1 /*

     2  * Copyright (c) 2008, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package com.sun.tracing;

    27 

    28 /**

    29  * The {@code Probe} interface represents a tracepoint.

    30  *

    31  * A {@code Probe} instance is obtained by calling the

    32  * {@code Provider.getProbe()} method of a provider instance created by

    33  * {@code ProviderFactory.createProvider()}.  A {@code Probe} can be used to

    34  * trigger a probe manually (provided the correct arguments are passed to

    35  * it), or to check a probe to see if anything is currently tracing it.

    36  * <p>

    37  * A tracing check can be used to avoid lengthy work that might be

    38  * needed to set up the probe's arguments.  However, checking

    39  * whether the probe is enabled generally takes the same amount of time

    40  * as actually triggering the probe. So, you should only check a probe's status

    41  * without triggering it if setting up the arguments is very expensive.

    42  * <p>

    43  * Users do not need to implement this interface: instances are

    44  * created automatically by the system when a {@code Provider)} instance is

    45  * created.

    46  * <p>

    47  * @since 1.7

    48  */

    49 

    50 public interface Probe {

    51     /**

    52      * Checks whether there is an active trace of this probe.

    53      *

    54      * @return true if an active trace is detected.

    55      */

    56     boolean isEnabled();

    57 

    58     /**

    59      * Determines whether a tracepoint is enabled.

    60      *

    61      * Typically, users do not need to use this method. It is called

    62      * automatically when a Provider's instance method is called. Calls to

    63      * this method expect the arguments to match the declared parameters for

    64      * the method associated with the probe.

    65      *

    66      * @param args the parameters to pass to the method.

    67      * @throws IllegalArgumentException if the provided parameters do not

    68      * match the method declaration for this probe.

    69      */

    70     void trigger(Object ... args);

    71 }