org.apache.sling.hc.util.HealthCheckFilter Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The SF licenses this file
* to you 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 org.apache.sling.hc.util;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.apache.sling.hc.api.HealthCheck;
import org.apache.sling.hc.api.execution.HealthCheckSelector;
import org.osgi.annotation.versioning.ProviderType;
import org.osgi.framework.BundleContext;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceReference;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import static org.apache.sling.hc.api.execution.HealthCheckSelector.tags;
import static org.apache.sling.hc.api.execution.HealthCheckSelector.empty;
/**
* Select from available {@link HealthCheck} services.
* Once this filter object and the returned health check services are no longer
* be used {@link #dispose()} should be called, to free the service
* references.
*
* This class is not thread safe and instances shouldn't be used concurrently
* from different threads.
*/
@ProviderType
public class HealthCheckFilter {
private final Logger log = LoggerFactory.getLogger(getClass());
private final BundleContext bundleContext;
public static final String OMIT_PREFIX = "-";
private final Set usedReferences = new HashSet();
/**
* Create a new filter object
*/
public HealthCheckFilter(final BundleContext bc) {
bundleContext = bc;
}
public List getHealthChecks(final HealthCheckSelector selector) {
final ServiceReference [] refs = this.getHealthCheckServiceReferences(selector);
final List result = new ArrayList();
if ( refs != null ) {
final List sortedRefs = Arrays.asList(refs);
Collections.sort(sortedRefs);
for(final ServiceReference ref : sortedRefs) {
final HealthCheck hc = (HealthCheck)bundleContext.getService(ref);
log.debug("Selected HealthCheck service {}", hc);
if ( hc != null ) {
this.usedReferences.add(ref);
result.add(hc);
}
}
}
return result;
}
public ServiceReference[] getHealthCheckServiceReferences(final HealthCheckSelector selector) {
return getHealthCheckServiceReferences(selector, false);
}
public ServiceReference[] getHealthCheckServiceReferences(final HealthCheckSelector selector, boolean combineTagsWithOr) {
final CharSequence filterBuilder = selector != null ? getServiceFilter(selector, combineTagsWithOr) : getServiceFilter(empty(), combineTagsWithOr);
log.debug("OSGi service filter in getHealthCheckServiceReferences(): {}", filterBuilder);
try {
final String filterString = filterBuilder.length() == 0 ? null : filterBuilder.toString();
bundleContext.createFilter(filterString); // check syntax early
final ServiceReference[] refs = bundleContext.getServiceReferences(HealthCheck.class.getName(), filterString);
if (refs == null) {
log.debug("Found no HealthCheck services with filter [{}]", filterString);
return new ServiceReference[0];
} else {
log.debug("Found {} HealthCheck services with filter [{}]", refs.length, filterString);
}
return refs;
} catch (final InvalidSyntaxException ise) {
// this should not happen, but we fail gracefully
log.error("Invalid OSGi filter syntax in '" + filterBuilder + "'", ise);
return new ServiceReference[0];
}
}
/**
* Get all health check services with one of the supplied tags.
* @return A list of services - might be the empty list if none matches
* @deprecated use getHealthChecks() instead
*/
@Deprecated
public List getTaggedHealthChecks(final String... tags) {
final HealthCheckSelector selector = tags(tags);
return getHealthChecks(selector);
}
/**
* Get all service references for health check services with one of the supplied tags. Uses logical "and" to combine tags.
* @return An array of service references - might be an empty error if none matches
* @deprecated use getHealthCheckServiceReferences() instead
*/
@Deprecated
public ServiceReference[] getTaggedHealthCheckServiceReferences(final String... tags) {
return getHealthCheckServiceReferences(tags(tags), false);
}
/**
* Get all service references for health check services with one of the supplied tags.
*
* @param combineWithOr If true will return all health checks that have at least one of the tags set.
* If false will return only health checks that have all given tags assigned.
* @param tags the tags to look for
* @return An array of service references - might be an empty error if none matches
* @deprecated use getHealthCheckServiceReferences() instead
*/
@Deprecated
public ServiceReference[] getTaggedHealthCheckServiceReferences(boolean combineWithOr, final String... tags) {
final HealthCheckSelector selector = tags(tags);
return getHealthCheckServiceReferences(selector, combineWithOr);
}
/**
* Dispose all used service references
*/
public void dispose() {
for(final ServiceReference ref : this.usedReferences) {
this.bundleContext.ungetService(ref);
}
this.usedReferences.clear();
}
CharSequence getServiceFilter(HealthCheckSelector selector, boolean combineTagsWithOr) {
// Build service filter
final StringBuilder filterBuilder = new StringBuilder();
filterBuilder.append("(&(objectClass=").append(HealthCheck.class.getName()).append(")");
final int prefixLen = HealthCheckFilter.OMIT_PREFIX.length();
final StringBuilder filterBuilderForOrOperator = new StringBuilder(); // or filters
final StringBuilder tagsBuilder = new StringBuilder();
int tagsAndClauses = 0;
if (selector.tags() != null) {
for (String tag : selector.tags()) {
tag = tag.trim();
if (tag.length() == 0) {
continue;
}
if (tag.startsWith(HealthCheckFilter.OMIT_PREFIX)) {
// ommit tags always have to be added as and-clause
filterBuilder.append("(!(").append(HealthCheck.TAGS).append("=").append(tag.substring(prefixLen)).append("))");
} else {
// add regular tags in the list either to outer and-clause or inner or-clause
if (combineTagsWithOr) {
filterBuilderForOrOperator.append("(").append(HealthCheck.TAGS).append("=").append(tag).append(")");
} else {
tagsBuilder.append("(").append(HealthCheck.TAGS).append("=").append(tag).append(")");
tagsAndClauses++;
}
}
}
}
boolean addedNameToOrBuilder = false;
if (selector.names() != null) {
for (String name : selector.names()) {
name = name.trim();
if (name.length() == 0) {
continue;
}
if (name.startsWith(HealthCheckFilter.OMIT_PREFIX)) {
// ommit tags always have to be added as and-clause
filterBuilder.append("(!(").append(HealthCheck.NAME).append("=").append(name.substring(prefixLen)).append("))");
} else {
// names are always ORd
filterBuilderForOrOperator.append("(").append(HealthCheck.NAME).append("=").append(name).append(")");
addedNameToOrBuilder = true;
}
}
}
if (addedNameToOrBuilder) {
if (tagsAndClauses > 1) {
filterBuilderForOrOperator.append("(&").append(tagsBuilder).append(")");
} else {
filterBuilderForOrOperator.append(tagsBuilder);
}
} else {
filterBuilder.append(tagsBuilder);
}
// add "or" clause if we have accumulated any
if (filterBuilderForOrOperator.length() > 0) {
filterBuilder.append("(|").append(filterBuilderForOrOperator).append(")");
}
filterBuilder.append(")");
return filterBuilder;
}
}