X-Git-Url: https://git.pterodactylus.net/?a=blobdiff_plain;f=src%2Fmain%2Fjava%2Fnet%2Fpterodactylus%2Fxdcc%2Fcore%2FConnectionBackoff.java;fp=src%2Fmain%2Fjava%2Fnet%2Fpterodactylus%2Fxdcc%2Fcore%2FConnectionBackoff.java;h=5ba44a6281b1e71f9182a4fec0b44dcb8295d99d;hb=9ec3cf37feeaa7a3daa8e21df2c7580597aacf0b;hp=0000000000000000000000000000000000000000;hpb=60eeb8cc8d2ccd56dfae68cea32012443bbe50a8;p=xudocci.git

diff --git a/src/main/java/net/pterodactylus/xdcc/core/ConnectionBackoff.java b/src/main/java/net/pterodactylus/xdcc/core/ConnectionBackoff.java
new file mode 100644
index 0000000..5ba44a6
--- /dev/null
+++ b/src/main/java/net/pterodactylus/xdcc/core/ConnectionBackoff.java
@@ -0,0 +1,105 @@
+package net.pterodactylus.xdcc.core;
+
+import java.time.Clock;
+import java.time.Instant;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+
+import net.pterodactylus.xdcc.data.Network;
+
+/**
+ * Manages backoff times for connections.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class ConnectionBackoff {
+
+	private static final long MILLIS_PER_SECOND = TimeUnit.MINUTES.toMillis(1);
+	private static final long MILLIS_PER_HOUR = TimeUnit.HOURS.toMillis(1);
+
+	private final Clock clock;
+	private final Map<Network, ConnectionFailureCounter> connectionFailures = new HashMap<>();
+
+	public ConnectionBackoff() {
+		this(Clock.systemDefaultZone());
+	}
+
+	public ConnectionBackoff(Clock clock) {
+		this.clock = clock;
+	}
+
+	public void connectionFailed(Network network) {
+		ConnectionFailureCounter connectionFailureCounter = getConnectionFailureCounter(network);
+		connectionFailureCounter.countFailure();
+	}
+
+	public void connectionSuccessful(Network network) {
+		ConnectionFailureCounter connectionFailureCounter = getConnectionFailureCounter(network);
+		connectionFailureCounter.reset();
+	}
+
+	public long getBackoff(Network network) {
+		ConnectionFailureCounter connectionFailureCounter = getConnectionFailureCounter(network);
+		if (!connectionFailureCounter.hasFailure()) {
+			return 0;
+		}
+		long delay = (long) (MILLIS_PER_SECOND *
+				Math.pow(1.2, connectionFailureCounter.getFailureCount() - 1));
+		return Math.min(MILLIS_PER_HOUR, Math.max(0,
+				(connectionFailureCounter.getLastFailureTime() + delay) - Instant.now(clock)
+						.toEpochMilli()));
+	}
+
+	private ConnectionFailureCounter getConnectionFailureCounter(Network network) {
+		ConnectionFailureCounter connectionFailureCounter;
+		synchronized (connectionFailures) {
+			if (!connectionFailures.containsKey(network)) {
+				connectionFailures.put(network, new ConnectionFailureCounter());
+			}
+			connectionFailureCounter = connectionFailures.get(network);
+		}
+		return connectionFailureCounter;
+	}
+
+	private class ConnectionFailureCounter {
+
+		private final Object lock = new Object();
+		private int count;
+		private long lastFailureTime;
+
+		public void reset() {
+			synchronized (lock) {
+				count = 0;
+				lastFailureTime = 0;
+			}
+		}
+
+		public void countFailure() {
+			synchronized (lock) {
+				count++;
+				lastFailureTime = Instant.now(clock).toEpochMilli();
+			}
+		}
+
+		public boolean hasFailure() {
+			synchronized (lock) {
+				return (count > 0);
+			}
+		}
+
+		public int getFailureCount() {
+			synchronized (lock) {
+				return count;
+			}
+		}
+
+		public long getLastFailureTime() {
+			synchronized (lock) {
+				return lastFailureTime;
+			}
+		}
+
+	}
+
+}