DataSourceViewPluginProvider.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * accompanied this code).
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package com.sun.tools.visualvm.core.ui;

import com.sun.tools.visualvm.core.datasource.DataSource;
import com.sun.tools.visualvm.core.snapshot.Snapshot;
import java.util.HashMap;
import java.util.Map;

/**
 * Provider of DataSourceViewPlugin for a DataSource.
 *
 * @author Jiri Sedlacek
 */
public abstract class DataSourceViewPluginProvider<X extends DataSource> {
    
    private final Map<X, DataSourceViewPlugin> pluginsCache = new HashMap();
    
    
    /**
     * Returns true if the plugin provider provides a plugin for the DataSource.
     * 
     * @param dataSource DataSource for which to provide the plugin.
     * @return true if the plugin provider provides a plugin for the DataSource, false otherwise.
     */
    protected abstract boolean supportsPluginFor(X dataSource);

    /**
     * Returns DataSourceViewPlugin instance for the DataSource.
     * 
     * @param dataSource DataSource for which to create the plugin.
     * @return DataSourceViewPlugin instance for the DataSource.
     */
    protected abstract DataSourceViewPlugin createPlugin(X dataSource);
    
    /**
     * Returns true if the plugin provider supports saving DataSourceViewPlugin for the DataSource into
     * the Snapshot type.
     * 
     * @param dataSource DataSource for which to save the plugin.
     * @param snapshotClass snapshot type into which to save the plugin.
     * @return true if the plugin provider supports saving DataSourceViewPlugin for the DataSource, false otherwise.
     */
    protected boolean supportsSavePluginFor(X dataSource, Class<? extends Snapshot> snapshotClass) { return false; };
    
    /**
     * Saves DataSourceViewPlugin for the DataSource into the Snapshot.
     * 
     * @param dataSource DataSource for which to save the plugin.
     * @param snapshot Snapshot into which to save the plugin.
     */
    protected void savePlugin(X dataSource, Snapshot snapshot) {};
    
    
    /**
     * Returns DataSourceViewPlugin for the DataSource if already created (cached).
     * 
     * @param dataSource DataSource of the plugin.
     * @return DataSourceViewPlugin for the DataSource if already created (cached), null otherwise.
     */
    protected final DataSourceViewPlugin getCachedPlugin(X dataSource) {
        synchronized(pluginsCache) {
            return pluginsCache.get(dataSource);
        }
    }
    
    
    void pluginWillBeAdded(DataSourceViewPlugin plugin) {
    }
    
    void pluginAdded(DataSourceViewPlugin plugin) {
    }
    
    void pluginRemoved(DataSourceViewPlugin plugin) {
        synchronized(pluginsCache) {
            pluginsCache.remove((X)plugin.getDataSource());
        }
    }
    
    /**
     * Returns DataSourceViewPlugin for the DataSource. Tries to resolve already
     * created plugin from cache, creates new DataSourceViewPlugin instance using
     * the createPlugin(DataSource) method if needed.
     * 
     * @param dataSource
     * @return DataSourceViewPlugin for the DataSource.
     */
    protected final DataSourceViewPlugin getPlugin(X dataSource) {
        synchronized(pluginsCache) {
            DataSourceViewPlugin plugin = getCachedPlugin(dataSource);
            if (plugin == null) {
                plugin = createPlugin(dataSource);
                if (plugin == null) throw new NullPointerException("DataSourceViewPluginProvider provides null plugin: " + this);   // NOI18N
                plugin.setController(this);
                pluginsCache.put(dataSource, plugin);
            }
            return plugin;
        }
    }

}