Refactor persisting state in push and merge scripts.

tools/push-to-trunk/common_includes.py

 #!/usr/bin/env python
 # Copyright 2013 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
 #       with the distribution.
 #     * Neither the name of Google Inc. nor the names of its
 #       contributors may be used to endorse or promote products derived
 #       from this software without specific prior written permission.
 #
 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 import datetime
+import json
 import os
 import re
 import subprocess
 import sys
 import textwrap
 import time
 import urllib2
 
 PERSISTFILE_BASENAME = "PERSISTFILE_BASENAME"
 TEMP_BRANCH = "TEMP_BRANCH"
@@ skipping 199 matching lines @@
     self._config = config
     self._state = state
     self._options = options
     self._side_effect_handler = handler
     assert self._number >= 0
     assert self._config is not None
     assert self._state is not None
     assert self._side_effect_handler is not None
     assert isinstance(options, CommonOptions)
 
+  def __getitem__(self, key):
+    # Convenience method to allow direct [] access on step classes for
+    # manipulating the backed state dict.
+    return self._state[key]
+
+  def __setitem__(self, key, value):
+    # Convenience method to allow direct [] access on step classes for
+    # manipulating the backed state dict.
+    self._state[key] = value
+
   def Config(self, key):
     return self._config[key]
 
   def Run(self):
-    if self._requires:
-      self.RestoreIfUnset(self._requires)
-      if not self._state[self._requires]:
-        return
+    # Restore state.
+    state_file = "%s-state.json" % self._config[PERSISTFILE_BASENAME]
+    if not self._state and os.path.exists(state_file):
+      self._state.update(json.loads(FileToText(state_file)))
+
+    # Skip step if requirement is not met.
+    if self._requires and not self._state.get(self._requires):
+      return
+
     print ">>> Step %d: %s" % (self._number, self._text)
     self.RunStep()
 
+    # Persist state.
+    TextToFile(json.dumps(self._state), state_file)
+
   def RunStep(self):
     raise NotImplementedError
 
   def Retry(self, cb, retry_on=None, wait_plan=None):
     """ Retry a function.
     Params:
       cb: The function to retry.
       retry_on: A callback that takes the result of the function and returns
                 True if the function should be retried. A function throwing an
                 exception is always retried.
@@ skipping 72 matching lines @@
       if re.match(r".*\s+%s$" % name, line):
         msg = "Branch %s exists, do you want to delete it?" % name
         if self.Confirm(msg):
           if self.Git("branch -D %s" % name) is None:
             self.Die("Deleting branch '%s' failed." % name)
           print "Branch %s deleted." % name
         else:
           msg = "Can't continue. Please delete branch %s and try again." % name
           self.Die(msg)
 
-  def Persist(self, var, value):
-    value = value or "__EMPTY__"
-    TextToFile(value, "%s-%s" % (self._config[PERSISTFILE_BASENAME], var))
-
-  def Restore(self, var):
-    value = FileToText("%s-%s" % (self._config[PERSISTFILE_BASENAME], var))
-    value = value or self.Die("Variable '%s' could not be restored." % var)
-    return "" if value == "__EMPTY__" else value
-
-  def RestoreIfUnset(self, var_name):
-    if self._state.get(var_name) is None:
-      self._state[var_name] = self.Restore(var_name)
-
   def InitialEnvironmentChecks(self):
     # Cancel if this is not a git checkout.
     if not os.path.exists(self._config[DOT_GIT_LOCATION]):
       self.Die("This is not a git checkout, this script won't work for you.")
 
     # Cancel if EDITOR is unset or not executable.
     if (self._options.requires_editor and (not os.environ.get("EDITOR") or
         Command("which", os.environ["EDITOR"]) is None)):
       self.Die("Please set your EDITOR environment variable, you'll need it.")
 
   def CommonPrepare(self):
     # Check for a clean workdir.
     if self.Git("status -s -uno").strip() != "":
       self.Die("Workspace is not clean. Please commit or undo your changes.")
 
