Ability to specify the build cache location (apache#16)

* add a configuration field for the build cache location * defaults to `build-cache` instead of `cache` * add the remote repository id in the build cache path

Author: gnodet

src/main/java/org/apache/maven/buildcache/LocalCacheRepositoryImpl.java

@@ -436,19 +436,28 @@ private Path buildCacheDir( CacheContext context ) throws IOException
 
  private Path artifactCacheDir( MavenSession session, String groupId, String artifactId ) throws IOException
  {
- final String localRepositoryRoot = session.getLocalRepository().getBasedir();
- final Path path = Paths.get( localRepositoryRoot, "..", "cache", CACHE_IMPLEMENTATION_VERSION, groupId,
- artifactId ).normalize();
- if ( !Files.exists( path ) )
+ final Path vga = Paths.get( CACHE_IMPLEMENTATION_VERSION, groupId, artifactId );
+ final Path path = baseDir( session ).resolve( vga );
+ Files.createDirectories( path );
+ return path;
+ }
+
+ private Path baseDir( MavenSession session )
+ {
+ String loc = cacheConfig.getLocalRepositoryLocation();
+ if ( loc != null )
  {
- Files.createDirectories( path );
+ return Paths.get( loc );
+ }
+ else
+ {
+ return Paths.get( session.getLocalRepository().getBasedir() ).getParent().resolve( "build-cache" );
  }
- return path;
  }
 
  private Path remoteBuildPath( CacheContext context, String filename ) throws IOException
  {
- return buildCacheDir( context ).resolve( filename );
+ return remoteBuildDir( context ).resolve( filename );
  }
 
  private Path localBuildPath( CacheContext context, String filename, boolean createDir ) throws IOException
@@ -461,6 +470,11 @@ private Path localBuildPath( CacheContext context, String filename, boolean crea
  return localBuildDir.resolve( filename );
  }
 
+ private Path remoteBuildDir( CacheContext context ) throws IOException
+ {
+ return buildCacheDir( context ).resolve( cacheConfig.getId() );
+ }
+
  private Path localBuildDir( CacheContext context ) throws IOException
  {
  return buildCacheDir( context ).resolve( "local" );

src/main/java/org/apache/maven/buildcache/xml/CacheConfig.java

@@ -98,6 +98,8 @@ public interface CacheConfig
 
  int getMaxLocalBuildsCached();
 
+ String getLocalRepositoryLocation();
+
  List<String> getAttachedOutputs();
 
  boolean adjustMetaInfVersion();

src/main/java/org/apache/maven/buildcache/xml/CacheConfigImpl.java

@@ -148,7 +148,6 @@ public CacheState initialize()
  {
  LOGGER.info( "Loading cache configuration from {}", configPath );
  cacheConfig = xmlService.loadCacheConfig( configPath.toFile() );
- fillWithDefaults( cacheConfig );
  }
  catch ( Exception e )
  {
@@ -585,6 +584,13 @@ public int getMaxLocalBuildsCached()
  return getLocal().getMaxBuildsCached();
  }
 
+ @Override
+ public String getLocalRepositoryLocation()
+ {
+ checkInitializedState();
+ return getLocal().getLocation();
+ }
+
  @Override
  public List<String> getAttachedOutputs()
  {

src/main/mdo/build-cache-config.mdo

@@ -387,6 +387,12 @@ under the License.
  <class>
  <name>Local</name>
  <fields>
+ <field>
+ <name>location</name>
+ <type>String</type>
+ <description>The base directory where the local cache is located.
+ Defaults to {@code $\{localRepository}/../cache}.</description>
+ </field>
  <field>
  <name>maxBuildsCached</name>
  <type>int</type>