procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
import unittest
import silenttestrunner
from mercurial import util
class testlrucachedict(unittest.TestCase):
def testsimple(self):
d = util.lrucachedict(4)
self.assertEqual(d.capacity, 4)
d.insert('a', 'va', cost=2)
d['b'] = 'vb'
d['c'] = 'vc'
d.insert('d', 'vd', cost=42)
self.assertEqual(d['a'], 'va')
self.assertEqual(d['b'], 'vb')
self.assertEqual(d['c'], 'vc')
self.assertEqual(d['d'], 'vd')
self.assertEqual(d.totalcost, 44)
# 'a' should be dropped because it was least recently used.
d['e'] = 've'
self.assertNotIn('a', d)
self.assertIsNone(d.get('a'))
self.assertEqual(d.totalcost, 42)
self.assertEqual(d['b'], 'vb')
self.assertEqual(d['c'], 'vc')
self.assertEqual(d['d'], 'vd')
self.assertEqual(d['e'], 've')
# Replacing item with different cost adjusts totalcost.
d.insert('e', 've', cost=4)
self.assertEqual(d.totalcost, 46)
# Touch entries in some order (both get and set).
d['e']
d['c'] = 'vc2'
d['d']
d['b'] = 'vb2'
# 'e' should be dropped now
d['f'] = 'vf'
self.assertNotIn('e', d)
self.assertEqual(d['b'], 'vb2')
self.assertEqual(d['c'], 'vc2')
self.assertEqual(d['d'], 'vd')
self.assertEqual(d['f'], 'vf')
d.clear()
for key in ('a', 'b', 'c', 'd', 'e', 'f'):
self.assertNotIn(key, d)
def testunfull(self):
d = util.lrucachedict(4)
d['a'] = 1
d['b'] = 2
d['a']
d['b']
for key in ('a', 'b'):
self.assertIn(key, d)
def testget(self):
d = util.lrucachedict(4)
d['a'] = 'va'
d['b'] = 'vb'
d['c'] = 'vc'
self.assertIsNone(d.get('missing'))
self.assertEqual(list(d), ['c', 'b', 'a'])
self.assertEqual(d.get('a'), 'va')
self.assertEqual(list(d), ['a', 'c', 'b'])
def testpeek(self):
d = util.lrucachedict(4)
d['a'] = 'va'
d['b'] = 'vb'
d['c'] = 'vc'
with self.assertRaises(KeyError):
d.peek('missing')
self.assertEqual(list(d), ['c', 'b', 'a'])
self.assertIsNone(d.peek('missing', None))
self.assertEqual(list(d), ['c', 'b', 'a'])
self.assertEqual(d.peek('a'), 'va')
self.assertEqual(list(d), ['c', 'b', 'a'])
def testpop(self):
d = util.lrucachedict(4)
d['a'] = 'va'
d['b'] = 'vb'
d['c'] = 'vc'
with self.assertRaises(KeyError):
d.pop('missing')
self.assertEqual(list(d), ['c', 'b', 'a'])
self.assertIsNone(d.pop('missing', None))
self.assertEqual(list(d), ['c', 'b', 'a'])
self.assertEqual(d.pop('b'), 'vb')
self.assertEqual(list(d), ['c', 'a'])
def testcopypartial(self):
d = util.lrucachedict(4)
d.insert('a', 'va', cost=4)
d.insert('b', 'vb', cost=2)
dc = d.copy()
self.assertEqual(len(dc), 2)
self.assertEqual(dc.totalcost, 6)
for key in ('a', 'b'):
self.assertIn(key, dc)
self.assertEqual(dc[key], 'v%s' % key)
self.assertEqual(len(d), 2)
for key in ('a', 'b'):
self.assertIn(key, d)
self.assertEqual(d[key], 'v%s' % key)
d['c'] = 'vc'
del d['b']
self.assertEqual(d.totalcost, 4)
dc = d.copy()
self.assertEqual(len(dc), 2)
self.assertEqual(dc.totalcost, 4)
for key in ('a', 'c'):
self.assertIn(key, dc)
self.assertEqual(dc[key], 'v%s' % key)
def testcopyempty(self):
d = util.lrucachedict(4)
dc = d.copy()
self.assertEqual(len(dc), 0)
def testcopyfull(self):
d = util.lrucachedict(4)
d.insert('a', 'va', cost=42)
d['b'] = 'vb'
d['c'] = 'vc'
d['d'] = 'vd'
dc = d.copy()
for key in ('a', 'b', 'c', 'd'):
self.assertIn(key, dc)
self.assertEqual(dc[key], 'v%s' % key)
self.assertEqual(d.totalcost, 42)
self.assertEqual(dc.totalcost, 42)
