view tests/test-propertycache.py @ 46667:93e9f448273c

rhg: Add support for automatic fallback to Python

`rhg` is a command-line application that can do a small subset of what
`hg` can. It is written entirely in Rust, which avoids the cost of starting
a Python interpreter and importing many Python modules.
In a script that runs many `hg` commands, this cost can add up.

However making users decide when to use `rhg` instead of `hg` is
not practical as we want the subset of supported functionality
to grow over time.

Instead we introduce "fallback" behavior where, when `rhg` encounters
something (a sub-command, a repository format, …) that is not implemented
in Rust-only, it does nothing but silently start a subprocess of
Python-based `hg` running the same command.
That way `rhg` becomes a drop-in replacement for `hg` that sometimes
goes faster. Whether Python is used should be an implementation detail
not apparent to users (other than through speed).

A new `fallback` value is added to the previously introduced
`rhg.on-unsupported` configuration key. When in this mode, the new
`rhg.fallback-executable` config is determine what command to use
to run a Python-based `hg`.

The previous `rhg.on-unsupported = abort-silent` configuration was designed
to let a wrapper script call `rhg` and then fall back to `hg` based on the
exit code. This is still available, but having fallback behavior built-in
in rhg might be easier for users instead of leaving that script "as an
exercise for the reader".

Using a subprocess like this is not idea, especially when `rhg` is to be
installed in `$PATH` as `hg`, since the other `hg.py` executable needs
to still be available… somewhere. Eventually this could be replaced
by using PyOxidizer to a have a single executable that embeds a Python
interpreter, but only starts it when needed.

Differential Revision: https://phab.mercurial-scm.org/D10093

"""test behavior of propertycache and unfiltered propertycache

The repoview overlay is quite complex. We test the behavior of
property cache of both localrepo and repoview to prevent
regression."""

from __future__ import absolute_import, print_function
import os
import subprocess

from mercurial import (
    hg,
    localrepo,
    pycompat,
    ui as uimod,
    util,
)

from mercurial.utils import procutil

# create some special property cache that trace they call

calllog = []


@util.propertycache
def testcachedfoobar(repo):
    name = repo.filtername
    if name is None:
        name = ''
    val = len(name)
    calllog.append(val)
    return val


unficalllog = []


@localrepo.unfilteredpropertycache
def testcachedunfifoobar(repo):
    name = repo.filtername
    if name is None:
        name = ''
    val = 100 + len(name)
    unficalllog.append(val)
    return val


# plug them on repo
localrepo.localrepository.testcachedfoobar = testcachedfoobar
localrepo.localrepository.testcachedunfifoobar = testcachedunfifoobar


# Create an empty repo and instantiate it. It is important to run
# these tests on the real object to detect regression.
repopath = pycompat.fsencode(os.path.join(os.environ['TESTTMP'], 'repo'))
assert (
    subprocess.call(
        pycompat.rapply(procutil.tonativestr, [b'hg', b'init', repopath])
    )
    == 0
)

ui = uimod.ui.load()
repo = hg.repository(ui, path=repopath).unfiltered()


print('')
print('=== property cache ===')
print('')
print('calllog:', calllog)
print(
    'cached value (unfiltered):', vars(repo).get('testcachedfoobar', 'NOCACHE')
)

print('')
print('= first access on unfiltered, should do a call')
print('access:', repo.testcachedfoobar)
print('calllog:', calllog)
print(
    'cached value (unfiltered):', vars(repo).get('testcachedfoobar', 'NOCACHE')
)

print('')
print('= second access on unfiltered, should not do call')
print('access', repo.testcachedfoobar)
print('calllog:', calllog)
print(
    'cached value (unfiltered):', vars(repo).get('testcachedfoobar', 'NOCACHE')
)

print('')
print('= first access on "visible" view, should do a call')
visibleview = repo.filtered('visible')
print(
    'cached value ("visible" view):',
    vars(visibleview).get('testcachedfoobar', 'NOCACHE'),
)
print('access:', visibleview.testcachedfoobar)
print('calllog:', calllog)
print(
    'cached value (unfiltered):', vars(repo).get('testcachedfoobar', 'NOCACHE')
)
print(
    'cached value ("visible" view):',
    vars(visibleview).get('testcachedfoobar', 'NOCACHE'),
)

print('')
print('= second access on "visible view", should not do call')
print('access:', visibleview.testcachedfoobar)
print('calllog:', calllog)
print(
    'cached value (unfiltered):', vars(repo).get('testcachedfoobar', 'NOCACHE')
)
print(
    'cached value ("visible" view):',
    vars(visibleview).get('testcachedfoobar', 'NOCACHE'),
)

