org.eclipse.jdt.debug/model/org/eclipse/jdt/internal/debug/core/breakpoints/JavaWatchpoint.java

/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.debug.core.breakpoints;

 
import java.util.HashMap;
import java.util.Map;

import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IWorkspaceRunnable;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.debug.core.DebugException;
import org.eclipse.debug.core.DebugPlugin;
import org.eclipse.debug.core.model.IDebugTarget;
import org.eclipse.jdt.debug.core.IJavaWatchpoint;
import org.eclipse.jdt.internal.debug.core.JDIDebugPlugin;
import org.eclipse.jdt.internal.debug.core.model.JDIDebugTarget;

import com.sun.jdi.Field;
import com.sun.jdi.ObjectReference;
import com.sun.jdi.ReferenceType;
import com.sun.jdi.ThreadReference;
import com.sun.jdi.VMDisconnectedException;
import com.sun.jdi.event.AccessWatchpointEvent;
import com.sun.jdi.event.Event;
import com.sun.jdi.event.ModificationWatchpointEvent;
import com.sun.jdi.request.AccessWatchpointRequest;
import com.sun.jdi.request.EventRequest;
import com.sun.jdi.request.EventRequestManager;
import com.sun.jdi.request.ModificationWatchpointRequest;
import com.sun.jdi.request.WatchpointRequest;

public class JavaWatchpoint extends JavaLineBreakpoint implements IJavaWatchpoint {
	
	private static final String JAVA_WATCHPOINT= "org.eclipse.jdt.debug.javaWatchpointMarker"; //$NON-NLS-1$
	/**
	 * Watchpoint attribute storing the access value (value <code>"org.eclipse.jdt.debug.core.access"</code>).
	 * This attribute is stored as a <code>boolean</code>, indicating whether a
	 * watchpoint is an access watchpoint.
	 */
	protected static final String ACCESS= "org.eclipse.jdt.debug.core.access"; //$NON-NLS-1$
	/**
	 * Watchpoint attribute storing the modification value (value <code>"org.eclipse.jdt.debug.core.modification"</code>).
	 * This attribute is stored as a <code>boolean</code>, indicating whether a
	 * watchpoint is a modification watchpoint.
	 */
	protected static final String MODIFICATION= "org.eclipse.jdt.debug.core.modification"; //$NON-NLS-1$	
	/**
	 * Watchpoint attribute storing the auto_disabled value (value <code>"org.eclipse.jdt.debug.core.auto_disabled"</code>).
	 * This attribute is stored as a <code>boolean</code>, indicating whether a
	 * watchpoint has been auto-disabled (as opposed to being disabled explicitly by the user)
	 */
	protected static final String AUTO_DISABLED="org.eclipse.jdt.debug.core.auto_disabled"; //$NON-NLS-1$

	/**
	 * Breakpoint attribute storing the name of the field
	 * on which a breakpoint is set.
	 * (value <code>"org.eclipse.jdt.debug.core.fieldName"</code>). This attribute is a <code>String</code>.
	 */
	protected static final String FIELD_NAME= "org.eclipse.jdt.debug.core.fieldName"; //$NON-NLS-1$		
	/**
	 * Flag indicating that this breakpoint last suspended execution
	 * due to a field access
	 */
	protected static final Integer ACCESS_EVENT= new Integer(0); //$NON-NLS-1$
	/**
	 * Flag indicating that this breakpoint last suspended execution
	 * due to a field modification
	 */	
	protected static final Integer MODIFICATION_EVENT= new Integer(1); //$NON-NLS-1$
	/**
	 * Maps each debug target that is suspended for this breakpiont to reason that 
	 * this breakpoint suspended it. Reasons include:
	 * <ol>
	 * <li>Field access (value <code>ACCESS_EVENT</code>)</li>
	 * <li>Field modification (value <code>MODIFICATION_EVENT</code>)</li>
	 * </ol>
	 */
	private HashMap fLastEventTypes= new HashMap(10); //$NON-NLS-1$
	
