Fix for #227 - Many2Many cache bug, incorrect query plan hash calculation

src/main/java/com/avaje/ebeaninternal/server/deploy/TableJoin.java

@@ -50,6 +50,11 @@ public final class TableJoin {
    */
   private final TableJoinColumn[] columns;
 
+  /**
+   * A hash that can be used with the query plan.
+   */
+  private final int queryHash;
+
   /**
    * Create a TableJoin.
    */
@@ -77,7 +82,26 @@ public final class TableJoin {
       BeanProperty prop = propMap.get(deployProps[i].getName());
       this.properties[i] = prop;
     }
+    this.queryHash = calcQueryHash();
+  }
 
+  /**
+   * Calculate a hash value for adding to a query plan.
+   */
+  private int calcQueryHash() {
+    int hc = type.hashCode();
+    hc = hc * 31 + (table == null ? 0 : table.hashCode());
+    for (int i = 0; i < columns.length; i++) {
+      hc = hc * 31 + columns[i].queryHash();
+    }
+    return hc;
+  }
+
+  /**
+   * Return a hash value for adding to a query plan.
+   */
+  public int queryHash() {
+    return queryHash;
   }
 
   public String toString() {

src/main/java/com/avaje/ebeaninternal/server/deploy/TableJoinColumn.java

@@ -21,7 +21,12 @@ public class TableJoinColumn {
     private final boolean insertable;
     
     private final boolean updateable;
-    
+
+    /**
+     * Hash for including in a query plan
+     */
+    private final int queryHash;
+
     /**
      * Create the pair.
      */
@@ -30,12 +35,23 @@ public class TableJoinColumn {
     	this.foreignDbColumn = InternString.intern(deploy.getForeignDbColumn());
     	this.insertable = deploy.isInsertable();
     	this.updateable = deploy.isUpdateable();
+      this.queryHash = hashOf(localDbColumn) * 31 + hashOf(foreignDbColumn);
     }
-    
+
+    private int hashOf(String value) {
+        return (value == null) ? 0 : value.hashCode();
+    }
+
     public String toString() {
         return localDbColumn+" = "+foreignDbColumn;
     }
 
+    /**
+     * Return a hash for including in a query plan.
+     */
+    public int queryHash() {
+      return queryHash;
+    }
 
     /**
      * Return the foreign database column name.

src/main/java/com/avaje/ebeaninternal/server/querydefn/DefaultOrmQuery.java

@@ -666,8 +666,7 @@ public class DefaultOrmQuery<T> implements SpiQuery<T> {
    */
   private HashQueryPlan calculateHash(BeanQueryRequest<?> request, HashQueryPlanBuilder builder) {
 
-    // exclude bind values and things unrelated to
-    // the sql being generated
+    // exclude bind values and things unrelated to the sql being generated
 
     if (builder == null) {
       builder = new HashQueryPlanBuilder();
@@ -680,6 +679,7 @@ public class DefaultOrmQuery<T> implements SpiQuery<T> {
     builder.add(mapKey);
     builder.add(id != null);
     builder.add(rawSql == null ? 0 : rawSql.queryHash());
+    builder.add(includeTableJoin != null ? includeTableJoin.queryHash() : 0);
 
     if (detail != null) {
       detail.queryPlanHash(request, builder);