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Tomcat example source code file (Pool.java)

This example Tomcat source code file (Pool.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

bytebuffer, bytebuffer, io, nio, object, object, pool, pool, string, string

The Tomcat Pool.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.tomcat.jni;

import java.nio.ByteBuffer;

/** Pool
 *
 * @author Mladen Turk
 * @version $Revision: 467222 $, $Date: 2006-10-24 05:17:11 +0200 (mar., 24 oct. 2006) $
 */

public class Pool {

    /**
     * Create a new pool.
     * @param parent The parent pool.  If this is 0, the new pool is a root
     * pool.  If it is non-zero, the new pool will inherit all
     * of its parent pool's attributes, except the apr_pool_t will
     * be a sub-pool.
     * @return The pool we have just created.
    */
    public static native long create(long parent);

    /**
     * Clear all memory in the pool and run all the cleanups. This also destroys all
     * subpools.
     * @param pool The pool to clear
     * This does not actually free the memory, it just allows the pool
     *         to re-use this memory for the next allocation.
     */
    public static native void clear(long pool);

    /**
     * Destroy the pool. This takes similar action as apr_pool_clear() and then
     * frees all the memory.
     * This will actually free the memory
     * @param pool The pool to destroy
     */
    public static native void destroy(long pool);

    /**
     * Get the parent pool of the specified pool.
     * @param pool The pool for retrieving the parent pool.
     * @return The parent of the given pool.
     */
    public static native long parentGet(long pool);

    /**
     * Determine if pool a is an ancestor of pool b
     * @param a The pool to search
     * @param b The pool to search for
     * @return True if a is an ancestor of b, NULL is considered an ancestor
     * of all pools.
     */
    public static native boolean isAncestor(long a, long b);


    /*
     * Cleanup
     *
     * Cleanups are performed in the reverse order they were registered.  That is:
     * Last In, First Out.  A cleanup function can safely allocate memory from
     * the pool that is being cleaned up. It can also safely register additional
     * cleanups which will be run LIFO, directly after the current cleanup
     * terminates.  Cleanups have to take caution in calling functions that
     * create subpools. Subpools, created during cleanup will NOT automatically
     * be cleaned up.  In other words, cleanups are to clean up after themselves.
     */

    /**
     * Register a function to be called when a pool is cleared or destroyed
     * @param pool The pool register the cleanup with
     * @param o The object to call when the pool is cleared
     *                      or destroyed
     * @return The cleanup handler.
     */
    public static native long cleanupRegister(long pool, Object o);

    /**
     * Remove a previously registered cleanup function
     * @param pool The pool remove the cleanup from
     * @param data The cleanup handler to remove from cleanup
     */
    public static native void cleanupKill(long pool, long data);

    /**
     * Register a process to be killed when a pool dies.
     * @param a The pool to use to define the processes lifetime
     * @param proc The process to register
     * @param how How to kill the process, one of:
     * <PRE>
     * APR_KILL_NEVER         -- process is never sent any signals
     * APR_KILL_ALWAYS        -- process is sent SIGKILL on apr_pool_t cleanup
     * APR_KILL_AFTER_TIMEOUT -- SIGTERM, wait 3 seconds, SIGKILL
     * APR_JUST_WAIT          -- wait forever for the process to complete
     * APR_KILL_ONLY_ONCE     -- send SIGTERM and then wait
     * </PRE>
     */
    public static native void noteSubprocess(long a, long proc, int how);

    /**
     * Allocate a block of memory from a pool
     * @param p The pool to allocate from
     * @param size The amount of memory to allocate
     * @return The ByteBuffer with allocated memory
     */
    public static native ByteBuffer alloc(long p, int size);

    /**
     * Allocate a block of memory from a pool and set all of the memory to 0
     * @param p The pool to allocate from
     * @param size The amount of memory to allocate
     * @return The ByteBuffer with allocated memory
     */
    public static native ByteBuffer calloc(long p, int size);

    /*
     * User data management
     */

    /**
     * Set the data associated with the current pool
     * @param data The user data associated with the pool.
     * @param key The key to use for association
     * @param pool The current pool
     * <br />Warning :
     * The data to be attached to the pool should have a life span
     * at least as long as the pool it is being attached to.
     * Object attached to the pool will be globaly referenced
     * untill the pool is cleared or dataSet is called with the null data.
     * @return APR Status code.
     */
     public static native int dataSet(long pool, String key, Object data);

    /**
     * Return the data associated with the current pool.
     * @param key The key for the data to retrieve
     * @param pool The current pool.
     */
     public static native Object dataGet(long pool, String key);

    /**
     * Run all of the child_cleanups, so that any unnecessary files are
     * closed because we are about to exec a new program
     */
    public static native void cleanupForExec();

}

Other Tomcat examples (source code examples)

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