Google Git
Sign in
apache / hbase-site / b97b88575409f37022ae97d95899d9c4b965f5ed / . / devapidocs / src-html / org / apache / hadoop / hbase / util / ReflectedFunctionCache.html
blob: ee0b5d88f8cf7f44a6972d6c937cb82a8fa463c8 [file] [log] [blame]
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html lang="en">
<head>
<title>Source code</title>
<link rel="stylesheet" type="text/css" href="../../../../../../stylesheet.css" title="Style">
</head>
<body>
<div class="sourceContainer">
<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Licensed to the Apache Software Foundation (ASF) under one<a name="line.2"></a>
<span class="sourceLineNo">003</span> * or more contributor license agreements. See the NOTICE file<a name="line.3"></a>
<span class="sourceLineNo">004</span> * distributed with this work for additional information<a name="line.4"></a>
<span class="sourceLineNo">005</span> * regarding copyright ownership. The ASF licenses this file<a name="line.5"></a>
<span class="sourceLineNo">006</span> * to you under the Apache License, Version 2.0 (the<a name="line.6"></a>
<span class="sourceLineNo">007</span> * "License"); you may not use this file except in compliance<a name="line.7"></a>
<span class="sourceLineNo">008</span> * with the License. You may obtain a copy of the License at<a name="line.8"></a>
<span class="sourceLineNo">009</span> *<a name="line.9"></a>
<span class="sourceLineNo">010</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.10"></a>
<span class="sourceLineNo">011</span> *<a name="line.11"></a>
<span class="sourceLineNo">012</span> * Unless required by applicable law or agreed to in writing, software<a name="line.12"></a>
<span class="sourceLineNo">013</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.13"></a>
<span class="sourceLineNo">014</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.14"></a>
<span class="sourceLineNo">015</span> * See the License for the specific language governing permissions and<a name="line.15"></a>
<span class="sourceLineNo">016</span> * limitations under the License.<a name="line.16"></a>
<span class="sourceLineNo">017</span> */<a name="line.17"></a>
<span class="sourceLineNo">018</span>package org.apache.hadoop.hbase.util;<a name="line.18"></a>
<span class="sourceLineNo">019</span><a name="line.19"></a>
<span class="sourceLineNo">020</span>import edu.umd.cs.findbugs.annotations.Nullable;<a name="line.20"></a>
<span class="sourceLineNo">021</span>import java.util.concurrent.ConcurrentHashMap;<a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.util.concurrent.ConcurrentMap;<a name="line.22"></a>
<span class="sourceLineNo">023</span>import java.util.concurrent.TimeUnit;<a name="line.23"></a>
<span class="sourceLineNo">024</span>import java.util.function.Function;<a name="line.24"></a>
<span class="sourceLineNo">025</span>import org.apache.yetus.audience.InterfaceAudience;<a name="line.25"></a>
<span class="sourceLineNo">026</span>import org.slf4j.Logger;<a name="line.26"></a>
<span class="sourceLineNo">027</span>import org.slf4j.LoggerFactory;<a name="line.27"></a>
<span class="sourceLineNo">028</span><a name="line.28"></a>
<span class="sourceLineNo">029</span>/**<a name="line.29"></a>
<span class="sourceLineNo">030</span> * Cache to hold resolved Functions of a specific signature, generated through reflection. These can<a name="line.30"></a>
<span class="sourceLineNo">031</span> * be (relatively) costly to create, but then are much faster than typical Method.invoke calls when<a name="line.31"></a>
<span class="sourceLineNo">032</span> * executing. The cache is built-up on demand as calls are made to new classes. The functions are<a name="line.32"></a>
<span class="sourceLineNo">033</span> * cached for the lifetime of the process. If a function cannot be created (security reasons, method<a name="line.33"></a>
