MONDRIAN: [MONDRIAN-994] Allows log4j's MDC context to be passed to t…

…he Execution thread.

[git-p4: depot-paths = "//open/mondrian/": change = 14955]

src/main/mondrian/rolap/RolapConnection.java

@@ -619,6 +619,7 @@ public Result execute(Query query) {
      *     the property file
      */
     public Result execute(final Execution execution) {
+        execution.copyMDC();
         return
             server.getResultShepherd()
                 .shepherdExecution(
@@ -631,6 +632,7 @@ public Result call() throws Exception {
     }
 
     private Result executeInternal(final Execution execution) {
+        execution.setContextMap();
         final Statement statement = execution.getMondrianStatement();
         // Cleanup any previous executions still running
         synchronized (statement) {

src/main/mondrian/server/Execution.java

@@ -19,6 +19,8 @@
 import java.util.Map.Entry;
 import java.util.concurrent.atomic.AtomicLong;
 
+import org.apache.log4j.MDC;
+
 /**
  * Execution context.
  *
@@ -81,6 +83,8 @@ public class Execution {
 
     public static final Execution NONE = new Execution(null, 0);
 
+    private Map<String, Object> mdc;
+
     public Execution(Statement statement, long timeoutIntervalMillis) {
         this.id = SEQ.getAndIncrement();
         this.statement = (StatementImpl) statement;
@@ -320,6 +324,29 @@ private void fireExecutionStartEvent() {
                 id,
                 getMdx()));
     }
+
+
+    /**
+     * Copy the current MDC so it can be used later
+     */
+    public void copyMDC() {
+        this.mdc = new HashMap<String, Object>(MDC.getContext());
+    }
+
+    /**
+     * Set the copied mdc into the current MDC. This should be called
+     * any time there will be logging in a thread handled by the
+     * RolapResultShepherd where original MDC needs to be retrieved
+     */
+    public void setContextMap() {
+        if(mdc == null) {
+            return;
+        }
+        Map<String, Object> old = MDC.getContext();
+        old.clear();
+        old.putAll(mdc);
+    }
+
     /**
      * Enumeration of the states of an Execution instance.
      */