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Apache Jena Fuseki server Kafka connector
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.kafka.clients;
import org.apache.kafka.common.Node;
import org.apache.kafka.common.errors.AuthenticationException;
import org.apache.kafka.common.errors.DisconnectException;
import org.apache.kafka.common.utils.Time;
import java.io.IOException;
import java.util.List;
/**
* Provides additional utilities for {@link NetworkClient} (e.g. to implement blocking behaviour).
*/
public final class NetworkClientUtils {
private NetworkClientUtils() {}
/**
* Checks whether the node is currently connected, first calling `client.poll` to ensure that any pending
* disconnects have been processed.
*
* This method can be used to check the status of a connection prior to calling the blocking version to be able
* to tell whether the latter completed a new connection.
*/
public static boolean isReady(KafkaClient client, Node node, long currentTime) {
client.poll(0, currentTime);
return client.isReady(node, currentTime);
}
/**
* Invokes `client.poll` to discard pending disconnects, followed by `client.ready` and 0 or more `client.poll`
* invocations until the connection to `node` is ready, the timeoutMs expires or the connection fails.
*
* It returns `true` if the call completes normally or `false` if the timeoutMs expires. If the connection fails,
* an `IOException` is thrown instead. Note that if the `NetworkClient` has been configured with a positive
* connection timeoutMs, it is possible for this method to raise an `IOException` for a previous connection which
* has recently disconnected. If authentication to the node fails, an `AuthenticationException` is thrown.
*
* This method is useful for implementing blocking behaviour on top of the non-blocking `NetworkClient`, use it with
* care.
*/
public static boolean awaitReady(KafkaClient client, Node node, Time time, long timeoutMs) throws IOException {
if (timeoutMs < 0) {
throw new IllegalArgumentException("Timeout needs to be greater than 0");
}
long startTime = time.milliseconds();
if (isReady(client, node, startTime) || client.ready(node, startTime))
return true;
long attemptStartTime = time.milliseconds();
while (!client.isReady(node, attemptStartTime) && attemptStartTime - startTime < timeoutMs) {
if (client.connectionFailed(node)) {
throw new IOException("Connection to " + node + " failed.");
}
long pollTimeout = timeoutMs - (attemptStartTime - startTime); // initialize in this order to avoid overflow
client.poll(pollTimeout, attemptStartTime);
if (client.authenticationException(node) != null)
throw client.authenticationException(node);
attemptStartTime = time.milliseconds();
}
return client.isReady(node, attemptStartTime);
}
/**
* Invokes `client.send` followed by 1 or more `client.poll` invocations until a response is received or a
* disconnection happens (which can happen for a number of reasons including a request timeout).
*
* In case of a disconnection, an `IOException` is thrown.
* If shutdown is initiated on the client during this method, an IOException is thrown.
*
* This method is useful for implementing blocking behaviour on top of the non-blocking `NetworkClient`, use it with
* care.
*/
public static ClientResponse sendAndReceive(KafkaClient client, ClientRequest request, Time time) throws IOException {
try {
client.send(request, time.milliseconds());
while (client.active()) {
List responses = client.poll(Long.MAX_VALUE, time.milliseconds());
for (ClientResponse response : responses) {
if (response.requestHeader().correlationId() == request.correlationId()) {
if (response.wasDisconnected()) {
throw new IOException("Connection to " + response.destination() + " was disconnected before the response was read");
}
if (response.versionMismatch() != null) {
throw response.versionMismatch();
}
return response;
}
}
}
throw new IOException("Client was shutdown before response was read");
} catch (DisconnectException e) {
if (client.active())
throw e;
else
throw new IOException("Client was shutdown before response was read");
}
}
/**
* Check if the code is disconnected and unavailable for immediate reconnection (i.e. if it is in
* reconnect backoff window following the disconnect).
*/
public static boolean isUnavailable(KafkaClient client, Node node, Time time) {
return client.connectionFailed(node) && client.connectionDelay(node, time.milliseconds()) > 0;
}
/**
* Check for an authentication error on a given node and raise the exception if there is one.
*/
public static void maybeThrowAuthFailure(KafkaClient client, Node node) {
AuthenticationException exception = client.authenticationException(node);
if (exception != null)
throw exception;
}
/**
* Initiate a connection if currently possible. This is only really useful for resetting the
* failed status of a socket.
*/
public static void tryConnect(KafkaClient client, Node node, Time time) {
client.ready(node, time.milliseconds());
}
}