/* * Copyright (c) 2002, 2006, 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. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * 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 sun.misc; import java.nio.ByteBuffer;import java.security.Permission;import java.security.PrivilegedAction;import java.io.IOException;import java.io.UnsupportedEncodingException; /** * The Perf class provides the ability to attach to an instrumentation * buffer maintained by a Java virtual machine. The instrumentation * buffer may be for the Java virtual machine running the methods of * this class or it may be for another Java virtual machine on the * same system. * <p> * In addition, this class provides methods to create instrumentation * objects in the instrumentation buffer for the Java virtual machine * that is running these methods. It also contains methods for acquiring * the value of a platform specific high resolution clock for time * stamp and interval measurement purposes. * * @author Brian Doherty * @since 1.4.2 * @see #getPerf * @see sun.misc.Perf$GetPerfAction * @see java.nio.ByteBuffer */public final class Perf { private static Perf instance; private static final int PERF_MODE_RO = 0; private static final int PERF_MODE_RW = 1; private Perf() { } // prevent instantiation /** * The GetPerfAction class is a convenience class for acquiring access * to the singleton Perf instance using the * <code>AccessController.doPrivileged()</code> method. * <p> * An instance of this class can be used as the argument to * <code>AccessController.doPrivileged(PrivilegedAction)</code>. * <p> Here is a suggested idiom for use of this class: * * <blockquote><pre> * class MyTrustedClass { * private static final Perf perf = * AccessController.doPrivileged(new Perf.GetPerfAction<Perf>()); * ... * } * </pre></blockquote> * <p> * In the presence of a security manager, the <code>MyTrustedClass</code> * class in the above example will need to be granted the * <em>"sun.misc.Perf.getPerf"</em> <code>RuntimePermission</code> * permission in order to successfully acquire the singleton Perf instance. * <p> * Please note that the <em>"sun.misc.Perf.getPerf"</em> permission * is not a JDK specified permission. * * @see java.security.AccessController#doPrivileged(PrivilegedAction) * @see java.lang.RuntimePermission */ public static class GetPerfAction implements PrivilegedAction<Perf> { /** * Run the <code>Perf.getPerf()</code> method in a privileged context. * * @see #getPerf */ public Perf run() { return getPerf(); } } /** * Return a reference to the singleton Perf instance. * <p> * The getPerf() method returns the singleton instance of the Perf * class. The returned object provides the caller with the capability * for accessing the instrumentation buffer for this or another local * Java virtual machine. * <p> * If a security manager is installed, its <code>checkPermission</code> * method is called with a <code>RuntimePermission</code> with a target * of <em>"sun.misc.Perf.getPerf"</em>. A security exception will result * if the caller has not been granted this permission. * <p> * Access to the returned <code>Perf</code> object should be protected * by its caller and not passed on to untrusted code. This object can * be used to attach to the instrumentation buffer provided by this Java * virtual machine or for those of other Java virtual machines running * on the same system. The instrumentation buffer may contain senstitive * information. API's built on top of this interface may want to provide * finer grained access control to the contents of individual * instrumentation objects contained within the buffer. * <p> * Please note that the <em>"sun.misc.Perf.getPerf"</em> permission * is not a JDK specified permission. * * @return A reference to the singleton Perf instance. * @throws AccessControlException if a security manager exists and * its <code>checkPermission</code> method doesn't allow * access to the <em>"sun.misc.Perf.getPerf"</em> target. * @see java.lang.RuntimePermission * @see #attach */ public static Perf getPerf() { SecurityManager security = System.getSecurityManager(); if (security != null) { Permission perm = new RuntimePermission("sun.misc.Perf.getPerf"); security.checkPermission(perm); } return instance; } /** * Attach to the instrumentation buffer for the specified Java virtual * machine. * <p> * This method will attach to the instrumentation buffer for the * specified virtual machine. It returns a <code>ByteBuffer</code> object * that is initialized to access the instrumentation buffer for the * indicated Java virtual machine. The <code>lvmid</code> parameter is * a integer value that uniquely identifies the target local Java virtual * machine. It is typically, but not necessarily, the process id of * the target Java virtual machine. * <p> * If the <code>lvmid</code> identifies a Java virtual machine different * from the one running this method, then the coherency characteristics * of the buffer are implementation