tags-cache: add a dedicated warm cache function to hgtagsfnodescache Having a dedicated API point will help to optimize that specific usage. Right doing a full phases weam takes a long time, even when the cache is already filled.

outgoing: add a simple fastpath when there is no common This further speed up case like `hg bundle --all` for larger repository. ### data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog # benchmark.name = hg.command.bundle # bin-env-vars.hg.flavor = default # bin-env-vars.hg.py-re2-module = default # benchmark.variants.revs = all # benchmark.variants.type = none-streamv2 before: 316.749699 after: 311.165461 (-1.76%, -5.58) There is further work to be done in this area like not doing any outgoing computation in the stream case for example. however the recent changes already gives use a large win for a small amount of local work. ### benchmark.name = hg.command.bundle # bin-env-vars.hg.flavor = default # bin-env-vars.hg.py-re2-module = default # benchmark.variants.revs = all # benchmark.variants.type = none-streamv2 ## data-env-vars.name = mercurial-public-2024-03-22-zstd-sparse-revlog pre-%ln-change: 1.263859 the-%ln-change: 0.700229 (-44.60%, -0.56) prev-changeset: 0.496050 (-60.75%, -0.77) this-changeset: 0.495243 (-60.81%, -0.77) ## data-env-vars.name = tryton-public-2024-03-22-zstd-sparse-revlog pre-%ln-change: 2.975765 the-%ln-change: 1.870798 (-37.13%, -1.10) prev-changeset: 1.461583 (-50.88%, -1.51) this-changeset: 1.469185 (-50.63%, -1.51) ## data-env-vars.name = pypy-2024-03-22-zstd-sparse-revlog pre-%ln-change: 4.540080 the-%ln-change: 3.401700 (-25.07%, -1.14) prev-changeset: 2.915810 (-35.78%, -1.62) this-changeset: 2.911643 (-35.87%, -1.63) ## data-env-vars.name = heptapod-public-2024-03-25-zstd-sparse-revlog pre-%ln-change: 10.138396 the-%ln-change: 7.750458 (-23.55%, -2.39) prev-changeset: 6.665565 (-34.25%, -3.47) this-changeset: 6.672078 (-34.19%, -3.47) ## data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog pre-%ln-change: 399.484481 the-%ln-change: 346.508952 (-13.26%, -52.98) prev-changeset: 316.749699 (-20.71%, -82.73) this-changeset: 311.165461 (-22.11%, -88.32)

outgoing: rework the handling of the `missingroots` case to be faster The previous implementation was slow, to the point it was taking a significant amount of `hg bundle --type none-streamv2` call. We rework the code to compute the same value much faster, making the operation disappear from the `hg bundle --type none-streamv2` profile. Someone would remark that producing a streamclone does not requires an `outgoing` object. However that is a matter for another day. There is other user of `missingroots` (non stream `hg bundle` call for example), and they will also benefit from this rework. We implement an old TODO in the process, directly computing the missing and common attribute as we have most element at hand already. ### benchmark.name = hg.command.bundle # bin-env-vars.hg.flavor = default # bin-env-vars.hg.py-re2-module = default # benchmark.variants.revs = all # benchmark.variants.type = none-streamv2 ## data-env-vars.name = heptapod-public-2024-03-25-zstd-sparse-revlog before: 7.750458 after: 6.665565 (-14.00%, -1.08) ## data-env-vars.name = mercurial-public-2024-03-22-zstd-sparse-revlog before: 0.700229 after: 0.496050 (-29.16%, -0.20) ## data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog before: 346.508952 after: 316.749699 (-8.59%, -29.76) ## data-env-vars.name = pypy-2024-03-22-zstd-sparse-revlog before: 3.401700 after: 2.915810 (-14.28%, -0.49) ## data-env-vars.name = tryton-public-2024-03-22-zstd-sparse-revlog before: 1.870798 after: 1.461583 (-21.87%, -0.41) note: this whole `missingroots` of outgoing has a limited number of callers and could likely be replace by something simpler (like taking an explicit "missing_revs" set for example). However this is a wider change and we focus on a small impact, quick rework that does not change the API for now.

proxy-vfs: also proxy the `audit` attribute In the previous changeset, we had to do a little dance to access the useful `audit` attribute. We now provide a proper accessors to it. We don't update the code in `perf.py` because it has to remain compatible with older version of Mercurial. This will just be nicer in the future.

perf: clear vfs audit_cache before each run When generating a stream clone, we spend a large amount of time auditing path. Before this changes, the first run was warming the vfs cache for the other runs, leading to a large runtime difference and a "faulty" reported timing for the operation. We now clear this important cache between run to get a more realistic timing. Below are some example of median time change when clearing these cases. The maximum time for a run did not changed significantly. ### data-env-vars.name = mozilla-central-2018-08-01-zstd-sparse-revlog # benchmark.name = hg.perf.exchange.stream.generate # bin-env-vars.hg.flavor = default # bin-env-vars.hg.py-re2-module = default # benchmark.variants.version = latest no-clearing: 17.289905 cache-clearing: 21.587965 (+24.86%, +4.30) ## data-env-vars.name = mozilla-central-2024-03-22-zstd-sparse-revlog no-clearing: 32.670748 cache-clearing: 40.467095 (+23.86%, +7.80) ## data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog no-clearing: 37.838858 cache-clearing: 46.072749 (+21.76%, +8.23) ## data-env-vars.name = mozilla-unified-2024-03-22-zstd-sparse-revlog no-clearing: 32.969395 cache-clearing: 39.646209 (+20.25%, +6.68) In addition, this significantly reduce the timing difference between the performance command, from the perf extensions and a `real `hg bundle` call producing a stream bundle. Some significant differences remain especially on the "mozilla-try" repositories, but they are now smaller. Note that some of that difference will actually not be attributable to the stream generation (like maybe phases or branch map computation). Below are some benchmarks done on a currently draft changeset fixing some unrelated slowness in `hg bundle` (34a78972af409d1ff37c29e60f6ca811ad1a457d) ### data-env-vars.name = mozilla-central-2018-08-01-zstd-sparse-revlog # bin-env-vars.hg.flavor = default # bin-env-vars.hg.py-re2-module = default hg.perf.exchange.stream.generate: 21.587965 hg.command.bundle: 24.301799 (+12.57%, +2.71) ## data-env-vars.name = mozilla-central-2024-03-22-zstd-sparse-revlog hg.perf.exchange.stream.generate: 40.467095 hg.command.bundle: 44.831317 (+10.78%, +4.36) ## data-env-vars.name = mozilla-unified-2024-03-22-zstd-sparse-revlog hg.perf.exchange.stream.generate: 39.646209 hg.command.bundle: 45.395258 (+14.50%, +5.75) ## data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog hg.perf.exchange.stream.generate: 46.072749 hg.command.bundle: 55.882608 (+21.29%, +9.81) ## data-env-vars.name = mozilla-try-2023-03-22-zlib-general-delta hg.perf.exchange.stream.generate: 334.716708 hg.command.bundle: 377.856767 (+12.89%, +43.14) ## data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog hg.perf.exchange.stream.generate: 302.972301 hg.command.bundle: 326.098755 (+7.63%, +23.13)

perf: start recording total time after warming The warming might be costly and this should not affect the "time profile" of the actual collection.

perf: run the gc before each run The python garbage collector is a large source of performance troubles, we run it right before the timed section to reduce the change for the gc to add noise to the benchmark.

perf: allow profiling of more than one run By default, we still profile the first run only. However profiling more run help to understand side effect from one run to the other. So we add an option to be able to do so.

profiler: flush after writing the profiler output Otherwise, the profiler output might only partially appears until the next flush of the buffer. Since profiling often happens for long operation, the next flush can be a long time away.

stream-clone: disable gc for the entry listing section for the v2 format This is similar to the change we did for the v3 format in 6e4c8366c5ce. The benchmark bellow show this gives us a notable gains, especially on larger repositories. ### benchmark.name = hg.perf.stream-locked-section # benchmark.name = hg.perf.stream-locked-section # bin-env-vars.hg.flavor = default # bin-env-vars.hg.py-re2-module = default # benchmark.variants.version = v2 ## data-env-vars.name = pypy-2018-08-01-zstd-sparse-revlog 5e931bf8707c: 0.503820 ~~~~~ 1106d1bf695e: 0.470078 (-6.70%, -0.03) ## data-env-vars.name = pypy-2024-03-22-zstd-sparse-revlog 5e931bf8707c: 0.535756 ~~~~~ 1106d1bf695e: 0.490249 (-8.49%, -0.05) ## data-env-vars.name = heptapod-public-2024-03-25-zstd-sparse-revlog 5e931bf8707c: 1.327041 ~~~~~ 1106d1bf695e: 1.174636 (-11.48%, -0.15) ## data-env-vars.name = netbeans-2018-08-01-zstd-sparse-revlog 5e931bf8707c: 2.439158 ~~~~~ 1106d1bf695e: 2.220515 (-8.96%, -0.22) ## data-env-vars.name = netbeans-2019-11-07-zstd-sparse-revlog 5e931bf8707c: 2.630794 ~~~~~ 1106d1bf695e: 2.261473 (-14.04%, -0.37) ## data-env-vars.name = mozilla-central-2018-08-01-zstd-sparse-revlog 5e931bf8707c: 5.769002 ~~~~~ 1106d1bf695e: 5.062000 (-12.26%, -0.71) ## data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog 5e931bf8707c: 13.351750 ~~~~~ 1106d1bf695e: 12.346655 (-7.53%, -1.01) ## data-env-vars.name = mozilla-central-2024-03-22-zstd-sparse-revlog 5e931bf8707c: 10.772939 ~~~~~ 1106d1bf695e: 9.495407 (-11.86%, -1.28) ## data-env-vars.name = mozilla-unified-2024-03-22-zstd-sparse-revlog 5e931bf8707c: 10.864297 ~~~~~ 1106d1bf695e: 9.475597 (-12.78%, -1.39) ## data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog 5e931bf8707c: 17.448335 ~~~~~ 1106d1bf695e: 16.027474 (-8.14%, -1.42)

phases: rework the logic of _pushdiscoveryphase to bound complexity This rework the various graph traversal in _pushdiscoveryphase to keep the complexity in check. This is done though a couple of things: - first, limiting the space we have to explore, for example, if we are not in publishing push, we don't need to consider remote draft roots that are also draft locally, as there is nothing to be moved there. - avoid unbounded descendant computation, and use the faster "rev between" computation. This provide a massive boost to performance when exchanging with repository with a massive amount of draft, like mozilla-try: ### data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog # benchmark.name = hg.command.push # bin-env-vars.hg.flavor = default # bin-env-vars.hg.py-re2-module = default # benchmark.variants.explicit-rev = all-out-heads # benchmark.variants.issue6528 = disabled # benchmark.variants.protocol = ssh # benchmark.variants.reuse-external-delta-parent = default ## benchmark.variants.revs = any-1-extra-rev before: 20.346590 seconds after: 11.232059 seconds (-38.15%, -7.48 seconds) ## benchmark.variants.revs = any-100-extra-rev before: 24.752051 seconds after: 15.367412 seconds (-37.91%, -9.38 seconds) After this changes, the push operation is still quite too slow. Some of this can be attributed to general phases slowness (reading all the roots from disk for example) and other know slowness (not using persistent-nodemap, branchmap, tags, etc. We are also working on them, but with this series, phase discovery during push no longer showing up in profile and this is a pretty nice and bit low-hanging fruit out of the way. ### (same case as the above) # benchmark.variants.revs = any-1-extra-rev pre-%ln-change: 44.235070 this-changeset: 11.232059 seconds (-74.61%, -33.00 seconds) # benchmark.variants.revs = any-100-extra-rev pre-%ln-change: 49.234697 this-changeset: 15.367412 seconds (-68.79%, -33.87 seconds) Note that with this change, the `hg push` performance is now much closer to the `hg pull` performance, even it still lagging behind a bit. (and the overall performance are still too slow). ### data-env-vars.name = mozilla-try-2023-03-22-ds2-pnm # benchmark.variants.explicit-rev = all-out-heads # benchmark.variants.issue6528 = disabled # benchmark.variants.protocol = ssh # benchmark.variants.pulled-delta-reuse-policy = default # bin-env-vars.hg.flavor = rust ## benchmark.variants.revs = any-1-extra-rev hg.command.pull: 6.517450 hg.command.push: 11.219888 ## benchmark.variants.revs = any-100-extra-rev hg.command.pull: 10.160991 hg.command.push: 14.251107 ### data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog # bin-env-vars.hg.py-re2-module = default # benchmark.variants.explicit-rev = all-out-heads # benchmark.variants.issue6528 = disabled # benchmark.variants.protocol = ssh # benchmark.variants.pulled-delta-reuse-policy = default ## bin-env-vars.hg.flavor = default ## benchmark.variants.revs = any-1-extra-rev hg.command.pull: 8.577772 hg.command.push: 11.232059 ## bin-env-vars.hg.flavor = default ## benchmark.variants.revs = any-100-extra-rev hg.command.pull: 13.152976 hg.command.push: 15.367412 ## bin-env-vars.hg.flavor = rust ## benchmark.variants.revs = any-1-extra-rev hg.command.pull: 8.731982 hg.command.push: 11.178751 ## bin-env-vars.hg.flavor = rust ## benchmark.variants.revs = any-100-extra-rev hg.command.pull: 13.184236 hg.command.push: 15.620843

phases: introduce a performant efficient way to access revision in a set This will be useful in the next changesets.

phases: use revision number in `_pushdiscoveryphase` We now reach our target checkpoint in terms of rev-num conversion. The `_pushdiscoveryphase` function is now performing graph computation based on revision number only. Avoiding repeated conversion from node-id to rev-num. See previous changeset updated `new_heads` for rationnal. Again, time saved in the 100 milliseconds order of magnitude for the mozilla-try benchmark I have been using. However, wow that the logic is done using revision number, we can look into having better logic in the next changesets, which will provide a much bigger speedup.

phases: move RemotePhasesSummary to revision number This continue our quest to align more logic on revision number instead of node-ids. The motivation is similar to the change to `new_heads` and `analyze_remote_phases` a few changeset earlier. Again, we take this as an opportunity to rename the class, and the attribute to the new naming scheme. This will highlight the need for code update for any code using it an expecting node-ids. Many of the rev-num → node-id conversion we had to introduce in the previous changesets can now be removed. More will be removed in the future as we continue to align code toward rev-num usage. time saved in the 100 milliseconds order of magnitude for the mozilla-try benchmark I have been using.

phases: stop using `repo.set` in `remotephasessummary` The `repository.set` create changectx on the fly, an expensive operation. Using `repo.revs` and a direct rev-num → node-id translation will be significantly faster. This is especially true as we prepare ourself to no longer do the rev-num → node-id transalation there. The speedup is a bit lost in the overall noisyness of the slow phase discovery algorithm, but it save a small amount of time in my benchmark.

phases: use revision number in analyze_remote_phases Same logic as the previous change to `new_heads`, see rationnal there. This avoids a small number of `nodes -> revs` conversion speeding thing up in the 100 milliseconds order of magnitude for the worses cases. However, the rest of the logic is noisy enough that it hardly matters for now.