/
test_diskspec.py
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/
test_diskspec.py
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from z3 import *
import disk
import unittest
from yggdrasil.util import *
from yggdrasil.diskspec import *
from yggdrasil import test
class AsyncDiskTest(test.DiskTest):
def setUp(self):
self._array = FreshDiskArray('array')
def test_prefix(self):
mach = Machine()
d = AsyncDisk(mach, self._array)
a = FreshBlock('block')
b = FreshBlock('block')
c = FreshBlock('block')
d.write(5, a)
d.write(6, b)
d.write(7, c)
d = d.crash(Machine())
self.show(Implies(mach.assumption,
And(d.read(5) == a, d.read(6) != b), d.read(7) != c))
def test_reorder(self):
mach = Machine()
d = AsyncDisk(mach, self._array)
a = FreshBlock('block')
b = FreshBlock('block')
c = FreshBlock('block')
d.write(5, a)
d.write(6, b)
d.write(7, c)
d = d.crash(Machine())
self.show(Implies(mach.assumption,
And(d.read(6) == a, d.read(5) != b)))
def test_nocrash(self):
mach = Machine()
d = AsyncDisk(mach, self._array)
a = FreshBlock('block')
b = FreshBlock('block')
c = FreshBlock('block')
d.write(5, a)
d.write(6, b)
d.write(7, c)
d = d.crash(Machine())
self.show(Implies(mach.assumption,
And(d.read(5) == a, d.read(6) == b, d.read(7) == c)))
def test_write_two(self):
mach = Machine()
d = AsyncDisk(mach, self._array)
i0 = FreshSize('i')
i1 = FreshSize('i')
x0 = FreshBlock('x')
x1 = FreshBlock('x')
assumption = i0 != i1
oldv0 = d.read(i0)
oldv1 = d.read(i1)
d.write(i0, x0)
d.write(i1, x1)
newv0 = d.read(i0)
newv1 = d.read(i1)
self.prove(Implies(assumption, newv0 == x0))
self.prove(Implies(assumption, newv1 == x1))
d = d.crash(Machine())
anyv0 = d.read(i0)
anyv1 = d.read(i1)
self.prove(Implies(assumption, And(
Or(anyv0 == oldv0, anyv0 == x0),
Or(anyv1 == oldv1, anyv1 == x1))))
def test_flush(self):
mach = Machine()
d = AsyncDisk(mach, self._array)
i0 = FreshSize('i')
i1 = FreshSize('i')
x0 = FreshBlock('x')
x1 = FreshBlock('x')
oldv0 = d.read(i0)
oldv1 = d.read(i1)
d.write(i0, x0)
d.flush()
d.write(i1, x1)
d = d.crash(Machine())
anyv0 = d.read(i0)
anyv1 = d.read(i1)
assumption = And(i0 != i1, x1 != oldv1, mach.assumption)
self.prove(Implies(assumption, Implies(anyv1 == x1, anyv0 == x0)))
# implement SyncDisk on top of AsyncDisk
class FlushingDisk:
def __init__(self, disk):
self._disk = disk
def write(self, bid, data):
self._disk.write(bid, data)
self._disk.flush()
def flush(self):
pass
def read(self, bid):
return self._disk.read(bid)
def crash(self, mach):
return self.__class__(self._disk.crash(mach))
class SyncDiskTest(test.DiskTest):
# SyncDisk is an AsyncDisk
def test_syncdisk_is_async(self):
array = DiskSort(fresh_name('array'))
bid = FreshSize('bid')
data = FreshBlock('data')
spec_mach = Machine()
impl_mach = Machine()
ad = AsyncDisk(spec_mach, array)
ad.write(bid, data)
sd = SyncDisk(impl_mach, array)
sd.write(bid, data)
self.prove(ForAll([array] + impl_mach.control,
Exists(spec_mach.control,
ForAll([bid], sd.read(bid) == ad.read(bid)))))
# AsyncDisk+flush is a SyncDisk
def test_flushingdisk_is_sync(self):
array = DiskSort(fresh_name('array'))
bid = FreshSize('bid')
data = FreshBlock('data')
spec_mach = Machine()
impl_mach = Machine()
sd = SyncDisk(spec_mach, array)
sd.write(bid, data)
fd = FlushingDisk(AsyncDisk(impl_mach, array))
fd.write(bid, data)
self.prove(ForAll([array] + impl_mach.control,
