We'll need this for a new 'preresolve' function we're adding.

merge.mergestate: add a wrapper around resolve The resolve function will be broken up into separate pre-resolve and resolve steps.

simplemerge: move conflict warning message to filemerge The current output for a failed merge with conflict markers looks something like: merging foo warning: conflicts during merge. merging foo incomplete! (edit conflicts, then use 'hg resolve --mark') merging bar warning: conflicts during merge. merging bar incomplete! (edit conflicts, then use 'hg resolve --mark') We're going to change the way merges are done to perform all premerges before all merges, so that the output above would look like: merging foo merging bar warning: conflicts during merge. merging foo incomplete! (edit conflicts, then use 'hg resolve --mark') warning: conflicts during merge. merging bar incomplete! (edit conflicts, then use 'hg resolve --mark') The 'warning: conflicts during merge' line has no context, so is pretty confusing. This patch will change the future output to: merging foo merging bar warning: conflicts while merging foo! (edit, then use 'hg resolve --mark') warning: conflicts while merging bar! (edit, then use 'hg resolve --mark') The hint on how to resolve the conflicts makes this a bit unwieldy, but solving that is tricky because we already hint that people run 'hg resolve' to retry unresolved merges. The 'hg resolve --mark' mostly applies to conflict marker based resolution.

filemerge: clean up some dead code We now exit early if we do a premerge, so extra checks are no longer necessary.

run-tests: add b-prefix on two strings to fix python3 support

filemerge: break overall filemerge into separate premerge and merge steps This means that in ms.resolve we must call merge after calling premerge. This doesn't yet mean that all premerges happen before any merges -- however, this does get us closer to our goal. The output differences are because we recompute the merge tool. The only user-visible difference caused by this patch is that if the tool is missing we'll print the warning twice. Not a huge deal, though.

filemerge: only copy to backup during premerge step The premerge might leave the original file in an unclean state. Therefore it's important to only copy the file in the beginning.

filemerge: only print out "merging f" output at premerge step We're soon going to call this function twice, once for premerge and once for merge. This makes sure the "merging" output only gets printed during the premerge step.

filemerge: deindent the parts of filemerge outside the try block It is no longer necessary to indent these parts.

filemerge: introduce a premerge flag and function This flag will let us get to our overall goal of performing all premerges before any merges.

filemerge: also return whether the merge is complete In future patches, we'll pause merges after the premerge step. After the premerge step we'll return complete = False.

filemerge: add a wrapper around the filemerge function We'll introduce a separate premerge function that calls the same code.

context: don't hex encode all unknown 20 char revision specs (issue4890) d3908c911d5e introduced nice hexified display of missing nodes. It did however also make missing 20 character revision specifications be shown as hex - very confusing. Users are often wrong and somehow specify revisions that don't exist. Nodes will however rarely be missing ... and they will only look like a user provided revision specification and be all ascii in 1 of 4*10**9. With this change, missing revisions will only be hexified if they really look like binary nodes. This change will thus improve the error reporting UI in the common case and only very rarely make it confusing in the opposite direction of how it was before.

discovery: put trivial branch first Having the simple and tiny branch of the conditional first help readability. The "else" that appears after a screen of code is harder to relate to a conditional.

shelve: rename 'publicancestors' to something accurate (issue4737) That function is actually not returning public ancestors at all. This is pointed by the second line of the docstring... The bundling behavior was made correct in a5141977198d but with confusion remaining regarding what each function was doing. This close issue4737, because this highlight that shelve is actually -not- bundling too much data (this was actually properly tested).

makefile: add wheel build target

setup: import setup from setuptools if FORCE_SETUPTOOLS is set This should allow easier experimentation with using setuptools in mercurial's build automation, without breaking anything that currently depends on distutils behavior

hgweb: remove obsolete -webkit-border-radius property

monoblue: add a link to the latest file revision For reference, this was added to paper/coal in bb00a159e594 and to gitweb in b3b57ecbda50.

discovery: reference relevant bug in the faulty code We extend the comment about this code flaw with more code flaw.

discovery: fix a typo in a comment The idea here is that the code is imperfect, not that it is impossible to get something behaving properly.

getsubset: get the unpacker version from the bundler 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.

test-convert-cvs: add sleep so cvs notices changes This change makes the test pass on gcc112.fsffrance.org.

cvsps: fix computation of parent revisions when log caching is on cvsps computes the parent revisions of log entries by walking the cvs log sorted by (rcs, revision) and by iteratively maintaining a 'versions' dictionary which maps a (rcs, branch) pair onto the last revision seen for that pair. When log caching is on and a log cache exists, cvsps fails to set the parent revisions of new log entries because it does not iterate over the log cache in the parents computation. A complication is that a file rcs can change (move to/from the attic), with respect to its value in the log cache, if the file is removed/added back. This patch adds an iteration over the log cache to update the rcs of cached log entries, if changed, and to properly populate the 'versions' dictionary.

dirstate: batch calls to statfiles (issue4878) This makes it more interruptible.

