from twisted.internet import defer, reactor
from twisted.python.failure import Failure
from twisted.python import log
+from hashlib import md5
from allmydata.util import base32, idlib, humanreadable, mathutil, hashutil
from allmydata.util import assertutil, fileutil, deferredutil, abbreviate
from allmydata.util import limiter, time_format, pollmixin, cachedir
from allmydata.util import statistics, dictutil, pipeline
from allmydata.util import log as tahoe_log
+from allmydata.util.spans import Spans, overlap, DataSpans
class Base32(unittest.TestCase):
def test_b2a_matches_Pythons(self):
tahoe_log.err(format="intentional sample error",
failure=f, level=tahoe_log.OPERATIONAL, umid="wO9UoQ")
self.flushLoggedErrors(SampleError)
+
+
+class SimpleSpans:
+ # this is a simple+inefficient form of util.spans.Spans . We compare the
+ # behavior of this reference model against the real (efficient) form.
+
+ def __init__(self, _span_or_start=None, length=None):
+ self._have = set()
+ if length is not None:
+ for i in range(_span_or_start, _span_or_start+length):
+ self._have.add(i)
+ elif _span_or_start:
+ for (start,length) in _span_or_start:
+ self.add(start, length)
+
+ def add(self, start, length):
+ for i in range(start, start+length):
+ self._have.add(i)
+ return self
+
+ def remove(self, start, length):
+ for i in range(start, start+length):
+ self._have.discard(i)
+ return self
+
+ def each(self):
+ return sorted(self._have)
+
+ def __iter__(self):
+ items = sorted(self._have)
+ prevstart = None
+ prevend = None
+ for i in items:
+ if prevstart is None:
+ prevstart = prevend = i
+ continue
+ if i == prevend+1:
+ prevend = i
+ continue
+ yield (prevstart, prevend-prevstart+1)
+ prevstart = prevend = i
+ if prevstart is not None:
+ yield (prevstart, prevend-prevstart+1)
+
+ def __len__(self):
+ # this also gets us bool(s)
+ return len(self._have)
+
+ def __add__(self, other):
+ s = self.__class__(self)
+ for (start, length) in other:
+ s.add(start, length)
+ return s
+
+ def __sub__(self, other):
+ s = self.__class__(self)
+ for (start, length) in other:
+ s.remove(start, length)
+ return s
+
+ def __iadd__(self, other):
+ for (start, length) in other:
+ self.add(start, length)
+ return self
+
+ def __isub__(self, other):
+ for (start, length) in other:
+ self.remove(start, length)
+ return self
+
+ def __and__(self, other):
+ s = self.__class__()
+ for i in other.each():
+ if i in self._have:
+ s.add(i, 1)
+ return s
+
+ def __contains__(self, (start,length)):
+ for i in range(start, start+length):
+ if i not in self._have:
+ return False
+ return True
+
+class ByteSpans(unittest.TestCase):
+ def test_basic(self):
+ s = Spans()
+ self.failUnlessEqual(list(s), [])
+ self.failIf(s)
+ self.failIf((0,1) in s)
+ self.failUnlessEqual(len(s), 0)
+
+ s1 = Spans(3, 4) # 3,4,5,6
+ self._check1(s1)
+
+ s2 = Spans(s1)
+ self._check1(s2)
+
+ s2.add(10,2) # 10,11
+ self._check1(s1)
+ self.failUnless((10,1) in s2)
+ self.failIf((10,1) in s1)
+ self.failUnlessEqual(list(s2.each()), [3,4,5,6,10,11])
+ self.failUnlessEqual(len(s2), 6)
+
+ s2.add(15,2).add(20,2)
+ self.failUnlessEqual(list(s2.each()), [3,4,5,6,10,11,15,16,20,21])
+ self.failUnlessEqual(len(s2), 10)
+
+ s2.remove(4,3).remove(15,1)
+ self.failUnlessEqual(list(s2.each()), [3,10,11,16,20,21])
+ self.failUnlessEqual(len(s2), 6)
+
+ s1 = SimpleSpans(3, 4) # 3 4 5 6
+ s2 = SimpleSpans(5, 4) # 5 6 7 8
+ i = s1 & s2
+ self.failUnlessEqual(list(i.each()), [5, 6])
+
+ def _check1(self, s):
+ self.failUnlessEqual(list(s), [(3,4)])