Exists(spec_mach.control,
ForAll([bid], sd.read(bid) == fd.read(bid)))))
# implement SyncDisk on top of AsyncDisk
class FlushingDisk:
def __init__(self, disk):
self._disk = disk
def write(self, bid, data):
self._disk.write(bid, data)
self._disk.flush()
def flush(self):
pass
def read(self, bid):
return self._disk.read(bid)
def crash(self, mach):
return self.__class__(self._disk.crash(mach))
class SyncDiskTest(test.DiskTest):
# SyncDisk is an AsyncDisk
def test_syncdisk_is_async(self):
array = FreshDiskArray('array')
bid = FreshSize('bid')
data = FreshBlock('data')
spec_mach = Machine()
impl_mach = Machine()
ad = AsyncDisk(spec_mach, array)
ad.write(bid, data)
sd = SyncDisk(impl_mach, array)
sd.write(bid, data)
self.solve(ForAll(spec_mach.control, Not(
ForAll([bid], sd.read(bid) == ad.read(bid)))))
# AsyncDisk+flush is a SyncDisk
def test_flushingdisk_is_sync(self):
array = FreshDiskArray('array')
bid = FreshSize('bid')
data = FreshBlock('data')
spec_mach = Machine()
impl_mach = Machine()
sd = SyncDisk(spec_mach, array)
sd.write(bid, data)
fd = FlushingDisk(AsyncDisk(impl_mach, array))
fd.write(bid, data)
self.solve(ForAll(spec_mach.control, Not(
ForAll([bid], sd.read(bid) == fd.read(bid)))))
class VirtualAsyncDiskTest(test.RefinementTest):
def create_spec(self, mach):
array = FreshDiskArray('array')
return AsyncDisk(mach, array)
def create_impl(self, mach):
array = FreshDiskArray('array')
mapped = FreshDiskArray('mapped')
return VirtualAsyncDisk(mach, mapped, array)
def equivalence(self, spec, impl, **kwargs):
vbn = Const(fresh_name('i'), spec.domain())
return ForAll([vbn],
Implies(impl.is_mapped(vbn),
impl.read(vbn) == spec.read(vbn)))
def match_write(self, spec=None, impl=None):
i0 = FreshSize('i')
x0 = FreshBlock('x')
yield (i0, x0)
class InodeSpecTest(test.DiskTest):
def setUp(self):
disk.native = False
disk.assertion.assertions = []
self._array = FreshDiskArray('array')
self._attr_array = FreshDiskArray('attrs')
self._mapped = FreshDiskArray('mapped')
def test_compare_to_async(self):
d1_mach = Machine()
d1 = AsyncDisk(d1_mach, self._array)
d2_mach = Machine()
d2 = InodeSpec(d2_mach, [self._mapped, self._attr_array, self._array])
vbn = Const(fresh_name('i'), d1.domain())
i0 = Const(fresh_name('i'), d1.domain())
x0 = FreshBlock('x')
pre = ForAll([vbn], Implies(d2.is_mapped(vbn), d1.read(vbn) == d2.read(vbn)))
d1.write(i0, x0)
d2.begin_tx()
d2.write(i0, x0)
d2.commit_tx()
d1 = d1.crash(Machine())
d2 = d2.crash(Machine())
assumption = And(d1_mach.assumption, d2_mach.assumption)
post = ForAll([vbn], Implies(d2.is_mapped(vbn), d1.read(vbn) == d2.read(vbn)))
C1 = d1_mach.control
self.solve(
ForAll(C1, Not(
Implies(assumption, Implies(pre, post)))))
def test_bmap(self):
self.enable_symbolic_execution()
mach = Machine()
d2 = InodeSpec(mach, [self._mapped, self._attr_array, self._array])
vbn = FreshSize('vbn')
mapped = d2.is_mapped(vbn)
d2.begin_tx()
d2.bmap(vbn)
d2.commit_tx()
self.prove(Implies(And(*disk.assertion.assertions), Implies(Not(mapped), d2.is_mapped(vbn))))
def test_bunmap(self):
mach = Machine()
d2 = InodeSpec(mach, [self._mapped, self._attr_array, self._array])
vbn = FreshSize('vbn')
mapped = d2.is_mapped(vbn)
d2.begin_tx()
d2.bunmap(vbn)
d2.commit_tx()
self.prove(Implies(mapped, Not(d2.is_mapped(vbn))))
if __name__ == '__main__':
test.main()