gitMergeCommon.py

   1 #
   2 # Copyright (C) 2005 Fredrik Kuivinen
   3 #
   4
   5 import sys, re, os, traceback
   6 from sets import Set
   7
   8 def die(*args):
   9     printList(args, sys.stderr)
  10     sys.exit(2)
  11
  12 def printList(list, file=sys.stdout):
  13     for x in list:
  14         file.write(str(x))
  15         file.write(' ')
  16     file.write('\n')
  17
  18 import subprocess
  19
  20 # Debugging machinery
  21 # -------------------
  22
  23 DEBUG = 0
  24 functionsToDebug = Set()
  25
  26 def addDebug(func):
  27     if type(func) == str:
  28         functionsToDebug.add(func)
  29     else:
  30         functionsToDebug.add(func.func_name)
  31
  32 def debug(*args):
  33     if DEBUG:
  34         funcName = traceback.extract_stack()[-2][2]
  35         if funcName in functionsToDebug:
  36             printList(args)
  37
  38 # Program execution
  39 # -----------------
  40
  41 class ProgramError(Exception):
  42     def __init__(self, progStr, error):
  43         self.progStr = progStr
  44         self.error = error
  45
  46     def __str__(self):
  47         return self.progStr + ': ' + self.error
  48
  49 addDebug('runProgram')
  50 def runProgram(prog, input=None, returnCode=False, env=None, pipeOutput=True):
  51     debug('runProgram prog:', str(prog), 'input:', str(input))
  52     if type(prog) is str:
  53         progStr = prog
  54     else:
  55         progStr = ' '.join(prog)
  56
  57     try:
  58         if pipeOutput:
  59             stderr = subprocess.STDOUT
  60             stdout = subprocess.PIPE
  61         else:
  62             stderr = None
  63             stdout = None
  64         pop = subprocess.Popen(prog,
  65                                shell = type(prog) is str,
  66                                stderr=stderr,
  67                                stdout=stdout,
  68                                stdin=subprocess.PIPE,
  69                                env=env)
  70     except OSError, e:
  71         debug('strerror:', e.strerror)
  72         raise ProgramError(progStr, e.strerror)
  73
  74     if input != None:
  75         pop.stdin.write(input)
  76     pop.stdin.close()
  77
  78     if pipeOutput:
  79         out = pop.stdout.read()
  80     else:
  81         out = ''
  82
  83     code = pop.wait()
  84     if returnCode:
  85         ret = [out, code]
  86     else:
  87         ret = out
  88     if code != 0 and not returnCode:
  89         debug('error output:', out)
  90         debug('prog:', prog)
  91         raise ProgramError(progStr, out)
  92 #    debug('output:', out.replace('\0', '\n'))
  93     return ret
  94
  95 # Code for computing common ancestors
  96 # -----------------------------------
  97
  98 currentId = 0
  99 def getUniqueId():
 100     global currentId
 101     currentId += 1
 102     return currentId
 103
 104 # The 'virtual' commit objects have SHAs which are integers
 105 shaRE = re.compile('^[0-9a-f]{40}$')
 106 def isSha(obj):
 107     return (type(obj) is str and bool(shaRE.match(obj))) or \
 108            (type(obj) is int and obj >= 1)
 109
 110 class Commit(object):
 111     __slots__ = ['parents', 'firstLineMsg', 'children', '_tree', 'sha',
 112                  'virtual']
 113
 114     def __init__(self, sha, parents, tree=None):
 115         self.parents = parents
 116         self.firstLineMsg = None
 117         self.children = []
 118
 119         if tree:
 120             tree = tree.rstrip()
 121             assert(isSha(tree))
 122         self._tree = tree
 123
 124         if not sha:
 125             self.sha = getUniqueId()
 126             self.virtual = True
 127             self.firstLineMsg = 'virtual commit'
 128             assert(isSha(tree))
 129         else:
 130             self.virtual = False
 131             self.sha = sha.rstrip()
 132         assert(isSha(self.sha))
 133
 134     def tree(self):
 135         self.getInfo()
 136         assert(self._tree != None)
 137         return self._tree
 138
 139     def shortInfo(self):
 140         self.getInfo()
 141         return str(self.sha) + ' ' + self.firstLineMsg
 142
 143     def __str__(self):
