diff options
Diffstat (limited to 'libjava/java/lang/Runtime.java')
| -rw-r--r-- | libjava/java/lang/Runtime.java | 747 |
1 files changed, 747 insertions, 0 deletions
diff --git a/libjava/java/lang/Runtime.java b/libjava/java/lang/Runtime.java new file mode 100644 index 000000000..3466f19f2 --- /dev/null +++ b/libjava/java/lang/Runtime.java @@ -0,0 +1,747 @@ +/* Runtime.java -- access to the VM process + Copyright (C) 1998, 2002, 2003, 2004, 2005, 2006 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 gnu.classpath.SystemProperties; + +import java.io.File; +import java.io.IOException; +import java.io.InputStream; +import java.io.OutputStream; +import java.util.HashSet; +import java.util.Iterator; +import java.util.Set; +import java.util.StringTokenizer; + +/** + * Runtime represents the Virtual Machine. + * + * @author John Keiser + * @author Eric Blake (ebb9@email.byu.edu) + * @author Jeroen Frijters + */ +// No idea why this class isn't final, since you can't build a subclass! +public class Runtime +{ + /** + * The library path, to search when loading libraries. We can also safely use + * this as a lock for synchronization. + */ + private final String[] libpath; + + static + { + init(); + } + + /** + * The thread that started the exit sequence. Access to this field must + * be thread-safe; lock on libpath to avoid deadlock with user code. + * <code>runFinalization()</code> may want to look at this to see if ALL + * finalizers should be run, because the virtual machine is about to halt. + */ + private Thread exitSequence; + + /** + * All shutdown hooks. This is initialized lazily, and set to null once all + * shutdown hooks have run. Access to this field must be thread-safe; lock + * on libpath to avoid deadlock with user code. + */ + private Set shutdownHooks; + + /** True if we should finalize on exit. */ + private boolean finalizeOnExit; + + /** + * The one and only runtime instance. + */ + private static final Runtime current = new Runtime(); + + /** + * Not instantiable by a user, this should only create one instance. + */ + private Runtime() + { + if (current != null) + throw new InternalError("Attempt to recreate Runtime"); + + // We don't use libpath in the libgcj implementation. We still + // set it to something to allow the various synchronizations to + // work. + libpath = new String[0]; + } + + /** + * Get the current Runtime object for this JVM. This is necessary to access + * the many instance methods of this class. + * + * @return the current Runtime object + */ + public static Runtime getRuntime() + { + return current; + } + + /** + * Exit the Java runtime. This method will either throw a SecurityException + * or it will never return. The status code is returned to the system; often + * a non-zero status code indicates an abnormal exit. Of course, there is a + * security check, <code>checkExit(status)</code>. + * + * <p>First, all shutdown hooks are run, in unspecified order, and + * concurrently. Next, if finalization on exit has been enabled, all pending + * finalizers are run. Finally, the system calls <code>halt</code>.</p> + * + * <p>If this is run a second time after shutdown has already started, there + * are two actions. If shutdown hooks are still executing, it blocks + * indefinitely. Otherwise, if the status is nonzero it halts immediately; + * if it is zero, it blocks indefinitely. This is typically called by + * <code>System.exit</code>.</p> + * + * @param status the status to exit with + * @throws SecurityException if permission is denied + * @see #addShutdownHook(Thread) + * @see #runFinalizersOnExit(boolean) + * @see #runFinalization() + * @see #halt(int) + */ + public void exit(int status) + { + SecurityManager sm = SecurityManager.current; // Be thread-safe! + if (sm != null) + sm.checkExit(status); + exitNoChecks(status); + } + + // Accessor to avoid adding a vtable slot. + static void exitNoChecksAccessor(int status) + { + current.exitNoChecks(status); + } + + // Private since we can't add a vtable slot in 4.1.x. + private void exitNoChecks(int status) + { + if (runShutdownHooks()) + exitInternal(status); + + // Someone else already called runShutdownHooks(). + // Make sure we are not/no longer in the shutdownHooks set. + // And wait till the thread that is calling runShutdownHooks() finishes. + synchronized (libpath) + { + if (shutdownHooks != null) + { + shutdownHooks.remove(Thread.currentThread()); + // Interrupt the exit sequence thread, in case it was waiting + // inside a join on our thread. + exitSequence.interrupt(); + // Shutdown hooks are still running, so we clear status to + // make sure we don't halt. + status = 0; + } + } + + // If exit() is called again after the shutdown hooks have run, but + // while finalization for exit is going on and the status is non-zero + // we halt immediately. + if (status != 0) + exitInternal(status); + + while (true) + try + { + exitSequence.join(); + } + catch (InterruptedException e) + { + // Ignore, we've suspended indefinitely to let all shutdown + // hooks complete, and to let any non-zero exits through, because + // this is a duplicate call to exit(0). + } + } + + /** + * On first invocation, run all the shutdown hooks and return true. + * Any subsequent invocations will simply return false. + * Note that it is package accessible so that VMRuntime can call it + * when VM exit is not triggered by a call to Runtime.exit(). + * + * @return was the current