view tests/test-dispatch.py @ 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

from __future__ import absolute_import, print_function
import os
import sys
from mercurial import dispatch


def printb(data, end=b'\n'):
    out = getattr(sys.stdout, 'buffer', sys.stdout)
    out.write(data + end)
    out.flush()


def testdispatch(cmd):
    """Simple wrapper around dispatch.dispatch()

    Prints command and result value, but does not handle quoting.
    """
    printb(b"running: %s" % (cmd,))
    req = dispatch.request(cmd.split())
    result = dispatch.dispatch(req)
    printb(b"result: %r" % (result,))


testdispatch(b"init test1")
os.chdir('test1')

# create file 'foo', add and commit
f = open('foo', 'wb')
f.write(b'foo\n')
f.close()
testdispatch(b"add foo")
testdispatch(b"commit -m commit1 -d 2000-01-01 foo")

# append to file 'foo' and commit
f = open('foo', 'ab')
f.write(b'bar\n')
f.close()
testdispatch(b"commit -m commit2 -d 2000-01-02 foo")

# check 88803a69b24 (fancyopts modified command table)
testdispatch(b"log -r 0")
testdispatch(b"log -r tip")