* i2psnark: Refactor request tracking to prevent possible deadlocks

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

@@ -12,13 +12,15 @@ class Piece implements Comparable {
 
     private int id;
     private Set<PeerID> peers;
-    private boolean requested;
+    /** @since 0.8.3 */
+    private Set<PeerID> requests;
     /** @since 0.8.1 */
     private int priority;
     
     public Piece(int id) {
         this.id = id;
-        this.peers = new ConcurrentHashSet();
+        this.peers = new ConcurrentHashSet(I2PSnarkUtil.MAX_CONNECTIONS);
+        this.requests = new ConcurrentHashSet(2);
     }
     
     /**
@@ -49,12 +51,36 @@ class Piece implements Comparable {
     }
     
     public int getId() { return this.id; }
-    /** @deprecated unused */
-    public Set<PeerID> getPeers() { return this.peers; }
     public boolean addPeer(Peer peer) { return this.peers.add(peer.getPeerID()); }
     public boolean removePeer(Peer peer) { return this.peers.remove(peer.getPeerID()); }
-    public boolean isRequested() { return this.requested; }
-    public void setRequested(boolean requested) { this.requested = requested; } 
+    public boolean isRequested() { return !this.requests.isEmpty(); }
+
+    /**
+     * Since 0.8.3, keep track of who is requesting here,
+     * to avoid deadlocks from querying each peer.
+     */
+    public void setRequested(Peer peer, boolean requested) {
+        if (requested)
+            this.requests.add(peer.getPeerID());
+        else
+            this.requests.remove(peer.getPeerID());
+    } 
+    
+    /**
+     * Is peer requesting this piece?
+     * @since 0.8.3
+     */
+    public boolean isRequestedBy(Peer peer) {
+        return this.requests.contains(peer.getPeerID());
+    } 
+    
+    /**
+     * How many peers are requesting this piece?
+     * @since 0.8.3
+     */
+    public int getRequestCount() {
+        return this.requests.size();
+    } 
     
     /** @return default 0 @since 0.8.1 */
     public int getPriority() { return this.priority; }