thread the first one to call this method? + */ + boolean runShutdownHooks() + { + boolean first = false; + synchronized (libpath) // Synch on libpath, not this, to avoid deadlock. + { + if (exitSequence == null) + { + first = true; + exitSequence = Thread.currentThread(); + if (shutdownHooks != null) + { + Iterator i = shutdownHooks.iterator(); + while (i.hasNext()) // Start all shutdown hooks. + try + { + ((Thread) i.next()).start(); + } + catch (IllegalThreadStateException e) + { + i.remove(); + } + } + } + } + if (first) + { + if (shutdownHooks != null) + { + // Check progress of all shutdown hooks. As a hook completes, + // remove it from the set. If a hook calls exit, it removes + // itself from the set, then waits indefinitely on the + // exitSequence thread. Once the set is empty, set it to null to + // signal all finalizer threads that halt may be called. + while (true) + { + Thread[] hooks; + synchronized (libpath) + { + hooks = new Thread[shutdownHooks.size()]; + shutdownHooks.toArray(hooks); + } + if (hooks.length == 0) + break; + for (int i = 0; i < hooks.length; i++) + { + try + { + synchronized (libpath) + { + if (!shutdownHooks.contains(hooks[i])) + continue; + } + hooks[i].join(); + synchronized (libpath) + { + shutdownHooks.remove(hooks[i]); + } + } + catch (InterruptedException x) + { + // continue waiting on the next thread + } + } + } + synchronized (libpath) + { + shutdownHooks = null; + } + } + // Run finalization on all finalizable objects (even if they are + // still reachable). + runFinalizationForExit(); + } + return first; + } + + /** + * Register a new shutdown hook. This is invoked when the program exits + * normally (because all non-daemon threads ended, or because + * <code>System.exit</code> was invoked), or when the user terminates + * the virtual machine (such as by typing ^C, or logging off). There is + * a security check to add hooks, + * <code>RuntimePermission("shutdownHooks")</code>. + * + * <p>The hook must be an initialized, but unstarted Thread. The threads + * are run concurrently, and started in an arbitrary order; and user + * threads or daemons may still be running. Once shutdown hooks have + * started, they must all complete, or else you must use <code>halt</code>, + * to actually finish the shutdown sequence. Attempts to modify hooks + * after shutdown has started result in IllegalStateExceptions.</p> + * + * <p>It is imperative that you code shutdown hooks defensively, as you + * do not want to deadlock, and have no idea what other hooks will be + * running concurrently. It is also a good idea to finish quickly, as the + * virtual machine really wants to shut down!</p> + * + * <p>There are no guarantees that such hooks will run, as there are ways + * to forcibly kill a process. But in such a drastic case, shutdown hooks + * would do little for you in the first place.</p> + * + * @param hook an initialized, unstarted Thread + * @throws IllegalArgumentException if the hook is already registered or run + * @throws IllegalStateException if the virtual machine is already in + * the shutdown sequence + * @throws SecurityException if permission is denied + * @since 1.3 + * @see #removeShutdownHook(Thread) + * @see #exit(int) + * @see #halt(int) + */ + public void addShutdownHook(Thread hook) + { + SecurityManager sm = SecurityManager.current; // Be thread-safe! + if (sm != null) + sm.checkPermission(new RuntimePermission("shutdownHooks")); + if (hook.isAlive() || hook.getThreadGroup() == null) + throw new IllegalArgumentException("The hook thread " + hook + " must not have been already run or started"); + synchronized (libpath) + { + if (exitSequence != null) + throw new IllegalStateException("The Virtual Machine is exiting. It is not possible anymore to add any hooks"); + if (shutdownHooks == null) + shutdownHooks = new HashSet(); // Lazy initialization. + if (! shutdownHooks.add(hook)) + throw new IllegalArgumentException(hook.toString() + " had already been inserted"); + } + } + + /** + * De-register a shutdown hook. As when you registered it, there is a + * security check to remove hooks, + * <code>RuntimePermission("shutdownHooks")</code>. + * + * @param hook the hook to remove + * @return true if the hook was successfully removed, false if it was not + * registered in the first place + * @throws IllegalStateException if the virtual machine is already in + * the shutdown sequence + * @throws SecurityException if permission is denied + * @since 1.3 + * @see #addShutdownHook(Thread) + * @see #exit(int) + * @see #halt(int) + */ + public boolean removeShutdownHook(Thread hook) + { + SecurityManager sm = SecurityManager.current; // Be thread-safe! + if (sm != null) + sm.checkPermission(new RuntimePermission("shutdownHooks")); + synchronized (libpath) + { + if (exitSequence != null) + throw new IllegalStateException(); + if (shutdownHooks != null) + return shutdownHooks.remove(hook); + } + return false; + } + + /** + * Forcibly terminate the virtual machine. This call never returns. It is + * much more severe than <code>exit</code>, as it bypasses all shutdown + * hooks and initializers. Use caution in calling this! Of course, there is + * a security check, <code>checkExit(status)</code>. + * + * @param status the status to exit with + * @throws SecurityException if permission is denied + * @since 1.3 + * @see #exit(int) + * @see #addShutdownHook(Thread) + */ + public void halt(int