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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Copyright (C) 2008-2013, fluid Operations AG<a name="line.2"></a>
<span class="sourceLineNo">003</span> *<a name="line.3"></a>
<span class="sourceLineNo">004</span> * FedX is free software: you can redistribute it and/or modify<a name="line.4"></a>
<span class="sourceLineNo">005</span> * it under the terms of the GNU Affero General Public License as<a name="line.5"></a>
<span class="sourceLineNo">006</span> * published by the Free Software Foundation, either version 3 of the<a name="line.6"></a>
<span class="sourceLineNo">007</span> * License, or (at your option) any later version.<a name="line.7"></a>
<span class="sourceLineNo">008</span> * <a name="line.8"></a>
<span class="sourceLineNo">009</span> * This program is distributed in the hope that it will be useful,<a name="line.9"></a>
<span class="sourceLineNo">010</span> * but WITHOUT ANY WARRANTY; without even the implied warranty of<a name="line.10"></a>
<span class="sourceLineNo">011</span> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the<a name="line.11"></a>
<span class="sourceLineNo">012</span> * GNU Affero General Public License for more details.<a name="line.12"></a>
<span class="sourceLineNo">013</span> * <a name="line.13"></a>
<span class="sourceLineNo">014</span> * You should have received a copy of the GNU Affero General Public License<a name="line.14"></a>
<span class="sourceLineNo">015</span> * along with this program.  If not, see &lt;http://www.gnu.org/licenses/&gt;.<a name="line.15"></a>
<span class="sourceLineNo">016</span> */<a name="line.16"></a>
<span class="sourceLineNo">017</span><a name="line.17"></a>
<span class="sourceLineNo">018</span>package com.fluidops.fedx.cache;<a name="line.18"></a>
<span class="sourceLineNo">019</span><a name="line.19"></a>
<span class="sourceLineNo">020</span>import java.util.List;<a name="line.20"></a>
<span class="sourceLineNo">021</span><a name="line.21"></a>
<span class="sourceLineNo">022</span>import info.aduna.iteration.CloseableIteration;<a name="line.22"></a>
<span class="sourceLineNo">023</span><a name="line.23"></a>
<span class="sourceLineNo">024</span>import org.openrdf.model.Statement;<a name="line.24"></a>
<span class="sourceLineNo">025</span><a name="line.25"></a>
<span class="sourceLineNo">026</span>import com.fluidops.fedx.exception.EntryAlreadyExistsException;<a name="line.26"></a>
<span class="sourceLineNo">027</span>import com.fluidops.fedx.exception.EntryUpdateException;<a name="line.27"></a>
<span class="sourceLineNo">028</span>import com.fluidops.fedx.exception.FedXException;<a name="line.28"></a>
<span class="sourceLineNo">029</span>import com.fluidops.fedx.structures.Endpoint;<a name="line.29"></a>
<span class="sourceLineNo">030</span>import com.fluidops.fedx.structures.SubQuery;<a name="line.30"></a>
<span class="sourceLineNo">031</span><a name="line.31"></a>
<span class="sourceLineNo">032</span>/**<a name="line.32"></a>
<span class="sourceLineNo">033</span> * Interface for any Cache.<a name="line.33"></a>
<span class="sourceLineNo">034</span> * <a name="line.34"></a>
<span class="sourceLineNo">035</span> * @author Andreas Schwarte<a name="line.35"></a>
<span class="sourceLineNo">036</span> *<a name="line.36"></a>
<span class="sourceLineNo">037</span> */<a name="line.37"></a>
<span class="sourceLineNo">038</span>public interface Cache {<a name="line.38"></a>
<span class="sourceLineNo">039</span><a name="line.39"></a>
<span class="sourceLineNo">040</span>        public static enum StatementSourceAssurance { NONE, HAS_LOCAL_STATEMENTS, HAS_REMOTE_STATEMENTS, POSSIBLY_HAS_STATEMENTS; }<a name="line.40"></a>
<span class="sourceLineNo">041</span>        <a name="line.41"></a>
<span class="sourceLineNo">042</span>        /**<a name="line.42"></a>
