MONDRIAN-821 Adds a unique ID property to the schema. This id is expe…

…cted to be different across different Mondrian instances. It allows clients to refresh their schema caches when that ID changes. This usually happened when a dynamic schema processor is used and the schema changes when a user login changes.

[git-p4: depot-paths = "//open/mondrian-release/3.2/": change = 13882]

src/main/mondrian/rolap/RolapSchema.java

@@ -153,6 +153,14 @@ public class RolapSchema implements Schema {
     private final List<Exception> warningList = new ArrayList<Exception>();
     private Map<String, Annotation> annotationMap;
 
+    /**
+     * This is a unique schema instance id which will be used
+     * to inform clients when the schema has changed.
+     *
+     * <p>Expect a different ID for each Mondrian instance node.
+     */
+    private final String id;
+
     /**
      * This is ONLY called by other constructors (and MUST be called
      * by them) and NEVER by the Pool.
@@ -168,6 +176,7 @@ private RolapSchema(
         final DataSource dataSource,
         final String md5Bytes)
     {
+        this.id = UUID.randomUUID().toString();
         this.key = key;
         this.md5Bytes = md5Bytes;
         // the order of the next two lines is important
@@ -345,6 +354,14 @@ public String getName() {
         return name;
     }
 
+    /**
+     * Returns this schema instance unique ID.
+     * @return A string representing the schema ID.
+     */
+    public String getId() {
+        return this.id;
+    }
+
     public Map<String, Annotation> getAnnotationMap() {
         return annotationMap;
     }