updated documentation and improve logger

Signed-off-by: Luiz Oliveira <luiz.oliveira@ibm.com>

Author: Ziul

README.md

@@ -176,7 +176,7 @@ req.setAttribute("error-info", "Page not found");
 
 ###### Improving error messages
 
-It is possible to filter the error message to avoid long messages or personal info exposed in the metrics. To do it, three params may be used: `error-info-regex`, `error-info-regex-index`, and `error-info-max-size`. The first will set the regex to apply in the message, with `^([a-zA-z0-9 ]{0,120})` as the default value. The second, `error-info-regex-index`, selects the group of the regex's result with `0` as the default value. The last one, `error-info-max-size`, defines the max size of the message to be truncated and has `120` as the default value.
+It is possible to filter the error message to avoid long messages or personal info exposed in the metrics. To do it, two params may be used: `error-info-regex` and `error-info-max-size`. The first will set the regex to apply in the message, with `[^A-zÀ-ú .,]+` as the default value. The second, `error-info-max-size`, defines the max size of the message to be truncated and has `50` as the default value.
 
 #### Setting application version
 

src/main/java/br/com/labbs/monitor/filter/MetricsCollectorFilter.java

@@ -19,6 +19,8 @@
 import java.util.Properties;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 /**
  * The MetricsFilter class provides a high-level filter that enables collection of (latency, amount and response
  * size metrics) for Servlet performance, based on schema, status code, HTTP method and URI path.
@@ -61,8 +63,8 @@ public class MetricsCollectorFilter implements Filter {
     private static final String DEFAULT_FILTER_REGEX = "[^A-zÀ-ú .,]+";
     private static final String FILTER_REGEX_PARAM = "error-info-regex";
     private static final String FILTER_MAX_SIZE_PARAM = "error-info-max-size";
+    private static final Logger LOGGER = Logger.getLogger(MetricsCollectorFilter.class.getName());
     private final List<String> exclusions = new ArrayList<String>();
-    private int filter_group_index = 0;
     private int filter_max_size = 50;
     private String filter_regex = "";
 
@@ -224,8 +226,8 @@ private boolean isErrorStatus(int status) {
      * If error message is null, sets the string to empty string.
      * If a regex is defined, use it to filter message
      * 
-     * Default regex: ^([a-zA-z0-9 ]{0,120})
-     * Default max size: 120
+     * Default regex: [^A-zÀ-ú .,]+
+     * Default max size: 50
      *
      * @param httpRequest request
      * @return string with the error message or empty string if error message not found.
@@ -250,6 +252,7 @@ private String getErrorMessage(HttpServletRequest httpRequest) {
         } catch (Exception e) {
             // avoid invalid regex or invalid matcher group index
             result = "";
+            LOGGER.warning("Invalid regex: " + e.getMessage());
         }
         return result;
     }