Merge Lucene core and backward-codecs jars

Both of these jars provide a provider-configuration file in
META-INF/services/org.apache.lucene.codecs.Codec registering their
respective implementations as providers of this codec. The proper way
to merge these files is to concatenate them, but the normal Buck build
process would otherwise choose one arbitrarily.

Add a new custom rule merge_maven_jars to merge multiple Maven jars
together using a simple Python script. The script concatenates all the
entries in two zip files, preferring the entry found in the first file
on the command line, which is still arbitrary but at least
deterministic. It specially handles files in the META-INF/services
directory by concatenating them.

Use this new rule to merge the old :core and :backward-codecs rules
into a single :core-and-backward-codecs rule.

Change-Id: I42fd1a130e42cb0eebf7bee61cfdf8545397cd09

gerrit-httpd/BUCK

@@ -34,7 +34,7 @@ java_library(
     '//lib/jgit:jgit',
     '//lib/jgit:jgit-servlet',
     '//lib/log:api',
-    '//lib/lucene:core',
+    '//lib/lucene:core-and-backward-codecs',
   ],
   provided_deps = ['//lib:servlet-api-3_1'],
   visibility = ['PUBLIC'],

gerrit-lucene/BUCK

@@ -11,7 +11,7 @@ java_library(
     '//gerrit-server:server',
     '//lib:gwtorm',
     '//lib:guava',
-    '//lib/lucene:core',
+    '//lib/lucene:core-and-backward-codecs',
   ],
   visibility = ['PUBLIC'],
 )
@@ -34,8 +34,7 @@ java_library(
     '//lib/jgit:jgit',
     '//lib/log:api',
     '//lib/lucene:analyzers-common',
-    '//lib/lucene:backward-codecs',
+    '//lib/lucene:core-and-backward-codecs',
-    '//lib/lucene:core',
     '//lib/lucene:misc',
   ],
   visibility = ['PUBLIC'],

gerrit-server/BUCK

@@ -63,7 +63,7 @@ java_library(
     '//lib/log:jsonevent-layout',
     '//lib/log:log4j',
     '//lib/lucene:analyzers-common',
-    '//lib/lucene:core',
+    '//lib/lucene:core-and-backward-codecs',
     '//lib/lucene:queryparser',
     '//lib/ow2:ow2-asm',
     '//lib/ow2:ow2-asm-tree',

lib/asciidoctor/BUCK

@@ -36,7 +36,7 @@ java_library(
     '//lib:args4j',
     '//lib:guava',
     '//lib/lucene:analyzers-common',
-    '//lib/lucene:core',
+    '//lib/lucene:core-and-backward-codecs',
   ],
   visibility = ['//tools/eclipse:classpath'],
 )

lib/lucene/BUCK

@@ -2,8 +2,19 @@ include_defs('//lib/maven.defs')
 
 VERSION = '5.2.1'
 
+# core and backward-codecs both provide
+# META-INF/services/org.apache.lucene.codecs.Codec, so they must be merged.
+merge_maven_jars(
+  name = 'core-and-backward-codecs',
+  srcs = [
+    ':backward-codecs_jar',
+    ':core_jar',
+  ],
+  visibility = ['PUBLIC'],
+)
+
 maven_jar(
-  name = 'core',
+  name = 'core_jar',
   id = 'org.apache.lucene:lucene-core:' + VERSION,
   sha1 = 'a175590aa8b04e079eb1a136fd159f9163482ba4',
   license = 'Apache2.0',
@@ -11,6 +22,7 @@ maven_jar(
     'META-INF/LICENSE.txt',
     'META-INF/NOTICE.txt',
   ],
+  visibility = [],
 )
 
 maven_jar(
@@ -18,7 +30,7 @@ maven_jar(
   id = 'org.apache.lucene:lucene-analyzers-common:' + VERSION,
   sha1 = '33b7cc17d5a7c939af6fe3f67563f4709926d7f5',
   license = 'Apache2.0',
-  deps = [':core'],
+  deps = [':core-and-backward-codecs'],
   exclude = [
     'META-INF/LICENSE.txt',
     'META-INF/NOTICE.txt',
@@ -26,15 +38,16 @@ maven_jar(
 )
 
