540 lines
23 KiB
Java
540 lines
23 KiB
Java
/*
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* Copyright (c) 2002, 2006, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.misc;
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import java.nio.ByteBuffer;
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import java.security.Permission;
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import java.security.PrivilegedAction;
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import java.io.IOException;
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import java.io.UnsupportedEncodingException;
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/**
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* The Perf class provides the ability to attach to an instrumentation
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* buffer maintained by a Java virtual machine. The instrumentation
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* buffer may be for the Java virtual machine running the methods of
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* this class or it may be for another Java virtual machine on the
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* same system.
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* <p>
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* In addition, this class provides methods to create instrumentation
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* objects in the instrumentation buffer for the Java virtual machine
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* that is running these methods. It also contains methods for acquiring
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* the value of a platform specific high resolution clock for time
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* stamp and interval measurement purposes.
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*
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* @author Brian Doherty
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* @since 1.4.2
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* @see #getPerf
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* @see sun.misc.Perf$GetPerfAction
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* @see java.nio.ByteBuffer
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*/
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public final class Perf {
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private static Perf instance;
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private static final int PERF_MODE_RO = 0;
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private static final int PERF_MODE_RW = 1;
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private Perf() { } // prevent instantiation
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/**
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* The GetPerfAction class is a convenience class for acquiring access
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* to the singleton Perf instance using the
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* <code>AccessController.doPrivileged()</code> method.
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* <p>
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* An instance of this class can be used as the argument to
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* <code>AccessController.doPrivileged(PrivilegedAction)</code>.
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* <p> Here is a suggested idiom for use of this class:
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*
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* <blockquote><pre>
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* class MyTrustedClass {
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* private static final Perf perf =
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* AccessController.doPrivileged(new Perf.GetPerfAction<Perf>());
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* ...
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* }
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* </pre></blockquote>
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* <p>
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* In the presence of a security manager, the <code>MyTrustedClass</code>
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* class in the above example will need to be granted the
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* <em>"sun.misc.Perf.getPerf"</em> <code>RuntimePermission</code>
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* permission in order to successfully acquire the singleton Perf instance.
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* <p>
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* Please note that the <em>"sun.misc.Perf.getPerf"</em> permission
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* is not a JDK specified permission.
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*
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* @see java.security.AccessController#doPrivileged(PrivilegedAction)
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* @see java.lang.RuntimePermission
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*/
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public static class GetPerfAction implements PrivilegedAction<Perf>
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{
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/**
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* Run the <code>Perf.getPerf()</code> method in a privileged context.
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*
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* @see #getPerf
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*/
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public Perf run() {
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return getPerf();
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}
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}
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/**
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* Return a reference to the singleton Perf instance.
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* <p>
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* The getPerf() method returns the singleton instance of the Perf
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* class. The returned object provides the caller with the capability
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* for accessing the instrumentation buffer for this or another local
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* Java virtual machine.
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* <p>
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* If a security manager is installed, its <code>checkPermission</code>
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* method is called with a <code>RuntimePermission</code> with a target
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* of <em>"sun.misc.Perf.getPerf"</em>. A security exception will result
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* if the caller has not been granted this permission.
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* <p>
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* Access to the returned <code>Perf</code> object should be protected
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* by its caller and not passed on to untrusted code. This object can
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* be used to attach to the instrumentation buffer provided by this Java
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* virtual machine or for those of other Java virtual machines running
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* on the same system. The instrumentation buffer may contain senstitive
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* information. API's built on top of this interface may want to provide
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* finer grained access control to the contents of individual
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* instrumentation objects contained within the buffer.
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* <p>
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* Please note that the <em>"sun.misc.Perf.getPerf"</em> permission
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* is not a JDK specified permission.
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*
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* @return A reference to the singleton Perf instance.
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* @throws AccessControlException if a security manager exists and
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* its <code>checkPermission</code> method doesn't allow
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* access to the <em>"sun.misc.Perf.getPerf"</em> target.
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* @see java.lang.RuntimePermission
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* @see #attach
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*/
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public static Perf getPerf()
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{
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SecurityManager security = System.getSecurityManager();
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if (security != null) {
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Permission perm = new RuntimePermission("sun.misc.Perf.getPerf");
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security.checkPermission(perm);
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}
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return instance;
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}
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/**
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* Attach to the instrumentation buffer for the specified Java virtual
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* machine.
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* <p>
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* This method will attach to the instrumentation buffer for the
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* specified virtual machine. It returns a <code>ByteBuffer</code> object
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* that is initialized to access the instrumentation buffer for the
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* indicated Java virtual machine. The <code>lvmid</code> parameter is
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* a integer value that uniquely identifies the target local Java virtual
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* machine. It is typically, but not necessarily, the process id of
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* the target Java virtual machine.