+ self.failUnless(s)
+ self.failUnlessEqual(len(s), 4)
+ self.failIf((0,1) in s)
+ self.failUnless((3,4) in s)
+ self.failUnless((3,1) in s)
+ self.failUnless((5,2) in s)
+ self.failUnless((6,1) in s)
+ self.failIf((6,2) in s)
+ self.failIf((7,1) in s)
+ self.failUnlessEqual(list(s.each()), [3,4,5,6])
+
+ def test_math(self):
+ s1 = Spans(0, 10) # 0,1,2,3,4,5,6,7,8,9
+ s2 = Spans(5, 3) # 5,6,7
+ s3 = Spans(8, 4) # 8,9,10,11
+
+ s = s1 - s2
+ self.failUnlessEqual(list(s.each()), [0,1,2,3,4,8,9])
+ s = s1 - s3
+ self.failUnlessEqual(list(s.each()), [0,1,2,3,4,5,6,7])
+ s = s2 - s3
+ self.failUnlessEqual(list(s.each()), [5,6,7])
+ s = s1 & s2
+ self.failUnlessEqual(list(s.each()), [5,6,7])
+ s = s2 & s1
+ self.failUnlessEqual(list(s.each()), [5,6,7])
+ s = s1 & s3
+ self.failUnlessEqual(list(s.each()), [8,9])
+ s = s3 & s1
+ self.failUnlessEqual(list(s.each()), [8,9])
+ s = s2 & s3
+ self.failUnlessEqual(list(s.each()), [])
+ s = s3 & s2
+ self.failUnlessEqual(list(s.each()), [])
+ s = Spans() & s3
+ self.failUnlessEqual(list(s.each()), [])
+ s = s3 & Spans()
+ self.failUnlessEqual(list(s.each()), [])
+
+ s = s1 + s2
+ self.failUnlessEqual(list(s.each()), [0,1,2,3,4,5,6,7,8,9])
+ s = s1 + s3
+ self.failUnlessEqual(list(s.each()), [0,1,2,3,4,5,6,7,8,9,10,11])
+ s = s2 + s3
+ self.failUnlessEqual(list(s.each()), [5,6,7,8,9,10,11])
+
+ s = Spans(s1)
+ s -= s2
+ self.failUnlessEqual(list(s.each()), [0,1,2,3,4,8,9])
+ s = Spans(s1)
+ s -= s3
+ self.failUnlessEqual(list(s.each()), [0,1,2,3,4,5,6,7])
+ s = Spans(s2)
+ s -= s3
+ self.failUnlessEqual(list(s.each()), [5,6,7])
+
+ s = Spans(s1)
+ s += s2
+ self.failUnlessEqual(list(s.each()), [0,1,2,3,4,5,6,7,8,9])
+ s = Spans(s1)
+ s += s3
+ self.failUnlessEqual(list(s.each()), [0,1,2,3,4,5,6,7,8,9,10,11])
+ s = Spans(s2)
+ s += s3
+ self.failUnlessEqual(list(s.each()), [5,6,7,8,9,10,11])
+
+ def test_random(self):
+ # attempt to increase coverage of corner cases by comparing behavior
+ # of a simple-but-slow model implementation against the
+ # complex-but-fast actual implementation, in a large number of random
+ # operations
+ S1 = SimpleSpans
+ S2 = Spans
+ s1 = S1(); s2 = S2()
+ seed = ""
+ def _create(subseed):
+ ns1 = S1(); ns2 = S2()
+ for i in range(10):
+ what = md5(subseed+str(i)).hexdigest()
+ start = int(what[2:4], 16)
+ length = max(1,int(what[5:6], 16))
+ ns1.add(start, length); ns2.add(start, length)
+ return ns1, ns2
+
+ #print
+ for i in range(1000):
+ what = md5(seed+str(i)).hexdigest()
+ op = what[0]
+ subop = what[1]
+ start = int(what[2:4], 16)
+ length = max(1,int(what[5:6], 16))
+ #print what
+ if op in "0":
+ if subop in "01234":
+ s1 = S1(); s2 = S2()
+ elif subop in "5678":
+ s1 = S1(start, length); s2 = S2(start, length)
+ else:
+ s1 = S1(s1); s2 = S2(s2)
+ #print "s2 = %s" % s2.dump()
+ elif op in "123":
+ #print "s2.add(%d,%d)" % (start, length)
+ s1.add(start, length); s2.add(start, length)
+ elif op in "456":
+ #print "s2.remove(%d,%d)" % (start, length)
+ s1.remove(start, length); s2.remove(start, length)
+ elif op in "78":
+ ns1, ns2 = _create(what[7:11])
+ #print "s2 + %s" % ns2.dump()
+ s1 = s1 + ns1; s2 = s2 + ns2
+ elif op in "9a":
+ ns1, ns2 = _create(what[7:11])
+ #print "%s - %s" % (s2.dump(), ns2.dump())
+ s1 = s1 - ns1; s2 = s2 - ns2
+ elif op in "bc":
+ ns1, ns2 = _create(what[7:11])
+ #print "s2 += %s" % ns2.dump()
+ s1 += ns1; s2 += ns2
+ elif op in "de":
+ ns1, ns2 = _create(what[7:11])
+ #print "%s -= %s" % (s2.dump(), ns2.dump())
+ s1 -= ns1; s2 -= ns2
