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Unified Java client for ClickHouse
package com.clickhouse.client;
import java.io.IOException;
import java.io.Serializable;
import java.util.Collection;
import java.util.Map;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.function.Function;
import com.clickhouse.client.config.ClickHouseClientOption;
import com.clickhouse.client.config.ClickHouseHealthCheckMethod;
import com.clickhouse.config.ClickHouseOption;
import com.clickhouse.data.ClickHouseChecker;
import com.clickhouse.data.ClickHouseUtils;
import com.clickhouse.logging.Logger;
import com.clickhouse.logging.LoggerFactory;
/**
* Base class for implementing a thread-safe ClickHouse client. It uses
* {@link ReadWriteLock} to manage access to underlying connection.
*/
public abstract class AbstractClient implements ClickHouseClient {
private static final Logger log = LoggerFactory.getLogger(AbstractClient.class);
private boolean initialized = false;
private ExecutorService executor = null;
private ClickHouseConfig config = null;
private ClickHouseNode server = null;
private T connection = null;
protected final ReadWriteLock lock = new ReentrantReadWriteLock();
private void ensureInitialized() {
if (!initialized) {
throw new IllegalStateException("Please initialize the client first");
}
}
// just for testing purpose
final boolean isInitialized() {
return initialized;
}
protected abstract boolean checkHealth(ClickHouseNode server, int timeout);
protected CompletableFuture failedResponse(Throwable ex) {
CompletableFuture future = new CompletableFuture<>();
future.completeExceptionally(ex);
return future;
}
/**
* Gets executor service for this client.
*
* @return executor service
* @throws IllegalStateException when the client is either closed or not
* initialized
*/
protected final ExecutorService getExecutor() {
lock.readLock().lock();
try {
ensureInitialized();
return executor;
} finally {
lock.readLock().unlock();
}
}
/**
* Gets list of supported protocols.
*
* @return non-null list of supported protocols
*/
protected abstract Collection getSupportedProtocols();
/**
* Gets current server.
*
* @return current server
* @throws IllegalStateException when the client is either closed or not
* initialized
*/
protected final ClickHouseNode getServer() {
lock.readLock().lock();
try {
ensureInitialized();
return server;
} finally {
lock.readLock().unlock();
}
}
/**
* Checks if the underlying connection can be reused. In general, new connection
* will be created when {@code connection} is {@code null} or
* {@code requestServer} is different from {@code currentServer} - the existing
* connection will be closed in the later case.
*
* @param connection existing connection which may or may not be null
* @param requestServer non-null requested server, returned from previous call
* of {@code request.getServer()}
* @param currentServer current server, same as {@code getServer()}
* @param request non-null request
* @return true if the connection should NOT be changed(e.g. requestServer is
* same as currentServer); false otherwise
*/
protected boolean checkConnection(T connection, ClickHouseNode requestServer, ClickHouseNode currentServer,
ClickHouseRequest request) {
return connection != null && requestServer.equals(currentServer);
}
/**
* Creates a new connection and optionally close existing connection. This
* method will be called from {@link #getConnection(ClickHouseRequest)} as
* needed.
*
* @param connection existing connection which may or may not be null
* @param server non-null requested server, returned from previous call of
* {@code request.getServer()}
* @param request non-null request
* @return new connection
* @throws CompletionException when error occured
*/
protected abstract T newConnection(T connection, ClickHouseNode server, ClickHouseRequest request);
/**
* Closes a connection. This method will be called from {@link #close()}.
*
* @param connection connection to close
* @param force whether force to close the connection or not
*/
protected abstract void closeConnection(T connection, boolean force);
/**
* Gets arguments required for async execution. This method will be executed in
* current thread right before {@link #sendAsync(ClickHouseRequest, Object...)}.
*
* @param sealedRequest non-null sealed request
* @return arguments required for async execution
*/
protected Object[] getAsyncExecArguments(ClickHouseRequest sealedRequest) {
return new Object[0];
}
/**
* Sends the request to server in a separate thread.
*
* @param sealedRequest non-null sealed request
* @param args arguments required for sending out the request
* @return non-null response
* @throws ClickHouseException when error server failed to process the request
* @throws IOException when error occurred sending the request
*/
protected ClickHouseResponse sendAsync(ClickHouseRequest sealedRequest, Object... args)
throws ClickHouseException, IOException {
return send(sealedRequest);
}
/**
* Sends the request to server in a current thread.
