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
#!/usr/bin/env python3
"""This does HTTP GET requests given a host:port and path and returns
a subset of the headers plus the body of the result."""
from __future__ import absolute_import
import argparse
import json
import os
import sys
from mercurial import (
pycompat,
util,
)
httplib = util.httplib
try:
import msvcrt
msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
except ImportError:
pass
stdout = getattr(sys.stdout, 'buffer', sys.stdout)
parser = argparse.ArgumentParser()
parser.add_argument('--twice', action='store_true')
parser.add_argument('--headeronly', action='store_true')
parser.add_argument('--json', action='store_true')
parser.add_argument('--hgproto')
parser.add_argument(
'--requestheader',
nargs='*',
default=[],
help='Send an additional HTTP request header. Argument '
'value is <header>=<value>',
)
parser.add_argument('--bodyfile', help='Write HTTP response body to a file')
parser.add_argument('host')
parser.add_argument('path')
parser.add_argument('show', nargs='*')
args = parser.parse_args()
twice = args.twice
headeronly = args.headeronly
formatjson = args.json
hgproto = args.hgproto
requestheaders = args.requestheader
tag = None
def request(host, path, show):
assert not path.startswith('/'), path
global tag
headers = {}
if tag:
headers['If-None-Match'] = tag
if hgproto:
headers['X-HgProto-1'] = hgproto
for header in requestheaders:
key, value = header.split('=', 1)
headers[key] = value
conn = httplib.HTTPConnection(host)
conn.request("GET", '/' + path, None, headers)
response = conn.getresponse()
stdout.write(
b'%d %s\n' % (response.status, response.reason.encode('ascii'))
)
if show[:1] == ['-']:
show = sorted(
h for h, v in response.getheaders() if h.lower() not in show
)
for h in [h.lower() for h in show]:
if response.getheader(h, None) is not None:
stdout.write(
b"%s: %s\n"
% (h.encode('ascii'), response.getheader(h).encode('ascii'))
)
if not headeronly:
stdout.write(b'\n')
data = response.read()
if args.bodyfile:
bodyfh = open(args.bodyfile, 'wb')
else:
bodyfh = stdout
# Pretty print JSON. This also has the beneficial side-effect
# of verifying emitted JSON is well-formed.
if formatjson:
# json.dumps() will print trailing newlines. Eliminate them
# to make tests easier to write.
data = pycompat.json_loads(data)
lines = json.dumps(data, sort_keys=True, indent=2).splitlines()
for line in lines:
bodyfh.write(pycompat.sysbytes(line.rstrip()))
bodyfh.write(b'\n')
else:
bodyfh.write(data)
if args.bodyfile:
bodyfh.close()
if twice and response.getheader('ETag', None):
tag = response.getheader('ETag')
return response.status
status = request(args.host, args.path, args.show)
if twice:
status = request(args.host, args.path, args.show)
if 200 <= status <= 305:
sys.exit(0)
sys.exit(1)