This just feels wrong. Filters are for determining whether log events should be
logged. This Filter doesn’t have anything to do with that. It is more like an
interceptor.
Secondly, I don’t like that the only criteria it is able to use to determine
whether to throw an exception is the log level.
This just feels way too specific.
Ralph
> On Oct 9, 2024, at 7:36 AM, Gary D. Gregory <ggreg...@apache.org> wrote:
>
> Typo, the new code would be:
>
> private static final Filter THROWING_FILTER =
> ThresholdFilter.createFilter(Level.WARN, Result.THROW, Result.NEUTRAL);
>
> Sorry about that.
>
> Gary
>
> On 2024/10/09 14:34:15 "Gary D. Gregory" wrote:
>> Hi All:
>>
>> As a user, I want to programmatically configure Log4j to throw an exception
>> when a specific component logs a WARN event.
>>
>> Background: I am working with a large and complex stack that include
>> Hibernate in the mix. I just fixed a bug that, that as a side-effect, caused
>> Hibernate to log WARN events. As a check on possible regressions, I want to
>> make sure that a test class fails when Hibernate logs a WARN event. This
>> whole Maven module shares a log4j configuration file and, for now, I only
>> want this check on this one test class.
>>
>> My current implementation uses a custom filter called
>> ThrowingThresholdFilter [see end of message], a copy of our ThresholdFilter
>> that throws a subclass of LoggingException called FilterLoggingException
>> when the configured Level is matched.
>>
>> I also have happen to have other checks with other custom filters:
>> ThrowingLevelFilter and ThrowingStringMatchFilter.
>>
>> The only change in the configuration file is the use of the
>> “ignoreExceptions” attribute to a Console Appender.
>>
>> The test contains:
>> private static final Filter THROWING_FILTER =
>> ThrowingThresholdFilter.createFilter(Level.WARN, Result.NEUTRAL);
>> @SuppressWarnings("resource")
>> @BeforeAll
>> static void beforeAddFilter() {
>>
>> LoggerContext.getContext(false).getLogger("org.hibernate").addFilter(THROWING_FILTER);
>> }
>>
>> My proposal is to allow a user to _not_ define any custom filters by reusing
>> a new Result enum value called “Throw”. When a filter returns “Throw”, then
>> Log4j throws a new LoggingException subclass called FilterLoggingException.
>>
>> Then my test can replace:
>>
>> private static final Filter THROWING_FILTER =
>> ThrowingThresholdFilter.createFilter(Level.WARN, Result.NEUTRAL);
>>
>> and drop all custom filters.
>>
>> With:
>>
>> private static final Filter THROWING_FILTER =
>> ThresholdFilter.createFilter(Level.WARN, Result.NEUTRAL);
>>
>> WDYT?
>>
>> Gary
>>
>> package my.company;
>>
>> import java.util.Objects;
>>
>> import org.apache.logging.log4j.Level;
>> import org.apache.logging.log4j.LoggingException;
>> import org.apache.logging.log4j.Marker;
>> import org.apache.logging.log4j.core.Filter;
>> import org.apache.logging.log4j.core.LogEvent;
>> import org.apache.logging.log4j.core.Logger;
>> import org.apache.logging.log4j.core.config.Node;
>> import org.apache.logging.log4j.core.config.plugins.Plugin;
>> import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
>> import org.apache.logging.log4j.core.config.plugins.PluginFactory;
>> import org.apache.logging.log4j.core.filter.AbstractFilter;
>> import org.apache.logging.log4j.message.Message;
>> import org.apache.logging.log4j.util.PerformanceSensitive;
>>
>> /**
>> * This filter returns the onMatch result if the level in the {@link
>> LogEvent} is the same or more specific
>> * than the configured level and the {@code onMismatch} value otherwise. For
>> example, if the ThresholdFilter
>> * is configured with Level {@code ERROR} and the LogEvent contains Level
>> {@code DEBUG} then the {@code onMismatch} value will
>> * be returned since {@code ERROR} events are more specific than {@code
>> DEBUG}.
>> * <p>
>> * The default Level is {@code ERROR}.