<span class="sourceLineNo">034</span> * not found, etc), a fallback function is cached which always returns null. Callers to<a name="line.34"></a>
<span class="sourceLineNo">035</span> * {@link #getAndCallByName(String, Object)} should have handling for null return values.<a name="line.35"></a>
<span class="sourceLineNo">036</span> * &lt;p&gt;<a name="line.36"></a>
<span class="sourceLineNo">037</span> * An instance is created for a specified baseClass (i.e. Filter), argClass (i.e. byte[]), and<a name="line.37"></a>
<span class="sourceLineNo">038</span> * static methodName to call. These are used to resolve a Function which delegates to that static<a name="line.38"></a>
<span class="sourceLineNo">039</span> * method, if it is found.<a name="line.39"></a>
<span class="sourceLineNo">040</span> * @param &lt;I&gt; the input argument type for the resolved functions<a name="line.40"></a>
<span class="sourceLineNo">041</span> * @param &lt;R&gt; the return type for the resolved functions<a name="line.41"></a>
<span class="sourceLineNo">042</span> */<a name="line.42"></a>
<span class="sourceLineNo">043</span>@InterfaceAudience.Private<a name="line.43"></a>
<span class="sourceLineNo">044</span>public final class ReflectedFunctionCache&lt;I, R&gt; {<a name="line.44"></a>
<span class="sourceLineNo">045</span><a name="line.45"></a>
<span class="sourceLineNo">046</span> private static final Logger LOG = LoggerFactory.getLogger(ReflectedFunctionCache.class);<a name="line.46"></a>
<span class="sourceLineNo">047</span><a name="line.47"></a>
<span class="sourceLineNo">048</span> private final ConcurrentMap&lt;String, Function&lt;I, ? extends R&gt;&gt; lambdasByClass =<a name="line.48"></a>
<span class="sourceLineNo">049</span> new ConcurrentHashMap&lt;&gt;();<a name="line.49"></a>
<span class="sourceLineNo">050</span> private final Class&lt;R&gt; baseClass;<a name="line.50"></a>
<span class="sourceLineNo">051</span> private final Class&lt;I&gt; argClass;<a name="line.51"></a>
<span class="sourceLineNo">052</span> private final String methodName;<a name="line.52"></a>
<span class="sourceLineNo">053</span> private final ClassLoader classLoader;<a name="line.53"></a>
<span class="sourceLineNo">054</span><a name="line.54"></a>
<span class="sourceLineNo">055</span> public ReflectedFunctionCache(Class&lt;R&gt; baseClass, Class&lt;I&gt; argClass, String staticMethodName) {<a name="line.55"></a>
<span class="sourceLineNo">056</span> this.classLoader = getClass().getClassLoader();<a name="line.56"></a>
<span class="sourceLineNo">057</span> this.baseClass = baseClass;<a name="line.57"></a>
<span class="sourceLineNo">058</span> this.argClass = argClass;<a name="line.58"></a>
<span class="sourceLineNo">059</span> this.methodName = staticMethodName;<a name="line.59"></a>
<span class="sourceLineNo">060</span> }<a name="line.60"></a>
<span class="sourceLineNo">061</span><a name="line.61"></a>
<span class="sourceLineNo">062</span> /**<a name="line.62"></a>
<span class="sourceLineNo">063</span> * Get and execute the Function for the given className, passing the argument to the function and<a name="line.63"></a>
<span class="sourceLineNo">064</span> * returning the result.<a name="line.64"></a>
<span class="sourceLineNo">065</span> * @param className the full name of the class to lookup<a name="line.65"></a>
<span class="sourceLineNo">066</span> * @param argument the argument to pass to the function, if found.<a name="line.66"></a>
<span class="sourceLineNo">067</span> * @return null if a function is not found for classname, otherwise the result of the function.<a name="line.67"></a>
<span class="sourceLineNo">068</span> */<a name="line.68"></a>
<span class="sourceLineNo">069</span> @Nullable<a name="line.69"></a>
<span class="sourceLineNo">070</span> public R getAndCallByName(String className, I argument) {<a name="line.70"></a>
<span class="sourceLineNo">071</span> // todo: if we ever make java9+ our lowest supported jdk version, we can<a name="line.71"></a>
