forked from pre-commit/pre-commit
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathxargs.py
More file actions
155 lines (123 loc) · 4.65 KB
/
xargs.py
File metadata and controls
155 lines (123 loc) · 4.65 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
from __future__ import absolute_import
from __future__ import division
from __future__ import unicode_literals
import concurrent.futures
import contextlib
import math
import os
import subprocess
import sys
import six
from pre_commit import parse_shebang
from pre_commit.util import cmd_output_b
from pre_commit.util import cmd_output_p
def _environ_size(_env=None):
environ = _env if _env is not None else getattr(os, 'environb', os.environ)
size = 8 * len(environ) # number of pointers in `envp`
for k, v in environ.items():
size += len(k) + len(v) + 2 # c strings in `envp`
return size
def _get_platform_max_length(): # pragma: no cover (platform specific)
if os.name == 'posix':
maximum = os.sysconf(str('SC_ARG_MAX')) - 2048 - _environ_size()
maximum = max(min(maximum, 2 ** 17), 2 ** 12)
return maximum
elif os.name == 'nt':
return 2 ** 15 - 2048 # UNICODE_STRING max - headroom
else:
# posix minimum
return 2 ** 12
def _command_length(*cmd):
full_cmd = ' '.join(cmd)
# win32 uses the amount of characters, more details at:
# https://github.com/pre-commit/pre-commit/pull/839
if sys.platform == 'win32':
# the python2.x apis require bytes, we encode as UTF-8
if six.PY2:
return len(full_cmd.encode('utf-8'))
else:
return len(full_cmd.encode('utf-16le')) // 2
else:
return len(full_cmd.encode(sys.getfilesystemencoding()))
class ArgumentTooLongError(RuntimeError):
pass
def partition(cmd, varargs, target_concurrency, _max_length=None):
_max_length = _max_length or _get_platform_max_length()
# Generally, we try to partition evenly into at least `target_concurrency`
# partitions, but we don't want a bunch of tiny partitions.
max_args = max(4, math.ceil(len(varargs) / target_concurrency))
cmd = tuple(cmd)
ret = []
ret_cmd = []
# Reversed so arguments are in order
varargs = list(reversed(varargs))
total_length = _command_length(*cmd) + 1
while varargs:
arg = varargs.pop()
arg_length = _command_length(arg) + 1
if (
total_length + arg_length <= _max_length and
len(ret_cmd) < max_args
):
ret_cmd.append(arg)
total_length += arg_length
elif not ret_cmd:
raise ArgumentTooLongError(arg)
else:
# We've exceeded the length, yield a command
ret.append(cmd + tuple(ret_cmd))
ret_cmd = []
total_length = _command_length(*cmd) + 1
varargs.append(arg)
ret.append(cmd + tuple(ret_cmd))
return tuple(ret)
@contextlib.contextmanager
def _thread_mapper(maxsize):
if maxsize == 1:
yield map
else:
with concurrent.futures.ThreadPoolExecutor(maxsize) as ex:
yield ex.map
def xargs(cmd, varargs, **kwargs):
"""A simplified implementation of xargs.
negate: Make nonzero successful and zero a failure
target_concurrency: Target number of partitions to run concurrently
"""
color = kwargs.pop('color', False)
negate = kwargs.pop('negate', False)
target_concurrency = kwargs.pop('target_concurrency', 1)
progress = kwargs.pop('progress', lambda _: None)
max_length = kwargs.pop('_max_length', _get_platform_max_length())
cmd_fn = cmd_output_p if color else cmd_output_b
retcode = 0
stdout = b''
try:
cmd = parse_shebang.normalize_cmd(cmd)
except parse_shebang.ExecutableNotFoundError as e:
return e.to_output()[:2]
partitions = partition(cmd, varargs, target_concurrency, max_length)
def run_cmd_partition(run_cmd):
ret = cmd_fn(
*run_cmd, retcode=None, stderr=subprocess.STDOUT, **kwargs
)
return ret, len(run_cmd) - len(cmd)
threads = min(len(partitions), target_concurrency)
with _thread_mapper(threads) as thread_map:
results = thread_map(run_cmd_partition, partitions)
total_processed = 0
for (proc_retcode, proc_out, _), processed in results:
# This is *slightly* too clever so I'll explain it.
# First the xor boolean table:
# T | F |
# +-------+
# T | F | T |
# --+-------+
# F | T | F |
# --+-------+
# When negate is True, it has the effect of flipping the return
# code. Otherwise, the returncode is unchanged.
retcode |= bool(proc_retcode) ^ negate
stdout += proc_out
total_processed += processed
progress(float(total_processed) / len(varargs))
return retcode, stdout