status) + { + SecurityManager sm = SecurityManager.current; // Be thread-safe! + if (sm != null) + sm.checkExit(status); + exitInternal(status); + } + + /** + * Tell the VM to run the finalize() method on every single Object before + * it exits. Note that the JVM may still exit abnormally and not perform + * this, so you still don't have a guarantee. And besides that, this is + * inherently unsafe in multi-threaded code, as it may result in deadlock + * as multiple threads compete to manipulate objects. This value defaults to + * <code>false</code>. There is a security check, <code>checkExit(0)</code>. + * + * @param finalizeOnExit whether to finalize all Objects on exit + * @throws SecurityException if permission is denied + * @see #exit(int) + * @see #gc() + * @since 1.1 + * @deprecated never rely on finalizers to do a clean, thread-safe, + * mop-up from your code + */ + public static void runFinalizersOnExit(boolean finalizeOnExit) + { + SecurityManager sm = SecurityManager.current; // Be thread-safe! + if (sm != null) + sm.checkExit(0); + current.finalizeOnExit = finalizeOnExit; + } + + /** + * Create a new subprocess with the specified command line. Calls + * <code>exec(cmdline, null, null)</code>. A security check is performed, + * <code>checkExec</code>. + * + * @param cmdline the command to call + * @return the Process object + * @throws SecurityException if permission is denied + * @throws IOException if an I/O error occurs + * @throws NullPointerException if cmdline is null + * @throws IndexOutOfBoundsException if cmdline is "" + */ + public Process exec(String cmdline) throws IOException + { + return exec(cmdline, null, null); + } + + /** + * Create a new subprocess with the specified command line and environment. + * If the environment is null, the process inherits the environment of + * this process. Calls <code>exec(cmdline, env, null)</code>. A security + * check is performed, <code>checkExec</code>. + * + * @param cmdline the command to call + * @param env the environment to use, in the format name=value + * @return the Process object + * @throws SecurityException if permission is denied + * @throws IOException if an I/O error occurs + * @throws NullPointerException if cmdline is null, or env has null entries + * @throws IndexOutOfBoundsException if cmdline is "" + */ + public Process exec(String cmdline, String[] env) throws IOException + { + return exec(cmdline, env, null); + } + + /** + * Create a new subprocess with the specified command line, environment, and + * working directory. If the environment is null, the process inherits the + * environment of this process. If the directory is null, the process uses + * the current working directory. This splits cmdline into an array, using + * the default StringTokenizer, then calls + * <code>exec(cmdArray, env, dir)</code>. A security check is performed, + * <code>checkExec</code>. + * + * @param cmdline the command to call + * @param env the environment to use, in the format name=value + * @param dir the working directory to use + * @return the Process object + * @throws SecurityException if permission is denied + * @throws IOException if an I/O error occurs + * @throws NullPointerException if cmdline is null, or env has null entries + * @throws IndexOutOfBoundsException if cmdline is "" + * @since 1.3 + */ + public Process exec(String cmdline, String[] env, File dir) + throws IOException + { + StringTokenizer t = new StringTokenizer(cmdline); + String[] cmd = new String[t.countTokens()]; + for (int i = 0; i < cmd.length; i++) + cmd[i] = t.nextToken(); + return exec(cmd, env, dir); + } + + /** + * Create a new subprocess with the specified command line, already + * tokenized. Calls <code>exec(cmd, null, null)</code>. A security check + * is performed, <code>checkExec</code>. + * + * @param cmd the command to call + * @return the Process object + * @throws SecurityException if permission is denied + * @throws IOException if an I/O error occurs + * @throws NullPointerException if cmd is null, or has null entries + * @throws IndexOutOfBoundsException if cmd is length 0 + */ + public Process exec(String[] cmd) throws IOException + { + return exec(cmd, null, null); + } + + /** + * Create a new subprocess with the specified command line, already + * tokenized, and specified environment. If the environment is null, the + * process inherits the environment of this process. Calls + * <code>exec(cmd, env, null)</code>. A security check is performed, + * <code>checkExec</code>. + * + * @param cmd the command to call + * @param env the environment to use, in the format name=value + * @return the Process object + * @throws SecurityException if permission is denied + * @throws IOException if an I/O error occurs + * @throws NullPointerException if cmd is null, or cmd or env has null + * entries + * @throws IndexOutOfBoundsException if cmd is length 0 + */ + public Process exec(String[] cmd, String[] env) throws IOException + { + return exec(cmd, env, null); + } + + /** + * Create a new subprocess with the specified command line, already + * tokenized, and the specified environment and working directory. If the + * environment is null, the process inherits the environment of this + * process. If the directory is null, the process uses the current working + * directory. A security check is performed, <code>checkExec</code>. + * + * @param cmd the command to call + * @param env the environment to use, in