Github user afine commented on a diff in the pull request: https://github.com/apache/zookeeper/pull/476#discussion_r171972029 --- Diff: src/java/test/org/apache/zookeeper/server/quorum/QuorumPeerMainTest.java --- @@ -1012,4 +1012,113 @@ public void testFailedTxnAsPartOfQuorumLoss() throws Exception { Assert.assertNull("server " + i + " should not have /zk" + leader, servers.zk[i].exists("/zk" + leader, false)); } } + + /** + * Verify that a node without the leader in its view will not attempt to connect to the leader. + */ + @Test + public void testLeaderOutOfView() throws Exception { + ClientBase.setupTestEnv(); + + Layout layout = new PatternLayout("%d{ISO8601} [,yid:%X{myid}] - %5p [%t:%C{1}@%L] - %m%n"); + ByteArrayOutputStream os = new ByteArrayOutputStream(); + WriterAppender appender = new WriterAppender(layout, os); + appender.setThreshold(Level.DEBUG); + Logger qlogger = Logger.getLogger("org.apache.zookeeper.server.quorum"); + qlogger.addAppender(appender); + + try { + final int CLIENT_PORT_QP1 = PortAssignment.unique(); + final int CLIENT_PORT_QP2 = PortAssignment.unique(); + final int CLIENT_PORT_QP3 = PortAssignment.unique(); + + String quorumCfgIncomplete = getUniquePortCfgForId(1) + "\n" + getUniquePortCfgForId(2); + String quorumCfgComplete = quorumCfgIncomplete + "\n" + getUniquePortCfgForId(3); + + // Node 1 is started without the leader (3) in its config view + MainThread q1 = new MainThread(1, CLIENT_PORT_QP1, quorumCfgIncomplete); + MainThread q2 = new MainThread(2, CLIENT_PORT_QP2, quorumCfgComplete); + MainThread q3 = new MainThread(3, CLIENT_PORT_QP3, quorumCfgComplete); + + // Node 1 must be started first, before quorum is formed, to trigger the attempted invalid connection to 3 + q1.start(); + QuorumPeer quorumPeer1 = waitForQuorumPeer(q1, CONNECTION_TIMEOUT); + Assert.assertTrue(quorumPeer1.getPeerState() == QuorumPeer.ServerState.LOOKING); + + // Node 3 started second to avoid 1 and 2 forming a quorum before 3 starts up + q3.start(); + QuorumPeer quorumPeer3 = waitForQuorumPeer(q3, CONNECTION_TIMEOUT); + Assert.assertTrue(quorumPeer3.getPeerState() == QuorumPeer.ServerState.LOOKING); + + // Node 2 started last, kicks off leader election + q2.start(); + + // Nodes 2 and 3 now form quorum and fully start. 1 attempts to vote for 3, fails, returns to LOOKING state + Assert.assertTrue("waiting for server 2 to start", + ClientBase.waitForServerUp("127.0.0.1:" + CLIENT_PORT_QP2, CONNECTION_TIMEOUT)); + Assert.assertTrue("waiting for server 3 to start", + ClientBase.waitForServerUp("127.0.0.1:" + CLIENT_PORT_QP3, CONNECTION_TIMEOUT)); + + Assert.assertTrue(q1.getQuorumPeer().getPeerState() == QuorumPeer.ServerState.LOOKING); + Assert.assertTrue(q2.getQuorumPeer().getPeerState() == QuorumPeer.ServerState.FOLLOWING); + Assert.assertTrue(q3.getQuorumPeer().getPeerState() == QuorumPeer.ServerState.LEADING); + + q1.shutdown(); + q2.shutdown(); + q3.shutdown(); + + Assert.assertTrue("waiting for server 1 down", + ClientBase.waitForServerDown("127.0.0.1:" + CLIENT_PORT_QP1, + ClientBase.CONNECTION_TIMEOUT)); + Assert.assertTrue("waiting for server 2 down", + ClientBase.waitForServerDown("127.0.0.1:" + CLIENT_PORT_QP2, + ClientBase.CONNECTION_TIMEOUT)); + Assert.assertTrue("waiting for server 3 down", + ClientBase.waitForServerDown("127.0.0.1:" + CLIENT_PORT_QP3, + ClientBase.CONNECTION_TIMEOUT)); + + } finally { + qlogger.removeAppender(appender); + } + + // Verify that Node 1 never threw an exception + LineNumberReader r = new LineNumberReader(new StringReader(os.toString())); + String line; + boolean found = false; + Pattern p = Pattern.compile(".*java.lang.NullPointerException.*"); + while ((line = r.readLine()) != null) { + found = p.matcher(line).matches(); + if (found) { + break; + } + } + + Assert.assertFalse("Node should not attempt connection to out of view leader", found); + } + + private String getUniquePortCfgForId(int id) { + return String.format("server.%d=127.0.0.1:%d:%d", id, PortAssignment.unique(), PortAssignment.unique()); + } + + private QuorumPeer waitForQuorumPeer(MainThread mainThread, int timeout) { + long start = Time.currentElapsedTime(); + while (true) { + QuorumPeer quorumPeer = mainThread.getQuorumPeer(); + if (quorumPeer != null) { + return quorumPeer; + } + + if (Time.currentElapsedTime() > start + timeout) { + LOG.error("Timed out while waiting for QuorumPeer"); + break; + } + + try { + Thread.sleep(250); + } catch (InterruptedException e) { + // ignore + } + } + throw new NullPointerException(); --- End diff -- Can we use a better exception?
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