# 'a' should be dropped because it was least recently used.
dc['e'] = 've'
self.assertNotIn('a', dc)
for key in ('b', 'c', 'd', 'e'):
self.assertIn(key, dc)
self.assertEqual(dc[key], 'v%s' % key)
self.assertEqual(d.totalcost, 42)
self.assertEqual(dc.totalcost, 0)
# Contents and order of original dict should remain unchanged.
dc['b'] = 'vb_new'
self.assertEqual(list(iter(d)), ['d', 'c', 'b', 'a'])
for key in ('a', 'b', 'c', 'd'):
self.assertEqual(d[key], 'v%s' % key)
d = util.lrucachedict(4, maxcost=42)
d.insert('a', 'va', cost=5)
d.insert('b', 'vb', cost=4)
d.insert('c', 'vc', cost=3)
dc = d.copy()
self.assertEqual(dc.maxcost, 42)
self.assertEqual(len(dc), 3)
# Max cost can be lowered as part of copy.
dc = d.copy(maxcost=10)
self.assertEqual(dc.maxcost, 10)
self.assertEqual(len(dc), 2)
self.assertEqual(dc.totalcost, 7)
self.assertIn('b', dc)
self.assertIn('c', dc)
def testcopydecreasecapacity(self):
d = util.lrucachedict(5)
d.insert('a', 'va', cost=4)
d.insert('b', 'vb', cost=2)
d['c'] = 'vc'
d['d'] = 'vd'
dc = d.copy(2)
self.assertEqual(dc.totalcost, 0)
for key in ('a', 'b'):
self.assertNotIn(key, dc)
for key in ('c', 'd'):
self.assertIn(key, dc)
self.assertEqual(dc[key], 'v%s' % key)
dc.insert('e', 've', cost=7)
self.assertEqual(dc.totalcost, 7)
self.assertNotIn('c', dc)
for key in ('d', 'e'):
self.assertIn(key, dc)
self.assertEqual(dc[key], 'v%s' % key)
# Original should remain unchanged.
self.assertEqual(d.totalcost, 6)
for key in ('a', 'b', 'c', 'd'):
self.assertIn(key, d)
self.assertEqual(d[key], 'v%s' % key)
def testcopyincreasecapacity(self):
d = util.lrucachedict(5)
d['a'] = 'va'
d['b'] = 'vb'
d['c'] = 'vc'
d['d'] = 'vd'
dc = d.copy(6)
for key in ('a', 'b', 'c', 'd'):
self.assertIn(key, dc)
self.assertEqual(dc[key], 'v%s' % key)
dc['e'] = 've'
dc['f'] = 'vf'
for key in ('a', 'b', 'c', 'd', 'e', 'f'):
self.assertIn(key, dc)
self.assertEqual(dc[key], 'v%s' % key)
dc['g'] = 'vg'
self.assertNotIn('a', dc)
for key in ('b', 'c', 'd', 'e', 'f', 'g'):
self.assertIn(key, dc)
self.assertEqual(dc[key], 'v%s' % key)