	public JavaWatchpoint() {
	}

	/**
	 * @see JDIDebugModel#createWatchpoint(IResource, String, String, int, int, int, int, boolean, Map)
	 */
	public JavaWatchpoint(final IResource resource, final String typeName, final String fieldName, final int lineNumber, final int charStart, final int charEnd, final int hitCount, final boolean add, final Map attributes) throws DebugException {
		IWorkspaceRunnable wr= new IWorkspaceRunnable() {
			public void run(IProgressMonitor monitor) throws CoreException {		
				setMarker(resource.createMarker(JAVA_WATCHPOINT));
				
				// add attributes
				addLineBreakpointAttributes(attributes, getModelIdentifier(), true, lineNumber, charStart, charEnd);
				addTypeNameAndHitCount(attributes, typeName, hitCount);
				// configure the field handle
				addFieldName(attributes, fieldName);
				// configure the access and modification flags to defaults
				addDefaultAccessAndModification(attributes);			
				
				// set attributes
				ensureMarker().setAttributes(attributes);
				
				register(add);
			}
		};
		run(null, wr);
	}
	
	/**
	 * @see JavaBreakpoint#createRequest(JDIDebugTarget, ReferenceType)
	 * 
	 * Creates and installs an access and modification watchpoint request
	 * in the given reference type, configuring the requests as appropriate
	 * for this watchpoint. The requests are then enabled based on whether
	 * this watchpoint is an access watchpoint, modification watchpoint, or
	 * both. Finally, the requests are registered with the given target.
	 */	
	protected boolean createRequest(JDIDebugTarget target, ReferenceType type) throws CoreException {
		if (shouldSkipBreakpoint()) {
			return false;
		}
		Field field= null;
		
		field= type.fieldByName(getFieldName());
		if (field == null) {
			// error
			return false;
		}
		AccessWatchpointRequest accessRequest= null;
		ModificationWatchpointRequest modificationRequest= null;			
		if (target.supportsAccessWatchpoints()) {
			accessRequest= createAccessWatchpoint(target, field);
			registerRequest(accessRequest, target);
		} else {
			notSupported(JDIDebugBreakpointMessages.getString("JavaWatchpoint.no_access_watchpoints"));				 //$NON-NLS-1$
		}
		if (target.supportsModificationWatchpoints()) {
			modificationRequest= createModificationWatchpoint(target, field);
			if (modificationRequest == null) {
				return false;
			} 
			registerRequest(modificationRequest, target);
			return true;
		}
		notSupported(JDIDebugBreakpointMessages.getString("JavaWatchpoint.no_modification_watchpoints")); //$NON-NLS-1$
		return false;
	}
	
	/**
	 * @see JavaBreakpoint#setRequestThreadFilter(EventRequest)
	 */
	protected void setRequestThreadFilter(EventRequest request, ThreadReference thread) {
		((WatchpointRequest)request).addThreadFilter(thread);
	}
	
	/**
	 * Either access or modification watchpoints are not supported. Throw an appropriate exception.
	 * 
	 * @param message the message that states that access or modification watchpoints
	 *  are not supported
	 */
	protected void notSupported(String message) throws DebugException {
		throw new DebugException(new Status(IStatus.ERROR, DebugPlugin.getUniqueIdentifier(), 
			DebugException.NOT_SUPPORTED, message, null)); //$NON-NLS-1$		
	}
	
	/**
	 * Create an access watchpoint for the given breakpoint and associated field
	 */
	protected AccessWatchpointRequest createAccessWatchpoint(JDIDebugTarget target, Field field) throws CoreException {
		return (AccessWatchpointRequest) createWatchpoint(target, field, true);
	}
	
	/**
	 * Create a modification watchpoint for the given breakpoint and associated field
	 */
	protected ModificationWatchpointRequest createModificationWatchpoint(JDIDebugTarget target, Field field) throws CoreException {
		return (ModificationWatchpointRequest) createWatchpoint(target, field, false);		
	}	
	
