Caching for Osgi-bundles.

project/Dependencies.scala

@@ -5,10 +5,12 @@ object Library {
   // Versions
   val bndVersion = "2.1.0"
   val specs2Version = "1.14"
+  val armVersion = "1.3"
 
   // Libraries
   val bndLib = "biz.aQute.bnd" % "bndlib" % bndVersion
   val specs2 = "org.specs2" %% "specs2" % specs2Version
+  val arm = "com.jsuereth" %% "scala-arm" % armVersion
 }
 
 object Dependencies {
@@ -17,6 +19,7 @@ object Dependencies {
 
   val sbtOsgi = List(
     bndLib,
-    specs2  % "test"
+    specs2  % "test",
+    arm
   )
 }

src/main/scala/com/typesafe/sbt/osgi/Osgi.scala

@@ -21,41 +21,72 @@ import aQute.bnd.osgi.Constants._
 import java.util.Properties
 import sbt._
 import sbt.Keys._
+import resource._
 import scala.collection.JavaConversions._
+import java.io.{ FileInputStream, FileOutputStream }
 
 private object Osgi {
-
   def bundleTask(
     headers: OsgiManifestHeaders,
     additionalHeaders: Map[String, String],
     fullClasspath: Seq[Attributed[File]],
     artifactPath: File,
     resourceDirectories: Seq[File],
     embeddedJars: Seq[File],
-    streams: TaskStreams): File = {
-    val builder = new Builder
-    builder.setClasspath(fullClasspath map (_.data) toArray)
-    builder.setProperties(headersToProperties(headers, additionalHeaders))
-    includeResourceProperty(resourceDirectories.filter(_.exists), embeddedJars) foreach (dirs =>
-      builder.setProperty(INCLUDERESOURCE, dirs)
-    )
-    bundleClasspathProperty(embeddedJars) foreach (jars =>
-      builder.setProperty(BUNDLE_CLASSPATH, jars)
-    )
-    // Write to a temporary file to prevent trying to simultaneously read from and write to the
-    // same jar file in exportJars mode (which causes a NullPointerException).
-    val tmpArtifactPath = file(artifactPath.absolutePath + ".tmp")
-    // builder.build is not thread-safe because it uses a static SimpleDateFormat.  This ensures
-    // that all calls to builder.build are serialized.
-    val jar = synchronized {
-      builder.build
+    streams: TaskStreams, 
+    target: File): File = {
+
+    //this is a cache file generated to check that the bnd parameters have not changed
+    val manifest = target / "manifest.xml"
+
+    val props = headersToProperties(headers, additionalHeaders)
+    val oldProps = new Properties()
+
+    //loads the previous set of headers into oldProps if we have a manifest.xml
+    if (manifest.exists) managed(new FileInputStream(manifest)) foreach oldProps.load
+    //saves the new properties into manifest.xml if they are different from the previous properties.
+    if (!oldProps.equals(props)) managed(new FileOutputStream(manifest)) foreach (props.store(_, ""))
+
+    //A helper function that turns a File object f into a flat array of Files, expanding f into its child files if f is a directory. If f has directories within it
+    //  it expands those recursively.
+    def expandClasspath(f: File): Array[File] = if (f.isDirectory) f.listFiles() flatMap expandClasspath else Array(f)
+
+    //FileFunction.cached produces a function that takes a Set[File] and runs the function if the files in that set have changed at all, producing another Set[File].
+    //  if the contents of the input set have not changed, the cached function returns the previously generated set of files. cachedFunction checks if the lastModified
+    //  date of the input files has changed, and if the output set already exists or not. It runs the generator function if either the input set last modified dates are
+    //  off or the generated files do not exist.
+    val cachedFunction = FileFunction.cached(target / "package-cache", FilesInfo.lastModified, FilesInfo.exists) {
+      (changes: Set[File]) ⇒
+        val builder = new Builder
+        builder.setClasspath(fullClasspath map (_.data) toArray)
+        builder.setProperties(props)
+        includeResourceProperty(resourceDirectories filter (_.exists), embeddedJars) foreach (dirs ⇒
+          builder.setProperty(INCLUDE_RESOURCE, dirs)
+        )
+        bundleClasspathProperty(embeddedJars) foreach (jars ⇒
+          builder.setProperty(BUNDLE_CLASSPATH, jars)
+        )
+
+
+	// Write to a temporary file to prevent trying to simultaneously read from and write to the
+	// same jar file in exportJars mode (which causes a NullPointerException).        
+        val tmpArtifactPath = file(artifactPath.absolutePath + ".tmp")
+
+        // builder.build is not thread-safe because it uses a static SimpleDateFormat.  This ensures
+	// that all calls to builder.build are serialized
+        val jar = synchronized {
+          builder.build
+        }
+
+        val log = streams.log
+        builder.getWarnings foreach (s => log.warn(s"bnd: $s"))
+        builder.getErrors foreach (s => log.error(s"bnd: $s"))
+        jar.write(tmpArtifactPath)
+        IO.move(tmpArtifactPath, artifactPath)
+        Set(artifactPath)
     }
-    val log = streams.log
-    builder.getWarnings.foreach(s => log.warn(s"bnd: $s"))
-    builder.getErrors.foreach(s => log.error(s"bnd: $s"))
-    jar.write(tmpArtifactPath)
-    IO.move(tmpArtifactPath, artifactPath)
-    artifactPath
+
+    cachedFunction((fullClasspath flatMap (a ⇒ expandClasspath(a.data)) toSet) ++ resourceDirectories.toSet ++ embeddedJars.toSet + manifest).head
   }
 
   def headersToProperties(headers: OsgiManifestHeaders, additionalHeaders: Map[String, String]): Properties = {

src/main/scala/com/typesafe/sbt/osgi/SbtOsgi.scala

@@ -40,7 +40,8 @@ object SbtOsgi extends Plugin {
         artifactPath in (Compile, packageBin),
         resourceDirectories in Compile,
         embeddedJars,
-        streams
+        streams,
+        target
       ) map Osgi.bundleTask,
       manifestHeaders <<= (
         bundleActivator,