<span class="sourceLineNo">043</span>         * Ask the cache if a given endpoint can provide results for a subQuery. Note that<a name="line.43"></a>
<span class="sourceLineNo">044</span>         * S1:={?x, c, c} and S2:={?y, c, c} are treated as the same statement.<a name="line.44"></a>
<span class="sourceLineNo">045</span>         * <a name="line.45"></a>
<span class="sourceLineNo">046</span>         * Subset inference:<a name="line.46"></a>
<span class="sourceLineNo">047</span>         * <a name="line.47"></a>
<span class="sourceLineNo">048</span>         * Cache knows that S1:={?x, c, c} brings results, hence also S2:={?x, ?y, c} will<a name="line.48"></a>
<span class="sourceLineNo">049</span>         * provide results. This method can be used to test this and will return HAS_STATEMENTS.<a name="line.49"></a>
<span class="sourceLineNo">050</span>         * <a name="line.50"></a>
<span class="sourceLineNo">051</span>         * Superset inference:<a name="line.51"></a>
<span class="sourceLineNo">052</span>         * <a name="line.52"></a>
<span class="sourceLineNo">053</span>         * Cache knows that S1:={?x, ?y, c} brings results, hence S2:={?x, c, c} may provide<a name="line.53"></a>
<span class="sourceLineNo">054</span>         * results. This method will return POSSIBLY_HAS_STATEMENTS in such a case.<a name="line.54"></a>
<span class="sourceLineNo">055</span>         * <a name="line.55"></a>
<span class="sourceLineNo">056</span>         * @param subQuery<a name="line.56"></a>
<span class="sourceLineNo">057</span>         * @param endpoint<a name="line.57"></a>
<span class="sourceLineNo">058</span>         * <a name="line.58"></a>
<span class="sourceLineNo">059</span>         * @return<a name="line.59"></a>
<span class="sourceLineNo">060</span>         *              NONE -&gt; the cache knows that endpoint cannot provide any results<a name="line.60"></a>
<span class="sourceLineNo">061</span>         *              HAS_LOCAL_STATEMENTS -&gt; the cache has local statements (highest priority)<a name="line.61"></a>
<span class="sourceLineNo">062</span>         *              HAS_REMOTE_STATEMENTS -&gt; the cache knows that endpoint does provide results<a name="line.62"></a>
<span class="sourceLineNo">063</span>         *              POSSIBLY_HAS_STATEMENTS -&gt; if the endpoint is not known or in case of superset inference<a name="line.63"></a>
<span class="sourceLineNo">064</span>         */<a name="line.64"></a>
<span class="sourceLineNo">065</span>        public StatementSourceAssurance canProvideStatements(SubQuery subQuery, Endpoint endpoint);<a name="line.65"></a>
<span class="sourceLineNo">066</span><a name="line.66"></a>
<span class="sourceLineNo">067</span>        <a name="line.67"></a>
<span class="sourceLineNo">068</span>        /**<a name="line.68"></a>
<span class="sourceLineNo">069</span>         * Ask the cache if it can provide results for a subQuery for any endpoint. Note that<a name="line.69"></a>
<span class="sourceLineNo">070</span>         * S1:={?x, c, c} and S2:={?y, c, c} are treated as the same statement.<a name="line.70"></a>
<span class="sourceLineNo">071</span>         * <a name="line.71"></a>
<span class="sourceLineNo">072</span>         * Subset inference:<a name="line.72"></a>
<span class="sourceLineNo">073</span>         * <a name="line.73"></a>
<span class="sourceLineNo">074</span>         * Cache knows that S1:={?x, c, c} has local results. However, cache will pessimistically<a name="line.74"></a>
<span class="sourceLineNo">075</span>         * assume that S2:={?x, ?y, c} has no local results as we cannot assure that the complete<a name="line.75"></a>
<span class="sourceLineNo">076</span>         * data is available locally. Hence, this method will return false.<a name="line.76"></a>
<span class="sourceLineNo">077</span>         * <a name="line.77"></a>
