1 files changed, 150 insertions, 0 deletions
diff --git a/src/main/java/com/btr/proxy/selector/misc/ProxyListFallbackSelector.java b/src/main/java/com/btr/proxy/selector/misc/ProxyListFallbackSelector.java
new file mode 100644
index 0000000..41859ec
--- /dev/null
+++ b/src/main/java/com/btr/proxy/selector/misc/ProxyListFallbackSelector.java
@@ -0,0 +1,150 @@
+package com.btr.proxy.selector.misc;
+
+import java.io.IOException;
+import java.net.Proxy;
+import java.net.ProxySelector;
+import java.net.SocketAddress;
+import java.net.URI;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map.Entry;
+import java.util.concurrent.ConcurrentHashMap;
+
+/*****************************************************************************
+ * Implements a fallback selector to warp it around an existing ProxySelector.
+ * This will remove proxies from a list of proxies and implement an automatic
+ * retry mechanism.
+ *  
+ * @author Bernd Rosstauscher (proxyvole@rosstauscher.de) Copyright 2011
+ ****************************************************************************/
+
+public class ProxyListFallbackSelector extends ProxySelector {
+
+	// Retry a unresponsive proxy after 10 minutes per default.
+	private static final int DEFAULT_RETRY_DELAY = 1000*60*10;
+	
+	private ProxySelector delegate;
+	private ConcurrentHashMap<SocketAddress, Long> failedDelayCache;
+	private long retryAfterMs; 
+	
+	/*************************************************************************
+	 * Constructor
+	 * @param delegate the delegate to use.
+	 ************************************************************************/
+	
+	public ProxyListFallbackSelector(ProxySelector delegate) {
+		this(DEFAULT_RETRY_DELAY, delegate);
+	}
+	
+	/*************************************************************************
+	 * Constructor
+	 * @param retryAfterMs the "retry delay" as amount of milliseconds. 
+	 * @param delegate the delegate to use.
+	 ************************************************************************/
+	
+	public ProxyListFallbackSelector(long retryAfterMs, ProxySelector delegate) {
+		super();
+		this.failedDelayCache = new ConcurrentHashMap<SocketAddress, Long>();
+		this.delegate = delegate;
+		this.retryAfterMs = retryAfterMs;
+	}
+	
+	/*************************************************************************
+	 * connectFailed
+	 * @see java.net.ProxySelector#connectFailed(java.net.URI, java.net.SocketAddress, java.io.IOException)
+	 ************************************************************************/
+
+	@Override
+	public void connectFailed(URI uri, SocketAddress sa, IOException ioe) {
+		this.failedDelayCache.put(sa, System.currentTimeMillis());
+	}
+
+	/*************************************************************************
+	 * select
+	 * @see java.net.ProxySelector#select(java.net.URI)
+	 ************************************************************************/
+
+	@Override
+	public List<Proxy> select(URI uri) {
+		cleanupCache();
+		List<Proxy> proxyList = this.delegate.select(uri);
+		List<Proxy> result = filterUnresponsiveProxiesFromList(proxyList);
+		return result;
+	}
+
+	/*************************************************************************
+	 * Cleanup the entries from the cache that are no longer unresponsive.
+	 ************************************************************************/
+	
+	private void cleanupCache() {
+		Iterator<Entry<SocketAddress, Long>> it 
+					= this.failedDelayCache.entrySet().iterator();
+		while (it.hasNext()) {
+			Entry<SocketAddress, Long> e = it.next();
+			Long lastFailTime = e.getValue();
+			if (retryDelayHasPassedBy(lastFailTime)) {
+				it.remove();
+			}
+		}
+	}
+
+	/*************************************************************************
+	 * @param proxyList
+	 * @return
+	 ************************************************************************/
+	
+	private List<Proxy> filterUnresponsiveProxiesFromList(List<Proxy> proxyList) {
+		if (this.failedDelayCache.isEmpty()) {
+			return proxyList;
+		}
+		List<Proxy> result = new ArrayList<Proxy>(proxyList.size());
+		for (Proxy proxy : proxyList) {
+			if (isDirect(proxy) || isNotUnresponsive(proxy)) {
+				result.add(proxy);
+			}
+		}
+		return result;
+	}
+
+	/*************************************************************************
+	 * @param proxy
+	 * @return
+	 ************************************************************************/
+	
+	private boolean isDirect(Proxy proxy) {
+		return Proxy.NO_PROXY.equals(proxy);
+	}
+
+	/*************************************************************************
+	 * @param proxy
+	 * @return
+	 ************************************************************************/
+	
+	private boolean isNotUnresponsive(Proxy proxy) {
+		Long lastFailTime = this.failedDelayCache.get(proxy.address());
+		return retryDelayHasPassedBy(lastFailTime);
+	}
+
+	/*************************************************************************
+	 * @param lastFailTime
+	 * @return
+	 ************************************************************************/
+	
+	private boolean retryDelayHasPassedBy(Long lastFailTime) {
+		return lastFailTime == null 
+				|| lastFailTime + this.retryAfterMs < System.currentTimeMillis();
+	}
+
+	/*************************************************************************
+	 * Only used for unit testing not part of the public API.
+	 * @param retryAfterMs The retryAfterMs to set.
+	 ************************************************************************/
+	
+	final void setRetryAfterMs(long retryAfterMs) {
+		this.retryAfterMs = retryAfterMs;
+	}
+	
+	
+
+}