org.glowroot.instrumentation.api.QueryMessageSupplier Maven / Gradle / Ivy
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/*
* Copyright 2017-2019 the original author or authors.
*
* 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 org.glowroot.instrumentation.api;
import java.util.Collections;
import java.util.Map;
/**
* A (lazy) supplier of {@link QueryMessage} instances. Needs to be thread safe since transaction
* thread creates it, but trace storage (and live viewing) is done in a separate thread.
*/
public abstract class QueryMessageSupplier {
private static final QueryMessageSupplier EMPTY = new QueryMessageSupplier() {
@Override
public Map get() {
return Collections.emptyMap();
}
};
/**
* Returns the {@code QueryMessage} for a {@link QuerySpan}.
*
* The {@code QueryMessage} does not need to be thread safe if it is instantiated by the
* implementation of this method.
*/
public abstract Map get();
protected QueryMessageSupplier() {}
/**
* Creates a {@code QueryMessageSupplier} for the specified {@code prefix} and {@code suffix}.
*/
public static QueryMessageSupplier create() {
return EMPTY;
}
/**
* Creates a {@code QueryMessageSupplier} for the specified {@code prefix}.
*/
public static QueryMessageSupplier create(final Map detail) {
return new QueryMessageSupplier() {
@Override
public Map get() {
return detail;
}
};
}
}