store done pieces on disk to enable resume

core/src/main/groovy/com/muwire/core/Core.groovy

@@ -54,7 +54,8 @@ public class Core {
     
     final EventBus eventBus
     final Persona me
-
+    final File home
+    
     private final TrustService trustService
     private final PersisterService persisterService
     private final HostCache hostCache
@@ -64,7 +65,8 @@ public class Core {
     private final ConnectionEstablisher connectionEstablisher
     private final HasherService hasherService
         
-    public Core(MuWireSettings props, File home) {		
+    public Core(MuWireSettings props, File home) {
+        this.home = home		
         log.info "Initializing I2P context"
         I2PAppContext.getGlobalContext().logManager()
         I2PAppContext.getGlobalContext()._logManager = new MuWireLogManager()
@@ -164,7 +166,7 @@ public class Core {
 		eventBus.register(ResultsEvent.class, searchManager)
 		
         log.info("initializing download manager")
-        DownloadManager downloadManager = new DownloadManager(eventBus, i2pConnector)
+        DownloadManager downloadManager = new DownloadManager(eventBus, i2pConnector, new File(home, "incompletes"))
         eventBus.register(UIDownloadEvent.class, downloadManager)
         
         log.info("initializing upload manager")

core/src/main/groovy/com/muwire/core/download/DownloadManager.groovy

@@ -11,10 +11,13 @@ public class DownloadManager {
     private final EventBus eventBus
     private final I2PConnector connector
     private final Executor executor
+    private final File incompletes
     
-    public DownloadManager(EventBus eventBus, I2PConnector connector) {
+    public DownloadManager(EventBus eventBus, I2PConnector connector, File incompletes) {
         this.eventBus = eventBus
         this.connector = connector
+        this.incompletes = incompletes
+        incompletes.mkdir()
         this.executor = Executors.newCachedThreadPool({ r ->
             Thread rv = new Thread(r)
             rv.setName("download-worker")
@@ -26,7 +29,8 @@ public class DownloadManager {
     
     public void onUIDownloadEvent(UIDownloadEvent e) {
         def downloader = new Downloader(e.target, e.result.size,
-            e.result.infohash, e.result.pieceSize, connector, e.result.sender.destination)
+            e.result.infohash, e.result.pieceSize, connector, e.result.sender.destination,
+            incompletes)
         executor.execute({downloader.download()} as Runnable)
         eventBus.publish(new DownloadStartedEvent(downloader : downloader))
     }

core/src/main/groovy/com/muwire/core/download/Downloader.groovy

@@ -23,6 +23,7 @@ public class Downloader {
     private final I2PConnector connector
     private final Destination destination
     private final int nPieces
+    private final File piecesFile
     
     private Endpoint endpoint
     private volatile DownloadSession currentSession
@@ -30,12 +31,14 @@ public class Downloader {
     private volatile boolean cancelled
     private volatile Thread downloadThread
     
-    public Downloader(File file, long length, InfoHash infoHash, int pieceSizePow2, I2PConnector connector, Destination destination) {
+    public Downloader(File file, long length, InfoHash infoHash, int pieceSizePow2, I2PConnector connector, Destination destination,
+        File incompletes) {
         this.file = file
         this.infoHash = infoHash
         this.length = length
         this.connector = connector
         this.destination = destination
+        this.piecesFile = new File(incompletes, file.getName()+".pieces")
         this.pieceSize = 1 << pieceSizePow2
         
         int nPieces
@@ -50,6 +53,7 @@ public class Downloader {
     }
     
     void download() {
+        readPieces()
         downloadThread = Thread.currentThread()
         Endpoint endpoint = null
         try {
@@ -58,8 +62,10 @@ public class Downloader {
             while(!pieces.isComplete()) {
                 currentSession = new DownloadSession(pieces, infoHash, endpoint, file, pieceSize, length)
                 currentSession.request()
+                writePieces()
             }
             currentState = DownloadState.FINISHED
+            piecesFile.delete()
         } catch (Exception bad) {
             log.log(Level.WARNING,"Exception while downloading",bad)
             if (cancelled)
@@ -71,6 +77,23 @@ public class Downloader {
         }
     }
     
+    void readPieces() {
+        if (!piecesFile.exists())
+            return
+        piecesFile.withReader { 
+            int piece = Integer.parseInt(it.readLine())
+            pieces.markDownloaded(piece)
+        }
+    }
+    
+    void writePieces() {
+        piecesFile.withPrintWriter { writer ->
+            pieces.getDownloaded().each { piece -> 
+                writer.println(piece)
+            }
+        }
+    }
+    
     public long donePieces() {
         pieces.donePieces()
     }

core/src/main/groovy/com/muwire/core/download/Pieces.groovy

@@ -33,6 +33,14 @@ class Pieces {
         }
     }
     
+    def getDownloaded() {
+        def rv = []
+        for (int i = bitSet.nextSetBit(0); i >= 0; i = bitSet.nextSetBit(i+1)) {
+            rv << i
+        }
+        rv
+    }
+    
     synchronized void markDownloaded(int piece) {
         bitSet.set(piece)
     }