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* <p>
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* If the <code>lvmid</code> identifies a Java virtual machine different
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* from the one running this method, then the coherency characteristics
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* of the buffer are implementation dependent. Implementations that do
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* not support named, coherent, shared memory may return a
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* <code>ByteBuffer</code> object that contains only a snap shot of the
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* data in the instrumentation buffer. Implementations that support named,
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* coherent, shared memory, may return a <code>ByteBuffer</code> object
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* that will be changing dynamically over time as the target Java virtual
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* machine updates its mapping of this buffer.
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* <p>
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* If the <code>lvmid</code> is 0 or equal to the actual <code>lvmid</code>
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* for the Java virtual machine running this method, then the returned
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* <code>ByteBuffer</code> object will always be coherent and dynamically
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* changing.
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* <p>
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* The attach mode specifies the access permissions requested for the
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* instrumentation buffer of the target virtual machine. The permitted
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* access permissions are:
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* <p>
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* <bl>
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* <li>"r" - Read only access. This Java virtual machine has only
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* read access to the instrumentation buffer for the target Java
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* virtual machine.
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* <li>"rw" - Read/Write access. This Java virtual machine has read and
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* write access to the instrumentation buffer for the target Java virtual
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* machine. This mode is currently not supported and is reserved for
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* future enhancements.
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* </bl>
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*
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* @param lvmid an integer that uniquely identifies the
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* target local Java virtual machine.
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* @param mode a string indicating the attach mode.
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* @return ByteBuffer a direct allocated byte buffer
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* @throws IllegalArgumentException The lvmid or mode was invalid.
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* @throws IOException An I/O error occurred while trying to acquire
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* the instrumentation buffer.
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* @throws OutOfMemoryError The instrumentation buffer could not be mapped
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* into the virtual machine's address space.
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* @see java.nio.ByteBuffer
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*/
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public ByteBuffer attach(int lvmid, String mode)
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throws IllegalArgumentException, IOException
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{
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if (mode.compareTo("r") == 0) {
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return attachImpl(null, lvmid, PERF_MODE_RO);
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}
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else if (mode.compareTo("rw") == 0) {
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return attachImpl(null, lvmid, PERF_MODE_RW);
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}
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else {
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throw new IllegalArgumentException("unknown mode");
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}
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}
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/**
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* Attach to the instrumentation buffer for the specified Java virtual
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* machine owned by the given user.
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* <p>
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* This method behaves just as the <code>attach(int lvmid, String mode)
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* </code> method, except that it only searches for Java virtual machines
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* owned by the specified user.
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*
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* @param user A <code>String</code> object containing the
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* name of the user that owns the target Java
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* virtual machine.
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* @param lvmid an integer that uniquely identifies the
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* target local Java virtual machine.
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* @param mode a string indicating the attach mode.
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* @return ByteBuffer a direct allocated byte buffer
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* @throws IllegalArgumentException The lvmid or mode was invalid.
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* @throws IOException An I/O error occurred while trying to acquire
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* the instrumentation buffer.
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* @throws OutOfMemoryError The instrumentation buffer could not be mapped
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* into the virtual machine's address space.
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* @see java.nio.ByteBuffer
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*/
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public ByteBuffer attach(String user, int lvmid, String mode)
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throws IllegalArgumentException, IOException
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{
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if (mode.compareTo("r") == 0) {
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return attachImpl(user, lvmid, PERF_MODE_RO);
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}
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else if (mode.compareTo("rw") == 0) {
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return attachImpl(user, lvmid, PERF_MODE_RW);
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}
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else {
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throw new IllegalArgumentException("unknown mode");
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}
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}
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/**
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* Call the implementation specific attach method.
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* <p>
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* This method calls into the Java virtual machine to perform the platform
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* specific attach method. Buffers returned from this method are
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* internally managed as <code>PhantomRefereces</code> to provide for
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* guaranteed, secure release of the native resources.
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*
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* @param user A <code>String</code> object containing the
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* name of the user that owns the target Java
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* virtual machine.
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* @param lvmid an integer that uniquely identifies the
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* target local Java virtual machine.
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* @param mode a string indicating the attach mode.
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* @return ByteBuffer a direct allocated byte buffer
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* @throws IllegalArgumentException The lvmid or mode was invalid.
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* @throws IOException An I/O error occurred while trying to acquire
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* the instrumentation buffer.
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* @throws OutOfMemoryError The instrumentation buffer could not be mapped
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* into the virtual machine's address space.
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*/
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private ByteBuffer attachImpl(String user, int lvmid, int mode)
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throws IllegalArgumentException, IOException
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{
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final ByteBuffer b = attach(user, lvmid, mode);
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if (lvmid == 0) {
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// The native instrumentation buffer for this Java virtual
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// machine is never unmapped.
