Initial revision

From-SVN: r102075

libjava/classpath/vm/reference/java/lang/VMRuntime.java

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+/* VMRuntime.java -- VM interface to Runtime
+   Copyright (C) 2003 Free Software Foundation
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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 for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+package java.lang;
+
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * VMRuntime represents the interface to the Virtual Machine.
+ *
+ * @author Jeroen Frijters
+ */
+final class VMRuntime
+{
+    /**
+     * No instance is ever created.
+     */
+    private VMRuntime() 
+    {
+    }
+
+    /**
+     * Returns the number of available processors currently available to the
+     * virtual machine. This number may change over time; so a multi-processor
+     * program want to poll this to determine maximal resource usage.
+     *
+     * @return the number of processors available, at least 1
+     */
+    static native int availableProcessors();
+
+    /**
+     * Find out how much memory is still free for allocating Objects on the heap.
+     *
+     * @return the number of bytes of free memory for more Objects
+     */
+    static native long freeMemory();
+
+    /**
+     * Find out how much memory total is available on the heap for allocating
+     * Objects.
+     *
+     * @return the total number of bytes of memory for Objects
+     */
+    static native long totalMemory();
+
+    /**
+     * Returns the maximum amount of memory the virtual machine can attempt to
+     * use. This may be <code>Long.MAX_VALUE</code> if there is no inherent
+     * limit (or if you really do have a 8 exabyte memory!).
+     *
+     * @return the maximum number of bytes the virtual machine will attempt
+     *         to allocate
+     */
+    static native long maxMemory();
+
+    /**
+     * Run the garbage collector. This method is more of a suggestion than
+     * anything. All this method guarantees is that the garbage collector will
+     * have "done its best" by the time it returns. Notice that garbage
+     * collection takes place even without calling this method.
+     */
+    static native void gc();
+
+    /**
+     * Run finalization on all Objects that are waiting to be finalized. Again,
+     * a suggestion, though a stronger one than {@link #gc()}. This calls the
+     * <code>finalize</code> method of all objects waiting to be collected.
+     *
+     * @see #finalize()
+     */
+    static native void runFinalization();
+
+    /**
+     * Run finalization on all finalizable Objects (even live ones). This
+     * should only be called immediately prior to VM termination.
+     *
+     * @see #finalize()
+     */
+    static native void runFinalizationForExit();
+
+    /**
+     * Tell the VM to trace every bytecode instruction that executes (print out
+     * a trace of it).  No guarantees are made as to where it will be printed,
+     * and the VM is allowed to ignore this request.
+     *
+     * @param on whether to turn instruction tracing on
+     */
+    static native void traceInstructions(boolean on);
+
+    /**
+     * Tell the VM to trace every method call that executes (print out a trace
+     * of it).  No guarantees are made as to where it will be printed, and the
+     * VM is allowed to ignore this request.
+     *
+     * @param on whether to turn method tracing on
+     */
+    static native void traceMethodCalls(boolean on);
+
+    /**
+     * Native method that actually sets the finalizer setting.
+     *
+     * @param value whether to run finalizers on exit
+     */
+    static native void runFinalizersOnExit(boolean value);
+
+    /**
+     * Native method that actually shuts down the virtual machine.
+     *
+     * @param status the status to end the process with
+     */
+    static native void exit(int status);
+
+    /**
+     * Load a file. If it has already been loaded, do nothing. The name has
+     * already been mapped to a true filename.
+     *
+     * @param filename the file to load
+     * @param loader class loader, or <code>null</code> for the boot loader
+     * @return 0 on failure, nonzero on success
+     */
+    static native int nativeLoad(String filename, ClassLoader loader);
+
+    /**
+     * Map a system-independent "short name" to the full file name.
+     *
+     * @param libname the short version of the library name
+     * @return the full filename
+     */
+    static native String mapLibraryName(String libname);
+
+    /**
+     * Execute a process. The command line has already been tokenized, and
+     * the environment should contain name=value mappings. If directory is null,
+     * use the current working directory; otherwise start the process in that
+     * directory.  If env is null, then the new process should inherit
+     * the environment of this process.
+     *
+     * @param cmd the non-null command tokens
+     * @param env the environment setup
+     * @param dir the directory to use, may be null
+     * @return the newly created process
+     * @throws NullPointerException if cmd or env have null elements
+     */
+    static Process exec(String[] cmd, String[] env, File dir)
+	throws IOException {
+      return VMProcess.exec(cmd, env, dir);
+    }
+
+    /**
+     * This method is called by Runtime.addShutdownHook() when it is
+     * called for the first time. It enables the VM to lazily setup
+     * an exit handler, should it so desire.
+     */
+    static void enableShutdownHooks()
+    {
+    }
+} // class VMRuntime