	/**
	 * Create a watchpoint for the given breakpoint and associated field.
	 * 
	 * @param target the target in which the request will be installed
	 * @param field the field on which the request will be set
	 * @param access <code>true</code> if an access watchpoint will be 
	 *  created. <code>false</code> if a modification watchpoint will
	 *  be created.
	 * 
	 * @return an WatchpointRequest (AccessWatchpointRequest if access is
	 *  <code>true</code>; ModificationWatchpointRequest if access is <code>false</code>).
	 */
	protected WatchpointRequest createWatchpoint(JDIDebugTarget target, Field field, boolean access) throws CoreException {
		WatchpointRequest request= null;
		EventRequestManager manager = target.getEventRequestManager();
		if (manager == null) {
			target.requestFailed(JDIDebugBreakpointMessages.getString("JavaWatchpoint.Unable_to_create_breakpoint_request_-_VM_disconnected._1"), null);  //$NON-NLS-1$
		}		
		try {
			if (access) {
				request= manager.createAccessWatchpointRequest(field);
			} else {
				request= manager.createModificationWatchpointRequest(field);
			}
			configureRequest(request, target);
		} catch (VMDisconnectedException e) {
			if (!target.isAvailable()) {
				return null;
			}
			target.internalError(e);
			return null;
		} catch (RuntimeException e) {
			target.internalError(e);
			return null;
		}
		return request;
	}

	/**
	 * @see JavaBreakpoint#recreateRequest(EventRequest, JDIDebugTarget)
	 */
	protected EventRequest recreateRequest(EventRequest request, JDIDebugTarget target) throws CoreException {
		try {	
			Field field= ((WatchpointRequest) request).field();
			if (request instanceof AccessWatchpointRequest) {
				request= createAccessWatchpoint(target, field);
			} else if (request instanceof ModificationWatchpointRequest) {
				request= createModificationWatchpoint(target, field);
			}
		} catch (VMDisconnectedException e) {
			if (!target.isAvailable()) {
				return request;
			}
			target.internalError(e);
			return request;
		} catch (RuntimeException e) {
			JDIDebugPlugin.log(e);
		}
		return request;
	}

	/**
	 * @see IBreakpoint#setEnabled(boolean)
	 * 
	 * If the watchpoint is not watching access or modification,
	 * set the default values. If this isn't done, the resulting
	 * state (enabled with access and modification both disabled)
	 * is ambiguous.
	 */
	public void setEnabled(boolean enabled) throws CoreException {
		if (enabled) {
			if (!(isAccess() || isModification())) {
				setDefaultAccessAndModification();
			}
		}
		super.setEnabled(enabled);
	}
	
	/**
	 * @see IJavaWatchpoint#isAccess()
	 */
	public boolean isAccess() throws CoreException {
		return ensureMarker().getAttribute(ACCESS, false);
	}
	
	/**
	 * @see IJavaWatchpoint#setAccess(boolean)
	 */
	public void setAccess(boolean access) throws CoreException {
		if (access == isAccess()) {
			return;
		}		
		setAttribute(ACCESS, access);
		if (access && !isEnabled()) {
			setEnabled(true);
		} else if (!(access || isModification())) {
			setEnabled(false);
		}
		recreate();
	}
	
	/**
	 * @see IJavaWatchpoint#isModification()
	 */	
	public boolean isModification() throws CoreException {
		return ensureMarker().getAttribute(MODIFICATION, false);
	}
	
	/**
	 * @see IJavaWatchpoint#setModification(boolean)
	 */
	public void setModification(boolean modification) throws CoreException {
		if (modification == isModification()) {
			return;
		}
		setAttribute(MODIFICATION, modification);
		if (modification && !isEnabled()) {
			setEnabled(true);
		} else if (!(modification || isAccess())) {
			setEnabled(false);
		}
		recreate();
	}
		