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return b;
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}
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else {
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// This is an instrumentation buffer for another Java virtual
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// machine with native resources that need to be managed. We
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// create a duplicate of the native ByteBuffer and manage it
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// with a Cleaner object (PhantomReference). When the duplicate
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// becomes only phantomly reachable, the native resources will
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// be released.
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final ByteBuffer dup = b.duplicate();
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Cleaner.create(dup, new Runnable() {
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public void run() {
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try {
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instance.detach(b);
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}
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catch (Throwable th) {
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// avoid crashing the reference handler thread,
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// but provide for some diagnosability
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assert false : th.toString();
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}
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}
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});
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return dup;
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}
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}
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/**
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* Native method to perform the implementation specific attach mechanism.
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* <p>
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* The implementation of this method may return distinct or identical
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* <code>ByteBuffer</code> objects for two distinct calls requesting
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* attachment to the same Java virtual machine.
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* <p>
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* For the Sun HotSpot JVM, two distinct calls to attach to the same
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* target Java virtual machine will result in two distinct ByteBuffer
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* objects returned by this method. This may change in a future release.
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*
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* @param user A <code>String</code> object containing the
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* name of the user that owns the target Java
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* virtual machine.
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* @param lvmid an integer that uniquely identifies the
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* target local Java virtual machine.
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* @param mode a string indicating the attach mode.
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* @return ByteBuffer a direct allocated byte buffer
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* @throws IllegalArgumentException The lvmid or mode was invalid.
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* @throws IOException An I/O error occurred while trying to acquire
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* the instrumentation buffer.
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* @throws OutOfMemoryError The instrumentation buffer could not be mapped
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* into the virtual machine's address space.
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*/
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private native ByteBuffer attach(String user, int lvmid, int mode)
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throws IllegalArgumentException, IOException;
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/**
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* Native method to perform the implementation specific detach mechanism.
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* <p>
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* If this method is passed a <code>ByteBuffer</code> object that is
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* not created by the <code>attach</code> method, then the results of
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* this method are undefined, with unpredictable and potentially damaging
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* effects to the Java virtual machine. To prevent accidental or malicious
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* use of this method, all native ByteBuffer created by the <code>
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* attach</code> method are managed internally as PhantomReferences
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* and resources are freed by the system.
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* <p>
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* If this method is passed a <code>ByteBuffer</code> object created
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* by the <code>attach</code> method with a lvmid for the Java virtual
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* machine running this method (lvmid=0, for example), then the detach
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* request is silently ignored.
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*
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* @param ByteBuffer A direct allocated byte buffer created by the
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* <code>attach</code> method.
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* @see java.nio.ByteBuffer
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* @see #attach
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*/
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private native void detach(ByteBuffer bb);
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/**
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* Create a <code>long</code> scalar entry in the instrumentation buffer
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* with the given variability characteristic, units, and initial value.
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* <p>
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* Access to the instrument is provided through the returned <code>
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* ByteBuffer</code> object. Typically, this object should be wrapped
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* with <code>LongBuffer</code> view object.
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*
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* @param variability the variability characteristic for this entry.
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* @param units the units for this entry.
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* @param name the name of this entry.
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* @param value the initial value for this entry.
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* @return ByteBuffer a direct allocated ByteBuffer object that
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* allows write access to a native memory location
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* containing a <code>long</code> value.
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*
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* see sun.misc.perf.Variability
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* see sun.misc.perf.Units
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* @see java.nio.ByteBuffer
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*/
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public native ByteBuffer createLong(String name, int variability,
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int units, long value);
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/**
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* Create a <code>String</code> entry in the instrumentation buffer with
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* the given variability characteristic, units, and initial value.
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* <p>
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* The maximum length of the <code>String</code> stored in this string
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* instrument is given in by <code>maxLength</code> parameter. Updates
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* to this instrument with <code>String</code> values with lengths greater
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* than <code>maxLength</code> will be truncated to <code>maxLength</code>.
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* The truncated value will be terminated by a null character.
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* <p>
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* The underlying implementation may further limit the length of the
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* value, but will continue to preserve the null terminator.
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* <p>
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* Access to the instrument is provided through the returned <code>
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* ByteBuffer</code> object.
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*
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* @param variability the variability characteristic for this entry.
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* @param units the units for this entry.
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* @param name the name of this entry.
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* @param value the initial value for this entry.
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* @param maxLength the maximum string length for this string
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* instrument.
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* @return ByteBuffer a direct allocated ByteBuffer that allows
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* write access to a native memory location
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* containing a <code>long</code> value.