dependent. Implementations that do * not support named, coherent, shared memory may return a * <code>ByteBuffer</code> object that contains only a snap shot of the * data in the instrumentation buffer. Implementations that support named, * coherent, shared memory, may return a <code>ByteBuffer</code> object * that will be changing dynamically over time as the target Java virtual * machine updates its mapping of this buffer. * <p> * If the <code>lvmid</code> is 0 or equal to the actual <code>lvmid</code> * for the Java virtual machine running this method, then the returned * <code>ByteBuffer</code> object will always be coherent and dynamically * changing. * <p> * The attach mode specifies the access permissions requested for the * instrumentation buffer of the target virtual machine. The permitted * access permissions are: * <p> * <bl> * <li>"r" - Read only access. This Java virtual machine has only * read access to the instrumentation buffer for the target Java * virtual machine. * <li>"rw" - Read/Write access. This Java virtual machine has read and * write access to the instrumentation buffer for the target Java virtual * machine. This mode is currently not supported and is reserved for * future enhancements. * </bl> * * @param lvmid an integer that uniquely identifies the * target local Java virtual machine. * @param mode a string indicating the attach mode. * @return ByteBuffer a direct allocated byte buffer * @throws IllegalArgumentException The lvmid or mode was invalid. * @throws IOException An I/O error occurred while trying to acquire * the instrumentation buffer. * @throws OutOfMemoryError The instrumentation buffer could not be mapped * into the virtual machine's address space. * @see java.nio.ByteBuffer */ public ByteBuffer attach(int lvmid, String mode) throws IllegalArgumentException, IOException { if (mode.compareTo("r") == 0) { return attachImpl(null, lvmid, PERF_MODE_RO); } else if (mode.compareTo("rw") == 0) { return attachImpl(null, lvmid, PERF_MODE_RW); } else { throw new IllegalArgumentException("unknown mode"); } } /** * Attach to the instrumentation buffer for the specified Java virtual * machine owned by the given user. * <p> * This method behaves just as the <code>attach(int lvmid, String mode) * </code> method, except that it only searches for Java virtual machines * owned by the specified user. * * @param user A <code>String</code> object containing the * name of the user that owns the target Java * virtual machine. * @param lvmid an integer that uniquely identifies the * target local Java virtual machine. * @param mode a string indicating the attach mode. * @return ByteBuffer a direct allocated byte buffer * @throws IllegalArgumentException The lvmid or mode was invalid. * @throws IOException An I/O error occurred while trying to acquire * the instrumentation buffer. * @throws OutOfMemoryError The instrumentation buffer could not be mapped * into the virtual machine's address space. * @see java.nio.ByteBuffer */ public ByteBuffer attach(String user, int lvmid, String mode) throws IllegalArgumentException, IOException { if (mode.compareTo("r") == 0) { return attachImpl(user, lvmid, PERF_MODE_RO); } else if (mode.compareTo("rw") == 0) { return attachImpl(user, lvmid, PERF_MODE_RW); } else { throw new IllegalArgumentException("unknown mode"); } } /** * Call the implementation specific attach method. * <p> * This method calls into the Java virtual machine to perform the platform * specific attach method. Buffers returned from this method are * internally managed as <code>PhantomRefereces</code> to provide for * guaranteed, secure release of the native resources. * * @param user A <code>String</code> object containing the * name of the user that owns the target Java * virtual machine. * @param lvmid an integer that uniquely identifies the * target local Java virtual machine. * @param mode a string indicating the attach mode. * @return ByteBuffer a direct allocated byte buffer * @throws IllegalArgumentException The lvmid or mode was invalid. * @throws IOException An I/O error occurred while trying to acquire * the instrumentation buffer. * @throws OutOfMemoryError The instrumentation buffer could not be mapped * into the virtual machine's address space. */ private ByteBuffer attachImpl(String user, int lvmid, int mode) throws IllegalArgumentException, IOException { final ByteBuffer b = attach(user, lvmid, mode); if (lvmid == 0) { // The native instrumentation buffer for this Java virtual // machine is never unmapped. return b; } else { // This is an instrumentation buffer for another Java virtual // machine with native resources that need to be managed. We // create a duplicate of the native ByteBuffer and manage it // with a Cleaner object (PhantomReference). When the duplicate // becomes only phantomly reachable, the native resources will // be released. final ByteBuffer dup = b.duplicate(); Cleaner.create(dup, new Runnable() { public void run() { try { instance.detach(b); } catch (Throwable th) { // avoid crashing the reference handler thread, // but provide for some diagnosability assert false : th.toString(); } } }); return dup; } } /** * Native method to perform the implementation specific attach mechanism. * <p> * The implementation of this method may return distinct or identical * <code>ByteBuffer</code> objects for two distinct calls requesting * attachment to the same Java virtual machine. * <p> * For the Sun HotSpot JVM, two distinct calls to attach to the same * target Java virtual machine will result in two distinct ByteBuffer * objects returned by this method. This may change in a future release. * * @param user A <code>String</code> object containing the * name of the user that owns the target Java * virtual machine. * @param lvmid an integer that uniquely identifies the * target local Java virtual machine. * @param mode a string indicating the attach mode. * @return ByteBuffer a direct allocated byte buffer * @throws IllegalArgumentException The lvmid or mode was invalid. * @throws IOException An I/O error occurred while trying to acquire * the instrumentation buffer. * @throws OutOfMemoryError The instrumentation buffer could not be mapped * into the virtual machine's address space. */ private native ByteBuffer attach(String user, int lvmid, int mode) throws IllegalArgumentException, IOException; /** * Native method to perform the implementation specific detach mechanism. * <p> * If this method is passed a <code>ByteBuffer</code> object that is * not created by the <code>attach</code> method, then the results of * this method are undefined, with unpredictable and potentially damaging * effects to the Java virtual machine. To prevent accidental or malicious * use of this method, all native ByteBuffer created by the <code> * attach</code> method are managed internally as PhantomReferences * and resources are freed by the system. * <p> * If this method is passed a <code>ByteBuffer</code> object created * by the <code>attach</code> method with a lvmid for the Java virtual * machine running this method (lvmid=0, for example), then the detach * request is silently ignored. * * @param ByteBuffer A direct allocated byte buffer created by the * <code>attach</code> method. * @see java.nio.ByteBuffer * @see #attach */ private native void detach(ByteBuffer bb); /** * Create a <code>long</code> scalar entry in the instrumentation buffer * with the given variability characteristic, units, and initial value. * <p> * Access to the instrument is provided through the returned <code> * ByteBuffer</code> object. Typically, this object should be wrapped * with <code>LongBuffer</code> view object. * * @param variability the variability characteristic for this entry. * @param units the units for this entry. * @param name the name of this entry. * @param value the initial value for this entry. * @return ByteBuffer a direct allocated ByteBuffer object that * allows write access to a native memory location * containing a <code>long</code> value. * * see sun.misc.perf.Variability * see sun.misc.perf.Units * @see java.nio.ByteBuffer */ public native ByteBuffer createLong(String name, int variability, int units, long value); /** * Create a <code>String</code> entry in the instrumentation buffer with * the given variability characteristic, units, and initial value. * <p> * The maximum length of the <code>String</code> stored in this string * instrument is given in by <code>maxLength</code> parameter. Updates * to this instrument with <code>String</code> values with lengths greater * than <code>maxLength</code> will be truncated to <code>maxLength</code>. * The truncated value will be terminated by a null character. * <p> * The underlying implementation may further limit the length of the * value, but will continue to preserve the null terminator. * <p> * Access to the instrument is provided through the returned <code> * ByteBuffer</code> object. * * @param variability the variability characteristic for this entry. * @param units the units for this entry. * @param name the name of this entry. * @param value the initial value for this entry. * @param maxLength the maximum string length for this string * instrument. * @return ByteBuffer a direct allocated ByteBuffer that allows * write access to a native memory location * containing a <code>long</code> value. * * see sun.misc.perf.Variability * see sun.misc.perf.Units * @see java.nio.ByteBuffer */ public ByteBuffer createString(String name, int variability, int units, String value, int maxLength) { byte[] v = getBytes(value); byte[] v1 = new byte[v.length+1]; System.arraycopy(v, 0, v1, 0, v.length); v1[v.length] = '\0'; return createByteArray(name, variability, units, v1, Math.max(v1.length, maxLength)); } /** * Create a <code>String</code> entry in the instrumentation buffer with * the given variability characteristic, units, and initial value. * <p> * The maximum length of the <code>String</code> stored in this string * instrument is implied