<span class="sourceLineNo">078</span>         * Superset inference:<a name="line.78"></a>
<span class="sourceLineNo">079</span>         * <a name="line.79"></a>
<span class="sourceLineNo">080</span>         * Cache knows that S1:={?x, ?y, c} has local results, hence S2:={?x, c, c} has local results<a name="line.80"></a>
<span class="sourceLineNo">081</span>         * as well as the cache maintains a superset of the requested results. In such a case this<a name="line.81"></a>
<span class="sourceLineNo">082</span>         * method will return true.<a name="line.82"></a>
<span class="sourceLineNo">083</span>         * <a name="line.83"></a>
<span class="sourceLineNo">084</span>         * @param subQuery<a name="line.84"></a>
<span class="sourceLineNo">085</span>         * @return<a name="line.85"></a>
<span class="sourceLineNo">086</span>         *                      the endpoints for which local data is available, an empty list otherwise<a name="line.86"></a>
<span class="sourceLineNo">087</span>         */<a name="line.87"></a>
<span class="sourceLineNo">088</span>        public List&lt;Endpoint&gt; hasLocalStatements(SubQuery subQuery);<a name="line.88"></a>
<span class="sourceLineNo">089</span>        <a name="line.89"></a>
<span class="sourceLineNo">090</span>        <a name="line.90"></a>
<span class="sourceLineNo">091</span>        /**<a name="line.91"></a>
<span class="sourceLineNo">092</span>         * Ask the cache if it can provide results for a subQuery for the specified endpoint. <a name="line.92"></a>
<span class="sourceLineNo">093</span>         * Note that S1:={?x, c, c} and S2:={?y, c, c} are treated as the same statement.<a name="line.93"></a>
<span class="sourceLineNo">094</span>         * <a name="line.94"></a>
<span class="sourceLineNo">095</span>         * Subset inference:<a name="line.95"></a>
<span class="sourceLineNo">096</span>         * <a name="line.96"></a>
<span class="sourceLineNo">097</span>         * Cache knows that S1:={?x, c, c} has local results. However, cache will pessimistically<a name="line.97"></a>
<span class="sourceLineNo">098</span>         * assume that S2:={?x, ?y, c} has no local results as we cannot assure that the complete<a name="line.98"></a>
<span class="sourceLineNo">099</span>         * data is available locally. Hence, this method will return false.<a name="line.99"></a>
<span class="sourceLineNo">100</span>         * <a name="line.100"></a>
<span class="sourceLineNo">101</span>         * Superset inference:<a name="line.101"></a>
<span class="sourceLineNo">102</span>         * <a name="line.102"></a>
<span class="sourceLineNo">103</span>         * Cache knows that S1:={?x, ?y, c} has local results, hence S2:={?x, c, c} has local results<a name="line.103"></a>
<span class="sourceLineNo">104</span>         * as well as the cache maintains a superset of the requested results. In such a case this<a name="line.104"></a>
<span class="sourceLineNo">105</span>         * method will return true.<a name="line.105"></a>
<span class="sourceLineNo">106</span>         * <a name="line.106"></a>
<span class="sourceLineNo">107</span>         * @param subQuery<a name="line.107"></a>
<span class="sourceLineNo">108</span>         * @return<a name="line.108"></a>
<span class="sourceLineNo">109</span>         */<a name="line.109"></a>
<span class="sourceLineNo">110</span>        public boolean hasLocalStatements(SubQuery subQuery, Endpoint endpoint);<a name="line.110"></a>
<span class="sourceLineNo">111</span>        <a name="line.111"></a>
<span class="sourceLineNo">112</span>        <a name="line.112"></a>
<span class="sourceLineNo">113</span>        /**<a name="line.113"></a>
<span class="sourceLineNo">114</span>         * Retrieve the CacheEntry instance matching the specified subQuery. Note that S1:={?x, c, c} <a name="line.114"></a>
