bundle2: implement consume() API on unbundlepart
We want bundle parts to not be seekable by default. That means
eliminating the generic seek() method.
A common pattern in bundle2.py is to seek to the end of the part
data. This is mainly used by the part iteration code to ensure
the underlying stream is advanced to the next bundle part.
In this commit, we establish a dedicated API for consuming a
bundle2 part data. We switch users of seek() to it.
The old implementation of seek(0, os.SEEK_END) would effectively
call self.read(). The new implementation calls self.read(32768)
in a loop. The old implementation would therefore assemble a
buffer to hold all remaining data being seeked over. For seeking
over large bundle parts, this would involve a large allocation and
a lot of overhead to collect intermediate data! This overhead can
be seen in the results for `hg perfbundleread`:
! bundle2 iterparts()
! wall 10.891305 comb 10.820000 user 7.990000 sys 2.830000 (best of 3)
! wall 8.070791 comb 8.060000 user 7.180000 sys 0.880000 (best of 3)
! bundle2 part seek()
! wall 12.991478 comb 10.390000 user 7.720000 sys 2.670000 (best of 3)
! wall 10.370142 comb 10.350000 user 7.430000 sys 2.920000 (best of 3)
Of course, skipping over large payload data isn't likely very common.
So I doubt the performance wins will be observed in the wild.
Differential Revision: https://phab.mercurial-scm.org/D1388
#require test-repo
$ . "$TESTDIR/helpers-testrepo.sh"
$ testrepohgenv
$ import_checker="$TESTDIR"/../contrib/import-checker.py
Run the doctests from the import checker, and make sure
it's working correctly.
$ TERM=dumb
$ export TERM
$ $PYTHON -m doctest $import_checker
Run additional tests for the import checker
$ mkdir testpackage
$ touch testpackage/__init__.py
$ cat > testpackage/multiple.py << EOF
> from __future__ import absolute_import
> import os, sys
> EOF
$ cat > testpackage/unsorted.py << EOF
> from __future__ import absolute_import
> import sys
> import os
> EOF
$ cat > testpackage/stdafterlocal.py << EOF
> from __future__ import absolute_import
> from . import unsorted
> import os
> EOF
$ cat > testpackage/requirerelative.py << EOF
> from __future__ import absolute_import
> import testpackage.unsorted
> EOF
$ cat > testpackage/importalias.py << EOF
> from __future__ import absolute_import
> import ui
> EOF
$ cat > testpackage/relativestdlib.py << EOF
> from __future__ import absolute_import
> from .. import os
> EOF
$ cat > testpackage/symbolimport.py << EOF
> from __future__ import absolute_import
> from .unsorted import foo
> EOF
$ cat > testpackage/latesymbolimport.py << EOF
> from __future__ import absolute_import
> from . import unsorted
> from mercurial.node import hex
> EOF
$ cat > testpackage/multiplegroups.py << EOF
> from __future__ import absolute_import
> from . import unsorted
> from . import more
> EOF
$ mkdir testpackage/subpackage
$ cat > testpackage/subpackage/levelpriority.py << EOF
> from __future__ import absolute_import
> from . import foo
> from .. import parent
> EOF
$ touch testpackage/subpackage/foo.py
$ cat > testpackage/subpackage/__init__.py << EOF
> from __future__ import absolute_import
> from . import levelpriority # should not cause cycle
> EOF
$ cat > testpackage/subpackage/localimport.py << EOF
> from __future__ import absolute_import
> from . import foo
> def bar():
> # should not cause "higher-level import should come first"
> from .. import unsorted
> # but other errors should be detected
> from .. import more
> import testpackage.subpackage.levelpriority
> EOF
$ cat > testpackage/importmodulefromsub.py << EOF
> from __future__ import absolute_import
> from .subpackage import foo # not a "direct symbol import"
> EOF
$ cat > testpackage/importsymbolfromsub.py << EOF
> from __future__ import absolute_import
> from .subpackage import foo, nonmodule
> EOF
$ cat > testpackage/sortedentries.py << EOF
> from __future__ import absolute_import
> from . import (
> foo,
> bar,
> )
> EOF
$ cat > testpackage/importfromalias.py << EOF
> from __future__ import absolute_import
> from . import ui
> EOF
$ cat > testpackage/importfromrelative.py << EOF
> from __future__ import absolute_import
> from testpackage.unsorted import foo
> EOF
$ mkdir testpackage2
$ touch testpackage2/__init__.py
$ cat > testpackage2/latesymbolimport.py << EOF
> from __future__ import absolute_import
> from testpackage import unsorted
> from mercurial.node import hex
> EOF
# Shadowing a stdlib module to test "relative import of stdlib module" is
# allowed if the module is also being checked
$ mkdir email
$ touch email/__init__.py
$ touch email/errors.py
$ cat > email/utils.py << EOF
> from __future__ import absolute_import
> from . import errors
> EOF
$ $PYTHON "$import_checker" testpackage*/*.py testpackage/subpackage/*.py \
> email/*.py
testpackage/importalias.py:2: ui module must be "as" aliased to uimod
testpackage/importfromalias.py:2: ui from testpackage must be "as" aliased to uimod
testpackage/importfromrelative.py:2: import should be relative: testpackage.unsorted
testpackage/importfromrelative.py:2: direct symbol import foo from testpackage.unsorted
testpackage/importsymbolfromsub.py:2: direct symbol import nonmodule from testpackage.subpackage
testpackage/latesymbolimport.py:3: symbol import follows non-symbol import: mercurial.node
testpackage/multiple.py:2: multiple imported names: os, sys
testpackage/multiplegroups.py:3: multiple "from . import" statements
testpackage/relativestdlib.py:2: relative import of stdlib module
testpackage/requirerelative.py:2: import should be relative: testpackage.unsorted
testpackage/sortedentries.py:2: imports from testpackage not lexically sorted: bar < foo
testpackage/stdafterlocal.py:3: stdlib import "os" follows local import: testpackage
testpackage/subpackage/levelpriority.py:3: higher-level import should come first: testpackage
testpackage/subpackage/localimport.py:7: multiple "from .. import" statements
testpackage/subpackage/localimport.py:8: import should be relative: testpackage.subpackage.levelpriority
testpackage/symbolimport.py:2: direct symbol import foo from testpackage.unsorted
testpackage/unsorted.py:3: imports not lexically sorted: os < sys
testpackage2/latesymbolimport.py:3: symbol import follows non-symbol import: mercurial.node
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