* i2psnark: Clean up and enhance the PeerCoordinator's partial piece handling,

in preparation for more improvements

apps/i2psnark/java/src/org/klomp/snark/PartialPiece.java

@@ -0,0 +1,102 @@
+package org.klomp.snark;
+
+/**
+ * This is the class passed from PeerCoordinator to PeerState so
+ * PeerState may start requests.
+ *
+ * It is also passed from PeerState to PeerCoordinator when
+ * a piece is not completely downloaded, for example
+ * when the Peer disconnects or chokes.
+ */
+class PartialPiece implements Comparable {
+
+    private final int piece;
+    private final byte[] bs;
+    private final int off;
+    private final long createdTime;
+
+    /**
+     * Used by PeerCoordinator.
+     * Creates a new PartialPiece, with no chunks yet downloaded.
+     * Allocates the data.
+     *
+     * @param piece Piece number requested.
+     * @param bs length must be equal to the piece length
+     */
+    public PartialPiece (int piece, int len) throws OutOfMemoryError {
+        this.piece = piece;
+        this.bs = new byte[len];
+        this.off = 0;
+        this.createdTime = 0;
+    }
+
+    /**
+     * Used by PeerState.
+     * Creates a new PartialPiece, with chunks up to but not including
+     * firstOutstandingRequest already downloaded and stored in the Request byte array.
+     *
+     * Note that this cannot handle gaps; chunks after a missing chunk cannot be saved.
+     * That would be harder.
+     *
+     * @param firstOutstandingRequest the first request not fulfilled for the piece
+     */
+    public PartialPiece (Request firstOutstandingRequest) {
+        this.piece = firstOutstandingRequest.piece;
+        this.bs = firstOutstandingRequest.bs;
+        this.off = firstOutstandingRequest.off;
+        this.createdTime = System.currentTimeMillis();
+    }
+
+    /**
+     *  Convert this PartialPiece to a request for the next chunk.
+     *  Used by PeerState only.
+     */
+
+    public Request getRequest() {
+        return new Request(this.piece, this.bs, this.off, Math.min(this.bs.length - this.off, PeerState.PARTSIZE));
+    }
+
+    /** piece number */
+    public int getPiece() {
+         return this.piece;
+    }
+
+    /** how many bytes are good */
+    public int getDownloaded() {
+         return this.off;
+    }
+
+    public long getCreated() {
+         return this.createdTime;
+    }
+
+    /**
+     *  Highest downloaded first
+     */
+    public int compareTo(Object o) throws ClassCastException {
+        return ((PartialPiece)o).off - this.off;  // reverse
+    }
+    
+    @Override
+    public int hashCode() {
+        return piece * 7777;
+    }
+
+    /**
+     *  Make this simple so PeerCoordinator can keep a List.
+     *  Warning - compares piece number only!
+     */
+    @Override
+    public boolean equals(Object o) {
+        if (o instanceof PartialPiece) {
+            PartialPiece pp = (PartialPiece)o;
+            return pp.piece == this.piece;
+        }
+        return false;
+    }
+
+    @Override
+    public String toString() {
+        return "Partial(" + piece + ',' + off + ',' + bs.length + ')';
+    }
+}