Merge tag 'v2.3.20' into testing

[gpl/argeo-jcr.git] / org.argeo.slc.repo / src / org / eclipse / aether / RequestTrace.java

diff --git a/org.argeo.slc.repo/src/org/eclipse/aether/RequestTrace.java b/org.argeo.slc.repo/src/org/eclipse/aether/RequestTrace.java
new file mode 100644 (file)
index 0000000..c6afa8e
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+++ b/org.argeo.slc.repo/src/org/eclipse/aether/RequestTrace.java
@@ -0,0 +1,108 @@
+/*******************************************************************************
+ * Copyright (c) 2010, 2011 Sonatype, Inc.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Sonatype, Inc. - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.aether;
+
+/**
+ * A trace of nested requests that are performed by the repository system. This trace information can be used to
+ * correlate repository events with higher level operations in the application code that eventually caused the events. A
+ * single trace can carry an arbitrary object as data which is meant to describe a request/operation that is currently
+ * executed. For call hierarchies within the repository system itself, this data will usually be the {@code *Request}
+ * object that is currently processed. When invoking methods on the repository system, client code may provide a request
+ * trace that has been prepopulated with whatever data is useful for the application to indicate its state for later
+ * evaluation when processing the repository events.
+ * 
+ * @see RepositoryEvent#getTrace()
+ */
+public class RequestTrace
+{
+
+    private final RequestTrace parent;
+
+    private final Object data;
+
+    /**
+     * Creates a child of the specified request trace. This method is basically a convenience that will invoke
+     * {@link RequestTrace#newChild(Object) parent.newChild()} when the specified parent trace is not {@code null} or
+     * otherwise instantiante a new root trace.
+     * 
+     * @param parent The parent request trace, may be {@code null}.
+     * @param data The data to associate with the child trace, may be {@code null}.
+     * @return The child trace, never {@code null}.
+     */
+    public static RequestTrace newChild( RequestTrace parent, Object data )
+    {
+        if ( parent == null )
+        {
+            return new RequestTrace( data );
+        }
+        return parent.newChild( data );
+    }
+
+    /**
+     * Creates a new root trace with the specified data.
+     * 
+     * @param data The data to associate with the trace, may be {@code null}.
+     */
+    public RequestTrace( Object data )
+    {
+        this( null, data );
+    }
+
+    /**
+     * Creates a new trace with the specified data and parent
+     * 
+     * @param parent The parent trace, may be {@code null} for a root trace.
+     * @param data The data to associate with the trace, may be {@code null}.
+     */
+    protected RequestTrace( RequestTrace parent, Object data )
+    {
+        this.parent = parent;
+        this.data = data;
+    }
+
+    /**
+     * Gets the data associated with this trace.
+     * 
+     * @return The data associated with this trace or {@code null} if none.
+     */
+    public final Object getData()
+    {
+        return data;
+    }
+
+    /**
+     * Gets the parent of this trace.
+     * 
+     * @return The parent of this trace or {@code null} if this is the root of the trace stack.
+     */
+    public final RequestTrace getParent()
+    {
+        return parent;
+    }
+
+    /**
+     * Creates a new child of this trace.
+     * 
+     * @param data The data to associate with the child, may be {@code null}.
+     * @return The child trace, never {@code null}.
+     */
+    public RequestTrace newChild( Object data )
+    {
+        return new RequestTrace( this, data );
+    }
+
+    @Override
+    public String toString()
+    {
+        return String.valueOf( getData() );
+    }
+
+}