<span class="sourceLineNo">115</span>         * and S2:={?y, c, c} are treated as the same statement.<a name="line.115"></a>
<span class="sourceLineNo">116</span>         * <a name="line.116"></a>
<span class="sourceLineNo">117</span>         * @param subQuery<a name="line.117"></a>
<span class="sourceLineNo">118</span>         * @return<a name="line.118"></a>
<span class="sourceLineNo">119</span>         *              the CacheResult or null (if no match was found) - read only clone!<a name="line.119"></a>
<span class="sourceLineNo">120</span>         */<a name="line.120"></a>
<span class="sourceLineNo">121</span>        public CacheEntry getCacheEntry(SubQuery subQuery);<a name="line.121"></a>
<span class="sourceLineNo">122</span>        <a name="line.122"></a>
<span class="sourceLineNo">123</span>        <a name="line.123"></a>
<span class="sourceLineNo">124</span>        /**<a name="line.124"></a>
<span class="sourceLineNo">125</span>         * Retrieve an Iterator containing the results for the given subQuery. If no match is<a name="line.125"></a>
<span class="sourceLineNo">126</span>         * available locally an empty iterator is returned. Note that S1:={?x, c, c} <a name="line.126"></a>
<span class="sourceLineNo">127</span>         * and S2:={?y, c, c} are treated as the same statement.<a name="line.127"></a>
<span class="sourceLineNo">128</span>         * <a name="line.128"></a>
<span class="sourceLineNo">129</span>         * @param subQuery<a name="line.129"></a>
<span class="sourceLineNo">130</span>         * @return<a name="line.130"></a>
<span class="sourceLineNo">131</span>         *                      an iterator, possible empty if no data is available locally<a name="line.131"></a>
<span class="sourceLineNo">132</span>         */<a name="line.132"></a>
<span class="sourceLineNo">133</span>        public CloseableIteration&lt;? extends Statement, Exception&gt; getStatements(SubQuery subQuery);<a name="line.133"></a>
<span class="sourceLineNo">134</span>        <a name="line.134"></a>
<span class="sourceLineNo">135</span>        /**<a name="line.135"></a>
<span class="sourceLineNo">136</span>         * Retrieve an Iterator containing the results for the given subQuery for the given endpoint.<a name="line.136"></a>
<span class="sourceLineNo">137</span>         * If no match is available locally an empty iterator is returned. Note that S1:={?x, c, c} <a name="line.137"></a>
<span class="sourceLineNo">138</span>         * and S2:={?y, c, c} are treated as the same statement.<a name="line.138"></a>
<span class="sourceLineNo">139</span>         * <a name="line.139"></a>
<span class="sourceLineNo">140</span>         * @param subQuery<a name="line.140"></a>
<span class="sourceLineNo">141</span>         * @return<a name="line.141"></a>
<span class="sourceLineNo">142</span>         *                      an iterator, possible empty if no data is available locally<a name="line.142"></a>
<span class="sourceLineNo">143</span>         */<a name="line.143"></a>
<span class="sourceLineNo">144</span>        public CloseableIteration&lt;? extends Statement, Exception&gt; getStatements(SubQuery subQuery, Endpoint endpoint);<a name="line.144"></a>
<span class="sourceLineNo">145</span>        <a name="line.145"></a>
<span class="sourceLineNo">146</span>        <a name="line.146"></a>
<span class="sourceLineNo">147</span>        /**<a name="line.147"></a>
<span class="sourceLineNo">148</span>         * Initialize this cache, e.g. from file system.<a name="line.148"></a>
<span class="sourceLineNo">149</span>         * <a name="line.149"></a>
<span class="sourceLineNo">150</span>         * @throws Exception<a name="line.150"></a>
<span class="sourceLineNo">151</span>         */<a name="line.151"></a>