*
* @param sealedRequest non-null sealed request
* @return non-null response
* @throws ClickHouseException when error server failed to process the request
* @throws IOException when error occurred sending the request
*/
protected abstract ClickHouseResponse send(ClickHouseRequest sealedRequest)
throws ClickHouseException, IOException;
/**
* Gets a connection according to the given request.
*
* @param request non-null request
* @return non-null connection
* @throws CompletionException when error occured
*/
protected final T getConnection(ClickHouseRequest request) {
ClickHouseNode newNode = ClickHouseChecker.nonNull(request, "request").getServer();
lock.readLock().lock();
try {
ensureInitialized();
if (checkConnection(connection, newNode, server, request)) {
return connection;
}
} finally {
lock.readLock().unlock();
}
lock.writeLock().lock();
try {
server = newNode;
log.debug("Connecting to: %s", newNode);
connection = newConnection(connection, server, request);
log.debug("Connection established: %s", connection);
return connection;
} finally {
lock.writeLock().unlock();
}
}
@Override
public boolean accept(ClickHouseProtocol protocol) {
for (ClickHouseProtocol p : getSupportedProtocols()) {
if (p == protocol) {
return true;
}
}
return ClickHouseClient.super.accept(protocol);
}
@Override
public ClickHouseRequest read(Function nodeFunc,
Map options) {
lock.readLock().lock();
try {
ensureInitialized();
return ClickHouseClient.super.read(nodeFunc, options);
} finally {
lock.readLock().unlock();
}
}
@Override
public final ClickHouseConfig getConfig() {
lock.readLock().lock();
try {
ensureInitialized();
return config;
} finally {
lock.readLock().unlock();
}
}
@Override
public void init(ClickHouseConfig config) {
ClickHouseChecker.nonNull(config, ClickHouseConfig.TYPE_NAME);
lock.writeLock().lock();
try {
Collection protocols = getSupportedProtocols();
this.config = new ClickHouseConfig(config.getAllOptions(), config.getDefaultCredentials(),
config.getNodeSelector() != ClickHouseNodeSelector.EMPTY || protocols.isEmpty()
? config.getNodeSelector()
: ClickHouseNodeSelector.of(protocols, null),
config.getMetricRegistry().orElse(null));
if (this.executor == null) { // only initialize once
int threads = config.getMaxThreadsPerClient();
this.executor = threads < 1 ? ClickHouseClient.getExecutorService()
: ClickHouseUtils.newThreadPool(this, threads, config.getMaxQueuedRequests());
}
initialized = true;
} finally {
lock.writeLock().unlock();
}
}
@Override
public CompletableFuture execute(ClickHouseRequest request) {
// sealedRequest is an immutable copy of the original request
final ClickHouseRequest sealedRequest = request.seal();
if (sealedRequest.getConfig().isAsync()) {
final Object[] args = getAsyncExecArguments(sealedRequest);
return CompletableFuture.supplyAsync(() -> {
try {
return sendAsync(sealedRequest, args);
} catch (ClickHouseException | IOException e) {
throw new CompletionException(ClickHouseException.of(e, sealedRequest.getServer()));
}
}, getExecutor());
} else {
try {
return CompletableFuture.completedFuture(send(sealedRequest));
} catch (ClickHouseException | IOException e) {
return failedResponse(ClickHouseException.of(e, sealedRequest.getServer()));
}
}
}
@Override
public final void close() {
lock.readLock().lock();
try {
if (!initialized) {
return;
}
} finally {
lock.readLock().unlock();
}
lock.writeLock().lock();
try {
server = null;
if (connection != null) {
closeConnection(connection, false);
connection = null;
}
// avoid shutting down shared thread pool
if (executor != null && config.getMaxThreadsPerClient() > 0 && !executor.isTerminated()) {
executor.shutdown();
}
executor = null;
} catch (Exception e) {
log.warn("Exception occurred when closing client", e);
} finally {
initialized = false;
try {
if (connection != null) {
closeConnection(connection, true);
}
if (executor != null && config.getMaxThreadsPerClient() > 0) {
executor.shutdownNow();
}
} finally {
executor = null;
connection = null;
lock.writeLock().unlock();
}
}
}
@Override
public boolean ping(ClickHouseNode server, int timeout) {
if (server == null) {
return false;
} else if (server.config.getOption(ClickHouseClientOption.HEALTH_CHECK_METHOD,
getConfig()) != ClickHouseHealthCheckMethod.PING) {
return ClickHouseClient.super.ping(server, timeout);
}
if (server.getProtocol() == ClickHouseProtocol.ANY) {
server = ClickHouseNode.probe(server.getHost(), server.getPort(), timeout);
}
return checkHealth(server, timeout);
}
}