/*
* Copyright (c) 2002-2012 Alibaba Group Holding Limited.
* All rights reserved.
*
* 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.alibaba.citrus.service.pipeline.impl.valve;
import static com.alibaba.citrus.springext.util.SpringExtUtil.*;
import static com.alibaba.citrus.util.Assert.*;
import static com.alibaba.citrus.util.ObjectUtil.*;
import static com.alibaba.citrus.util.StringUtil.*;
import com.alibaba.citrus.service.pipeline.Pipeline;
import com.alibaba.citrus.service.pipeline.PipelineContext;
import com.alibaba.citrus.service.pipeline.PipelineInvocationHandle;
import com.alibaba.citrus.service.pipeline.TooManyLoopsException;
import com.alibaba.citrus.service.pipeline.support.AbstractValve;
import com.alibaba.citrus.service.pipeline.support.AbstractValveDefinitionParser;
import com.alibaba.citrus.util.ToStringBuilder;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.xml.ParserContext;
import org.w3c.dom.Element;
/**
* 用来反复执行同一个子pipeline。
*
* @author Michael Zhou
*/
public class LoopValve extends AbstractValve {
private final static int DEFAULT_MAX_LOOP = 10;
private final static String DEFAULT_LOOP_COUNTER_NAME = "loopCount";
private Pipeline loopBody;
private Integer maxLoopCount;
private String loopCounterName;
public Pipeline getLoopBody() {
return loopBody;
}
public void setLoopBody(Pipeline loopBody) {
this.loopBody = loopBody;
}
public int getMaxLoopCount() {
return maxLoopCount == null ? DEFAULT_MAX_LOOP : maxLoopCount;
}
public void setMaxLoopCount(int maxLoopCount) {
this.maxLoopCount = maxLoopCount <= 0 ? 0 : maxLoopCount;
}
public String getLoopCounterName() {
return defaultIfNull(loopCounterName, DEFAULT_LOOP_COUNTER_NAME);
}
public void setLoopCounterName(String loopCounterName) {
this.loopCounterName = trimToNull(loopCounterName);
}
@Override
protected void init() throws Exception {
assertNotNull(loopBody, "no loop body");
}
public void invoke(PipelineContext pipelineContext) throws Exception {
assertInitialized();
PipelineInvocationHandle handle = initLoop(pipelineContext);
do {
invokeBody(handle);
} while (!handle.isBroken());
pipelineContext.invokeNext();
}
protected PipelineInvocationHandle initLoop(PipelineContext pipelineContext) {
PipelineInvocationHandle handle = getLoopBody().newInvocation(pipelineContext);
handle.setAttribute(getLoopCounterName(), 0);
return handle;
}
protected void invokeBody(PipelineInvocationHandle handle) {
String loopCounterName = getLoopCounterName();
int loopCount = (Integer) handle.getAttribute(loopCounterName);
int maxLoopCount = getMaxLoopCount();
// maxLoopCount<=0，意味着没有循环次数的限制。
if (maxLoopCount > 0 && loopCount >= maxLoopCount) {
throw new TooManyLoopsException("Too many loops: exceeds the maximum count: " + maxLoopCount);
}
handle.invoke();
handle.setAttribute(loopCounterName, ++loopCount);
}
@Override
public String toString() {
return new ToStringBuilder().append("LoopValve").start("[", "]").append(loopBody).end().toString();
}
public static class DefinitionParser extends AbstractValveDefinitionParser<LoopValve> {
@Override
protected final void doParse(Element element, ParserContext parserContext, BeanDefinitionBuilder builder) {
attributesToProperties(element, builder, "maxLoopCount", "loopCounterName");
builder.addPropertyValue("loopBody", parsePipeline(element, parserContext));
}
}
}