+ else:
+ ns1, ns2 = _create(what[7:11])
+ #print "%s &= %s" % (s2.dump(), ns2.dump())
+ s1 = s1 & ns1; s2 = s2 & ns2
+ #print "s2 now %s" % s2.dump()
+ self.failUnlessEqual(list(s1.each()), list(s2.each()))
+ self.failUnlessEqual(len(s1), len(s2))
+ self.failUnlessEqual(bool(s1), bool(s2))
+ self.failUnlessEqual(list(s1), list(s2))
+ for j in range(10):
+ what = md5(what[12:14]+str(j)).hexdigest()
+ start = int(what[2:4], 16)
+ length = max(1, int(what[5:6], 16))
+ span = (start, length)
+ self.failUnlessEqual(bool(span in s1), bool(span in s2))
+
+
+ # s()
+ # s(start,length)
+ # s(s0)
+ # s.add(start,length) : returns s
+ # s.remove(start,length)
+ # s.each() -> list of byte offsets, mostly for testing
+ # list(s) -> list of (start,length) tuples, one per span
+ # (start,length) in s -> True if (start..start+length-1) are all members
+ # NOT equivalent to x in list(s)
+ # len(s) -> number of bytes, for testing, bool(), and accounting/limiting
+ # bool(s) (__len__)
+ # s = s1+s2, s1-s2, +=s1, -=s1
+
+ def test_overlap(self):
+ for a in range(20):
+ for b in range(10):
+ for c in range(20):
+ for d in range(10):
+ self._test_overlap(a,b,c,d)
+
+ def _test_overlap(self, a, b, c, d):
+ s1 = set(range(a,a+b))
+ s2 = set(range(c,c+d))
+ #print "---"
+ #self._show_overlap(s1, "1")
+ #self._show_overlap(s2, "2")
+ o = overlap(a,b,c,d)
+ expected = s1.intersection(s2)
+ if not expected:
+ self.failUnlessEqual(o, None)
+ else:
+ start,length = o
+ so = set(range(start,start+length))
+ #self._show(so, "o")
+ self.failUnlessEqual(so, expected)
+
+ def _show_overlap(self, s, c):
+ import sys
+ out = sys.stdout
+ if s:
+ for i in range(max(s)):
+ if i in s:
+ out.write(c)
+ else:
+ out.write(" ")
+ out.write("\n")
+
+def extend(s, start, length, fill):
+ if len(s) >= start+length:
+ return s
+ assert len(fill) == 1
+ return s + fill*(start+length-len(s))
+
+def replace(s, start, data):
+ assert len(s) >= start+len(data)
+ return s[:start] + data + s[start+len(data):]
+
+class SimpleDataSpans:
+ def __init__(self, other=None):
+ self.missing = "" # "1" where missing, "0" where found
+ self.data = ""
+ if other:
+ for (start, data) in other.get_chunks():
+ self.add(start, data)
+
+ def __len__(self):
+ return len(self.missing.translate(None, "1"))
+ def _dump(self):
+ return [i for (i,c) in enumerate(self.missing) if c == "0"]
+ def _have(self, start, length):
+ m = self.missing[start:start+length]
+ if not m or len(m)<length or int(m):
+ return False
+ return True
+ def get_chunks(self):
+ for i in self._dump():
+ yield (i, self.data[i])
+ def get_spans(self):
+ return SimpleSpans([(start,len(data))
+ for (start,data) in self.get_chunks()])
+ def get(self, start, length):
+ if self._have(start, length):
+ return self.data[start:start+length]
+ return None
+ def pop(self, start, length):
+ data = self.get(start, length)
+ if data:
+ self.remove(start, length)
+ return data
+ def remove(self, start, length):
+ self.missing = replace(extend(self.missing, start, length, "1"),
+ start, "1"*length)
+ def add(self, start, data):
+ self.missing = replace(extend(self.missing, start, len(data), "1"),
+ start, "0"*len(data))
+ self.data = replace(extend(self.data, start, len(data), " "),
+ start, data)
+
+
+class StringSpans(unittest.TestCase):
+ def do_basic(self, klass):
+ ds = klass()
+ self.failUnlessEqual(len(ds), 0)
+ self.failUnlessEqual(list(ds._dump()), [])
+ self.failUnlessEqual(sum([len(d) for (s,d) in ds.get_chunks()]), 0)
+ s = ds.get_spans()