	/**
	 * Sets the default access and modification attributes of the watchpoint.
	 * The default values are:
	 * <ul>
	 * <li>access = <code>false</code>
	 * <li>modification = <code>true</code>
	 * <ul>
	 */
	protected void setDefaultAccessAndModification() throws CoreException {
		Object[] values= new Object[]{Boolean.TRUE, Boolean.TRUE};
		String[] attributes= new String[]{ACCESS, MODIFICATION};
		setAttributes(attributes, values);
	}


	/**
	 * Adds the default access and modification attributes of
	 * the watchpoint to the given map
	 * <ul>
	 * <li>access = true
	 * <li>modification = true
	 * <li>auto disabled = false
	 * <ul>
	 */
	protected void addDefaultAccessAndModification(Map attributes) {
		attributes.put(ACCESS, Boolean.TRUE);
		attributes.put(MODIFICATION, Boolean.TRUE);
		attributes.put(AUTO_DISABLED, Boolean.FALSE);
	}
	
	/**
	 * Adds the field name to the given attribute map
	 */
	protected void addFieldName(Map attributes, String fieldName) {
		attributes.put(FIELD_NAME, fieldName);
	}	

	/**
	 * @see IJavaWatchpoint#getFieldName()
	 */
	public String getFieldName() throws CoreException {
		return ensureMarker().getAttribute(FIELD_NAME, null);
	}
	
	/**
	 * Store the type of the event, then handle it as specified in
	 * the superclass. This is useful for correctly generating the
	 * thread text when asked (assumes thread text is requested after
	 * the event is passed to this breakpoint.
	 * 
	 * Also, @see JavaBreakpoint#handleEvent(Event, JDIDebugTarget)
	 */
	public boolean handleEvent(Event event, JDIDebugTarget target)  {
		if (event instanceof AccessWatchpointEvent) {
			fLastEventTypes.put(target, ACCESS_EVENT);
		} else if (event instanceof ModificationWatchpointEvent) {
			fLastEventTypes.put(target, MODIFICATION_EVENT);
		}
		return super.handleEvent(event, target);
	}	
	
	
	/**
	 * @see JavaBreakpoint#updateEnabledState(EventRequest)
	 */
	protected void updateEnabledState(EventRequest request) throws CoreException  {
		boolean enabled = isEnabled();
		if (request instanceof AccessWatchpointRequest) {
			if (isAccess()) {
				if (enabled != request.isEnabled()) {
					internalUpdateEnabledState(request, enabled);
				}
			} else {
				if (request.isEnabled()) {
					internalUpdateEnabledState(request, false);
				}
			}
		}
		if (request instanceof ModificationWatchpointRequest) {
			if (isModification()) {
				if (enabled != request.isEnabled()) {
					internalUpdateEnabledState(request, enabled);
				}
			} else {
				if (request.isEnabled()) {
					internalUpdateEnabledState(request, false);
				}
			}
		}
	}
	
	/**
	 * @see IJavaWatchpoint#isAccessSuspend(IDebugTarget)
	 */
	public boolean isAccessSuspend(IDebugTarget target) {
		Integer lastEventType= (Integer) fLastEventTypes.get(target);
		if (lastEventType == null) {
			return false;
		}
		return lastEventType.equals(ACCESS_EVENT);
	}
	/**
	 * @see IJavaLineBreakpoint#supportsCondition()
	 */
	public boolean supportsCondition() {
		return false;
	}

	/**
	 * @see org.eclipse.jdt.internal.debug.core.breakpoints.JavaBreakpoint#removeFromTarget(JDIDebugTarget)
	 */
	public void removeFromTarget(JDIDebugTarget target) throws CoreException {
		fLastEventTypes.remove(target);
		super.removeFromTarget(target);
	}
	
	/**
	 * @see org.eclipse.jdt.internal.debug.core.breakpoints.JavaBreakpoint#addInstanceFilter(EventRequest, ObjectReference)
	 */
	protected void addInstanceFilter(EventRequest request, ObjectReference object) {
		if (request instanceof WatchpointRequest) {
			((WatchpointRequest)request).addInstanceFilter(object);
		}
	}	
}