 maven_jar(
-  name = 'backward-codecs',
+  name = 'backward-codecs_jar',
   id = 'org.apache.lucene:lucene-backward-codecs:' + VERSION,
   sha1 = '603d1f06b133449272799d698e5118db65e523ba',
   license = 'Apache2.0',
-  deps = [':core'],
+  deps = [':core_jar'],
   exclude = [
     'META-INF/LICENSE.txt',
     'META-INF/NOTICE.txt',
   ],
+  visibility = [],
 )
 
 maven_jar(
@@ -42,7 +55,7 @@ maven_jar(
   id = 'org.apache.lucene:lucene-misc:' + VERSION,
   sha1 = 'be0a4f0ac06f0a2fa3689b4bf6cd1fe6847f9969',
   license = 'Apache2.0',
-  deps = [':core'],
+  deps = [':core-and-backward-codecs'],
   exclude = [
     'META-INF/LICENSE.txt',
     'META-INF/NOTICE.txt',
@@ -54,7 +67,7 @@ maven_jar(
   id = 'org.apache.lucene:lucene-queryparser:' + VERSION,
   sha1 = '73be0a2d4ab3e6b574be1938bfb27f7f730f0ad9',
   license = 'Apache2.0',
-  deps = [':core'],
+  deps = [':core-and-backward-codecs'],
   exclude = [
     'META-INF/LICENSE.txt',
     'META-INF/NOTICE.txt',

lib/maven.defs

@@ -150,3 +150,30 @@ def maven_jar(
       visibility = visibility,
     )
 
+
+def merge_maven_jars(
+    name,
+    srcs,
+    visibility = []):
+
+  def cmd(jars):
+    return ('$(location //tools:merge_jars) $OUT '
+            + ' '.join(['$(location %s)' % j for j in jars]))
+
+  genrule(
+    name = '%s__merged_bin' % name,
+    cmd = cmd(['%s__download_bin' % s for s in srcs]),
+    out = '%s__merged.jar' % name,
+  )
+  genrule(
+    name = '%s__merged_src' % name,
+    cmd = cmd(['%s__download_src' % s for s in srcs]),
+    # tools/eclipse/project.py requires -src.jar suffix.
+    out = '%s__merged-src.jar' % name,
+  )
+  prebuilt_jar(
+    name = name,
+    binary_jar = ':%s__merged_bin' % name,
+    source_jar = ':%s__merged_src' % name,
+    visibility = visibility,
+  )

tools/BUCK

@@ -5,6 +5,12 @@ python_binary(
   visibility = ['PUBLIC'],
 )
 
+python_binary(
+  name = 'merge_jars',
+  main = 'merge_jars.py',
+  visibility = ['PUBLIC'],
+)
+
 python_binary(
   name = 'pack_war',
   main = 'pack_war.py',

tools/merge_jars.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python
+# Copyright (C) 2015 The Android Open Source Project
+#
+# Licensed 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.
+
+from __future__ import print_function
+import collections
+import sys
+import zipfile
+
+
+if len(sys.argv) < 3:
+  print('usage: %s <out.zip> <in.zip>...' % sys.argv[0], file=sys.stderr)
+  exit(1)
+
+outfile = sys.argv[1]
+infiles = sys.argv[2:]
+seen = set()
+SERVICES = 'META-INF/services/'
+
+try:
+  with zipfile.ZipFile(outfile, 'w') as outzip:
+    services = collections.defaultdict(lambda: '')
+    for infile in infiles:
+      with zipfile.ZipFile(infile) as inzip:
+        for info in inzip.infolist():
+          n = info.filename
+          if n in seen:
+            continue
+          elif n.startswith(SERVICES):
+            # Concatenate all provider configuration files.
+            services[n] += inzip.read(n)
+            continue
+          outzip.writestr(info, inzip.read(n))
+          seen.add(n)
+
+    for n, v in services.iteritems():
+      outzip.writestr(n, v)
+except Exception as err:
+  exit('Failed to merge jars: %s' % err)