# Original should remain unchanged.
for key in ('a', 'b', 'c', 'd'):
self.assertIn(key, d)
self.assertEqual(d[key], 'v%s' % key)
def testpopoldest(self):
d = util.lrucachedict(4)
d.insert('a', 'va', cost=10)
d.insert('b', 'vb', cost=5)
self.assertEqual(len(d), 2)
self.assertEqual(d.popoldest(), ('a', 'va'))
self.assertEqual(len(d), 1)
self.assertEqual(d.totalcost, 5)
self.assertEqual(d.popoldest(), ('b', 'vb'))
self.assertEqual(len(d), 0)
self.assertEqual(d.totalcost, 0)
self.assertIsNone(d.popoldest())
d['a'] = 'va'
d['b'] = 'vb'
d['c'] = 'vc'
d['d'] = 'vd'
self.assertEqual(d.popoldest(), ('a', 'va'))
self.assertEqual(len(d), 3)
for key in ('b', 'c', 'd'):
self.assertEqual(d[key], 'v%s' % key)
d['a'] = 'va'
self.assertEqual(d.popoldest(), ('b', 'vb'))
def testmaxcost(self):
# Item cost is zero by default.
d = util.lrucachedict(6, maxcost=10)
d['a'] = 'va'
d['b'] = 'vb'
d['c'] = 'vc'
d['d'] = 'vd'
self.assertEqual(len(d), 4)
self.assertEqual(d.totalcost, 0)
d.clear()
# Insertion to exact cost threshold works without eviction.
d.insert('a', 'va', cost=6)
d.insert('b', 'vb', cost=4)
self.assertEqual(len(d), 2)
self.assertEqual(d['a'], 'va')
self.assertEqual(d['b'], 'vb')
# Inserting a new element with 0 cost works.
d['c'] = 'vc'
self.assertEqual(len(d), 3)
# Inserting a new element with cost putting us above high
# water mark evicts oldest single item.
d.insert('d', 'vd', cost=1)
self.assertEqual(len(d), 3)
self.assertEqual(d.totalcost, 5)
self.assertNotIn('a', d)
for key in ('b', 'c', 'd'):
self.assertEqual(d[key], 'v%s' % key)
# Inserting a new element with enough room for just itself
# evicts all items before.
d.insert('e', 've', cost=10)
self.assertEqual(len(d), 1)
self.assertEqual(d.totalcost, 10)
self.assertIn('e', d)
# Inserting a new element with cost greater than threshold
# still retains that item.
d.insert('f', 'vf', cost=11)
self.assertEqual(len(d), 1)
self.assertEqual(d.totalcost, 11)
self.assertIn('f', d)
# Inserting a new element will evict the last item since it is
# too large.
d['g'] = 'vg'
self.assertEqual(len(d), 1)
self.assertEqual(d.totalcost, 0)
self.assertIn('g', d)
d.clear()
d.insert('a', 'va', cost=7)
d.insert('b', 'vb', cost=3)
self.assertEqual(len(d), 2)
# Replacing a value with smaller cost won't result in eviction.
d.insert('b', 'vb2', cost=2)
self.assertEqual(len(d), 2)
# Replacing a value with a higher cost will evict when threshold
# exceeded.
d.insert('b', 'vb3', cost=4)
self.assertEqual(len(d), 1)
self.assertNotIn('a', d)
def testmaxcostcomplex(self):
d = util.lrucachedict(100, maxcost=100)
d.insert('a', 'va', cost=9)
d.insert('b', 'vb', cost=21)
d.insert('c', 'vc', cost=7)
d.insert('d', 'vc', cost=50)
self.assertEqual(d.totalcost, 87)
# Inserting new element should free multiple elements so we hit
# low water mark.
d.insert('e', 'vd', cost=25)
self.assertEqual(len(d), 2)
self.assertNotIn('a', d)
self.assertNotIn('b', d)
self.assertNotIn('c', d)
self.assertIn('d', d)
self.assertIn('e', d)
if __name__ == '__main__':
silenttestrunner.main(__name__)