From 1a2497d1a6ab3c577faf81ca692c218bbdc33fa6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kjetil=20=C3=98rbekk?= <kjetil.orbekk@gmail.com>
Date: Thu, 15 Mar 2012 13:18:25 +0100
Subject: Add tools for concurrent master proposal.

---
 .../main/java/com/orbekk/paxos/MasterProposer.java | 45 ++++++++++++++++++----
 1 file changed, 37 insertions(+), 8 deletions(-)

(limited to 'same/src/main/java')

diff --git a/same/src/main/java/com/orbekk/paxos/MasterProposer.java b/same/src/main/java/com/orbekk/paxos/MasterProposer.java
index 5eb7ebb..8469cf4 100644
--- a/same/src/main/java/com/orbekk/paxos/MasterProposer.java
+++ b/same/src/main/java/com/orbekk/paxos/MasterProposer.java
@@ -1,18 +1,24 @@
 package com.orbekk.paxos;
 
-import com.orbekk.same.ConnectionManager;
 import static com.orbekk.same.StackTraceUtil.throwableToString;
+
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.Callable;
+import java.util.concurrent.Future;
+import java.util.concurrent.FutureTask;
+
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class MasterProposer {
+import com.orbekk.same.ConnectionManager;
+
+public class MasterProposer extends Thread {
     private Logger logger = LoggerFactory.getLogger(getClass());
     private String myUrl;
     private List<String> paxosUrls = new ArrayList<String>();
     private ConnectionManager connections;
-
+    
     public MasterProposer(String clientUrl, List<String> paxosUrls,
             ConnectionManager connections) {
         this.myUrl = clientUrl;
@@ -68,7 +74,7 @@ public class MasterProposer {
         }
     }
 
-    public boolean propose(int proposalNumber) {
+    boolean propose(int proposalNumber) {
         int result = internalPropose(proposalNumber);
         if (result == proposalNumber) {
             result = internalAcceptRequest(proposalNumber);
@@ -80,11 +86,16 @@ public class MasterProposer {
         }
     }
 
-    public boolean proposeRetry(int proposalNumber) {
+    boolean proposeRetry(int proposalNumber) {
+        return proposeRetry(proposalNumber, null) != null;
+    }
+    
+    Integer proposeRetry(int proposalNumber, Runnable retryAction) {
+        assert proposalNumber >= 0;
         int nextProposal = proposalNumber;
-        int result = 0;
+        int result = -1;
 
-        while (result != nextProposal) {
+        while (!Thread.interrupted() && result != nextProposal) {
             result = internalPropose(nextProposal);
             if (result == nextProposal) {
                 result = internalAcceptRequest(nextProposal);
@@ -92,9 +103,27 @@ public class MasterProposer {
             logger.info("Proposed value {}, result {}", nextProposal, result);
             if (result < 0) {
                 nextProposal = -result + 1;
+                if (retryAction != null) {
+                    retryAction.run();
+                }
             }
         }
+        if (Thread.interrupted()) {
+            return null;
+        }
 
-        return true;
+        return result;
+    }
+    
+    public Future<Integer> startProposalTask(final int proposalNumber,
+            final Runnable retryAction) {
+        Callable<Integer> proposalCallable = new Callable<Integer>() {
+            @Override public Integer call() throws Exception {
+                return proposeRetry(proposalNumber, retryAction);
+            }
+        };
+        FutureTask<Integer> task = new FutureTask<Integer>(proposalCallable);
+        new Thread(task).start();
+        return task;
     }
 }
-- 
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