print('')
print('= no effect on other view')
immutableview = repo.filtered('immutable')
print(
    'cached value ("immutable" view):',
    vars(immutableview).get('testcachedfoobar', 'NOCACHE'),
)
print('access:', immutableview.testcachedfoobar)
print('calllog:', calllog)
print(
    'cached value (unfiltered):', vars(repo).get('testcachedfoobar', 'NOCACHE')
)
print(
    'cached value ("visible" view):',
    vars(visibleview).get('testcachedfoobar', 'NOCACHE'),
)
print(
    'cached value ("immutable" view):',
    vars(immutableview).get('testcachedfoobar', 'NOCACHE'),
)

# unfiltered property cache test
print('')
print('')
print('=== unfiltered property cache ===')
print('')
print('unficalllog:', unficalllog)
print(
    'cached value (unfiltered):      ',
    vars(repo).get('testcachedunfifoobar', 'NOCACHE'),
)
print(
    'cached value ("visible" view):  ',
    vars(visibleview).get('testcachedunfifoobar', 'NOCACHE'),
)
print(
    'cached value ("immutable" view):',
    vars(immutableview).get('testcachedunfifoobar', 'NOCACHE'),
)

print('')
print('= first access on unfiltered, should do a call')
print('access (unfiltered):', repo.testcachedunfifoobar)
print('unficalllog:', unficalllog)
print(
    'cached value (unfiltered):      ',
    vars(repo).get('testcachedunfifoobar', 'NOCACHE'),
)

print('')
print('= second access on unfiltered, should not do call')
print('access (unfiltered):', repo.testcachedunfifoobar)
print('unficalllog:', unficalllog)
print(
    'cached value (unfiltered):      ',
    vars(repo).get('testcachedunfifoobar', 'NOCACHE'),
)

print('')
print('= access on view should use the unfiltered cache')
print('access (unfiltered):      ', repo.testcachedunfifoobar)
print('access ("visible" view):  ', visibleview.testcachedunfifoobar)
print('access ("immutable" view):', immutableview.testcachedunfifoobar)
print('unficalllog:', unficalllog)
print(
    'cached value (unfiltered):      ',
    vars(repo).get('testcachedunfifoobar', 'NOCACHE'),
)
print(
    'cached value ("visible" view):  ',
    vars(visibleview).get('testcachedunfifoobar', 'NOCACHE'),
)
print(
    'cached value ("immutable" view):',
    vars(immutableview).get('testcachedunfifoobar', 'NOCACHE'),
)

print('')
print('= even if we clear the unfiltered cache')
del repo.__dict__['testcachedunfifoobar']
print(
    'cached value (unfiltered):      ',
    vars(repo).get('testcachedunfifoobar', 'NOCACHE'),
)
print(
    'cached value ("visible" view):  ',
    vars(visibleview).get('testcachedunfifoobar', 'NOCACHE'),
)
print(
    'cached value ("immutable" view):',
    vars(immutableview).get('testcachedunfifoobar', 'NOCACHE'),
)
print('unficalllog:', unficalllog)
print('access ("visible" view):  ', visibleview.testcachedunfifoobar)
print('unficalllog:', unficalllog)
print(
    'cached value (unfiltered):      ',
    vars(repo).get('testcachedunfifoobar', 'NOCACHE'),
)
print(
    'cached value ("visible" view):  ',
    vars(visibleview).get('testcachedunfifoobar', 'NOCACHE'),
)
print(
    'cached value ("immutable" view):',
    vars(immutableview).get('testcachedunfifoobar', 'NOCACHE'),
)
print('access ("immutable" view):', immutableview.testcachedunfifoobar)
print('unficalllog:', unficalllog)
print(
    'cached value (unfiltered):      ',
    vars(repo).get('testcachedunfifoobar', 'NOCACHE'),
)
print(
    'cached value ("visible" view):  ',
    vars(visibleview).get('testcachedunfifoobar', 'NOCACHE'),
)
print(
    'cached value ("immutable" view):',
    vars(immutableview).get('testcachedunfifoobar', 'NOCACHE'),
)
print('access (unfiltered):      ', repo.testcachedunfifoobar)
print('unficalllog:', unficalllog)
print(
    'cached value (unfiltered):      ',
    vars(repo).get('testcachedunfifoobar', 'NOCACHE'),
)
print(
    'cached value ("visible" view):  ',
    vars(visibleview).get('testcachedunfifoobar', 'NOCACHE'),
)
print(
    'cached value ("immutable" view):',
    vars(immutableview).get('testcachedunfifoobar', 'NOCACHE'),
)