new piece selection logic to avoid high cpu bug

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

@@ -16,6 +16,7 @@ import java.nio.file.Files
 import java.nio.file.StandardOpenOption
 import java.security.MessageDigest
 import java.security.NoSuchAlgorithmException
+import java.util.logging.Level
 
 @Log
 class DownloadSession {
@@ -23,7 +24,7 @@ class DownloadSession {
     private static int SAMPLES = 10
     
     private final String meB64
-    private final Pieces downloaded, claimed
+    private final Pieces pieces
     private final InfoHash infoHash
     private final Endpoint endpoint
     private final File file
@@ -36,11 +37,10 @@ class DownloadSession {
     
     private ByteBuffer mapped
     
-    DownloadSession(String meB64, Pieces downloaded, Pieces claimed, InfoHash infoHash, Endpoint endpoint, File file, 
+    DownloadSession(String meB64, Pieces pieces, InfoHash infoHash, Endpoint endpoint, File file, 
         int pieceSize, long fileLength) {
         this.meB64 = meB64
-        this.downloaded = downloaded
-        this.claimed = claimed
+        this.pieces = pieces
         this.endpoint = endpoint
         this.infoHash = infoHash
         this.file = file
@@ -63,22 +63,11 @@ class DownloadSession {
         OutputStream os = endpoint.getOutputStream()
         InputStream is = endpoint.getInputStream()
         
-        int piece
-        while(true) {
-            piece = downloaded.getRandomPiece()
-            if (piece == -1)
-                return false
-            if (claimed.isMarked(piece)) {
-                if (downloaded.donePieces() + claimed.donePieces() == downloaded.nPieces) {
-                    log.info("all pieces claimed")
-                    return false
-                }
-                continue
-            }
-            break
-        }
-        claimed.markDownloaded(piece)
-        
+        int piece = pieces.claim()
+        if (piece == -1)
+            return false
+        boolean unclaim = true
+            
         log.info("will download piece $piece")
         
         long start = piece * pieceSize
@@ -171,9 +160,11 @@ class DownloadSession {
             } finally {
                 try { channel?.close() } catch (IOException ignore) {}
             }
-            downloaded.markDownloaded(piece)
+            pieces.markDownloaded(piece)
+            unclaim = false
         } finally {
-            claimed.clear(piece)
+            if (unclaim)
+                pieces.unclaim(piece)
         }
         return true
     }

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

@@ -35,7 +35,7 @@ public class Downloader {
     private final DownloadManager downloadManager 
     private final Persona me   
     private final File file
-    private final Pieces downloaded, claimed
+    private final Pieces pieces
     private final long length
     private InfoHash infoHash
     private final int pieceSize
@@ -74,8 +74,7 @@ public class Downloader {
             nPieces = length / pieceSize + 1
         this.nPieces = nPieces
         
-        downloaded = new Pieces(nPieces, Constants.DOWNLOAD_SEQUENTIAL_RATIO)
-        claimed = new Pieces(nPieces)
+        pieces = new Pieces(nPieces, Constants.DOWNLOAD_SEQUENTIAL_RATIO)
     }
     
     public synchronized InfoHash getInfoHash() {
@@ -102,7 +101,7 @@ public class Downloader {
             return
         piecesFile.eachLine { 
             int piece = Integer.parseInt(it)
-            downloaded.markDownloaded(piece)
+            pieces.markDownloaded(piece)
         }
     }
     
@@ -111,7 +110,7 @@ public class Downloader {
             if (piecesFileClosed)
                 return
             piecesFile.withPrintWriter { writer ->
-                downloaded.getDownloaded().each { piece ->
+                pieces.getDownloaded().each { piece ->
                     writer.println(piece)
                 }
             }
@@ -119,7 +118,7 @@ public class Downloader {
     }
     
     public long donePieces() {
-        downloaded.donePieces()
+        pieces.donePieces()
     }
     
     
@@ -142,7 +141,7 @@ public class Downloader {
             allFinished &= it.currentState == WorkerState.FINISHED
         }
         if (allFinished) {
-            if (downloaded.isComplete())
+            if (pieces.isComplete())
                 return DownloadState.FINISHED
             return DownloadState.FAILED
         }
@@ -240,8 +239,8 @@ public class Downloader {
                 }
                 currentState = WorkerState.DOWNLOADING
                 boolean requestPerformed
-                while(!downloaded.isComplete()) {
-                    currentSession = new DownloadSession(me.toBase64(), downloaded, claimed, getInfoHash(), endpoint, file, pieceSize, length)
+                while(!pieces.isComplete()) {
+                    currentSession = new DownloadSession(me.toBase64(), pieces, getInfoHash(), endpoint, file, pieceSize, length)
                     requestPerformed = currentSession.request()
                     if (!requestPerformed)
                         break
@@ -251,7 +250,7 @@ public class Downloader {
                 log.log(Level.WARNING,"Exception while downloading",bad)
             } finally {
                 currentState = WorkerState.FINISHED
-                if (downloaded.isComplete() && eventFired.compareAndSet(false, true)) {
+                if (pieces.isComplete() && eventFired.compareAndSet(false, true)) {
                     synchronized(piecesFile) {
                         piecesFileClosed = true
                         piecesFile.delete()

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

@@ -1,7 +1,7 @@
 package com.muwire.core.download
 
 class Pieces {
-    private final BitSet bitSet
+    private final BitSet done, claimed
     private final int nPieces
     private final float ratio
     private final Random random = new Random()
@@ -13,52 +13,53 @@ class Pieces {
     Pieces(int nPieces, float ratio) {
         this.nPieces = nPieces
         this.ratio = ratio
-        bitSet = new BitSet(nPieces)
+        done = new BitSet(nPieces)
+        claimed = new BitSet(nPieces)
     }
     
-    synchronized int getRandomPiece() {
-        int cardinality = bitSet.cardinality()
-        if (cardinality == nPieces)
+    synchronized int claim() {
+        int claimedCardinality = claimed.cardinality()
+        if (claimedCardinality == nPieces)
             return -1
         
         // if fuller than ratio just do sequential
-        if ( (1.0f * cardinality) / nPieces > ratio) {
-            return bitSet.nextClearBit(0)
+        if ( (1.0f * claimedCardinality) / nPieces > ratio) {
+            int rv = claimed.nextClearBit(0)
+            claimed.set(rv)
+            return rv
         }
         
         while(true) {
             int start = random.nextInt(nPieces)
-            if (bitSet.get(start))
+            if (claimed.get(start))
                 continue
+            claimed.set(start)
             return start
         }
     }
     
-    def getDownloaded() {
+    synchronized def getDownloaded() {
         def rv = []
-        for (int i = bitSet.nextSetBit(0); i >= 0; i = bitSet.nextSetBit(i+1)) {
+        for (int i = done.nextSetBit(0); i >= 0; i = done.nextSetBit(i+1)) {
             rv << i
         }
         rv
     }
     
     synchronized void markDownloaded(int piece) {
-        bitSet.set(piece)
+        done.set(piece)
+        claimed.set(piece)
     }
     
-    synchronized void clear(int piece) {
-        bitSet.clear(piece)
+    synchronized void unclaim(int piece) {
+        claimed.clear(piece)
     }
     
     synchronized boolean isComplete() {
-        bitSet.cardinality() == nPieces
-    }
-    
-    synchronized boolean isMarked(int piece) {
-        bitSet.get(piece)
+        done.cardinality() == nPieces
     }
     
     synchronized int donePieces() {
-        bitSet.cardinality()
+        done.cardinality()
     }
 }