+ self.failUnlessEqual(ds.get(0, 4), None)
+ self.failUnlessEqual(ds.pop(0, 4), None)
+ ds.remove(0, 4)
+
+ ds.add(2, "four")
+ self.failUnlessEqual(len(ds), 4)
+ self.failUnlessEqual(list(ds._dump()), [2,3,4,5])
+ self.failUnlessEqual(sum([len(d) for (s,d) in ds.get_chunks()]), 4)
+ s = ds.get_spans()
+ self.failUnless((2,2) in s)
+ self.failUnlessEqual(ds.get(0, 4), None)
+ self.failUnlessEqual(ds.pop(0, 4), None)
+ self.failUnlessEqual(ds.get(4, 4), None)
+
+ ds2 = klass(ds)
+ self.failUnlessEqual(len(ds2), 4)
+ self.failUnlessEqual(list(ds2._dump()), [2,3,4,5])
+ self.failUnlessEqual(sum([len(d) for (s,d) in ds2.get_chunks()]), 4)
+ self.failUnlessEqual(ds2.get(0, 4), None)
+ self.failUnlessEqual(ds2.pop(0, 4), None)
+ self.failUnlessEqual(ds2.pop(2, 3), "fou")
+ self.failUnlessEqual(sum([len(d) for (s,d) in ds2.get_chunks()]), 1)
+ self.failUnlessEqual(ds2.get(2, 3), None)
+ self.failUnlessEqual(ds2.get(5, 1), "r")
+ self.failUnlessEqual(ds.get(2, 3), "fou")
+ self.failUnlessEqual(sum([len(d) for (s,d) in ds.get_chunks()]), 4)
+
+ ds.add(0, "23")
+ self.failUnlessEqual(len(ds), 6)
+ self.failUnlessEqual(list(ds._dump()), [0,1,2,3,4,5])
+ self.failUnlessEqual(sum([len(d) for (s,d) in ds.get_chunks()]), 6)
+ self.failUnlessEqual(ds.get(0, 4), "23fo")
+ self.failUnlessEqual(ds.pop(0, 4), "23fo")
+ self.failUnlessEqual(sum([len(d) for (s,d) in ds.get_chunks()]), 2)
+ self.failUnlessEqual(ds.get(0, 4), None)
+ self.failUnlessEqual(ds.pop(0, 4), None)
+
+ ds = klass()
+ ds.add(2, "four")
+ ds.add(3, "ea")
+ self.failUnlessEqual(ds.get(2, 4), "fear")
+
+ def do_scan(self, klass):
+ # do a test with gaps and spans of size 1 and 2
+ # left=(1,11) * right=(1,11) * gapsize=(1,2)
+ # 111, 112, 121, 122, 211, 212, 221, 222
+ # 211
+ # 121
+ # 112
+ # 212
+ # 222
+ # 221
+ # 111
+ # 122
+ # 11 1 1 11 11 11 1 1 111
+ # 0123456789012345678901234567
+ # abcdefghijklmnopqrstuvwxyz-=
+ pieces = [(1, "bc"),
+ (4, "e"),
+ (7, "h"),
+ (9, "jk"),
+ (12, "mn"),
+ (16, "qr"),
+ (20, "u"),
+ (22, "w"),
+ (25, "z-="),
+ ]
+ p_elements = set([1,2,4,7,9,10,12,13,16,17,20,22,25,26,27])
+ S = "abcdefghijklmnopqrstuvwxyz-="
+ # TODO: when adding data, add capital letters, to make sure we aren't
+ # just leaving the old data in place
+ l = len(S)
+ def base():
+ ds = klass()
+ for start, data in pieces:
+ ds.add(start, data)
+ return ds
+ def dump(s):
+ p = set(s._dump())
+ # wow, this is the first time I've ever wanted ?: in python
+ # note: this requires python2.5
+ d = "".join([(S[i] if i in p else " ") for i in range(l)])
+ assert len(d) == l
+ return d
+ DEBUG = False
+ for start in range(0, l):
+ for end in range(start+1, l):
+ # add [start-end) to the baseline
+ which = "%d-%d" % (start, end-1)
+ p_added = set(range(start, end))
+ b = base()
+ if DEBUG:
+ print
+ print dump(b), which
+ add = klass(); add.add(start, S[start:end])
+ print dump(add)
+ b.add(start, S[start:end])
+ if DEBUG:
+ print dump(b)
+ # check that the new span is there
+ d = b.get(start, end-start)
+ self.failUnlessEqual(d, S[start:end], which)
+ # check that all the original pieces are still there
+ for t_start, t_data in pieces:
+ t_len = len(t_data)
+ self.failUnlessEqual(b.get(t_start, t_len),
+ S[t_start:t_start+t_len],
+ "%s %d+%d" % (which, t_start, t_len))
+ # check that a lot of subspans are mostly correct
+ for t_start in range(l):
+ for t_len in range(1,4):
+ d = b.get(t_start, t_len)
+ if d is not None:
+ which2 = "%s+(%d-%d)" % (which, t_start,
+ t_start+t_len-1)
+ self.failUnlessEqual(d, S[t_start:t_start+t_len],
