revlog: make the index always return the same tuple It is simpler to manage the diferrence in on disk format in the internal index code itself and lets the rest of the code always handle the same object. This will become even more important when the data we store will be entirely different (for example the changelog does not need the "linkrev" field. We start with item reading, we will deal with item writing in the next changesets. Differential Revision: https://phab.mercurial-scm.org/D10568

revlog: introduce an explicit `format_version` member in the index struct This will allow for cleaner check than assuming each version has a different size. Unsurprisingly I am planning to use this to introduce more format variant. Differential Revision: https://phab.mercurial-scm.org/D10567

revlog: rename `hdrsize` to `entry_size` in the C code This is the size of and index entry, so lets make it clearer. Differential Revision: https://phab.mercurial-scm.org/D10566

revlog: split the `version` attribute into its two components The `revlog.version` attribute contained an integer coding 2 different informations: * the revlog version number * a bit field defining some specific feature of the revlog We now explicitly store the two components independently. This avoid exposing the implementation details all around the code and prepare for future revlog version that would encode the information in a different way. In the process we drop the `version` attribute from the interface. It was flagged for removal when that interface was created. Differential Revision: https://phab.mercurial-scm.org/D10565

verify: pass a revlog to `_checkrevlog` in `_verifymanifest` Since `manifestrevlog` is not a `revlog`, we are passing strange thing to `_checkrevlog`. We fix this to avoid breakage during future change. Differential Revision: https://phab.mercurial-scm.org/D10564

revlog: replace flag check related to generaldelta with attribute check Same logic as the previous changesets. Differential Revision: https://phab.mercurial-scm.org/D10563

revlog: replace REVLOGV2 check related to sidedata with `hassidedata` checks This is more flexible and semantically more correct. The associated revlog's attribute exist since 827cb4fe62a3, so well we start linking sidedata to revlogv2. Differential Revision: https://phab.mercurial-scm.org/D10562

revlog: explicitely pass the "indexfile" parameter Most of this was already done when introducing the `target` parameter, but some remained. Having "indexfile" passed explicitely will help us to change the way we address a revlog later in the stack. With the introduction of more generic `docket`, the entry point will not necessarly be `xxx.i` file, and the actual index files will have a variable name. Differential Revision: https://phab.mercurial-scm.org/D10561

revlog: highlight current incompatibility in `rewrite_sidedata` See comment for details. We will need to fix the test coverage when this incompatibility is lifted. Differential Revision: https://phab.mercurial-scm.org/D10544

revlog: adjust rewrite_sidedata code to not delete existing revlog content The "w+" file mode is deleting all the content of the opened file. Which is bad… This is not caught by the test because the test only check for a full, initial pull where not pre-existing content exists. So we need to fix our test coverage here. However they are another issue that prevent "incremental" pull to work here. See next changeset for details. Differential Revision: https://phab.mercurial-scm.org/D10543

status: Add tests for some more edge cases * Size-preserving file contents modification * Filtering output to a deleted or removed file Differential Revision: https://phab.mercurial-scm.org/D10701

status: Extend issue 6483 test to exclude patterns With `hg status -X`, not just include pattern with `hg status -I` Differential Revision: https://phab.mercurial-scm.org/D10700

dirstate-tree: Add a test showing that issue 6335 is fixed … when using the new status algorithm and the tree-based dirstate. The previous algorithm still has this bug. Differential Revision: https://phab.mercurial-scm.org/D10699

dirstate-tree: Add a dirstate-v1-tree variant of some tests The `dirstate-v1` variant has the previous behavior. `dirstate-v1-tree` uses the same format on disk, but uses the new `DirstateMap` with a tree data structure and the new `status` algorithm. These were untested so far. Differential Revision: https://phab.mercurial-scm.org/D10698