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*
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* see sun.misc.perf.Variability
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* see sun.misc.perf.Units
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* @see java.nio.ByteBuffer
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*/
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public ByteBuffer createString(String name, int variability,
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int units, String value, int maxLength)
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{
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byte[] v = getBytes(value);
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byte[] v1 = new byte[v.length+1];
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System.arraycopy(v, 0, v1, 0, v.length);
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v1[v.length] = '\0';
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return createByteArray(name, variability, units, v1, Math.max(v1.length, maxLength));
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}
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/**
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* Create a <code>String</code> entry in the instrumentation buffer with
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* the given variability characteristic, units, and initial value.
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* <p>
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* The maximum length of the <code>String</code> stored in this string
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* instrument is implied by the length of the <code>value</code> parameter.
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* Subsequent updates to the value of this instrument will be truncated
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* to this implied maximum length. The truncated value will be terminated
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* by a null character.
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* <p>
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* The underlying implementation may further limit the length of the
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* initial or subsequent value, but will continue to preserve the null
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* terminator.
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* <p>
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* Access to the instrument is provided through the returned <code>
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* ByteBuffer</code> object.
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*
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* @param variability the variability characteristic for this entry.
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* @param units the units for this entry.
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* @param name the name of this entry.
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* @param value the initial value for this entry.
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* @return ByteBuffer a direct allocated ByteBuffer that allows
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* write access to a native memory location
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* containing a <code>long</code> value.
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*
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* see sun.misc.perf.Variability
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* see sun.misc.perf.Units
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* @see java.nio.ByteBuffer
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*/
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public ByteBuffer createString(String name, int variability,
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int units, String value)
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{
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byte[] v = getBytes(value);
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byte[] v1 = new byte[v.length+1];
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System.arraycopy(v, 0, v1, 0, v.length);
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v1[v.length] = '\0';
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return createByteArray(name, variability, units, v1, v1.length);
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}
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/**
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* Create a <code>byte</code> vector entry in the instrumentation buffer
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* with the given variability characteristic, units, and initial value.
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* <p>
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* The <code>maxLength</code> parameter limits the size of the byte
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* array instrument such that the initial or subsequent updates beyond
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* this length are silently ignored. No special handling of truncated
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* updates is provided.
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* <p>
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* The underlying implementation may further limit the length of the
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* length of the initial or subsequent value.
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* <p>
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* Access to the instrument is provided through the returned <code>
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* ByteBuffer</code> object.
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*
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* @param variability the variability characteristic for this entry.
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* @param units the units for this entry.
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* @param name the name of this entry.
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* @param value the initial value for this entry.
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* @param maxLength the maximum length of this byte array.
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* @return ByteBuffer a direct allocated byte buffer that allows
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* write access to a native memory location
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* containing a <code>long</code> value.
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*
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* see sun.misc.perf.Variability
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* see sun.misc.perf.Units
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* @see java.nio.ByteBuffer
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*/
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public native ByteBuffer createByteArray(String name, int variability,
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int units, byte[] value,
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int maxLength);
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/**
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|
* convert string to an array of UTF-8 bytes
|
|
*/
|
|
private static byte[] getBytes(String s)
|
|
{
|
|
byte[] bytes = null;
|
|
|
|
try {
|
|
bytes = s.getBytes("UTF-8");
|
|
}
|
|
catch (UnsupportedEncodingException e) {
|
|
// ignore, UTF-8 encoding is always known
|
|
}
|
|
|
|
return bytes;
|
|
}
|
|
|
|
/**
|
|
* Return the value of the High Resolution Counter.
|
|
*
|
|
* The High Resolution Counter returns the number of ticks since
|
|
* since the start of the Java virtual machine. The resolution of
|
|
* the counter is machine dependent and can be determined from the
|
|
* value return by the {@link #highResFrequency} method.
|
|
*
|
|
* @return the number of ticks of machine dependent resolution since
|
|
* the start of the Java virtual machine.
|
|
*
|
|
* @see #highResFrequency
|
|
* @see java.lang.System#currentTimeMillis()
|
|
*/
|
|
public native long highResCounter();
|
|
|
|
/**
|
|
* Returns the frequency of the High Resolution Counter, in ticks per
|
|
* second.
|
|
*
|
|
* This value can be used to convert the value of the High Resolution
|
|
* Counter, as returned from a call to the {@link #highResCounter} method,
|
|
* into the number of seconds since the start of the Java virtual machine.
|
|
*
|
|
* @return the frequency of the High Resolution Counter.
|
|
* @see #highResCounter
|
|
*/
|
|
public native long highResFrequency();
|
|
|
|
private static native void registerNatives();
|
|
|
|
static {
|
|
registerNatives();
|
|
instance = new Perf();
|
|
}
|
|
}
|