track last successful attempt. Only re-attempt hosts if they have ever been successful. Do not serialize hosts considered hopeless

core/src/main/groovy/com/muwire/core/hostcache/Host.groovy

@@ -10,6 +10,7 @@ class Host {
     private final int clearInterval
     int failures,successes
     long lastAttempt
+    long lastSuccessfulAttempt
 
     public Host(Destination destination, int clearInterval) {
         this.destination = destination
@@ -20,6 +21,7 @@ class Host {
         failures = 0
         successes++
         lastAttempt = System.currentTimeMillis()
+        lastSuccessfulAttempt = lastAttempt
     }
 
     synchronized void onFailure() {
@@ -41,6 +43,12 @@ class Host {
     }
 
     synchronized void canTryAgain() {
-        System.currentTimeMillis() - lastAttempt > (clearInterval * 60 * 1000)
+        lastSuccessfulAttempt > 0 && 
+            System.currentTimeMillis() - lastAttempt > (clearInterval * 60 * 1000)
+    }
+    
+    synchronized void isHopeless() {
+        isFailed() && 
+            System.currentTimeMillis() - lastSuccessfulAttempt > (clearInterval * 24 * 60 * 1000)
     }
 }

core/src/main/groovy/com/muwire/core/hostcache/HostCache.groovy

@@ -111,6 +111,8 @@ class HostCache extends Service {
                 host.successes = Integer.valueOf(String.valueOf(entry.successes))
                 if (entry.lastAttempt != null)
                     host.lastAttempt = entry.lastAttempt
+                if (entry.lastSuccessfulAttempt != null)
+                    host.lastSuccessfulAttempt = entry.lastSuccessfulAttempt
                 if (allowHost(host)) 
                     hosts.put(dest, host)
             }
@@ -140,12 +142,13 @@ class HostCache extends Service {
         storage.delete()
         storage.withPrintWriter { writer ->
             hosts.each { dest, host ->
-                if (allowHost(host)) {
+                if (allowHost(host) && !host.isHopeless()) {
                     def map = [:]
                     map.destination = dest.toBase64()
                     map.failures = host.failures
                     map.successes = host.successes
                     map.lastAttempt = host.lastAttempt
+                    map.lastSuccessfulAttempt = host.lastSuccessfulAttempt
                     def json = JsonOutput.toJson(map)
                     writer.println json
                 }