2 from __future__ import absolute_import
3 import glob, mmap, os, struct
5 from bup import _helpers
6 from bup.helpers import log, mmap_read
11 extract_bits = _helpers.extract_bits
17 """Wrapper which contains data from multiple index files.
18 Multiple index (.midx) files constitute a wrapper around index (.idx) files
19 and make it possible for bup to expand Git's indexing capabilities to vast
22 def __init__(self, filename):
24 self.force_keep = False
26 assert(filename.endswith('.midx'))
27 self.map = mmap_read(open(filename))
28 if str(self.map[0:4]) != 'MIDX':
29 log('Warning: skipping: invalid MIDX header in %r\n' % filename)
30 self.force_keep = True
31 return self._init_failed()
32 ver = struct.unpack('!I', self.map[4:8])[0]
33 if ver < MIDX_VERSION:
34 log('Warning: ignoring old-style (v%d) midx %r\n'
36 self.force_keep = False # old stuff is boring
37 return self._init_failed()
38 if ver > MIDX_VERSION:
39 log('Warning: ignoring too-new (v%d) midx %r\n'
41 self.force_keep = True # new stuff is exciting
42 return self._init_failed()
44 self.bits = _helpers.firstword(self.map[8:12])
45 self.entries = 2**self.bits
46 self.fanout = buffer(self.map, 12, self.entries*4)
47 self.sha_ofs = 12 + self.entries*4
48 self.nsha = nsha = self._fanget(self.entries-1)
49 self.shatable = buffer(self.map, self.sha_ofs, nsha*20)
50 self.which_ofs = self.sha_ofs + 20*nsha
51 self.whichlist = buffer(self.map, self.which_ofs, nsha*4)
52 self.idxnames = str(self.map[self.which_ofs + 4*nsha:]).split('\0')
57 def _init_failed(self):
60 self.fanout = buffer('\0\0\0\0')
61 self.shatable = buffer('\0'*20)
66 s = self.fanout[start:start+4]
67 return _helpers.firstword(s)
70 return str(self.shatable[i*20:(i+1)*20])
72 def _get_idx_i(self, i):
73 return struct.unpack('!I', self.whichlist[i*4:(i+1)*4])[0]
75 def _get_idxname(self, i):
76 return self.idxnames[self._get_idx_i(i)]
79 if self.map is not None:
83 def exists(self, hash, want_source=False):
84 """Return nonempty if the object exists in the index files."""
85 global _total_searches, _total_steps
88 el = extract_bits(want, self.bits)
90 start = self._fanget(el-1)
91 startv = el << (32-self.bits)
95 end = self._fanget(el)
96 endv = (el+1) << (32-self.bits)
97 _total_steps += 1 # lookup table is a step
98 hashv = _helpers.firstword(hash)
99 #print '(%08x) %08x %08x %08x' % (extract_bits(want, 32), startv, hashv, endv)
102 #print '! %08x %08x %08x %d - %d' % (startv, hashv, endv, start, end)
103 mid = start + (hashv-startv)*(end-start-1)/(endv-startv)
104 #print ' %08x %08x %08x %d %d %d' % (startv, hashv, endv, start, mid, end)
106 #print ' %08x' % self._num(v)
109 startv = _helpers.firstword(v)
112 endv = _helpers.firstword(v)
114 return want_source and self._get_idxname(mid) or True
118 for i in xrange(self._fanget(self.entries-1)):
119 yield buffer(self.shatable, i*20, 20)
122 return int(self._fanget(self.entries-1))
125 def clear_midxes(dir=None):
126 for midx in glob.glob(os.path.join(dir, '*.midx')):