the format name=value + * @param dir the working directory to use + * @return the Process object + * @throws SecurityException if permission is denied + * @throws IOException if an I/O error occurs + * @throws NullPointerException if cmd is null, or cmd or env has null + * entries + * @throws IndexOutOfBoundsException if cmd is length 0 + * @since 1.3 + */ + public Process exec(String[] cmd, String[] env, File dir) + throws IOException + { + SecurityManager sm = SecurityManager.current; // Be thread-safe! + if (sm != null) + sm.checkExec(cmd[0]); + return execInternal(cmd, env, dir); + } + + /** + * 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 + */ + public 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 + */ + public 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 + */ + public 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 + */ + public 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. + */ + public 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() + */ + public native void runFinalization(); + + /** + * 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 + */ + public 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 + */ + public native void traceMethodCalls(boolean on); + + /** + * Load a native library using the system-dependent filename. This is similar + * to loadLibrary, except the only name mangling done is inserting "_g" + * before the final ".so" if the VM was invoked by the name "java_g". There + * may be a security check, of <code>checkLink</code>. + * + * @param filename the file to load + * @throws SecurityException if permission is denied + * @throws UnsatisfiedLinkError if the library is not found + */ + public void load(String filename) + { + SecurityManager sm = SecurityManager.current; // Be thread-safe! + if (sm != null) + sm.checkLink(filename); + _load(filename, false); + } + + /** + * Load a native library using a system-independent "short name" for the + * library. It will be transformed to a correct filename in a + * system-dependent manner (for example, in Windows, "mylib" will be turned + * into "mylib.dll"). This is done as follows: if the context that called + * load has a ClassLoader cl, then <code>cl.findLibrary(libpath)</code> is + * used to convert the name. If that result was null, or there was no class + * loader, this searches each directory of the system property + * <code>java.library.path</code> for a file named + * <code>System.mapLibraryName(libname)</code>. There may be a security + * check, of <code>checkLink</code>. + * + * @param libname the library to load + * + * @throws SecurityException if permission is denied + * @throws UnsatisfiedLinkError if the library is not found + * + * @see System#mapLibraryName(String) + * @see ClassLoader#findLibrary(String) + */ + public void loadLibrary(String libname) + { + // This is different from the Classpath implementation, but I + // believe it is more correct. + SecurityManager sm = SecurityManager.current; // Be thread-safe! + if (sm != null) + sm.checkLink(libname); + _load(libname, true); + } + + /** + * Return a localized version of this InputStream, meaning all characters + * are localized before they come out the other end. + * + * @param in the stream to localize + * @return the localized stream + * @deprecated <code>InputStreamReader</code> is the preferred way to read + * local encodings + */ + public InputStream getLocalizedInputStream(InputStream in) + { + return in; + } + + /** + * Return a localized version of this OutputStream, meaning all characters + * are localized before they are sent to the other end. + * + * @param out the stream to localize + * @return the localized stream + * @deprecated <code>OutputStreamWriter</code> is the preferred way to write + * local encodings + */ + public OutputStream getLocalizedOutputStream(OutputStream out) + { + return out; + } + + /** + * Native method that actually shuts down the virtual machine. + * + * @param status the status to end the process with + */ + native void exitInternal(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 do_search True if we should search the load path for the file + */ + native void _load(String filename, boolean do_search); + + /** + *This is a helper function for the ClassLoader which can load + * compiled libraries. Returns true if library (which is just the + * base name -- path searching is done by this function) was loaded, + * false otherwise. + */ + native boolean loadLibraryInternal(String libname); + + /** + * A helper for Runtime static initializer which does some internal native + * initialization. + */ + private static native void init (); + + /** + * Run finalizers when exiting. + */ + private native void runFinalizationForExit(); + + /** + * Map a system-independent "short name" to the full file name, and append + * it to the path. + * XXX This method is being replaced by System.mapLibraryName. + * + * @param pathname the path + * @param libname the short version of the library name + * @return the full filename + */ + static native String nativeGetLibname(String pathname, 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. + * + * @param cmd the non-null command tokens + * @param env the non-null 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 + * @throws IOException if the exec fails + */ + native Process execInternal(String[] cmd, String[] env, File dir) + throws IOException; +} // class Runtime |