Merge pull request #565 from pwendell/dev-scripts. Closes #565.

SPARK-1066: Add developer scripts to repository.

These are some developer scripts I've been maintaining in a separate public repo. This patch adds them to the Spark repository so they can evolve here and are clearly accessible to all committers.

I may do some small additional clean-up in this PR, but wanted to put them here in case others want to review. There are a few types of scripts here:

1. A tool to merge pull requests.
2. A script for packaging releases.
3. A script for auditing release candidates.

Author: Patrick Wendell <pwendell@gmail.com>

== Merge branch commits ==

commit 5d5d331d01f6fd59c2eb830f652955119b012173
Author: Patrick Wendell <pwendell@gmail.com>
Date:   Sat Feb 8 22:11:47 2014 -0800

    SPARK-1066: Add developer scripts to repository.

1 files changed, 197 insertions, 0 deletions

diff --git a/dev/merge_spark_pr.py b/dev/merge_spark_pr.py
new file mode 100755
index 0000000000..40a02cba82
--- /dev/null
+++ b/dev/merge_spark_pr.py
@@ -0,0 +1,197 @@
+#!/usr/bin/python
+
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# Utility for creating well-formed pull request merges and pushing them to Apache.
+#   usage: ./apache-pr-merge.py    (see config env vars below)
+#
+# This utility assumes you already have local a Spark git folder and that you
+# have added remotes corresponding to both (i) the github apache Spark 
+# mirror and (ii) the apache git repo.
+
+import json
+import os
+import subprocess
+import sys
+import tempfile
+import urllib2
+
+# Location of your Spark git development area
+SPARK_HOME = os.environ.get("SPARK_HOME", "/home/patrick/Documents/spark")
+# Remote name which points to the Gihub site
+PR_REMOTE_NAME = os.environ.get("PR_REMOTE_NAME", "apache-github")
+# Remote name which points to Apache git
+PUSH_REMOTE_NAME = os.environ.get("PUSH_REMOTE_NAME", "apache")
+
+GIT_API_BASE = "https://api.github.com/repos/apache/incubator-spark"
+# Prefix added to temporary branches
+BRANCH_PREFIX = "PR_TOOL"
+
+os.chdir(SPARK_HOME)
+
+def get_json(url):
+  try:
+    return json.load(urllib2.urlopen(url))
+  except urllib2.HTTPError as e:
+    print "Unable to fetch URL, exiting: %s" % url
+    sys.exit(-1)
+
+def fail(msg):
+  print msg
+  clean_up()
+  sys.exit(-1)
+
+def run_cmd(cmd):
+  if isinstance(cmd, list):
+    return subprocess.check_output(cmd)
+  else:
+    return subprocess.check_output(cmd.split(" "))
+
+def continue_maybe(prompt):
+  result = raw_input("\n%s (y/n): " % prompt)
+  if result.lower() != "y":
+    fail("Okay, exiting")
+
+original_head = run_cmd("git rev-parse HEAD")[:8]
+
+def clean_up():
+  print "Restoring head pointer to %s" % original_head
+  run_cmd("git checkout %s" % original_head)
+
+  branches = run_cmd("git branch").replace(" ", "").split("\n")
+
+  for branch in filter(lambda x: x.startswith(BRANCH_PREFIX), branches):
+    print "Deleting local branch %s" % branch
+    run_cmd("git branch -D %s" % branch)
+
+# merge the requested PR and return the merge hash
+def merge_pr(pr_num, target_ref):
+  pr_branch_name = "%s_MERGE_PR_%s" % (BRANCH_PREFIX, pr_num)
+  target_branch_name = "%s_MERGE_PR_%s_%s" % (BRANCH_PREFIX, pr_num, target_ref.upper())
+  run_cmd("git fetch %s pull/%s/head:%s" % (PR_REMOTE_NAME, pr_num, pr_branch_name))
+  run_cmd("git fetch %s %s:%s" % (PUSH_REMOTE_NAME, target_ref, target_branch_name))
+  run_cmd("git checkout %s" % target_branch_name)
+  
+  run_cmd(['git', 'merge', pr_branch_name, '--squash'])
+
+  commit_authors = run_cmd(['git', 'log', 'HEAD..%s' % pr_branch_name, 
+    '--pretty=format:%an <%ae>']).split("\n")
+  distinct_authors = sorted(set(commit_authors), key=lambda x: commit_authors.count(x), reverse=True)
+  primary_author = distinct_authors[0]
+  commits = run_cmd(['git', 'log', 'HEAD..%s' % pr_branch_name]).split("\n\n")
