view rust/rhg/Cargo.toml @ 47120:7109a38830c9

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

[package]
name = "rhg"
version = "0.1.0"
authors = [
    "Antoine Cezar <[e-mail]>",
    "Raphaël Gomès <[e-mail]>",
]
edition = "2018"

[dependencies]
hg-core = { path = "../hg-core"}
chrono = "0.4.19"
clap = "2.33.1"
derive_more = "0.99"
lazy_static = "1.4.0"
log = "0.4.11"
micro-timer = "0.3.1"
regex = "1.3.9"
env_logger = "0.7.1"
format-bytes = "0.2.1"
users = "0.11.0"