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

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 * accompanied this code).

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package com.sun.jdi.request;

/**

 * Represents a request for notification of an event.  Examples include

 * {@link BreakpointRequest} and {@link ExceptionRequest}.

 * When an event occurs for which an enabled request is present,

 * The collection of existing event requests is

 * managed by the {@link EventRequestManager}.

 * <p>

 * The number of events generated for an event request can be controlled

 * through filters. Filters provide additional constraints that an event

 * must satisfy before it is placed on the event queue. Multiple filters can

 * be used by making multiple calls to filter addition methods such as

 * {@link ExceptionRequest#addClassFilter(java.lang.String classPattern)}.

 * Filters are added to an event one at a time only while the event is

 * disabled. Multiple filters are applied with CUT-OFF AND, in the order

 * it was added to the request. Only events that satisfy all filters are

 * placed in the event queue.

 * <p>

 * The set of available filters is dependent on the event request,

 * some examples of filters are:

 * <ul>

 * <li>Thread filters allow control over the thread for which events are

 * generated.

 * <li>Class filters allow control over the class in which the event

 * occurs.

 * <li>Instance filters allow control over the instance in which

 * the event occurs.

 * <li>Count filters allow control over the number of times an event

 * is reported.

 * </ul>

 * Filters can dramatically improve debugger performance by reducing the

 * amount of event traffic sent from the target VM to the debugger VM.

 * <p>

 * Any method on {@code EventRequest} which

 * takes {@code EventRequest} as an parameter may throw

 * <p>

 * Any method on {@code EventRequest} which

 * takes {@code EventRequest} as an parameter may throw

 *

 * @see EventRequestManager

 *

 * @author Robert Field

 * @since  1.3

 */

public interface EventRequest extends Mirror {

    /**

     * Determines if this event request is currently enabled.

     *

     * @return {@code true} if enabled;

     * {@code false} otherwise.

     */

    boolean isEnabled();

    /**

     * Enables or disables this event request. While this event request is

     * disabled, the event request will be ignored and the target VM

     * will not be stopped if any of its threads reaches the

     * event request.  Disabled event requests still exist,

     * and are included in event request lists such as

     * {@link EventRequestManager#breakpointRequests()}.

     *

     * @param val {@code true} if the event request is to be enabled;

     * {@code false} otherwise.

     * @throws InvalidRequestStateException if this request

     * has been deleted.

     * @throws IllegalThreadStateException if this is a StepRequest,

     * {@code val} is {@code true}, and the

     * thread named in the request has died or is not yet started.

     */

    void setEnabled(boolean val);

    /**

     * Same as {@link #setEnabled setEnabled(true)}.

     * @throws InvalidRequestStateException if this request

     * has been deleted.

     * @throws IllegalThreadStateException if this is a StepRequest

     * and the thread named in the request has died or is not yet started.

     */

    void enable();

    /**

     * Same as {@link #setEnabled setEnabled(false)}.

     * @throws InvalidRequestStateException if this request

     * has been deleted.

     */

    void disable();

    /**

     * Limit the requested event to be reported at most once after a

     * given number of occurrences.  The event is not reported

     * the first {@code count - 1} times this filter is reached.

     * To request a one-off event, call this method with a count of 1.

     * <p>

     * Once the count reaches 0, any subsequent filters in this request

     * are applied. If none of those filters cause the event to be

     * suppressed, the event is reported. Otherwise, the event is not

     * reported. In either case subsequent events are never reported for

     * this request.

     *

     * @param count the number of ocurrences before generating an event.

     * @throws InvalidRequestStateException if this request is currently

     * enabled or has been deleted.

     * Filters may be added only to disabled requests.

     * @throws IllegalArgumentException if {@code count}

     * is less than one.

     */

    void addCountFilter(int count);

    /** Suspend no threads when the event occurs */

    int SUSPEND_NONE = 0;

    /** Suspend only the thread which generated the event when the event occurs */

    int SUSPEND_EVENT_THREAD = 1;

    /** Suspend all threads when the event occurs */

    int SUSPEND_ALL = 2;

    /**

     * Determines the threads to suspend when the requested event occurs

     * in the target VM. Use {@link #SUSPEND_ALL} to suspend all

     * threads in the target VM (the default). Use {@link #SUSPEND_EVENT_THREAD}

     * to suspend only the thread which generated the event. Use

     * {@link #SUSPEND_NONE} to suspend no threads.

     * <p>

     * Thread suspensions through events have the same functionality

     * as explicitly requested suspensions. See

     *

     * @param policy the selected suspend policy.

     * @throws InvalidRequestStateException if this request is currently

     * enabled or has been deleted.

     * Suspend policy may only be set in disabled requests.

     * @throws IllegalArgumentException if the policy argument

     * contains an illegal value.

     */

    void setSuspendPolicy(int policy);

    /**

     * Returns a value which describes the threads to suspend when the

     * requested event occurs in the target VM.

     * The returned value is  {@link #SUSPEND_ALL},

     * {@link #SUSPEND_EVENT_THREAD}, or {@link #SUSPEND_NONE}.

     *

     * @return the current suspend mode for this request

     */

    int suspendPolicy();

    /**

     * Add an arbitrary key/value "property" to this request.

     * The property can be used by a client of the JDI to

     * associate application information with the request;

     * These client-set properties are not used internally

     * by the JDI.

     * <p>

     * The {@code get/putProperty} methods provide access to

     * a small per-instance map. This is <b>not</b> to be confused

     * with {@link java.util.Properties}.

     * <p>

     * If value is null this method will remove the property.

     *

     * @see #getProperty

     */

    void putProperty(Object key, Object value);

    /**

     * Returns the value of the property with the specified key.  Only

     * properties added with {@link #putProperty} will return

     * a non-null value.

     *

     * @return the value of this property or null

     * @see #putProperty

     */

    Object getProperty(Object key);

}