view tests/printenv.py @ 44363:f7459da77f23

nodemap: introduce an option to use mmap to read the nodemap mapping

The performance and memory benefit is much greater if we don't have to copy all
the data in memory for each information. So we introduce an option (on by
default) to read the data using mmap.

This changeset is the last one definition the API for index support nodemap
data. (they have to be able to use the mmaping).

Below are some benchmark comparing the best we currently have in 5.3 with the
final step of this series (using the persistent nodemap implementation in
Rust). The benchmark run `hg perfindex` with various revset and the following
variants:

Before:

 * do not use the persistent nodemap
 * use the CPython implementation of the index for nodemap
 * use mmapping of the changelog index

After:

 * use the MixedIndex Rust code, with the NodeTree object for nodemap access
   (still in review)
 * use the persistent nodemap data from disk
 * access the persistent nodemap data through mmap
 * use mmapping of the changelog index

The persistent nodemap greatly speed up  most operation on very large
repositories. Some of the previously very fast lookup end up a bit slower because
the persistent nodemap has to be setup. However the absolute slowdown is very
small and won't matters in the big picture.

Here are some numbers (in seconds) for the reference copy of mozilla-try:

Revset            Before   After     abs-change speedup

-10000:           0.004622 0.005532   0.000910  ×   0.83
-10:              0.000050 0.000132   0.000082  ×   0.37
tip               0.000052 0.000085   0.000033  ×   0.61
0 + (-10000:)     0.028222 0.005337  -0.022885  ×   5.29
0                 0.023521 0.000084  -0.023437  × 280.01
(-10000:) + 0     0.235539 0.005308  -0.230231  ×  44.37
(-10:) + :9       0.232883 0.000180  -0.232703  ×1293.79
(-10000:) + (:99) 0.238735 0.005358  -0.233377  ×  44.55
:99 + (-10000:)   0.317942 0.005593  -0.312349  ×  56.84
:9 + (-10:)       0.313372 0.000179  -0.313193  ×1750.68
:9                0.316450 0.000143  -0.316307  ×2212.93


On smaller repositories, the cost of nodemap related operation is not as big, so
the win is much more modest. Yet it helps shaving a handful of millisecond here
and there.

Here are some numbers (in seconds) for the reference copy of mercurial:

Revset            Before   After     abs-change speedup
-10:              0.000065 0.000097   0.000032  × 0.67
tip               0.000063 0.000078   0.000015  × 0.80
0                 0.000561 0.000079  -0.000482  × 7.10
-10000:           0.004609 0.003648  -0.000961  × 1.26
0 + (-10000:)     0.005023 0.003715  -0.001307  × 1.35
(-10:) + :9       0.002187 0.000108  -0.002079  ×20.25
(-10000:) + 0     0.006252 0.003716  -0.002536  × 1.68
(-10000:) + (:99) 0.006367 0.003707  -0.002660  × 1.71
:9 + (-10:)       0.003846 0.000110  -0.003736  ×34.96
:9                0.003854 0.000099  -0.003755  ×38.92
:99 + (-10000:)   0.007644 0.003778  -0.003866  × 2.02

Differential Revision: https://phab.mercurial-scm.org/D7894

#!/usr/bin/env python
#
# simple script to be used in hooks
#
# put something like this in the repo .hg/hgrc:
#
#     [hooks]
#     changegroup = python "$TESTDIR/printenv.py" <hookname> [exit] [output]
#
#   - <hookname> is a mandatory argument (e.g. "changegroup")
#   - [exit] is the exit code of the hook (default: 0)
#   - [output] is the name of the output file (default: use sys.stdout)
#              the file will be opened in append mode.
#
from __future__ import absolute_import
import argparse
import os
import sys

try:
    import msvcrt

    msvcrt.setmode(sys.stdin.fileno(), os.O_BINARY)
    msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
    msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
except ImportError:
    pass

parser = argparse.ArgumentParser()
parser.add_argument("name", help="the hook name, used for display")
parser.add_argument(
    "exitcode",
    nargs="?",
    default=0,
    type=int,
    help="the exit code for the hook",
)
parser.add_argument(
    "out", nargs="?", default=None, help="where to write the output"
)
parser.add_argument(
    "--line",
    action="store_true",
    help="print environment variables one per line instead of on a single line",
)
args = parser.parse_args()

if args.out is None:
    out = sys.stdout
    out = getattr(out, "buffer", out)
else:
    out = open(args.out, "ab")

# variables with empty values may not exist on all platforms, filter
# them now for portability sake.
env = [(k, v) for k, v in os.environ.items() if k.startswith("HG_") and v]
env.sort()

out.write(b"%s hook: " % args.name.encode('ascii'))
if os.name == 'nt':
    filter = lambda x: x.replace('\\', '/')
else:
    filter = lambda x: x

vars = [
    b"%s=%s" % (k.encode('ascii'), filter(v).encode('ascii')) for k, v in env
]

# Print variables on out
if not args.line:
    out.write(b" ".join(vars))
else:
    for var in vars:
        out.write(var)
        out.write(b"\n")

out.write(b"\n")
out.close()

sys.exit(args.exitcode)