Java tutorial
/* * Copyright 2015 JBoss Inc * * Licensed 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 io.apiman.gateway.engine.jdbc; import io.apiman.gateway.engine.async.IAsyncResult; import io.apiman.gateway.engine.async.IAsyncResultHandler; import io.apiman.gateway.engine.beans.Api; import io.apiman.gateway.engine.beans.Client; import java.sql.Connection; import java.sql.ResultSet; import java.sql.SQLException; import java.util.Map; import org.apache.commons.dbutils.DbUtils; import org.apache.commons.dbutils.QueryRunner; import org.apache.commons.dbutils.ResultSetHandler; /** * Extends the {@link JdbcRegistry} to provide multi-node caching. This caching solution * will work in a cluster, although it is a rather naive implementation. The approach * taken is that whenever the data in the DB is modified, a "last modified" record is * inserted/updated. The registry utilizes a thread to periodically poll the DB to * check if this data has been changed. If the data *has* been changed, then the cache * is invalidated. * * @author eric.wittmann@redhat.com */ public class PollCachingJdbcRegistry extends CachingJdbcRegistry { private static final int DEFAULT_POLLING_INTERVAL = 10; private static final int DEFAULT_STARTUP_DELAY = 30; private int pollIntervalMillis; private int startupDelayMillis; private boolean polling = false; private long dataVersion = -1; /** * Constructor. */ public PollCachingJdbcRegistry(Map<String, String> config) { super(config); String intervalVal = config.get("cache-polling-interval"); //$NON-NLS-1$ String startupVal = config.get("cache-polling-startup-delay"); //$NON-NLS-1$ if (intervalVal != null) { pollIntervalMillis = new Integer(intervalVal) * 1000; } else { pollIntervalMillis = DEFAULT_POLLING_INTERVAL * 1000; } if (startupVal != null) { startupDelayMillis = new Integer(startupVal) * 1000; } else { startupDelayMillis = DEFAULT_STARTUP_DELAY * 1000; } startCacheInvalidator(); } /** * @see io.apiman.gateway.engine.CachingJdbcRegistry.CachingESRegistry#publishApi(io.apiman.gateway.engine.beans.Api, io.apiman.gateway.engine.async.IAsyncResultHandler) */ @Override public void publishApi(Api api, final IAsyncResultHandler<Void> handler) { super.publishApi(api, new IAsyncResultHandler<Void>() { @Override public void handle(IAsyncResult<Void> result) { if (result.isSuccess()) { updateDataVersion(); } handler.handle(result); } }); } /** * @see io.apiman.gateway.engine.CachingJdbcRegistry.CachingESRegistry#retireApi(io.apiman.gateway.engine.beans.Api, io.apiman.gateway.engine.async.IAsyncResultHandler) */ @Override public void retireApi(Api api, final IAsyncResultHandler<Void> handler) { super.retireApi(api, new IAsyncResultHandler<Void>() { @Override public void handle(IAsyncResult<Void> result) { if (result.isSuccess()) { updateDataVersion(); } handler.handle(result); } }); } /** * @see io.apiman.gateway.engine.CachingJdbcRegistry.CachingESRegistry#registerClient(io.apiman.gateway.engine.beans.Client, io.apiman.gateway.engine.async.IAsyncResultHandler) */ @Override public void registerClient(Client client, final IAsyncResultHandler<Void> handler) { super.registerClient(client, new IAsyncResultHandler<Void>() { /** * @see io.apiman.gateway.engine.async.IAsyncHandler#handle(java.lang.Object) */ @Override public void handle(IAsyncResult<Void> result) { if (result.isSuccess()) { updateDataVersion(); } handler.handle(result); } }); } /** * @see io.apiman.gateway.engine.CachingJdbcRegistry.CachingESRegistry#unregisterClient(io.apiman.gateway.engine.beans.Client, io.apiman.gateway.engine.async.IAsyncResultHandler) */ @Override public void unregisterClient(Client client, final IAsyncResultHandler<Void> handler) { super.unregisterClient(client, new IAsyncResultHandler<Void>() { @Override public void handle(IAsyncResult<Void> result) { if (result.isSuccess()) { updateDataVersion(); } handler.handle(result); } }); } /** * Stores a "dataversion" record in the ES store. There is only a single one of these. The * return value of the add will include the version number of the entity. This version * number is what we use to determine whether our cache is stale. */ protected void updateDataVersion() { Connection conn = null; try { long newVersion = System.currentTimeMillis(); conn = ds.getConnection(); conn.setAutoCommit(false); QueryRunner run = new QueryRunner(); run.update(conn, "DELETE FROM gw_dataversion"); //$NON-NLS-1$ run.update(conn, "INSERT INTO gw_dataversion (version) VALUES (?)", //$NON-NLS-1$ newVersion); DbUtils.commitAndClose(conn); dataVersion = newVersion; } catch (SQLException e) { dataVersion = -1; } } /** * Starts up a thread that polls the ES store for updates. */ protected void startCacheInvalidator() { polling = true; Thread thread = new Thread(new Runnable() { @Override public void run() { // Wait on startup before starting to poll. try { Thread.sleep(startupDelayMillis); } catch (InterruptedException e1) { e1.printStackTrace(); } while (polling) { try { Thread.sleep(pollIntervalMillis); } catch (Exception e) { e.printStackTrace(); } checkCacheVersion(); } } }, "JdbcRegistryCacheInvalidator"); //$NON-NLS-1$ thread.setDaemon(true); thread.start(); } /** * Stop polling. */ public void stop() { polling = false; } /** * Checks the ES store to see if the 'dataVersion' entry has been updated with a newer * version #. If it has, then we need to invalidate our cache. */ protected void checkCacheVersion() { // Be very aggressive in invalidating the cache. boolean invalidate = true; QueryRunner run = new QueryRunner(ds); try { long latestVersion = run.query("SELECT version FROM gw_dataversion", Handlers.LONG_HANDLER); //$NON-NLS-1$ if (latestVersion > -1 && dataVersion > -1 && latestVersion == dataVersion) { invalidate = false; } else { dataVersion = latestVersion; } } catch (SQLException e) { // TODO need to use the gateway logger to log this! e.printStackTrace(); } if (invalidate) { invalidateCache(); } } private static final class Handlers { public static final ResultSetHandler<Long> LONG_HANDLER = (ResultSet rs) -> { if (!rs.next()) { return -1L; } return rs.getLong(1); }; } }