/**
* Copyright (C) 2012 Ryan W Tenney (ryan@10e.us)
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.ryantenney.metrics.spring;
import java.lang.reflect.Field;
import org.springframework.core.Ordered;
import org.springframework.util.ReflectionUtils;
import com.codahale.metrics.Counter;
import com.codahale.metrics.Histogram;
import com.codahale.metrics.Meter;
import com.codahale.metrics.MetricRegistry;
import com.codahale.metrics.Timer;
import com.ryantenney.metrics.annotation.Metric;
import static com.ryantenney.metrics.spring.AnnotationFilter.INJECTABLE_FIELDS;
class MetricAnnotationBeanPostProcessor extends AbstractAnnotationBeanPostProcessor implements Ordered {
private static final AnnotationFilter FILTER = new AnnotationFilter(Metric.class, INJECTABLE_FIELDS);
private final MetricRegistry metrics;
public MetricAnnotationBeanPostProcessor(final MetricRegistry metrics) {
super(Members.FIELDS, Phase.PRE_INIT, FILTER);
this.metrics = metrics;
}
@Override
protected void withField(Object bean, String beanName, Class<?> targetClass, Field field) {
final Metric annotation = field.getAnnotation(Metric.class);
final String metricName = Util.forMetricField(targetClass, field, annotation);
final Class<?> type = field.getType();
if (!com.codahale.metrics.Metric.class.isAssignableFrom(type)) {
throw new IllegalArgumentException("Field " + targetClass.getCanonicalName() + "." + field.getName() + " must be a subtype of "
+ com.codahale.metrics.Metric.class.getCanonicalName());
}
ReflectionUtils.makeAccessible(field);
// Get the value of the field annotated with @Metric
com.codahale.metrics.Metric metric = (com.codahale.metrics.Metric) ReflectionUtils.getField(field, bean);
if (metric == null) {
// If null, create a metric of the appropriate type and inject it
metric = getMetric(metrics, type, metricName);
ReflectionUtils.setField(field, bean, metric);
LOG.debug("Injected metric {} for field {}.{}", metricName, targetClass.getCanonicalName(), field.getName());
}
else {
// If non-null, register that instance of the metric
try {
// Attempt to register that instance of the metric
metrics.register(metricName, metric);
LOG.debug("Registered metric {} for field {}.{}", metricName, targetClass.getCanonicalName(), field.getName());
}
catch (IllegalArgumentException ex1) {
// A metric is already registered under that name
// (Cannot determine the cause without parsing the Exception's message)
try {
metric = getMetric(metrics, type, metricName);
ReflectionUtils.setField(field, bean, metric);
LOG.debug("Injected metric {} for field {}.{}", metricName, targetClass.getCanonicalName(), field.getName());
}
catch (IllegalArgumentException ex2) {
// A metric of a different type is already registered under that name
throw new IllegalArgumentException("Error injecting metric for field " + targetClass.getCanonicalName() + "." + field.getName(), ex2);
}
}
}
}
private com.codahale.metrics.Metric getMetric(MetricRegistry metricRegistry, Class<?> type, String metricName) {
com.codahale.metrics.Metric metric;
if (Meter.class == type) {
metric = metrics.meter(metricName);
}
else if (Timer.class == type) {
metric = metrics.timer(metricName);
}
else if (Counter.class == type) {
metric = metrics.counter(metricName);
}
else if (Histogram.class == type) {
metric = metrics.histogram(metricName);
}
else {
throw new IllegalArgumentException("Invalid @Metric type " + type.getCanonicalName());
}
return metric;
}
@Override
public int getOrder() {
return LOWEST_PRECEDENCE - 2;
}
}