suppport multiple preferred leader

Signed-off-by: zhangyang21 <[email protected]>
openmessaging · Sep 29, 2021 · 28309cd · 28309cd
1 parent 9ea565e
commit 28309cd
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Showing 3 changed files with 54 additions and 14 deletions.
diff --git a/src/main/java/io/openmessaging/storage/dledger/DLedgerConfig.java b/src/main/java/io/openmessaging/storage/dledger/DLedgerConfig.java
@@ -80,7 +80,7 @@ public class DLedgerConfig {
     private boolean enablePushToFollower = true;
 
     @Parameter(names = {"--preferred-leader-id"}, description = "Preferred LeaderId")
-    private String preferredLeaderId;
+    private String preferredLeaderIds;
     private long maxLeadershipTransferWaitIndex = 1000;
     private int minTakeLeadershipVoteIntervalMs =  30;
     private int maxTakeLeadershipVoteIntervalMs =  100;
@@ -341,12 +341,22 @@ public void setCheckPointInterval(long checkPointInterval) {
         this.checkPointInterval = checkPointInterval;
     }
 
+    @Deprecated
     public String getPreferredLeaderId() {
-        return preferredLeaderId;
+        return preferredLeaderIds;
     }
 
+    @Deprecated
     public void setPreferredLeaderId(String preferredLeaderId) {
-        this.preferredLeaderId = preferredLeaderId;
+        this.preferredLeaderIds = preferredLeaderId;
+    }
+
+    public String getPreferredLeaderIds() {
+        return preferredLeaderIds;
+    }
+
+    public void setPreferredLeaderIds(String preferredLeaderIds) {
+        this.preferredLeaderIds = preferredLeaderIds;
     }
 
     public long getMaxLeadershipTransferWaitIndex() {

diff --git a/src/main/java/io/openmessaging/storage/dledger/DLedgerLeaderElector.java b/src/main/java/io/openmessaging/storage/dledger/DLedgerLeaderElector.java
@@ -27,6 +27,7 @@
 import io.openmessaging.storage.dledger.utils.DLedgerUtils;
 import java.sql.Timestamp;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Random;
 import java.util.concurrent.CompletableFuture;
@@ -372,8 +373,11 @@ private List<CompletableFuture<VoteResponse>> voteForQuorumResponses(long term,
     }
 
     private boolean isTakingLeadership() {
-        return memberState.getSelfId().equals(dLedgerConfig.getPreferredLeaderId())
-            || memberState.getTermToTakeLeadership() == memberState.currTerm();
+        if (dLedgerConfig.getPreferredLeaderIds() != null && memberState.getTermToTakeLeadership() == memberState.currTerm()) {
+            List<String> preferredLeaderIds = Arrays.asList(dLedgerConfig.getPreferredLeaderIds().split(";"));
+            return preferredLeaderIds.contains(memberState.getSelfId());
+        }
+        return false;
     }
 
     private long getNextTimeToRequestVote() {

diff --git a/src/main/java/io/openmessaging/storage/dledger/DLedgerServer.java b/src/main/java/io/openmessaging/storage/dledger/DLedgerServer.java
@@ -44,8 +44,11 @@
 import io.openmessaging.storage.dledger.utils.PreConditions;
 
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.Iterator;
+import java.util.List;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
@@ -313,32 +316,55 @@ private void checkPreferredLeader() {
         if (!memberState.isLeader()) {
             return;
         }
-        String preferredLeaderId = dLedgerConfig.getPreferredLeaderId();
-        if (preferredLeaderId == null || preferredLeaderId.equals(dLedgerConfig.getSelfId())) {
+
+        if (dLedgerConfig.getPreferredLeaderIds() == null) {
             return;
         }
 
-        if (!memberState.isPeerMember(preferredLeaderId)) {
-            logger.warn("preferredLeaderId = {} is not a peer member", preferredLeaderId);
+        if (memberState.getTransferee() != null) {
             return;
         }
 
-        if (memberState.getTransferee() != null) {
+        List<String> preferredLeaderIds = new ArrayList<>(Arrays.asList(dLedgerConfig.getPreferredLeaderIds().split(";")));
+        if (preferredLeaderIds.contains(dLedgerConfig.getSelfId())) {
             return;
         }
 
-        if (!memberState.getPeersLiveTable().containsKey(preferredLeaderId) ||
-            memberState.getPeersLiveTable().get(preferredLeaderId) == Boolean.FALSE) {
-            logger.warn("preferredLeaderId = {} is not online", preferredLeaderId);
+        Iterator<String> it = preferredLeaderIds.iterator();
+        while (it.hasNext()) {
+            String preferredLeaderId = it.next();
+            if (!memberState.isPeerMember(preferredLeaderId)) {
+                it.remove();
+                logger.warn("preferredLeaderId = {} is not a peer member", preferredLeaderId);
+                continue;
+            }
+
+            if (!memberState.getPeersLiveTable().containsKey(preferredLeaderId) ||
+                memberState.getPeersLiveTable().get(preferredLeaderId) == Boolean.FALSE.booleanValue()) {
+                it.remove();
+                logger.warn("preferredLeaderId = {} is not online", preferredLeaderId);
+                continue;
+            }
+
+            long fallBehind = dLedgerStore.getLedgerEndIndex() - dLedgerEntryPusher.getPeerWaterMark(memberState.currTerm(), preferredLeaderId);
+            if (fallBehind >= dLedgerConfig.getMaxLeadershipTransferWaitIndex()) {
+                logger.warn("preferredLeaderId = {} transferee fall behind index : {}", preferredLeaderId, fallBehind);
+                continue;
+            }
+        }
+
+        if (preferredLeaderIds.size() == 0) {
             return;
         }
 
+        String preferredLeaderId = preferredLeaderIds.get(0);
+
         long fallBehind = dLedgerStore.getLedgerEndIndex() - dLedgerEntryPusher.getPeerWaterMark(memberState.currTerm(), preferredLeaderId);
         logger.info("transferee fall behind index : {}", fallBehind);
         if (fallBehind < dLedgerConfig.getMaxLeadershipTransferWaitIndex()) {
             LeadershipTransferRequest request = new LeadershipTransferRequest();
             request.setTerm(memberState.currTerm());
-            request.setTransfereeId(dLedgerConfig.getPreferredLeaderId());
+            request.setTransfereeId(preferredLeaderId);
 
             try {
                 long startTransferTime = System.currentTimeMillis();