1 /*
   2  * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package jdk.internal.module;
  27 
  28 import java.lang.module.ModuleFinder;
  29 import java.util.Objects;
  30 import jdk.internal.misc.VM;
  31 
  32 /**
  33  * Used by ModuleBootstrap to obtain the archived system modules and finder.
  34  */
  35 final class ArchivedModuleGraph {
  36     private static String archivedMainModule;
  37     private static SystemModules archivedSystemModules;
  38     private static ModuleFinder archivedModuleFinder;
  39 
  40     private final SystemModules systemModules;
  41     private final ModuleFinder finder;
  42 
  43     private ArchivedModuleGraph(SystemModules modules, ModuleFinder finder) {
  44         this.systemModules = modules;
  45         this.finder = finder;
  46     }
  47 
  48     SystemModules systemModules() {
  49         return systemModules;
  50     }
  51 
  52     ModuleFinder finder() {
  53         return finder;
  54     }
  55 
  56     // A factory method that ModuleBootstrap can use to obtain the
  57     // ArchivedModuleGraph.
  58     static ArchivedModuleGraph get(String mainModule) {
  59         if (Objects.equals(mainModule, archivedMainModule)
  60                 && archivedSystemModules != null
  61                 && archivedModuleFinder != null) {
  62             return new ArchivedModuleGraph(archivedSystemModules,
  63                                            archivedModuleFinder);
  64         } else {
  65             return null;
  66         }
  67     }
  68 
  69     // Used at CDS dump time
  70     static void archive(String mainModule, SystemModules systemModules,
  71                         ModuleFinder finder) {
  72         if (archivedMainModule != null)
  73             throw new UnsupportedOperationException();
  74         archivedMainModule = mainModule;
  75         archivedSystemModules = systemModules;
  76         archivedModuleFinder = finder;
  77     }
  78 
  79     static {
  80         VM.initializeFromArchive(ArchivedModuleGraph.class);
  81     }
  82 }