+ which2)
+ # check that removing a subspan gives the right value
+ b2 = klass(b)
+ b2.remove(t_start, t_len)
+ removed = set(range(t_start, t_start+t_len))
+ for i in range(l):
+ exp = (((i in p_elements) or (i in p_added))
+ and (i not in removed))
+ which2 = "%s-(%d-%d)" % (which, t_start,
+ t_start+t_len-1)
+ self.failUnlessEqual(bool(b2.get(i, 1)), exp,
+ which2+" %d" % i)
+
+ def test_test(self):
+ self.do_basic(SimpleDataSpans)
+ self.do_scan(SimpleDataSpans)
+
+ def test_basic(self):
+ self.do_basic(DataSpans)
+ self.do_scan(DataSpans)
+
+ def test_random(self):
+ # attempt to increase coverage of corner cases by comparing behavior
+ # of a simple-but-slow model implementation against the
+ # complex-but-fast actual implementation, in a large number of random
+ # operations
+ S1 = SimpleDataSpans
+ S2 = DataSpans
+ s1 = S1(); s2 = S2()
+ seed = ""
+ def _randstr(length, seed):
+ created = 0
+ pieces = []
+ while created < length:
+ piece = md5(seed + str(created)).hexdigest()
+ pieces.append(piece)
+ created += len(piece)
+ return "".join(pieces)[:length]
+ def _create(subseed):
+ ns1 = S1(); ns2 = S2()
+ for i in range(10):
+ what = md5(subseed+str(i)).hexdigest()
+ start = int(what[2:4], 16)
+ length = max(1,int(what[5:6], 16))
+ ns1.add(start, _randstr(length, what[7:9]));
+ ns2.add(start, _randstr(length, what[7:9]))
+ return ns1, ns2
+
+ #print
+ for i in range(1000):
+ what = md5(seed+str(i)).hexdigest()
+ op = what[0]
+ subop = what[1]
+ start = int(what[2:4], 16)
+ length = max(1,int(what[5:6], 16))
+ #print what
+ if op in "0":
+ if subop in "0123456":
+ s1 = S1(); s2 = S2()
+ else:
+ s1, s2 = _create(what[7:11])
+ #print "s2 = %s" % list(s2._dump())
+ elif op in "123456":
+ #print "s2.add(%d,%d)" % (start, length)
+ s1.add(start, _randstr(length, what[7:9]));
+ s2.add(start, _randstr(length, what[7:9]))
+ elif op in "789abc":
+ #print "s2.remove(%d,%d)" % (start, length)
+ s1.remove(start, length); s2.remove(start, length)
+ else:
+ #print "s2.pop(%d,%d)" % (start, length)
+ d1 = s1.pop(start, length); d2 = s2.pop(start, length)
+ self.failUnlessEqual(d1, d2)
+ #print "s1 now %s" % list(s1._dump())
+ #print "s2 now %s" % list(s2._dump())
+ self.failUnlessEqual(len(s1), len(s2))
+ self.failUnlessEqual(list(s1._dump()), list(s2._dump()))
+ for j in range(100):
+ what = md5(what[12:14]+str(j)).hexdigest()
+ start = int(what[2:4], 16)
+ length = max(1, int(what[5:6], 16))
+ d1 = s1.get(start, length); d2 = s2.get(start, length)
+ self.failUnlessEqual(d1, d2, "%d+%d" % (start, length))
--- /dev/null
+
+class Spans:
+ """I represent a compressed list of booleans, one per index (an integer).
+ Typically, each index represents an offset into a large string, pointing
+ to a specific byte of a share. In this context, True means that byte has
+ been received, or has been requested.
+
+ Another way to look at this is maintaining a set of integers, optimized
+ for operations on spans like 'add range to set' and 'is range in set?'.
+
+ This is a python equivalent of perl's Set::IntSpan module, frequently
+ used to represent .newsrc contents.
+
+ Rather than storing an actual (large) list or dictionary, I represent my
+ internal state as a sorted list of spans, each with a start and a length.
+ My API is presented in terms of start+length pairs. I provide set
+ arithmetic operators, to efficiently answer questions like 'I want bytes
+ XYZ, I already requested bytes ABC, and I've already received bytes DEF:
+ what bytes should I request now?'.
