HBASE-19642 Fix locking for peer modification procedure

hbase-server/src/main/java/org/apache/hadoop/hbase/master/procedure/MasterProcedureScheduler.java

@@ -610,6 +610,20 @@ public class MasterProcedureScheduler extends AbstractProcedureScheduler {
     public boolean requireExclusiveLock(Procedure proc) {
       return requirePeerExclusiveLock((PeerProcedureInterface) proc);
     }
+
+    @Override
+    public boolean isAvailable() {
+      if (isEmpty()) {
+        return false;
+      }
+      if (getLockStatus().hasExclusiveLock()) {
+        // if we have an exclusive lock already taken
+        // only child of the lock owner can be executed
+        Procedure nextProc = peek();
+        return nextProc != null && getLockStatus().hasLockAccess(nextProc);
+      }
+      return true;
+    }
   }
 
   // ============================================================================

hbase-server/src/main/java/org/apache/hadoop/hbase/master/replication/ModifyPeerProcedure.java

@@ -46,6 +46,8 @@ public abstract class ModifyPeerProcedure
 
   protected String peerId;
 
+  private volatile boolean locked;
+
   // used to keep compatible with old client where we can only returns after updateStorage.
   protected ProcedurePrepareLatch latch;
 
@@ -145,16 +147,29 @@ public abstract class ModifyPeerProcedure
 
   @Override
   protected LockState acquireLock(MasterProcedureEnv env) {
-    return env.getProcedureScheduler().waitPeerExclusiveLock(this, peerId)
-      ? LockState.LOCK_EVENT_WAIT
-      : LockState.LOCK_ACQUIRED;
+    if (env.getProcedureScheduler().waitPeerExclusiveLock(this, peerId)) {
+      return  LockState.LOCK_EVENT_WAIT;
+    }
+    locked = true;
+    return LockState.LOCK_ACQUIRED;
   }
 
   @Override
   protected void releaseLock(MasterProcedureEnv env) {
+    locked = false;
     env.getProcedureScheduler().wakePeerExclusiveLock(this, peerId);
   }
 
+  @Override
+  protected boolean holdLock(MasterProcedureEnv env) {
+    return true;
+  }
+
+  @Override
+  protected boolean hasLock(MasterProcedureEnv env) {
+    return locked;
+  }
+
   @Override
   protected void rollbackState(MasterProcedureEnv env, PeerModificationState state)
       throws IOException, InterruptedException {