by the length of the <code>value</code> parameter. * Subsequent updates to the value of this instrument will be truncated * to this implied maximum length. The truncated value will be terminated * by a null character. * <p> * The underlying implementation may further limit the length of the * initial or subsequent value, but will continue to preserve the null * terminator. * <p> * Access to the instrument is provided through the returned <code> * ByteBuffer</code> object. * * @param variability the variability characteristic for this entry. * @param units the units for this entry. * @param name the name of this entry. * @param value the initial value for this entry. * @return ByteBuffer a direct allocated ByteBuffer that allows * write access to a native memory location * containing a <code>long</code> value. * * see sun.misc.perf.Variability * see sun.misc.perf.Units * @see java.nio.ByteBuffer */ public ByteBuffer createString(String name, int variability, int units, String value) { byte[] v = getBytes(value); byte[] v1 = new byte[v.length+1]; System.arraycopy(v, 0, v1, 0, v.length); v1[v.length] = '\0'; return createByteArray(name, variability, units, v1, v1.length); } /** * Create a <code>byte</code> vector entry in the instrumentation buffer * with the given variability characteristic, units, and initial value. * <p> * The <code>maxLength</code> parameter limits the size of the byte * array instrument such that the initial or subsequent updates beyond * this length are silently ignored. No special handling of truncated * updates is provided. * <p> * The underlying implementation may further limit the length of the * length of the initial or subsequent value. * <p> * Access to the instrument is provided through the returned <code> * ByteBuffer</code> object. * * @param variability the variability characteristic for this entry. * @param units the units for this entry. * @param name the name of this entry. * @param value the initial value for this entry. * @param maxLength the maximum length of this byte array. * @return ByteBuffer a direct allocated byte buffer that allows * write access to a native memory location * containing a <code>long</code> value. * * see sun.misc.perf.Variability * see sun.misc.perf.Units * @see java.nio.ByteBuffer */ public native ByteBuffer createByteArray(String name, int variability, int units, byte[] value, int maxLength); /** * 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 } Lines 1–500 of 539. 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/* * Copyright (c) 2002, 2006, 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. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * 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 sun.misc; import java.nio.ByteBuffer; import java.security.Permission; import java.security.PrivilegedAction; import java.io.IOException; import java.io.UnsupportedEncodingException; /** * The Perf class provides the ability to attach to an instrumentation * buffer maintained by a Java virtual machine. The instrumentation * buffer may be for the Java virtual machine running the methods of * this class or it may be for another Java virtual machine on the * same system. * <p> * In addition, this class provides methods to create instrumentation * objects in the instrumentation buffer for the Java virtual machine * that is running these methods. It also contains methods for acquiring * the value of a platform specific high resolution clock for time * stamp and interval measurement purposes. * * @author Brian Doherty * @since 1.4.2 * @see #getPerf * @see sun.misc.Perf$GetPerfAction * @see java.nio.ByteBuffer */ public final class Perf { private static Perf instance; private static final int PERF_MODE_RO = 0; private static final int PERF_MODE_RW = 1; private Perf() { } // prevent instantiation /** * The GetPerfAction class is a convenience class for acquiring access * to the singleton Perf instance using the * <code>AccessController.doPrivileged()</code> method. * <p> * An instance of this class can be used as the argument to * <code>AccessController.doPrivileged(PrivilegedAction)</code>. * <p> Here is a suggested idiom for use of this class: * * <blockquote><pre> * class MyTrustedClass { * private static final Perf perf = * AccessController.doPrivileged(new Perf.GetPerfAction<Perf>()); * ... * } * </pre></blockquote> * <p> * In the presence of a security manager, the <code>MyTrustedClass</code> * class in the above example will need to be granted the * <em>"sun.misc.Perf.getPerf"</em> <code>RuntimePermission</code> * permission in order to successfully acquire the singleton Perf instance. * <p> * Please note that the <em>"sun.misc.Perf.getPerf"</em> permission * is not a JDK specified permission. * * @see java.security.AccessController#doPrivileged(PrivilegedAction) * @see java.lang.RuntimePermission */ public static class GetPerfAction implements PrivilegedAction<Perf> { /** * Run the <code>Perf.getPerf()</code> method in a privileged