Changeset 28382 for main/trunk/greenstone3/src/java/org/greenstone/gsdl3/action/ProcessAction.java

Timestamp:

2013-10-10T17:21:30+13:00 (11 years ago)

Author:

davidb

Message:

Elimination of the 'this.doc' field from the Action baseclass and the subclasses that rely on it. For Greenstone3 purposes it is unsafe to create this object in the constructor to the action and then store it for other methods to access. This is because the Greenstone 3 (and in particular calls to 'process' operate in a multi-threaded context, that is managed by the Servlet server (e.g. Tomcat by default). Calls to DOM methods are not guaranteed to be thread safe, this became apparent when we started looking in to an exception that was being thrown, and centred around use of the DOM method 'item(i)'. The change this commit makes is to remove 'this.doc' being stored as a field. A document is now created in the top level of a call to 'process()' and when a DOM reference is needed in a subsequent method an Element variable (typically passed in as a parameter to the method) is used (through 'Document doc = element.getOwnerDocument()') to gain access to the DOM

File:

• main/trunk/greenstone3/src/java/org/greenstone/gsdl3/action/ProcessAction.java (modified) (9 diffs)

main/trunk/greenstone3/src/java/org/greenstone/gsdl3/action/ProcessAction.java

@@ -21 +21 @@
     public Node process(Node message_node)
     {
-
         Element message = this.converter.nodeToElement(message_node);
-
+        Document doc = message.getOwnerDocument();
+        
         // the result
-        Element result = this.doc.createElement(GSXML.MESSAGE_ELEM);
-        Element page_response = this.doc.createElement(GSXML.RESPONSE_ELEM);
+        Element result = doc.createElement(GSXML.MESSAGE_ELEM);
+        Element page_response = doc.createElement(GSXML.RESPONSE_ELEM);
         result.appendChild(page_response);
 
@@ -70 +70 @@
             // if rt=s or rt=r, do the request
 
-            Element mr_query_message = this.doc.createElement(GSXML.MESSAGE_ELEM);
+            Element mr_query_message = doc.createElement(GSXML.MESSAGE_ELEM);
             String request_type_att;
             Element param_list = null;
@@ -76 +76 @@
             { // status
                 request_type_att = GSXML.REQUEST_TYPE_STATUS;
-                param_list = this.doc.createElement(GSXML.PARAM_ELEM + GSXML.LIST_MODIFIER);
-                Element param = this.doc.createElement(GSXML.PARAM_ELEM);
+                param_list = doc.createElement(GSXML.PARAM_ELEM + GSXML.LIST_MODIFIER);
+                Element param = doc.createElement(GSXML.PARAM_ELEM);
                 param.setAttribute(GSXML.NAME_ATT, GSParams.PROCESS_ID);
                 param.setAttribute(GSXML.VALUE_ATT, (String) params.get(GSParams.PROCESS_ID));
@@ -89 +89 @@
                 if (service_params != null)
                 {
-                    param_list = this.doc.createElement(GSXML.PARAM_ELEM + GSXML.LIST_MODIFIER);
-                    GSXML.addParametersToList(this.doc, param_list, service_params);
+                    param_list = doc.createElement(GSXML.PARAM_ELEM + GSXML.LIST_MODIFIER);
+                    GSXML.addParametersToList(doc, param_list, service_params);
                 }
 
             }
-            Element mr_query_request = GSXML.createBasicRequest(this.doc, request_type_att, to, userContext);
+            Element mr_query_request = GSXML.createBasicRequest(doc, request_type_att, to, userContext);
             if (param_list != null)
             {
@@ -112 +112 @@
             // else append the contents of the response to the page - just the status elem for now
             Element status = (Element) GSXML.getChildByTagName(result_response, GSXML.STATUS_ELEM);
-            page_response.appendChild(this.doc.importNode(status, true));
+            page_response.appendChild(doc.importNode(status, true));
         }
 
@@ -118 +118 @@
 
         // request the service info for the selected service - should be cached
-        Element mr_info_message = this.doc.createElement(GSXML.MESSAGE_ELEM);
-        Element mr_info_request = GSXML.createBasicRequest(this.doc, GSXML.REQUEST_TYPE_DESCRIBE, to, userContext);
+        Element mr_info_message = doc.createElement(GSXML.MESSAGE_ELEM);
+        Element mr_info_request = GSXML.createBasicRequest(doc, GSXML.REQUEST_TYPE_DESCRIBE, to, userContext);
         mr_info_message.appendChild(mr_info_request);
         Element mr_info_response = (Element) this.mr.process(mr_info_message);
@@ -125 +125 @@
         String path = GSXML.RESPONSE_ELEM;
         path = GSPath.appendLink(path, GSXML.SERVICE_ELEM);
-        Element description = (Element) this.doc.importNode(GSXML.getNodeByPath(mr_info_response, path), true);
+        Element description = (Element) doc.importNode(GSXML.getNodeByPath(mr_info_response, path), true);
 
         page_response.appendChild(description);
@@ -134 +134 @@
     protected Element getServiceParamList(Element cgi_param_list)
     {
-
-        Element new_param_list = this.doc.createElement(GSXML.PARAM_ELEM + GSXML.LIST_MODIFIER);
+        Document doc = cgi_param_list.getOwnerDocument();
+        
+        Element new_param_list = doc.createElement(GSXML.PARAM_ELEM + GSXML.LIST_MODIFIER);
         Element param;
         NodeList cgi_params = cgi_param_list.getChildNodes();
@@ -147 +148 @@
             }
             // else add it in to the list
-            new_param_list.appendChild(this.doc.importNode(p, true));
+            new_param_list.appendChild(doc.importNode(p, true));
         }
         return new_param_list;