Merge branch 'ls/p4-changes-block-size'

"git p4" learned "--changes-block-size <n>" to read the changes in
chunks from Perforce, instead of making one call to "p4 changes"
that may trigger "too many rows scanned" error from Perforce.

* ls/p4-changes-block-size:
git-p4: use -m when running p4 changes

diff --combined git-p4.py
index 2e1c4af1910d6c246aa7a73e76d0026f67580cc1,e28033f4e1f95f8509c912660eed29843c9dbb62..a57a28f4ba5deab1fcc4f2e79257f129cf254fd1
--- 1/git-p4.py
--- 2/git-p4.py
+++ b/git-p4.py
@@@ -368,7 -368,7 +368,7 @@@ def getP4OpenedType(file)
      # Returns the perforce file type for the given file.
  
      result = p4_read_pipe(["opened", wildcard_encode(file)])
 -    match = re.match(".*\((.+)\)\r?$", result)
 +    match = re.match(".*\((.+)\)( \*exclusive\*)?\r?$", result)
      if match:
          return match.group(1)
      else:
@@@ -740,17 -740,43 +740,43 @@@ def createOrUpdateBranchesFromOrigin(lo
  def originP4BranchesExist():
          return gitBranchExists("origin") or gitBranchExists("origin/p4") or gitBranchExists("origin/p4/master")
  
- def p4ChangesForPaths(depotPaths, changeRange):
+ def p4ChangesForPaths(depotPaths, changeRange, block_size):
      assert depotPaths
-     cmd = ['changes']
-     for p in depotPaths:
-         cmd += ["%s...%s" % (p, changeRange)]
-     output = p4_read_pipe_lines(cmd)
+     assert block_size
+ 
+     # Parse the change range into start and end
+     if changeRange is None or changeRange == '':
+         changeStart = '@1'
+         changeEnd = '#head'
+     else:
+         parts = changeRange.split(',')
+         assert len(parts) == 2
+         changeStart = parts[0]
+         changeEnd = parts[1]
  
+     # Accumulate change numbers in a dictionary to avoid duplicates
      changes = {}
-     for line in output:
-         changeNum = int(line.split(" ")[1])
-         changes[changeNum] = True
+ 
+     for p in depotPaths:
+         # Retrieve changes a block at a time, to prevent running
+         # into a MaxScanRows error from the server.
+         start = changeStart
+         end = changeEnd
+         get_another_block = True
+         while get_another_block:
+             new_changes = []
+             cmd = ['changes']
+             cmd += ['-m', str(block_size)]
+             cmd += ["%s...%s,%s" % (p, start, end)]
+             for line in p4_read_pipe_lines(cmd):
+                 changeNum = int(line.split(" ")[1])
+                 new_changes.append(changeNum)
+                 changes[changeNum] = True
+             if len(new_changes) == block_size:
+                 get_another_block = True
+                 end = '@' + str(min(new_changes))
+             else:
+                 get_another_block = False
  
      changelist = changes.keys()
      changelist.sort()
@@@ -1911,7 -1937,10 +1937,10 @@@ class P4Sync(Command, P4UserMap)
                  optparse.make_option("--import-labels", dest="importLabels", action="store_true"),
                  optparse.make_option("--import-local", dest="importIntoRemotes", action="store_false",
                                       help="Import into refs/heads/ , not refs/remotes"),
-                 optparse.make_option("--max-changes", dest="maxChanges"),
+                 optparse.make_option("--max-changes", dest="maxChanges",
+                                      help="Maximum number of changes to import"),
+                 optparse.make_option("--changes-block-size", dest="changes_block_size", type="int",
+                                      help="Internal block size to use when iteratively calling p4 changes"),
                  optparse.make_option("--keep-path", dest="keepRepoPath", action='store_true',
                                       help="Keep entire BRANCH/DIR/SUBDIR prefix during import"),
                  optparse.make_option("--use-client-spec", dest="useClientSpec", action='store_true',
@@@ -1940,6 -1969,7 +1969,7 @@@
          self.syncWithOrigin = True
          self.importIntoRemotes = True
          self.maxChanges = ""
+         self.changes_block_size = 500
          self.keepRepoPath = False
          self.depotPaths = None
          self.p4BranchesInGit = []
@@@ -2586,7 -2616,7 +2616,7 @@@
          branchPrefix = self.depotPaths[0] + branch + "/"
          range = "@1,%s" % maxChange
          #print "prefix" + branchPrefix
-         changes = p4ChangesForPaths([branchPrefix], range)
+         changes = p4ChangesForPaths([branchPrefix], range, self.changes_block_size)
          if len(changes) <= 0:
              return False
          firstChange = changes[0]
@@@ -3002,7 -3032,7 +3032,7 @@@
                  if self.verbose:
                      print "Getting p4 changes for %s...%s" % (', '.join(self.depotPaths),
                                                                self.changeRange)
-                 changes = p4ChangesForPaths(self.depotPaths, self.changeRange)
+                 changes = p4ChangesForPaths(self.depotPaths, self.changeRange, self.changes_block_size)
  
                  if len(self.maxChanges) > 0:
                      changes = changes[:min(int(self.maxChanges), len(changes))]