Class JDBCStatementCache

java.lang.Object
org.apache.derby.client.am.stmtcache.JDBCStatementCache

public final class JDBCStatementCache extends Object
A cache for JDBC statement objects.

The entries in the cache contains objects implementing the java.sql.PreparedStatement interface, and they are inserted with a key object implementing the interface StatementKey. The cached objects can be either java.sql.PreparedStatement or java.sql.CallableStatement. These two should be separated by using different types of keys.

The cache only contains free statement objects, and on a successful request for a cached statement the statement is removed from the cache. The cache is not intended to hold duplicate statements. The physical prepared statement should be (re-)inserted into the cache when close is called on the logical prepared statement using it.

There is a maximum number of cached statements associated with the cache. If this number is exceeded, the oldest entry will be thrown out. One can always throw out an entry, because the fact that it is in the cache means it is free and not in use.

  • Field Details

  • Constructor Details

    • JDBCStatementCache

      public JDBCStatementCache(int maxSize)
      Creates a new, empty JDBC statement cache.
      Parameters:
      maxSize - maximum number of statements in the cache
      Throws:
      IllegalArgumentException - if maxSize is less than one
  • Method Details

    • getCached

      public PreparedStatement getCached(StatementKey statementKey)
      Retrieves a cached prepared statement if one exists.
      Parameters:
      statementKey - key for the prepared statement to look up
      Returns:
      A cached statement if one exists, null otherwise.
    • cacheStatement

      public boolean cacheStatement(StatementKey statementKey, PreparedStatement ps)
      Cache the prepared statement if it does not already exist.
      Parameters:
      statementKey - key to insert prepared statement with
      ps - prepared statement to cache
      Returns:
      true if added to the cache, false if not.