merge with stable

rename: add hint about --at-rev if source file doesn't exist It's quite common that users want to record copy (rename) information after committing the working copy changes (i.e. an added and a deleted file). When they try `hg mv [--after] <src> <dst>`, that just fails because the source file doesn't exist. It seems helpful if we can point them to `--at-rev=.` in this case. Differential Revision: https://phab.mercurial-scm.org/D10697

dirstate-tree: Borrow paths from the "on disk" bytes Use std::borrow::Cow to avoid some memory allocations and copying. Differential Revision: https://phab.mercurial-scm.org/D10560

dirstate-tree: Borrow copy source paths from the "on disk" bytes Use std::borrow::Cow to avoid some memory allocations and copying. These particular allocations are not visible when profiling (as many files in a typical repo don’t have a copy source). This change is "warm up" for doing the same with paths of files themselves, which is more involved since those paths are used as `HashMap` keys. This gets of the way the addition of a lifetime parameter to several types. Differential Revision: https://phab.mercurial-scm.org/D10559

rust: Use `&HgPath` instead of `&HgPathBuf` in may APIs Getting the former (through `Deref`) is almost the only useful thing one can do with the latter anyway. With this changes, API become more flexible for the "provider" of these paths which may store something else that Deref’s to HgPath, such as `std::borrow::Cow<HgPath>`. Using `Cow` can help reduce memory alloactions and copying. Differential Revision: https://phab.mercurial-scm.org/D10558

dirstate-tree: Make `DirstateMap` borrow from a bytes buffer … that has the contents of the `.hg/dirstate` file. This only applies to the tree-based flavor of `DirstateMap`. For now only the entire `&[u8]` slice is stored, so this is not useful yet. Adding a lifetime parameter to the `DirstateMap` struct (in hg-core) makes Python bindings non-trivial because we keep that struct in a Python object that has a dynamic lifetime tied to Python’s reference-counting and GC. As long as we keep the `PyBytes` that owns the borrowed bytes buffer next to the borrowing struct, the buffer will live long enough for the borrows to stay valid. However this relationship cannot be expressed in safe Rust code in a way that would statisfy they borrow-checker. We use `unsafe` code to erase that lifetime parameter, and encapsulate it in a safe abstraction similar to the owning-ref crate: https://docs.rs/owning_ref/ Differential Revision: https://phab.mercurial-scm.org/D10557

rust: Read dirstate from disk in DirstateMap constructor Before this changeset, Python code first creates an empty `DirstateMap` Rust object, then immediately calls its `read` method with a byte string of the contents of the `.hg/dirstate` file. This makes that byte string available to the constructor of `DirstateMap` in the hg-cpython crate. This is a first step towards enabling parts of `DirstateMap` in the hg-core crate to borrow from this buffer without copying. Differential Revision: https://phab.mercurial-scm.org/D10556

rust: Remove handling of `parents` in `DirstateMap` The Python wrapper class `dirstatemap` can take care of it. This removes the need to have both `_rustmap` and `_inner_rustmap`. Differential Revision: https://phab.mercurial-scm.org/D10555

dirstate-tree: Fold "tracked descendants" counter update in main walk For the purpose of implementing `has_tracked_dir` (which means "has tracked descendants) without an expensive sub-tree traversal, we maintaing a counter of tracked descendants on each "directory" node of the tree-shaped dirstate. Before this changeset, mutating or inserting a node at a given path would involve: * Walking the tree from root through ancestors to find the node or the spot where to insert it * Looking at the previous node if any to decide what counter update is needed * Performing any node mutation * Walking the tree *again* to update counters in ancestor nodes When profiling `hg status` on a large repo, this second walk takes times while loading a the dirstate from disk. It turns out we have enough information to decide before he first tree walk what counter update is needed. This changeset merges the two walks, gaining ~10% of the total time for `hg update` (in the same hyperfine benchmark as the previous changeset). --- Profiling was done by compiling with this `.cargo/config`: [profile.release] debug = true then running with: py-spy record -r 500 -n -o /tmp/hg.json --format speedscope -- \ ./hg status -R $REPO --config experimental.dirstate-tree.in-memory=1 then visualizing the recorded JSON file in https://www.speedscope.app/ Differential Revision: https://phab.mercurial-scm.org/D10554

dirstate-tree: Use HashMap instead of BTreeMap BTreeMap has the advantage of its "natural" iteration order being the one we need in the status algorithm. With HashMap however, iteration order is undefined so we need to allocate a Vec and sort it explicitly. Unfortunately many BTreeMap operations are slower than in HashMap, and skipping that extra allocation and sort is not enough to compensate. Switching to HashMap + sort makes `hg status` 17% faster in one test case, as measure with hyperfine: ``` Benchmark #1: ../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1 Time (mean ± σ): 765.0 ms ± 8.8 ms [User: 1.352 s, System: 0.747 s] Range (min … max): 751.8 ms … 778.7 ms 10 runs Benchmark #2: ./hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1 Time (mean ± σ): 651.8 ms ± 9.9 ms [User: 1.251 s, System: 0.799 s] Range (min … max): 642.2 ms … 671.8 ms 10 runs Summary './hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1' ran 1.17 ± 0.02 times faster than '../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1' ``` * ./hg is this revision * ../hg2/hg is its parent * $REPO is an old snapshot of mozilla-central Differential Revision: https://phab.mercurial-scm.org/D10553

dirstate-tree: Add #[timed] attribute to `status` and `DirstateMap::read` When running with a `RUST_LOG=trace` environment variable, the `micro_timer` crate prints the duration taken by each call to functions with that attribute. Differential Revision: https://phab.mercurial-scm.org/D10552

dirstate-tree: Paralellize the status algorithm with Rayon The `rayon` crate exposes "parallel iterators" that work like normal iterators but dispatch work on different items to an implicit global thread pool. Differential Revision: https://phab.mercurial-scm.org/D10551

dirstate-tree: Avoid BTreeMap double-lookup when inserting a dirstate entry The child nodes of a given node in the tree-shaped dirstate are kept in a `BTreeMap` where keys are file names as strings. Finding or inserting a value in the map takes `O(log(n))` string comparisons, which adds up when constructing the tree. The `entry` API allows finding a "spot" in the map that may or may not be occupied and then access that value or insert a new one without doing map lookup again. However the current API is limited in that calling `entry` requires an owned key (and so a memory allocation), even if it ends up not being used in the case where the map already has a value with an equal key. This is still a win, with 4% better end-to-end time for `hg status` measured here with hyperfine: ``` Benchmark #1: ../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1 Time (mean ± σ): 1.337 s ± 0.018 s [User: 892.9 ms, System: 437.5 ms] Range (min … max): 1.316 s … 1.373 s 10 runs Benchmark #2: ./hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1 Time (mean ± σ): 1.291 s ± 0.008 s [User: 853.4 ms, System: 431.1 ms] Range (min … max): 1.283 s … 1.309 s 10 runs Summary './hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1' ran 1.04 ± 0.02 times faster than '../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1' ``` * ./hg is this revision * ../hg2/hg is its parent * $REPO is an old snapshot of mozilla-central Differential Revision: https://phab.mercurial-scm.org/D10550

dirstate-tree: Handle I/O errors in status Errors such as insufficient permissions when listing a directory are logged, and the algorithm continues without considering that directory. Differential Revision: https://phab.mercurial-scm.org/D10549

dirstate-tree: Ignore FIFOs etc. in the status algorithm If a filesystem directory contains anything that is not: * a "normal" file * a symbolic link * or a directory … act as if that directory entry was not there. For example, if that path was previously a tracked file, mark it as deleted or removed. Differential Revision: https://phab.mercurial-scm.org/D10548

dirstate-tree: Add the new `status()` algorithm With the dirstate organized in a tree that mirrors the structure of the filesystem tree, we can traverse both trees at the same time in order to compare them. This is hopefully more efficient that building multiple big hashmaps for all of the repository’s contents. Differential Revision: https://phab.mercurial-scm.org/D10547