+
+ The new downloader will use it to keep track of which bytes we've requested
+ or received already.
+ """
+
+ def __init__(self, _span_or_start=None, length=None):
+ self._spans = list()
+ if length is not None:
+ self._spans.append( (_span_or_start, length) )
+ elif _span_or_start:
+ for (start,length) in _span_or_start:
+ self.add(start, length)
+ self._check()
+
+ def _check(self):
+ assert sorted(self._spans) == self._spans
+ prev_end = None
+ try:
+ for (start,length) in self._spans:
+ if prev_end is not None:
+ assert start > prev_end
+ prev_end = start+length
+ except AssertionError:
+ print "BAD:", self.dump()
+ raise
+
+ def add(self, start, length):
+ assert start >= 0
+ assert length > 0
+ #print " ADD [%d+%d -%d) to %s" % (start, length, start+length, self.dump())
+ first_overlap = last_overlap = None
+ for i,(s_start,s_length) in enumerate(self._spans):
+ #print " (%d+%d)-> overlap=%s adjacent=%s" % (s_start,s_length, overlap(s_start, s_length, start, length), adjacent(s_start, s_length, start, length))
+ if (overlap(s_start, s_length, start, length)
+ or adjacent(s_start, s_length, start, length)):
+ last_overlap = i
+ if first_overlap is None:
+ first_overlap = i
+ continue
+ # no overlap
+ if first_overlap is not None:
+ break
+ #print " first_overlap", first_overlap, last_overlap
+ if first_overlap is None:
+ # no overlap, so just insert the span and sort by starting
+ # position.
+ self._spans.insert(0, (start,length))
+ self._spans.sort()
+ else:
+ # everything from [first_overlap] to [last_overlap] overlapped
+ first_start,first_length = self._spans[first_overlap]
+ last_start,last_length = self._spans[last_overlap]
+ newspan_start = min(start, first_start)
+ newspan_end = max(start+length, last_start+last_length)
+ newspan_length = newspan_end - newspan_start
+ newspan = (newspan_start, newspan_length)
+ self._spans[first_overlap:last_overlap+1] = [newspan]
+ #print " ADD done: %s" % self.dump()
+ self._check()
+
+ return self
+
+ def remove(self, start, length):
+ assert start >= 0
+ assert length > 0
+ #print " REMOVE [%d+%d -%d) from %s" % (start, length, start+length, self.dump())
+ first_complete_overlap = last_complete_overlap = None
+ for i,(s_start,s_length) in enumerate(self._spans):
+ s_end = s_start + s_length
+ o = overlap(s_start, s_length, start, length)
+ if o:
+ o_start, o_length = o
+ o_end = o_start+o_length
+ if o_start == s_start and o_end == s_end:
+ # delete this span altogether
+ if first_complete_overlap is None:
+ first_complete_overlap = i
+ last_complete_overlap = i
+ elif o_start == s_start:
+ # we only overlap the left side, so trim the start
+ # 1111
+ # rrrr
+ # oo
+ # -> 11
+ new_start = o_end
+ new_end = s_end
+ assert new_start > s_start
+ new_length = new_end - new_start
+ self._spans[i] = (new_start, new_length)
+ elif o_end == s_end:
+ # we only overlap the right side
+ # 1111
+ # rrrr
+ # oo
+ # -> 11
+ new_start = s_start
+ new_end = o_start
+ assert new_end < s_end
+ new_length = new_end - new_start
+ self._spans[i] = (new_start, new_length)
+ else:
+ # we overlap the middle, so create a new span. No need to
+ # examine any other spans.