+
+  merge_message = "Merge pull request #%s from %s. Closes #%s.\n\n%s\n\n%s" % (
+    pr_num, pr_repo_desc, pr_num, title, body)
+  merge_message_parts = merge_message.split("\n\n")
+  merge_message_flags = []
+
+  for p in merge_message_parts:
+    merge_message_flags = merge_message_flags + ["-m", p]
+  authors = "\n".join(["Author: %s" % a for a in distinct_authors])
+  merge_message_flags = merge_message_flags + ["-m", authors]
+  merge_message_flags = merge_message_flags + ["-m", "== Merge branch commits =="]
+  for c in commits:
+    merge_message_flags = merge_message_flags + ["-m", c]
+
+  run_cmd(['git', 'commit', '--author="%s"' % primary_author] + merge_message_flags)
+
+  continue_maybe("Merge complete (local ref %s). Push to %s?" % (
+    target_branch_name, PUSH_REMOTE_NAME))
+
+  try:
+    run_cmd('git push %s %s:%s' % (PUSH_REMOTE_NAME, target_branch_name, target_ref))
+  except Exception as e:
+    clean_up()
+    fail("Exception while pushing: %s" % e)
+  
+  merge_hash = run_cmd("git rev-parse %s" % target_branch_name)[:8]
+  clean_up()
+  print("Pull request #%s merged!" % pr_num)
+  print("Merge hash: %s" % merge_hash)
+  return merge_hash
+
+
+def maybe_cherry_pick(pr_num, merge_hash, default_branch):
+  continue_maybe("Would you like to pick %s into another branch?" % merge_hash)
+  pick_ref = raw_input("Enter a branch name [%s]: " % default_branch)
+  if pick_ref == "":
+    pick_ref = default_branch
+
+  pick_branch_name = "%s_PICK_PR_%s_%s" % (BRANCH_PREFIX, pr_num, pick_ref.upper())
+
+  run_cmd("git fetch %s %s:%s" % (PUSH_REMOTE_NAME, pick_ref, pick_branch_name))
+  run_cmd("git checkout %s" % pick_branch_name)
+  run_cmd("git cherry-pick -sx %s" % merge_hash)
+  
+  continue_maybe("Pick complete (local ref %s). Push to %s?" % (
+    pick_branch_name, PUSH_REMOTE_NAME))
+
+  try:
+    run_cmd('git push %s %s:%s' % (PUSH_REMOTE_NAME, pick_branch_name, pick_ref))
+  except Exception as e:
+    clean_up()
+    fail("Exception while pushing: %s" % e)
+
+  pick_hash = run_cmd("git rev-parse %s" % pick_branch_name)[:8]
+  clean_up()
+
+  print("Pull request #%s picked into %s!" % (pr_num, pick_ref))
+  print("Pick hash: %s" % pick_hash)
+
+branches = get_json("%s/branches" % GIT_API_BASE)
+branch_names = filter(lambda x: x.startswith("branch-"), [x['name'] for x in branches])
+# Assumes branch names can be sorted lexicographically
+latest_branch = sorted(branch_names, reverse=True)[0]
+
+pr_num = raw_input("Which pull request would you like to merge? (e.g. 34): ")
+pr = get_json("%s/pulls/%s" % (GIT_API_BASE, pr_num))
+
+url = pr["url"]
+title = pr["title"]
+body = pr["body"]
+target_ref = pr["base"]["ref"]
+user_login = pr["user"]["login"]
+base_ref = pr["head"]["ref"]
+pr_repo_desc = "%s/%s" % (user_login, base_ref)
+
+if pr["merged"] == True:
+  print "Pull request %s has already been merged, assuming you want to backport" % pr_num
+  merge_commit_desc = run_cmd(['git', 'log', '--merges', '--first-parent', 
+    '--grep=pull request #%s' % pr_num, '--oneline']).split("\n")[0]
+  if merge_commit_desc == "":
+    fail("Couldn't find any merge commit for #%s, you may need to update HEAD." % pr_num)
+
+  merge_hash = merge_commit_desc[:7]  
+  message = merge_commit_desc[8:]
+  
+  print "Found: %s" % message
+  maybe_cherry_pick(pr_num, merge_hash, latest_branch)
+  sys.exit(0)
+
+if bool(pr["mergeable"]) == False:
+  fail("Pull request %s is not mergeable in its current form" % pr_num)
+
+print ("\n=== Pull Request #%s ===" % pr_num)
+print("title\t%s\nsource\t%s\ntarget\t%s\nurl\t%s" % (
+  title, pr_repo_desc, target_ref, url))
+continue_maybe("Proceed with merging pull request #%s?" % pr_num)
+
+merge_hash = merge_pr(pr_num, target_ref)
+
+while True:
+  maybe_cherry_pick(pr_num, merge_hash, latest_branch)