<span class="sourceLineNo">152</span>        public void initialize() throws FedXException;<a name="line.152"></a>
<span class="sourceLineNo">153</span>        <a name="line.153"></a>
<span class="sourceLineNo">154</span>        <a name="line.154"></a>
<span class="sourceLineNo">155</span>        /**<a name="line.155"></a>
<span class="sourceLineNo">156</span>         * Invalidate some of the contents of this cache, e.g. free not used resources.<a name="line.156"></a>
<span class="sourceLineNo">157</span>         * <a name="line.157"></a>
<span class="sourceLineNo">158</span>         * @throws Exception<a name="line.158"></a>
<span class="sourceLineNo">159</span>         */<a name="line.159"></a>
<span class="sourceLineNo">160</span>        public void invalidate() throws FedXException;<a name="line.160"></a>
<span class="sourceLineNo">161</span>        <a name="line.161"></a>
<span class="sourceLineNo">162</span>        <a name="line.162"></a>
<span class="sourceLineNo">163</span>        /**<a name="line.163"></a>
<span class="sourceLineNo">164</span>         * Persist the state of the Cache (optional operation)<a name="line.164"></a>
<span class="sourceLineNo">165</span>         * <a name="line.165"></a>
<span class="sourceLineNo">166</span>         * @throws Exception<a name="line.166"></a>
<span class="sourceLineNo">167</span>         */<a name="line.167"></a>
<span class="sourceLineNo">168</span>        public void persist() throws FedXException;<a name="line.168"></a>
<span class="sourceLineNo">169</span>        <a name="line.169"></a>
<span class="sourceLineNo">170</span>        <a name="line.170"></a>
<span class="sourceLineNo">171</span>        <a name="line.171"></a>
<span class="sourceLineNo">172</span>        public void addEntry(SubQuery subQuery, CacheEntry cacheEntry) throws EntryAlreadyExistsException;<a name="line.172"></a>
<span class="sourceLineNo">173</span>        <a name="line.173"></a>
<span class="sourceLineNo">174</span>        <a name="line.174"></a>
<span class="sourceLineNo">175</span>        /**<a name="line.175"></a>
<span class="sourceLineNo">176</span>         * Update the given entry using a merge procedure:<a name="line.176"></a>
<span class="sourceLineNo">177</span>         * <a name="line.177"></a>
<span class="sourceLineNo">178</span>         * Data present in the original is overwritten, if not present it is simply added. Note that data<a name="line.178"></a>
<span class="sourceLineNo">179</span>         * not touched in the specified merge structure will remain as is.<a name="line.179"></a>
<span class="sourceLineNo">180</span>         * <a name="line.180"></a>
<span class="sourceLineNo">181</span>         * @param subQuery<a name="line.181"></a>
<span class="sourceLineNo">182</span>         * @param merge<a name="line.182"></a>
<span class="sourceLineNo">183</span>         * @throws EntryUpdateException<a name="line.183"></a>
<span class="sourceLineNo">184</span>         */<a name="line.184"></a>
<span class="sourceLineNo">185</span>        public void updateEntry(SubQuery subQuery, CacheEntry merge) throws EntryUpdateException;<a name="line.185"></a>
<span class="sourceLineNo">186</span>        <a name="line.186"></a>
<span class="sourceLineNo">187</span>        <a name="line.187"></a>
<span class="sourceLineNo">188</span>        <a name="line.188"></a>
<span class="sourceLineNo">189</span>        public void removeEntry(SubQuery subQuery) throws EntryUpdateException;<a name="line.189"></a>
<span class="sourceLineNo">190</span>        <a name="line.190"></a>
<span class="sourceLineNo">191</span>        <a name="line.191"></a>
<span class="sourceLineNo">192</span>        public void clear();<a name="line.192"></a>
<span class="sourceLineNo">193</span>}<a name="line.193"></a>




























































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