+ # 111111
+ # rr
+ # LL RR
+ left_start = s_start
+ left_end = o_start
+ left_length = left_end - left_start
+ right_start = o_end
+ right_end = s_end
+ right_length = right_end - right_start
+ self._spans[i] = (left_start, left_length)
+ self._spans.append( (right_start, right_length) )
+ self._spans.sort()
+ break
+ if first_complete_overlap is not None:
+ del self._spans[first_complete_overlap:last_complete_overlap+1]
+ #print " REMOVE done: %s" % self.dump()
+ self._check()
+ return self
+
+ def dump(self):
+ return "len=%d: %s" % (len(self),
+ ",".join(["[%d-%d]" % (start,start+l-1)
+ for (start,l) in self._spans]) )
+
+ def each(self):
+ for start, length in self._spans:
+ for i in range(start, start+length):
+ yield i
+
+ def __iter__(self):
+ for s in self._spans:
+ yield s
+
+ def __len__(self):
+ # this also gets us bool(s)
+ return sum([length for start,length in self._spans])
+
+ def __add__(self, other):
+ s = self.__class__(self)
+ for (start, length) in other:
+ s.add(start, length)
+ return s
+
+ def __sub__(self, other):
+ s = self.__class__(self)
+ for (start, length) in other:
+ s.remove(start, length)
+ return s
+
+ def __iadd__(self, other):
+ for (start, length) in other:
+ self.add(start, length)
+ return self
+
+ def __isub__(self, other):
+ for (start, length) in other:
+ self.remove(start, length)
+ return self
+
+ def __and__(self, other):
+ if not self._spans:
+ return self.__class__()
+ bounds = self.__class__(self._spans[0][0],
+ self._spans[-1][0]+self._spans[-1][1])
+ not_other = bounds - other
+ return self - not_other
+
+ def __contains__(self, (start,length)):
+ for span_start,span_length in self._spans:
+ o = overlap(start, length, span_start, span_length)
+ if o:
+ o_start,o_length = o
+ if o_start == start and o_length == length:
+ return True
+ return False
+
+def overlap(start0, length0, start1, length1):
+ # return start2,length2 of the overlapping region, or None
+ # 00 00 000 0000 00 00 000 00 00 00 00
+ # 11 11 11 11 111 11 11 1111 111 11 11
+ left = max(start0, start1)
+ right = min(start0+length0, start1+length1)
+ # if there is overlap, 'left' will be its start, and right-1 will
+ # be the end'
+ if left < right:
+ return (left, right-left)
+ return None
+
+def adjacent(start0, length0, start1, length1):
+ if (start0 < start1) and start0+length0 == start1:
+ return True
+ elif (start1 < start0) and start1+length1 == start0:
+ return True
+ return False
+
+class DataSpans:
+ """I represent portions of a large string. Equivalently, I can be said to
+ maintain a large array of characters (with gaps of empty elements). I can
+ be used to manage access to a remote share, where some pieces have been
+ retrieved, some have been requested, and others have not been read.
+ """
+
+ def __init__(self, other=None):
+ self.spans = [] # (start, data) tuples, non-overlapping, merged
+ if other:
+ for (start, data) in other.get_chunks():
+ self.add(start, data)
+
+ def __len__(self):
+ # return number of bytes we're holding
+ return sum([len(data) for (start,data) in self.spans])
+
+ def _dump(self):
+ # return iterator of sorted list of offsets, one per byte
+ for (start,data) in self.spans:
+ for i in range(start, start+len(data)):
+ yield i
+
+ def dump(self):
+ return "len=%d: %s" % (len(self),
+ ",".join(["[%d-%d]" % (start,start+len(data)-1)
+ for (start,data) in self.spans]) )
+
+ def get_chunks(self):
+ return list(self.spans)
+
+ def get_spans(self):
+ """Return a Spans object with a bit set for each byte I hold"""
+ return Spans([(start, len(data)) for (start,data) in self.spans])
+
+ def assert_invariants(self):
+ if not self.spans:
+ return
+ prev_start = self.spans[0][0]
+ prev_end = prev_start + len(self.spans[0][1])
+ for start, data in self.spans[1:]:
+ if not start > prev_end:
+ # adjacent or overlapping: bad
+ print "ASSERTION FAILED", self.spans
+ raise AssertionError
+
+ def get(self, start, length):
+ # returns a string of LENGTH, or None
+ #print "get", start, length, self.spans
+ end = start+length
+ for (s_start,s_data) in self.spans:
+ s_end = s_start+len(s_data)
+ #print " ",s_start,s_end
+ if s_start <= start < s_end:
+ # we want some data from this span. Because we maintain
+ # strictly merged and non-overlapping spans, everything we
+ # want must be in this span.
+ offset = start - s_start
+ if offset + length > len(s_data):
+ #print " None, span falls short"
+ return None # span falls short
+ #print " some", s_data[offset:offset+length]
+ return s_data[offset:offset+length]
+ if s_start >= end:
+ # we've gone too far: no further spans will overlap
+ #print " None, gone too far"
+ return None
+ #print " None, ran out of spans"
+ return None
+
+ def add(self, start, data):
+ # first: walk through existing spans, find overlap, modify-in-place
+ # create list of new spans
+ # add new spans
+ # sort
+ # merge adjacent spans
+ #print "add", start, data, self.spans
+ end = start + len(data)
+ i = 0
+ while len(data):
+ #print " loop", start, data, i, len(self.spans), self.spans
+ if i >= len(self.spans):
+ #print " append and done"
+ # append a last span
+ self.spans.append( (start, data) )
+ break
+ (s_start,s_data) = self.spans[i]
+ # five basic cases:
+ # a: OLD b:OLDD c1:OLD c2:OLD d1:OLDD d2:OLD e: OLLDD
+ # NEW NEW NEW NEWW NEW NEW NEW
+ #
+ # we handle A by inserting a new segment (with "N") and looping,
+ # turning it into B or C. We handle B by replacing a prefix and
+ # terminating. We handle C (both c1 and c2) by replacing the
+ # segment (and, for c2, looping, turning it into A). We handle D
+ # by replacing a suffix (and, for d2, looping, turning it into
+ # A). We handle E by replacing the middle and terminating.
