--- /dev/null 2015-10-08 07:26:10.000000000 -1000 +++ new/src/jdk.vm.ci/share/classes/jdk.vm.ci.service/src/jdk/vm/ci/service/Services.java 2015-10-08 07:26:10.000000000 -1000 @@ -0,0 +1,73 @@ +/* + * Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ +package jdk.vm.ci.service; + +import java.util.*; + +/** + * A mechanism for accessing service providers via JVMCI. + */ +public final class Services { + + private Services() { + } + + /** + * Gets an {@link Iterable} of the JVMCI providers available for a given service. + */ + public static Iterable load(Class service) { + return ServiceLoader.load(service); + } + + /** + * Gets the JVMCI provider for a given service for which at most one provider must be available. + * + * @param service the service whose provider is being requested + * @param required specifies if an {@link InternalError} should be thrown if no provider of + * {@code service} is available + */ + public static S loadSingle(Class service, boolean required) { + Iterable providers = ServiceLoader.load(service); + S singleProvider = null; + try { + for (Iterator it = providers.iterator(); it.hasNext();) { + singleProvider = it.next(); + if (it.hasNext()) { + throw new InternalError(String.format("Multiple %s providers found", service.getName())); + } + } + } catch (ServiceConfigurationError e) { + // If the service is required we will bail out below. + } + if (singleProvider == null && required) { + String javaHome = System.getProperty("java.home"); + String vmName = System.getProperty("java.vm.name"); + Formatter errorMessage = new Formatter(); + errorMessage.format("The VM does not expose required service %s.%n", service.getName()); + errorMessage.format("Currently used Java home directory is %s.%n", javaHome); + errorMessage.format("Currently used VM configuration is: %s", vmName); + throw new UnsupportedOperationException(errorMessage.toString()); + } + return singleProvider; + } +}