     # Persist current branch.
-    current_branch = ""
+    self["current_branch"] = ""
     git_result = self.Git("status -s -b -uno").strip()
     for line in git_result.splitlines():
       match = re.match(r"^## (.+)", line)
       if match:
-        current_branch = match.group(1)
+        self["current_branch"] = match.group(1)
         break
-    self.Persist("current_branch", current_branch)
 
     # Fetch unfetched revisions.
     if self.Git("svn fetch") is None:
       self.Die("'git svn fetch' failed.")
 
   def PrepareBranch(self):
     # Get ahold of a safe temporary branch and check it out.
-    self.RestoreIfUnset("current_branch")
-    if self._state["current_branch"] != self._config[TEMP_BRANCH]:
+    if self["current_branch"] != self._config[TEMP_BRANCH]:
       self.DeleteBranch(self._config[TEMP_BRANCH])
       self.Git("checkout -b %s" % self._config[TEMP_BRANCH])
 
     # Delete the branch that will be created later if it exists already.
     self.DeleteBranch(self._config[BRANCHNAME])
 
   def CommonCleanup(self):
-    self.RestoreIfUnset("current_branch")
-    self.Git("checkout -f %s" % self._state["current_branch"])
-    if self._config[TEMP_BRANCH] != self._state["current_branch"]:
+    self.Git("checkout -f %s" % self["current_branch"])
+    if self._config[TEMP_BRANCH] != self["current_branch"]:
       self.Git("branch -D %s" % self._config[TEMP_BRANCH])
-    if self._config[BRANCHNAME] != self._state["current_branch"]:
+    if self._config[BRANCHNAME] != self["current_branch"]:
       self.Git("branch -D %s" % self._config[BRANCHNAME])
 
     # Clean up all temporary files.
     Command("rm", "-f %s*" % self._config[PERSISTFILE_BASENAME])
 
   def ReadAndPersistVersion(self, prefix=""):
     def ReadAndPersist(var_name, def_name):
       match = re.match(r"^#define %s\s+(\d*)" % def_name, line)
       if match:
         value = match.group(1)
-        self.Persist("%s%s" % (prefix, var_name), value)
-        self._state["%s%s" % (prefix, var_name)] = value
+        self["%s%s" % (prefix, var_name)] = value
     for line in LinesInFile(self._config[VERSION_FILE]):
       for (var_name, def_name) in [("major", "MAJOR_VERSION"),
                                    ("minor", "MINOR_VERSION"),
                                    ("build", "BUILD_NUMBER"),
                                    ("patch", "PATCH_LEVEL")]:
         ReadAndPersist(var_name, def_name)
 
-  def RestoreVersionIfUnset(self, prefix=""):
-    for v in ["major", "minor", "build", "patch"]:
-      self.RestoreIfUnset("%s%s" % (prefix, v))
-
   def WaitForLGTM(self):
     print ("Please wait for an LGTM, then type \"LGTM<Return>\" to commit "
            "your change. (If you need to iterate on the patch or double check "
            "that it's sane, do so in another shell, but remember to not "
            "change the headline of the uploaded CL.")
     answer = ""
     while answer != "LGTM":
       print "> ",
       answer = self.ReadLine(None if self._options.wait_for_lgtm else "LGTM")
       if answer != "LGTM":
@@ skipping 59 matching lines @@
 
     return step_class(message, requires, number=number, config=config,
                       state=state, options=options,
                       handler=side_effect_handler)
 
 
 def RunScript(step_classes,
               config,
               options,
               side_effect_handler=DEFAULT_SIDE_EFFECT_HANDLER):
+  state_file = "%s-state.json" % config[PERSISTFILE_BASENAME]
+  if options.s == 0 and os.path.exists(state_file):
+    os.remove(state_file)
   state = {}
   steps = []
   for (number, step_class) in enumerate(step_classes):
     steps.append(MakeStep(step_class, number, state, config,
                           options, side_effect_handler))
 
   for step in steps[options.s:]:
     step.Run()