+ if start < s_start:
+ # case A: insert a new span, then loop with the remainder
+ #print " insert new psan"
+ s_len = s_start-start
+ self.spans.insert(i, (start, data[:s_len]))
+ i += 1
+ start = s_start
+ data = data[s_len:]
+ continue
+ s_len = len(s_data)
+ s_end = s_start+s_len
+ if s_start <= start < s_end:
+ #print " modify this span", s_start, start, s_end
+ # we want to modify some data in this span: a prefix, a
+ # suffix, or the whole thing
+ if s_start == start:
+ if s_end <= end:
+ #print " replace whole segment"
+ # case C: replace this segment
+ self.spans[i] = (s_start, data[:s_len])
+ i += 1
+ start += s_len
+ data = data[s_len:]
+ # C2 is where len(data)>0
+ continue
+ # case B: modify the prefix, retain the suffix
+ #print " modify prefix"
+ self.spans[i] = (s_start, data + s_data[len(data):])
+ break
+ if start > s_start and end < s_end:
+ # case E: modify the middle
+ #print " modify middle"
+ prefix_len = start - s_start # we retain this much
+ suffix_len = s_end - end # and retain this much
+ newdata = s_data[:prefix_len] + data + s_data[-suffix_len:]
+ self.spans[i] = (s_start, newdata)
+ break
+ # case D: retain the prefix, modify the suffix
+ #print " modify suffix"
+ prefix_len = start - s_start # we retain this much
+ suffix_len = s_len - prefix_len # we replace this much
+ #print " ", s_data, prefix_len, suffix_len, s_len, data
+ self.spans[i] = (s_start,
+ s_data[:prefix_len] + data[:suffix_len])
+ i += 1
+ start += suffix_len
+ data = data[suffix_len:]
+ #print " now", start, data
+ # D2 is where len(data)>0
+ continue
+ # else we're not there yet
+ #print " still looking"
+ i += 1
+ continue
+ # now merge adjacent spans
+ #print " merging", self.spans
+ newspans = []
+ for (s_start,s_data) in self.spans:
+ if newspans and adjacent(newspans[-1][0], len(newspans[-1][1]),
+ s_start, len(s_data)):
+ newspans[-1] = (newspans[-1][0], newspans[-1][1] + s_data)
+ else:
+ newspans.append( (s_start, s_data) )
+ self.spans = newspans
+ self.assert_invariants()
+ #print " done", self.spans
+
+ def remove(self, start, length):
+ i = 0
+ end = start + length
+ #print "remove", start, length, self.spans
+ while i < len(self.spans):
+ (s_start,s_data) = self.spans[i]
+ if s_start >= end:
+ # this segment is entirely right of the removed region, and
+ # all further segments are even further right. We're done.
+ break
+ s_len = len(s_data)
+ s_end = s_start + s_len
+ o = overlap(start, length, s_start, s_len)
+ if not o:
+ i += 1
+ continue
+ o_start, o_len = o
+ o_end = o_start + o_len
+ if o_len == s_len:
+ # remove the whole segment
+ del self.spans[i]
+ continue
+ if o_start == s_start:
+ # remove a prefix, leaving the suffix from o_end to s_end
+ prefix_len = o_end - o_start
+ self.spans[i] = (o_end, s_data[prefix_len:])
+ i += 1
+ continue
+ elif o_end == s_end:
+ # remove a suffix, leaving the prefix from s_start to o_start
+ prefix_len = o_start - s_start
+ self.spans[i] = (s_start, s_data[:prefix_len])
+ i += 1
+ continue
+ # remove the middle, creating a new segment
+ # left is s_start:o_start, right is o_end:s_end
+ left_len = o_start - s_start
+ left = s_data[:left_len]
+ right_len = s_end - o_end
+ right = s_data[-right_len:]
+ self.spans[i] = (s_start, left)
+ self.spans.insert(i+1, (o_end, right))
+ break
+ #print " done", self.spans
+
+ def pop(self, start, length):
+ data = self.get(start, length)
+ if data:
+ self.remove(start, length)
+ return data
projects / tahoe-lafs / tahoe-lafs.git / commitdiff