>> * </p>
>> *
>> * @see Level#isMoreSpecificThan(Level)
>> */
>> @Plugin(name = "ThrowingThresholdFilter", category = Node.CATEGORY,
>> elementType = Filter.ELEMENT_TYPE, printObject = true)
>> @PerformanceSensitive("allocation")
>> public final class ThrowingThresholdFilter extends AbstractFilter {
>>
>> public static class FilterLoggingException extends LoggingException {
>>
>> private static final long serialVersionUID = 1L;
>>
>> public FilterLoggingException(String message) {
>> super(message);
>> }
>>
>> }
>>
>> private final Level level;
>>
>> private ThrowingThresholdFilter(final Level level, final Result
>> onMismatch) {
>> super(Result.NEUTRAL, onMismatch);
>> this.level = level;
>> }
>>
>> @Override
>> public Result filter(final Logger logger, final Level testLevel, final
>> Marker marker, final String msg,
>> final Object... params) {
>> return filter(testLevel);
>> }
>>
>> @Override
>> public Result filter(final Logger logger, final Level testLevel, final
>> Marker marker, final Object msg,
>> final Throwable t) {
>> return filter(testLevel);
>> }
>>
>> @Override
>> public Result filter(final Logger logger, final Level testLevel, final
>> Marker marker, final Message msg,
>> final Throwable t) {
>> return filter(testLevel);
>> }
>>
>> @Override
>> public Result filter(final LogEvent event) {
>> return filter(event.getLevel());
>> }
>>
>> private Result filter(final Level testLevel) {
>> if (testLevel.isMoreSpecificThan(this.level)) {
>> throw new FilterLoggingException(Objects.toString(testLevel));
>> }
>> return onMismatch;
>> }
>>
>> @Override
>> public Result filter(final Logger logger, final Level level, final Marker
>> marker, final String msg,
>> final Object p0) {
>> return filter(level);
>> }
>>
>> @Override
>> public Result filter(final Logger logger, final Level level, final Marker
>> marker, final String msg,
>> final Object p0, final Object p1) {
>> return filter(level);
>> }
>>
>> @Override
>> public Result filter(final Logger logger, final Level level, final Marker
>> marker, final String msg,
>> final Object p0, final Object p1, final Object p2) {
>> return filter(level);
>> }
>>
>> @Override
>> public Result filter(final Logger logger, final Level level, final Marker
>> marker, final String msg,
>> final Object p0, final Object p1, final Object p2, final Object
>> p3) {
>> return filter(level);
>> }
>>
>> @Override
>> public Result filter(final Logger logger, final Level level, final Marker
>> marker, final String msg,
>> final Object p0, final Object p1, final Object p2, final Object
>> p3,
>> final Object p4) {
>> return filter(level);
>> }
>>
>> @Override
>> public Result filter(final Logger logger, final Level level, final Marker
>> marker, final String msg,
>> final Object p0, final Object p1, final Object p2, final Object
>> p3,
>> final Object p4, final Object p5) {
>> return filter(level);
>> }
>>
>> @Override
>> public Result filter(final Logger logger, final Level level, final Marker
>> marker, final String msg,
>> final Object p0, final Object p1, final Object p2, final Object
>> p3,
>> final Object p4, final Object p5, final Object p6) {
>> return filter(level);
>> }
>>
>> @Override
>> public Result filter(final Logger logger, final Level level, final Marker
>> marker, final String msg,
>> final Object p0, final Object p1, final Object p2, final Object
>> p3,
>> final Object p4, final Object p5, final Object p6,
>> final Object p7) {
>> return filter(level);
>> }
>>
>> @Override
>> public Result filter(final Logger logger, final Level level, final Marker
>> marker, final String msg,
>> final Object p0, final Object p1, final Object p2, final Object
>> p3,
>> final Object p4, final Object p5, final Object p6,
>> final Object p7, final Object p8) {
>> return filter(level);
>> }
>>
>> @Override
>> public Result filter(final Logger logger, final Level level, final Marker
>> marker, final String msg,
>> final Object p0, final Object p1, final Object p2, final Object
>> p3,
>> final Object p4, final Object p5, final Object p6,
>> final Object p7, final Object p8, final Object p9) {
>> return filter(level);
>> }
>>
>> public Level getLevel() {
>> return level;
>> }
>>
>> @Override
>> public String toString() {
>> return level.toString();
>> }
>>
>> /**
>> * Creates a ThrowingThresholdFilter.
>> * @param level The log Level.
>> * @param mismatch The action to take on a mismatch.
>> * @return The created ThrowingThresholdFilter.
>> */
>> // TODO Consider refactoring to use AbstractFilter.AbstractFilterBuilder
>> @PluginFactory
>> public static ThrowingThresholdFilter createFilter(
>> @PluginAttribute("level") final Level level,
>> @PluginAttribute("onMismatch") final Result mismatch) {
>> final Level actualLevel = level == null ? Level.ERROR : level;
>> final Result onMismatch = mismatch == null ? Result.DENY : mismatch;
>> return new ThrowingThresholdFilter(actualLevel, onMismatch);
>> }
>>
>> }
>>