context. * * @see #getPerf */ public Perf run() { return getPerf(); } } /** * Return a reference to the singleton Perf instance. * <p> * The getPerf() method returns the singleton instance of the Perf * class. The returned object provides the caller with the capability * for accessing the instrumentation buffer for this or another local * Java virtual machine. * <p> * If a security manager is installed, its <code>checkPermission</code> * method is called with a <code>RuntimePermission</code> with a target * of <em>"sun.misc.Perf.getPerf"</em>. A security exception will result * if the caller has not been granted this permission. * <p> * Access to the returned <code>Perf</code> object should be protected * by its caller and not passed on to untrusted code. This object can * be used to attach to the instrumentation buffer provided by this Java * virtual machine or for those of other Java virtual machines running * on the same system. The instrumentation buffer may contain senstitive * information. API's built on top of this interface may want to provide * finer grained access control to the contents of individual * instrumentation objects contained within the buffer. * <p> * Please note that the <em>"sun.misc.Perf.getPerf"</em> permission * is not a JDK specified permission. * * @return A reference to the singleton Perf instance. * @throws AccessControlException if a security manager exists and * its <code>checkPermission</code> method doesn't allow * access to the <em>"sun.misc.Perf.getPerf"</em> target. * @see java.lang.RuntimePermission * @see #attach */ public static Perf getPerf() { SecurityManager security = System.getSecurityManager(); if (security != null) { Permission perm = new RuntimePermission("sun.misc.Perf.getPerf"); security.checkPermission(perm); } return instance; } /** * Attach to the instrumentation buffer for the specified Java virtual * machine. * <p> * This method will attach to the instrumentation buffer for the * specified virtual machine. It returns a <code>ByteBuffer</code> object * that is initialized to access the instrumentation buffer for the * indicated Java virtual machine. The <code>lvmid</code> parameter is * a integer value that uniquely identifies the target local Java virtual * machine. It is typically, but not necessarily, the process id of * the target Java virtual machine. * <p> * If the <code>lvmid</code> identifies a Java virtual machine different * from the one running this method, then the coherency characteristics * of the buffer are implementation dependent. Implementations that do * not support named, coherent, shared memory may return a * <code>ByteBuffer</code> object that contains only a snap shot of the * data in the instrumentation buffer. Implementations that support named, * coherent, shared memory, may return a <code>ByteBuffer</code> object * that will be changing dynamically over time as the target Java virtual * machine updates its mapping of this buffer. * <p> * If the <code>lvmid</code> is 0 or equal to the actual <code>lvmid</code> * for the Java virtual machine running this method, then the returned * <code>ByteBuffer</code> object will always be coherent and dynamically * changing. * <p> * The attach mode specifies the access permissions requested for the * instrumentation buffer of the target virtual machine. The permitted * access permissions are: * <p> * <bl> * <li>"r" - Read only access. This Java virtual machine has only * read access to the instrumentation buffer for the target Java * virtual machine. * <li>"rw" - Read/Write access. This Java virtual machine has read and * write access to the instrumentation buffer for the target Java virtual * machine. This mode is currently not supported and is reserved for * future enhancements. * </bl> * * @param lvmid an integer that uniquely identifies the * target local Java virtual machine. * @param mode a string indicating the attach mode. * @return ByteBuffer a direct allocated byte buffer * @throws IllegalArgumentException The lvmid or mode was invalid. * @throws IOException An I/O error occurred while trying to acquire * the instrumentation buffer. * @throws OutOfMemoryError The instrumentation buffer could not be mapped * into the virtual machine's address space. * @see java.nio.ByteBuffer */ public ByteBuffer attach(int lvmid, String mode) throws IllegalArgumentException, IOException { if (mode.compareTo("r") == 0) { return attachImpl(null, lvmid, PERF_MODE_RO); } else if (mode.compareTo("rw") == 0) { return attachImpl(null, lvmid, PERF_MODE_RW); } else { throw new IllegalArgumentException("unknown mode"); } } /** * Attach to the instrumentation buffer for the specified Java virtual * machine owned by the given user. * <p> * This method behaves just as the <code>attach(int lvmid, String mode) * </code> method, except that it only searches for Java virtual machines * owned by the specified user. * * @param user A <code>String</code> object containing the * name of the user that owns the