rudimentary speed gauge

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

@@ -20,6 +20,8 @@ import java.security.NoSuchAlgorithmException
 @Log
 class DownloadSession {
     
+    private static int SAMPLES = 10
+    
     private final String meB64
     private final Pieces pieces
     private final InfoHash infoHash
@@ -29,6 +31,9 @@ class DownloadSession {
     private final long fileLength
     private final MessageDigest digest
     
+    private final ArrayDeque<Long> timestamps = new ArrayDeque<>(SAMPLES)
+    private final ArrayDeque<Integer> reads = new ArrayDeque<>(SAMPLES)
+    
     private ByteBuffer mapped
     
     DownloadSession(String meB64, Pieces pieces, InfoHash infoHash, Endpoint endpoint, File file, 
@@ -122,6 +127,13 @@ class DownloadSession {
                     throw new IOException()
                 synchronized(this) {
                     mapped.put(tmp, 0, read)
+                    
+                    if (timestamps.size() == SAMPLES) {
+                        timestamps.removeFirst()
+                        reads.removeFirst()
+                    }
+                    timestamps.addLast(System.currentTimeMillis())
+                    reads.addLast(read)
                 }
             }
             
@@ -144,4 +156,13 @@ class DownloadSession {
             return 0
         mapped.position()
     }
+    
+    synchronized int speed() {
+        if (timestamps.size() < SAMPLES)
+            return 0
+        long interval = timestamps.last - timestamps.first
+        int totalRead = 0
+        reads.each { totalRead += it }
+        (int)(totalRead * 1000.0 / interval)
+    }
 }

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

@@ -109,6 +109,12 @@ public class Downloader {
         currentSession.positionInPiece()
     }
     
+    public int speed() {
+        if (currentSession == null)
+            return 0
+        currentSession.speed()
+    }
+    
     public DownloadState getCurrentState() {
         currentState
     }

gui/griffon-app/views/com/muwire/gui/MainFrameView.groovy

@@ -109,6 +109,7 @@ class MainFrameView {
                                                 int pieceSize = row.downloader.pieceSize // TODO: fix for last piece
                                                 "$position/$pieceSize bytes"
                                             })
+                                            closureColumn(header: "Speed (bytes/second)", type:Integer, read :{row -> row.downloader.speed()})
                                         }
                                     }
                                 }