parsers: fix infinite loop or out-of-bound read in fm1readmarkers (issue4888) The issue4888 was caused by 0-length obsolete marker. If msize is zero, fm1readmarkers() never ends. This patch adds several bound checks to fm1readmarker(). Therefore, 0-length and invalid-size marker should be rejected.

parsers: read sizes of metadata pair of obsolete marker at once This will make it easy to implement bound checking. Currently fm1readmarker() has no protection for corrupted obsstore and can cause infinite loop or out-of-bound reads.

filemerge: clean up temp files in a finally block This isn't really a big deal because the temp files are created in $TMPDIR, but it makes some upcoming work simpler.

check-code: detect and ban 'util.Abort' We have seen the light, please use the new way.

error: get Abort from 'error' instead of 'util' 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.

eol: rename 'error' to 'haserror' The variable 'error' conflict with the module name that we would like to import and use in a coming changeset.

discovery: rename 'error' to 'errormsg' The variable 'error' conflict with the module name that we would like to import and use in a coming changeset.

histedit: delete histedit statefile on any exception during abort When an user aborts a histedit, many things could go wrong. At a minimum, after a histedit abort failure, their repository should be out of that state. We've found situations where the user could not exit the histedit state without manually deleting the histedit state file. This patch ensures that if any exception happens during an abort, the histedit statefile will be deleted so that users are out of the histedit state and can at least manually get the repo back to a workable condition.

histedit: check presence of statefile before deleting it When the histeditstate class instance has it's clear() method called, there is nothing to check to see if the state file exists before deleting it. It may not exist, which would create an exception. This patch allows clear to be called at any time. This will be needed for the following patch.

histedit: add inprogress method to state class If a histedit is progress, the 'histedit-state' file should exist. The patch implements a convenience function to do check if a histedit is in progress. This method will be use in next patch in the series.

commands: use dirstateguard instead of begin/end-parentchange for backout Before this patch, "hg backout" uses 'begin'/'end'-'parentchange()' of 'dirstate' class to avoid writing incomplete dirstate changes out at failure. But this framework doesn't work as expected, if 'dirstate.write()' is invoked between them. In fact, in-memory dirstate changes may be written out at 'repo.status()' implied by 'merge.update()', even before this patch. To restore dirstate as expected at failure of "hg backout", this patch uses 'dirstateguard' instead of 'begin'/'end'-'parentchange()'.

commands: make "hg import" use dirstateguard only for --no-commit Previous patch made dirstate changes in a transaction scope "all or nothing". Therefore, 'dirstateguard' is meaningless, if its scope is as same as one of the related transaction. Before this patch, "hg import" uses 'dirstateguard' always, but transaction is also started if '--no-commit' isn't specified. To avoid redundancy, this patch makes "hg import" use dirstateguard only if transaction isn't started (= '--no-commit' is specified). In this patch, 'if dsguard' can be examined safely, because 'dsguard' is initialized (with None) before outermost 'try'.

cmdutil: stop tryimportone from using dirstateguard (BC) There is no user of 'cmdutil.tryimportone()' other than 'commands.import_()', which can restore dirstate at failure of applying patches by transaction or dirstateguard. Therefore, it is reasonable to stop 'tryimportone()' from using redundant 'dirstateguard', even though it changes behavior of 'tryimportone()'. After this patch, 3rd party extensions should use 'dirstateguard' or so explicitly, if they want to restore dirstate at failure of importing a patch.

dirstate: remove meaningless dirstateguard Previous patch made dirstate changes in a transaction scope "all or nothing". Therefore, 'dirstateguard' is meaningless, if its scope is as same as one of the related transaction. This patch removes such meaningless 'dirstateguard' usage.

localrepo: execute appropriate actions for dirstate at releasing transaction Before this patch, in-memory dirstate changes are still kept over a transaction scope boundary regardless of the result of it. For "all or nothing" policy of the transaction, in-memory dirstate changes should be: - written out at successful closing a transaction, because subsequent 'dirstate.invalidate()' can lose them - discarded at failure of a transaction, because outer 'wlock.release()' or so may write them out To discard all changes in a transaction completely, this patch also restores '.hg/dirstate' by '.hg/journal.dirstate' at failure, because 'transaction' itself does nothing for files related to '.hg/journal.*' in such case (therefore, renaming in this patch is safe enough). This is a part of preparations for "transactional dirstate". See also the wiki page below for detail about it. https://mercurial.selenic.com/wiki/DirstateTransactionPlan This patch also removes redundant 'dirstate.invalidate()' just before aborting a transaction for shelve/unshelve.

transaction: add releasefn to notify the end of a transaction scope 'releasefn' is used by subsequent patch, to do appropriate action according to the result of it at the end of a transaction scope. To ensure that 'releasefn' is invoked only once, this patch invokes it after assignment 'self.journal = None', because such assignment prevents from invoked 'transaction._abort()' again via '__del__()'. def __del__(self): if self.journal: self._abort()