H2Set.java

/*
** Module   : H2Set.java
** Abstract : Define a H2-backed set.
**
** Copyright (c) 2020, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------Description----------------------------------
** 001 CA  20200412 Created initial version, for incremental conversion support.
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
** 
** Additional terms under GNU Affero GPL version 3 section 7:
** 
**   Under Section 7 of the GNU Affero GPL version 3, the following additional
**   terms apply to the works covered under the License.  These additional terms
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*/

package com.goldencode.p2j.convert.db;

import java.sql.*;
import java.util.*;
import java.util.function.*;

import com.goldencode.ast.*;
import com.goldencode.p2j.convert.db.LoggedCollection.AstKey;
import com.goldencode.p2j.pattern.*;

/**
 * A H2-backed set, which has any changes to it logged in a separate work table.
 */
class H2Set
extends TreeSet
implements StoredCollection
{
   /** The change logger for this collection. */
   protected final LoggedCollection changes = new LoggedCollection();

   /** The AST symbol resolver. */
   private final AstSymbolResolver resolver;

   /** The AST manager. */
   private final AstManager manager;

   /** The helper for SQL usage. */
   private final DBHelper helper;
   
   /** The element's class. */
   private final Class<?> keyClass;

   /** The set's table name. */
   private final String tableName;
   
   /** The set's work table name. */
   private final String workTable;

   /** The set's insert SQL. */
   private final String insertSql;
   
   /** The set's clear SQL. */
   private final String clearSql;

   /** The set's work table insert SQL. */
   private final String workInsertSql;
   
   /** The set's work table clear SQL. */
   private final String workClearSql;
   
   /**
    * Create a new db-backed set, with the specified name.
    * 
    * @param    keyClass
    *           The element's class.
    * @param    table
    *           The set's (and main table) name.
    * @param    helper
    *           The SQL helper.
    */
   public H2Set(Class<?> keyClass, String table, DBHelper helper)
   {
      this.resolver = AstSymbolResolver.getResolver();
      this.manager = AstManager.get();
      
      this.tableName = table;
      this.keyClass = keyClass;
      this.helper = helper;

      String sqlKeyType = helper.convertToSql(keyClass);
      String createSQL = "CREATE TABLE IF NOT EXISTS " + tableName + 
                         " (key " + sqlKeyType + " PRIMARY KEY);";
      helper.executeSQL(createSQL);
      
      // the work map table
      workTable = tableName + "__work";
      String createWorkSQL = "CREATE TABLE IF NOT EXISTS " + workTable + " (" + 
                             " fileId BIGINT NOT NULL," +
                             " astId BIGINT NOT NULL," +
                             " key " + sqlKeyType + " NOT NULL);";
      helper.executeSQL(createWorkSQL);
      helper.executeSQL("CREATE UNIQUE INDEX IF NOT EXISTS idx_" + workTable + "__pk ON " + 
                        workTable + " (fileId, astId, key);");
      
      /*
      // load the main table
      Consumer<ResultSet> main = (rs) ->
      {
         try
         {
            Object key = rs.getObject(1);
            if (this.contains(key))
            {
               throw new IllegalStateException("Key already exists!");
            }
            
            super.add(key);
         }
         catch (SQLException e)
         {
            throw new RuntimeException(e);
         }
      };
      helper.executeQuery("select key from " + tableName, main);
      */
      
      // load the work table
      Consumer<ResultSet> work = (rs) ->
      {
         try
         {
            Object key = rs.getObject(3);

            /*
            if (this.contains(key))
            {
               throw new IllegalStateException("Key already exists!");
            }
            */
            
            super.add(key);
            this.changes.log(rs.getLong(1), rs.getLong(2), key);
         }
         catch (SQLException e)
         {
            throw new RuntimeException(e);
         }
      };
      helper.executeQuery("select fileId, astId, key from " + workTable, work);
      
      // misc used sqls
      this.insertSql   = "insert into " + tableName + " values (?)";
      this.clearSql    = "delete from " + tableName;
      
      // misc used work table sqls
      this.workInsertSql    = "INSERT INTO " + workTable + " VALUES (?, ?, ?)";
      this.workClearSql     = "DELETE FROM " + workTable;
   }

   /**
    * Constructor used for sub-classes, which delegate the db-storage to another collection.
    */
   protected H2Set()
   {
      this.resolver = AstSymbolResolver.getResolver();
      this.manager = AstManager.get();

      helper = null;
      keyClass = null;
      tableName = null;
      workTable = null;
      insertSql = null;
      clearSql = null;
      workInsertSql = null;
      workClearSql = null;
   }
   
   /**
    * Check if the set contains the specified key.
    * <p>
    * If the key exists, the access will be logged.  This assumes the source AST requires for
    * the key to have this specific value.
    * 
    * @param    key
    *           The key to check.
    * 
    * @return   <code>true</code> if the key exists in the set.
    */
   @Override
   public boolean contains(Object key)
   {
      boolean has = super.contains(key);
      
      if (has)
      {
         logChange(key);
      }
      
      return has;
   }
   
   /**
    * Perform an add operation.
    * <p>
    * The access will be logged.  This assumes the source AST requires for the key to have this 
    * specific value.
    * 
    * @param    key
    *           The key.
    * 
    * @return   <code>true</code> if the key already exists.
    */
   @Override
   public boolean add(Object key)
   {
      boolean has = super.add(key);

      logChange(key);
      
      return has;
   }

   /**
    * Merge the specified collection into this one.  This will rely on {@link #add} to log the 
    * access to the set.
    * 
    * @param    c
    *           The collection to merge.
    */
   @Override
   public boolean addAll(Collection c)
   {
      boolean changed = false;
      for (Object o : c)
      {
         changed = add(o) || changed;
      }
      
      return changed;
   }

   /**
    * Remove this key from the set.
    * <p>
    * If the key exists, then all changes related to it will be cleared.
    * 
    * @param    key
    *           The key to remove.
    */
   @Override
   public boolean remove(Object key)
   {
      boolean has = super.remove(key);
      
      if (has)
      {
         changes.remove(key);
      }
      
      return has;
   }

   /**
    * Clear the set and all its changes.
    */
   @Override
   public void clear()
   {
      super.clear();
      
      changes.clear();
   }
   
   /**
    * Persist this set and all the changes to the database.
    */
   @Override
   public void persist()
   {
      // clear the table and save the data
      helper.executeSQL(clearSql);
      
      helper.persistCollection(this, insertSql, (PreparedStatement ps, Object key) ->
      {
         try
         {
            ps.setObject(1, key);
            ps.addBatch();
         }
         catch (SQLException e)
         {
            throw new RuntimeException(e);
         }
      });
      
      // clear the work table and save the data
      helper.executeSQL(workClearSql);
      
      // ensure the changes are in sync with the main collection
      changes.retainAll(this);

      changes.persist(workInsertSql, 
                      helper,
                      (AstKey key, Object val) -> new Object[] { key.fileId, key.astId, key.key });
   }
   
   /**
    * Log this access in the set as a change.
    * 
    * @param    key
    *           The accessed key.
    */
   private void logChange(Object key)
   {
      if (inPersist())
      {
         return;
      }

      // add to work table
      Aast src = resolver.getSourceAst();
      long astId = -1;
      long fileId = -1;
      if (src != null)
      {
         astId = src.getId();
         fileId = manager.getTreeId(astId);
      }

      // log the change
      changes.log(fileId, astId, key);
   }
}