target Java * virtual machine. * @param lvmid an integer that uniquely identifies the * target local Java virtual machine. * @param mode a string indicating the attach mode. * @return ByteBuffer a direct allocated byte buffer * @throws IllegalArgumentException The lvmid or mode was invalid. * @throws IOException An I/O error occurred while trying to acquire * the instrumentation buffer. * @throws OutOfMemoryError The instrumentation buffer could not be mapped * into the virtual machine's address space. * @see java.nio.ByteBuffer */ public ByteBuffer attach(String user, int lvmid, String mode) throws IllegalArgumentException, IOException { if (mode.compareTo("r") == 0) { return attachImpl(user, lvmid, PERF_MODE_RO); } else if (mode.compareTo("rw") == 0) { return attachImpl(user, lvmid, PERF_MODE_RW); } else { throw new IllegalArgumentException("unknown mode"); } } /** * Call the implementation specific attach method. * <p> * This method calls into the Java virtual machine to perform the platform * specific attach method. Buffers returned from this method are * internally managed as <code>PhantomRefereces</code> to provide for * guaranteed, secure release of the native resources. * * @param user A <code>String</code> object containing the * name of the user that owns the target Java * virtual machine. * @param lvmid an integer that uniquely identifies the * target local Java virtual machine. * @param mode a string indicating the attach mode. * @return ByteBuffer a direct allocated byte buffer * @throws IllegalArgumentException The lvmid or mode was invalid. * @throws IOException An I/O error occurred while trying to acquire * the instrumentation buffer. * @throws OutOfMemoryError The instrumentation buffer could not be mapped * into the virtual machine's address space. */ private ByteBuffer attachImpl(String user, int lvmid, int mode) throws IllegalArgumentException, IOException { final ByteBuffer b = attach(user, lvmid, mode); if (lvmid == 0) { // The native instrumentation buffer for this Java virtual // machine is never unmapped. return b; } else { // This is an instrumentation buffer for another Java virtual // machine with native resources that need to be managed. We // create a duplicate of the native ByteBuffer and manage it // with a Cleaner object (PhantomReference). When the duplicate // becomes only phantomly reachable, the native resources will // be released. final ByteBuffer dup = b.duplicate(); Cleaner.create(dup, new Runnable() { public void run() { try { instance.detach(b); } catch (Throwable th) { // avoid crashing the reference handler thread, // but provide for some diagnosability assert false : th.toString(); } } }); return dup; } } /** * Native method to perform the implementation specific attach mechanism. * <p> * The implementation of this method may return distinct or identical * <code>ByteBuffer</code> objects for two distinct calls requesting * attachment to the same Java virtual machine. * <p> * For the Sun HotSpot JVM, two distinct calls to attach to the same * target Java virtual machine will result in two distinct ByteBuffer * objects returned by this method. This may change in a future release. * * @param user A <code>String</code> object containing the * name of the user that owns the target Java * virtual machine. * @param lvmid an integer that uniquely identifies the * target local Java virtual machine. * @param mode a string indicating the attach mode. * @return ByteBuffer a direct allocated byte buffer * @throws IllegalArgumentException The lvmid or mode was invalid. * @throws IOException An I/O error occurred while trying to acquire * the instrumentation buffer. * @throws OutOfMemoryError The instrumentation buffer could not be mapped * into the virtual machine's address space. */ private native ByteBuffer attach(String user, int lvmid, int mode) throws IllegalArgumentException, IOException; /** * Native method to perform the implementation specific detach mechanism. * <p> * If this method is passed a <code>ByteBuffer</code> object that is * not created by the <code>attach</code> method, then the results of * this method are undefined, with unpredictable and potentially damaging * effects to the Java virtual machine. To prevent accidental or malicious * use of this method, all native ByteBuffer created by the <code> * attach</code> method are managed internally as PhantomReferences * and resources are freed by the system. * <p> * If this method is passed a <code>ByteBuffer</code> object created * by the <code>attach</code> method with a lvmid for the Java virtual * machine running this method (lvmid=0, for example), then the detach * request is silently ignored. * * @param ByteBuffer A direct allocated byte buffer created by the * <code>attach</code> method. * @see java.nio.ByteBuffer * @see #attach */ private native void detach(ByteBuffer bb); /** * Create a <code>long</code> scalar entry in the instrumentation buffer * with the given variability characteristic, units, and