 144         return self.shortInfo()
 145
 146     def getInfo(self):
 147         if self.virtual or self.firstLineMsg != None:
 148             return
 149         else:
 150             info = runProgram(['git-cat-file', 'commit', self.sha])
 151             info = info.split('\n')
 152             msg = False
 153             for l in info:
 154                 if msg:
 155                     self.firstLineMsg = l
 156                     break
 157                 else:
 158                     if l.startswith('tree'):
 159                         self._tree = l[5:].rstrip()
 160                     elif l == '':
 161                         msg = True
 162
 163 class Graph:
 164     def __init__(self):
 165         self.commits = []
 166         self.shaMap = {}
 167
 168     def addNode(self, node):
 169         assert(isinstance(node, Commit))
 170         self.shaMap[node.sha] = node
 171         self.commits.append(node)
 172         for p in node.parents:
 173             p.children.append(node)
 174         return node
 175
 176     def reachableNodes(self, n1, n2):
 177         res = {}
 178         def traverse(n):
 179             res[n] = True
 180             for p in n.parents:
 181                 traverse(p)
 182
 183         traverse(n1)
 184         traverse(n2)
 185         return res
 186
 187     def fixParents(self, node):
 188         for x in range(0, len(node.parents)):
 189             node.parents[x] = self.shaMap[node.parents[x]]
 190
 191 # addDebug('buildGraph')
 192 def buildGraph(heads):
 193     debug('buildGraph heads:', heads)
 194     for h in heads:
 195         assert(isSha(h))
 196
 197     g = Graph()
 198
 199     out = runProgram(['git-rev-list', '--parents'] + heads)
 200     for l in out.split('\n'):
 201         if l == '':
 202             continue
 203         shas = l.split(' ')
 204
 205         # This is a hack, we temporarily use the 'parents' attribute
 206         # to contain a list of SHA1:s. They are later replaced by proper
 207         # Commit objects.
 208         c = Commit(shas[0], shas[1:])
 209
 210         g.commits.append(c)
 211         g.shaMap[c.sha] = c
 212
 213     for c in g.commits:
 214         g.fixParents(c)
 215
 216     for c in g.commits:
 217         for p in c.parents:
 218             p.children.append(c)
 219     return g
 220
 221 # Write the empty tree to the object database and return its SHA1
 222 def writeEmptyTree():
 223     tmpIndex = os.environ.get('GIT_DIR', '.git') + '/merge-tmp-index'
 224     def delTmpIndex():
 225         try:
 226             os.unlink(tmpIndex)
 227         except OSError:
 228             pass
 229     delTmpIndex()
 230     newEnv = os.environ.copy()
 231     newEnv['GIT_INDEX_FILE'] = tmpIndex
 232     res = runProgram(['git-write-tree'], env=newEnv).rstrip()
 233     delTmpIndex()
 234     return res
 235
 236 def addCommonRoot(graph):
 237     roots = []
 238     for c in graph.commits:
 239         if len(c.parents) == 0:
 240             roots.append(c)
 241
 242     superRoot = Commit(sha=None, parents=[], tree=writeEmptyTree())
 243     graph.addNode(superRoot)
 244     for r in roots:
 245         r.parents = [superRoot]
 246     superRoot.children = roots
 247     return superRoot
 248
 249 def getCommonAncestors(graph, commit1, commit2):
 250     '''Find the common ancestors for commit1 and commit2'''
 251     assert(isinstance(commit1, Commit) and isinstance(commit2, Commit))
 252
 253     def traverse(start, set):
 254         stack = [start]
 255         while len(stack) > 0:
 256             el = stack.pop()
 257             set.add(el)
 258             for p in el.parents:
 259                 if p not in set:
 260                     stack.append(p)
 261     h1Set = Set()
 262     h2Set = Set()
 263     traverse(commit1, h1Set)
 264     traverse(commit2, h2Set)
 265     shared = h1Set.intersection(h2Set)
 266
 267     if len(shared) == 0:
 268         shared = [addCommonRoot(graph)]
 269
 270     res = Set()
 271
 272     for s in shared:
 273         if len([c for c in s.children if c in shared]) == 0:
 274             res.add(s)
 275     return list(res)