+ * The following example shows a naive implementation of a setting control for + * regular expressions: + * + *
+ *
+ * final class RegExpControl extends SettingControl {
+ * private Pattern pattern = Pattern.compile(".*");
+ *
+ * {@literal @}Override
+ * public void setValue(String value) {
+ * this.pattern = Pattern.compile(value);
+ * }
+ *
+ * {@literal @}Override
+ * public String combine(Set{@literal <}String{@literal >} values) {
+ * return String.join("|", values);
+ * }
+ *
+ * {@literal @}Override
+ * public String getValue() {
+ * return pattern.toString();
+ * }
+ *
+ * public String matches(String s) {
+ * return pattern.matcher(s).find();
+ * }
+ * }
+ *
+ *
+ *
+ * The {@code setValue(String)}, {@code getValue()} and
+ * {@code combine(Set+ * The setting control must have a default constructor that can be invoked when + * the event is registered. + *
+ * To use a setting control with an event, add a method that returns a + * {@code boolean} value and takes the setting control as a parameter. Annotate + * the method with the {@code @SettingDefinition} annotation. By default, the + * method name is used as the setting name, but the name can be set explicitly + * bby using the {@code @Name} annotation. If the method returns {@code true}, + * the event will be committed. + *
+ * It is recommended that the {@code setValue(String)} method updates an + * efficient data structure that can be quickly checked when the event is + * committed. + *
+ * Example, + * + *
+ *
+ * abstract class HTTPRequest extends Event {
+ * {@literal @}Label("Request URI")
+ * protected String uri;
+ *
+ * {@literal @}Label("Servlet URI Filter")
+ * {@literal @}SettingDefinition
+ * protected boolean uriFilter(RegExpControl regExp) {
+ * return regExp.matches(uri);
+ * }
+ * }
+ *
+ * {@literal @}Label("HTTP Get Request")
+ * class HTTPGetRequest extends HTTPRequest {
+ * }
+ *
+ * {@literal @}Label("HTTP Post Request")
+ * class HTTPPostRequest extends HTTPRequest {
+ * }
+ *
+ * class ExampleServlet extends HTTPServlet {
+ * protected void doGet(HttpServletRequest req, HttpServletResponse resp) {
+ * HTTPGetRequest request = new HTTPGetRequest();
+ * request.begin();
+ * request.uri = req.getRequestURI();
+ * ...
+ * request.commit();
+ * }
+ *
+ * protected void doPost(HttpServletRequest req, HttpServletResponse resp) {
+ * HTTPPostRequest request = new HTTPPostRequest();
+ * request.begin();
+ * request.uri = req.getRequestURI();
+ * ...
+ * request.commit();
+ * }
+ * }
+ *
+ *
+ *
+ * The following examples show how an event can be filtered by assigning the
+ * {@code "uriFilter"} setting with the specified regular expressions, in a
+ * configuration file or programmatically.
+ *
+ *
+ *
+ * Recording r = new Recording();
+ * r.enable("HTTPGetRequest").with("uriFilter", "https://www.example.com/list/.*");
+ * r.enable("HTTPPostRequest").with("uriFilter", "https://www.example.com/login/.*");
+ * r.start();
+ *
+ *
+ *
+ *
+ *
+ * @see SettingDefinition
+ *
+ * @since 9
+ */
+@MetadataDefinition
+public abstract class SettingControl extends Control {
+
+ /**
+ * Constructor for invocation by subclass constructors.
+ */
+ protected SettingControl() {
+ super(AccessController.getContext());
+
+ }
+
+ /**
+ * Combines the setting values for all running recordings into one value when
+ * multiple recordings are running at the same time,
+ * + * The semantics of how setting values are combined depends on the setting + * control that is implemented, but all recordings should get at least all the + * events they request.. + *
+ * This method should have no side effects, because the caller might cache values. + * This method should never return {@code null} or throw an exception. If a + * value is not valid for this setting control, the value should be ignored. + *
+ * Examples: + *
+ * if the setting control represents a threshold and three recordings are + * running at the same time with the setting values {@code "10 ms"}, + * {@code "8 s"}, and {@code "1 ms"}, this method returns {@code "1 ms"} + * because it means that all recordings get at least all the requested data. + *
+ * If the setting control represents a set of names and two recordings are + * running at the same time with the setting values "Smith, Jones" and "Jones, + * Williams" the returned value is "Smith, Jones, Williams" because all names would be accepted. + *
+ * If the setting control represents a boolean condition and four recordings are
+ * running at the same time with the following values "true", "false", "false", and
+ * "incorrect", this method returns "true", because all
+ * recordings get at least all the requested data.
+ *
+ * @param settingValues the set of values, not {@code null}
+ *
+ * @return the value to use, not {@code null}
+ */
+ @Override
+ public abstract String combine(Set
+ * If the setting value is not valid for this setting, this method
+ * should not throw an exception. Instead, the value is ignored.
+ *
+ * @param settingValue the string value, not {@code null}
+ */
+ @Override
+ public abstract void setValue(String settingValue);
+
+ /**
+ * Returns the currently used value for this setting, not {@code null}.
+ *
+ * The value returned by this method should be valid as an argument to both
+ * the {@code setValue(String)} method and {@code combine(Set)} method.
+ *
+ * This method is invoked when an event is registered to obtain the
+ * default value. It is therefore important that a valid value can be
+ * returned immediately after an instance of this class is created. It is
+ * not valid to return {@code null}.
+ *
+ * @return the setting value, not {@code null}
+ */
+ @Override
+ public abstract String getValue();
+}