initial value. * <p> * Access to the instrument is provided through the returned <code> * ByteBuffer</code> object. Typically, this object should be wrapped * with <code>LongBuffer</code> view object. * * @param variability the variability characteristic for this entry. * @param units the units for this entry. * @param name the name of this entry. * @param value the initial value for this entry. * @return ByteBuffer a direct allocated ByteBuffer object that * allows write access to a native memory location * containing a <code>long</code> value. * * see sun.misc.perf.Variability * see sun.misc.perf.Units * @see java.nio.ByteBuffer */ public native ByteBuffer createLong(String name, int variability, int units, long value); /** * Create a <code>String</code> entry in the instrumentation buffer with * the given variability characteristic, units, and initial value. * <p> * The maximum length of the <code>String</code> stored in this string * instrument is given in by <code>maxLength</code> parameter. Updates * to this instrument with <code>String</code> values with lengths greater * than <code>maxLength</code> will be truncated to <code>maxLength</code>. * The truncated value will be terminated by a null character. * <p> * The underlying implementation may further limit the length of the * value, but will continue to preserve the null terminator. * <p> * Access to the instrument is provided through the returned <code> * ByteBuffer</code> object. * * @param variability the variability characteristic for this entry. * @param units the units for this entry. * @param name the name of this entry. * @param value the initial value for this entry. * @param maxLength the maximum string length for this string * instrument. * @return ByteBuffer a direct allocated ByteBuffer that allows * write access to a native memory location * containing a <code>long</code> value. * * see sun.misc.perf.Variability * see sun.misc.perf.Units * @see java.nio.ByteBuffer */ public ByteBuffer createString(String name, int variability, int units, String value, int maxLength) { byte[] v = getBytes(value); byte[] v1 = new byte[v.length+1]; System.arraycopy(v, 0, v1, 0, v.length); v1[v.length] = '\0'; return createByteArray(name, variability, units, v1, Math.max(v1.length, maxLength)); } /** * Create a <code>String</code> entry in the instrumentation buffer with * the given variability characteristic, units, and initial value. * <p> * The maximum length of the <code>String</code> stored in this string * instrument is implied by the length of the <code>value</code> parameter. * Subsequent updates to the value of this instrument will be truncated * to this implied maximum length. The truncated value will be terminated * by a null character. * <p> * The underlying implementation may further limit the length of the * initial or subsequent value, but will continue to preserve the null * terminator. * <p> * Access to the instrument is provided through the returned <code> * ByteBuffer</code> object. * * @param variability the variability characteristic for this entry. * @param units the units for this entry. * @param name the name of this entry. * @param value the initial value for this entry. * @return ByteBuffer a direct allocated ByteBuffer that allows * write access to a native memory location * containing a <code>long</code> value. * * see sun.misc.perf.Variability * see sun.misc.perf.Units * @see java.nio.ByteBuffer */ public ByteBuffer createString(String name, int variability, int units, String value) { byte[] v = getBytes(value); byte[] v1 = new byte[v.length+1]; System.arraycopy(v, 0, v1, 0, v.length); v1[v.length] = '\0'; return createByteArray(name, variability, units, v1, v1.length); } /** * Create a <code>byte</code> vector entry in the instrumentation buffer * with the given variability characteristic, units, and initial value. * <p> * The <code>maxLength</code> parameter limits the size of the byte * array instrument such that the initial or subsequent updates beyond * this length are silently ignored. No special handling of truncated * updates is provided. * <p> * The underlying implementation may further limit the length of the * length of the initial or subsequent value. * <p> * Access to the instrument is provided through the returned <code> * ByteBuffer</code> object. * * @param variability the variability characteristic for this entry. * @param units the units for this entry. * @param name the name of this entry. * @param value the initial value for this entry. * @param maxLength the maximum length of this byte array. * @return ByteBuffer a direct allocated byte buffer that allows * write access to a native memory location * containing a <code>long</code> value. * * see sun.misc.perf.Variability * see sun.misc.perf.Units * @see java.nio.ByteBuffer */ public native ByteBuffer createByteArray(String name, int variability, int units, byte[] value, int maxLength); /** * 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 }