Mercurial > dive4elements > river
view flys-artifacts/src/main/java/de/intevation/flys/artifacts/datacage/templating/CompiledStatement.java @ 5779:ebec12def170
Datacage: Add a pool of builders to make it multi threadable.
XML DOM is not thread safe. Therefore the old implementation only allowed one thread
to use the builder at a time. As the complexity of the configuration
has increased over time this has become a bottleneck of the whole application
because it took quiet some time to build a result. Furthermore the builder code path
is visited very frequent. So many concurrent requests were piled up
resulting in long waits for the users.
To mitigate this problem a round robin pool of builders is used now.
Each of the pooled builders has an independent copy of the XML template
and can be run in parallel.
The number of builders is determined by the system property
'flys.datacage.pool.size'. It defaults to 4.
author | Sascha L. Teichmann <teichmann@intevation.de> |
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date | Sun, 21 Apr 2013 12:48:09 +0200 |
parents | ad9f1bdd51ba |
children |
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package de.intevation.flys.artifacts.datacage.templating; import java.util.regex.Pattern; import java.util.regex.Matcher; import java.util.List; import java.util.Map; import java.util.TreeMap; import java.util.ArrayList; import java.sql.PreparedStatement; import java.sql.SQLException; import java.sql.Connection; import java.sql.ResultSet; import net.sf.ehcache.Cache; import net.sf.ehcache.Element; import de.intevation.flys.artifacts.cache.CacheFactory; import org.apache.log4j.Logger; /** SQL Statement, create PreparedStatement. */ public class CompiledStatement { private static Logger log = Logger.getLogger(CompiledStatement.class); public static final String DATACAGE_DB_CACHE = "datacage.db"; public static final Pattern VAR = Pattern.compile("\\$\\{([a-zA-Z0-9_-]+)\\}"); protected String original; protected String statement; protected Map<String, List<Integer>> positions; protected int numVars; public class Instance { protected PreparedStatement preparedStatement; public Instance() { } /** Executes a Statement. */ protected ResultData executeCached( Cache cache, Connection connection, StackFrames frames ) throws SQLException { log.debug("executeCached"); Object [] values = new Object[numVars]; StringBuilder sb = new StringBuilder(original); for (Map.Entry<String, List<Integer>> entry: positions.entrySet()) { String key = entry.getKey(); Object value = frames.get(key); sb.append(';').append(key).append(':').append(value); for (Integer index: entry.getValue()) { values[index] = value; } } // XXX: Maybe too many collisions? // String key = original + Arrays.hashCode(values); String key = sb.toString(); Element element = cache.get(key); if (element != null) { return (ResultData)element.getValue(); } if (preparedStatement == null) { preparedStatement = connection.prepareStatement(statement); } for (int i = 0; i < values.length; ++i) { preparedStatement.setObject(i+1, values[i]); } ResultData data; if (log.isDebugEnabled()) { log.debug("executing: " + statement); } ResultSet result = preparedStatement.executeQuery(); try { data = new ResultData(preparedStatement.getMetaData()) .addAll(result); } finally { result.close(); } element = new Element(key, data); cache.put(element); return data; } protected ResultData executeUncached( Connection connection, StackFrames frames ) throws SQLException { log.debug("executeUncached"); if (preparedStatement == null) { if (log.isDebugEnabled()) { log.debug("preparing statement: " + statement); } preparedStatement = connection.prepareStatement(statement); } for (Map.Entry<String, List<Integer>> entry: positions.entrySet()) { Object value = frames.get(entry.getKey()); for (Integer index: entry.getValue()) { preparedStatement.setObject(index+1, value); } } if (log.isDebugEnabled()) { log.debug("executing: " + statement); } ResultSet result = preparedStatement.executeQuery(); try { return new ResultData(preparedStatement.getMetaData()) .addAll(result); } finally { result.close(); } } public ResultData execute( Connection connection, StackFrames frames, boolean cached ) throws SQLException { if (!cached) { return executeUncached(connection, frames); } Cache cache = CacheFactory.getCache(DATACAGE_DB_CACHE); return cache != null ? executeCached(cache, connection, frames) : executeUncached(connection, frames); } public void close() { if (preparedStatement != null) { try { preparedStatement.close(); } catch (SQLException sqle) { } preparedStatement = null; } } } // class Instance public CompiledStatement() { } public CompiledStatement(String original) { this.original = original; // TreeMap to ensure order positions = new TreeMap<String, List<Integer>>(); compile(); } protected void compile() { StringBuffer sb = new StringBuffer(); Matcher m = VAR.matcher(original); int index = 0; // Find variables like ${varname}. while (m.find()) { String key = m.group(1).toUpperCase(); List<Integer> indices = positions.get(key); if (indices == null) { indices = new ArrayList<Integer>(); positions.put(key, indices); } indices.add(index); m.appendReplacement(sb, "?"); ++index; } m.appendTail(sb); numVars = index; statement = sb.toString(); } public String getStatement() { return statement; } } // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :