gitMergeCommon.py

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