<span class="sourceLineNo">072</span> // handle generating these for newly loaded classes from our DynamicClassLoader using<a name="line.72"></a>
<span class="sourceLineNo">073</span> // MethodHandles.privateLookupIn(). For now this is not possible, because we can't easily<a name="line.73"></a>
<span class="sourceLineNo">074</span> // create a privileged lookup in a non-default ClassLoader. So while this cache loads<a name="line.74"></a>
<span class="sourceLineNo">075</span> // over time, it will never load a custom filter from "hbase.dynamic.jars.dir".<a name="line.75"></a>
<span class="sourceLineNo">076</span> Function&lt;I, ? extends R&gt; lambda =<a name="line.76"></a>
<span class="sourceLineNo">077</span> ConcurrentMapUtils.computeIfAbsent(lambdasByClass, className, () -&gt; loadFunction(className));<a name="line.77"></a>
<span class="sourceLineNo">078</span><a name="line.78"></a>
<span class="sourceLineNo">079</span> return lambda.apply(argument);<a name="line.79"></a>
<span class="sourceLineNo">080</span> }<a name="line.80"></a>
<span class="sourceLineNo">081</span><a name="line.81"></a>
<span class="sourceLineNo">082</span> private Function&lt;I, ? extends R&gt; loadFunction(String className) {<a name="line.82"></a>
<span class="sourceLineNo">083</span> long startTime = System.nanoTime();<a name="line.83"></a>
<span class="sourceLineNo">084</span> try {<a name="line.84"></a>
<span class="sourceLineNo">085</span> Class&lt;?&gt; clazz = Class.forName(className, false, classLoader);<a name="line.85"></a>
<span class="sourceLineNo">086</span> if (!baseClass.isAssignableFrom(clazz)) {<a name="line.86"></a>
<span class="sourceLineNo">087</span> LOG.debug("Requested class {} is not assignable to {}, skipping creation of function",<a name="line.87"></a>
<span class="sourceLineNo">088</span> className, baseClass.getName());<a name="line.88"></a>
<span class="sourceLineNo">089</span> return this::notFound;<a name="line.89"></a>
<span class="sourceLineNo">090</span> }<a name="line.90"></a>
<span class="sourceLineNo">091</span> return ReflectionUtils.getOneArgStaticMethodAsFunction(clazz, methodName, argClass,<a name="line.91"></a>
<span class="sourceLineNo">092</span> (Class&lt;? extends R&gt;) clazz);<a name="line.92"></a>
<span class="sourceLineNo">093</span> } catch (Throwable t) {<a name="line.93"></a>
<span class="sourceLineNo">094</span> LOG.debug("Failed to create function for {}", className, t);<a name="line.94"></a>
<span class="sourceLineNo">095</span> return this::notFound;<a name="line.95"></a>
<span class="sourceLineNo">096</span> } finally {<a name="line.96"></a>
<span class="sourceLineNo">097</span> LOG.debug("Populated cache for {} in {}ms", className,<a name="line.97"></a>
<span class="sourceLineNo">098</span> TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTime));<a name="line.98"></a>
<span class="sourceLineNo">099</span> }<a name="line.99"></a>
<span class="sourceLineNo">100</span> }<a name="line.100"></a>
<span class="sourceLineNo">101</span><a name="line.101"></a>
<span class="sourceLineNo">102</span> /**<a name="line.102"></a>
<span class="sourceLineNo">103</span> * In order to use computeIfAbsent, we can't store nulls in our cache. So we store a lambda which<a name="line.103"></a>
<span class="sourceLineNo">104</span> * resolves to null. The contract is that getAndCallByName returns null in this case.<a name="line.104"></a>
<span class="sourceLineNo">105</span> */<a name="line.105"></a>
<span class="sourceLineNo">106</span> private R notFound(I argument) {<a name="line.106"></a>
<span class="sourceLineNo">107</span> return null;<a name="line.107"></a>
<span class="sourceLineNo">108</span> }<a name="line.108"></a>
<span class="sourceLineNo">109</span><a name="line.109"></a>
<span class="sourceLineNo">110</span>}<a name="line.110"></a>
</pre>
</div>
</body>
</html>