128 lines
5.1 KiB
Java
128 lines
5.1 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.tomcat.jni;
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import java.nio.ByteBuffer;
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/** Shm
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*
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* @author Mladen Turk
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*/
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public class Shm {
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/**
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* Create and make accessible a shared memory segment.
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* <br>
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* A note about Anonymous vs. Named shared memory segments:<br>
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* Not all platforms support anonymous shared memory segments, but in
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* some cases it is preferred over other types of shared memory
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* implementations. Passing a NULL 'file' parameter to this function
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* will cause the subsystem to use anonymous shared memory segments.
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* If such a system is not available, APR_ENOTIMPL is returned.
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* <br>
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* A note about allocation sizes:<br>
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* On some platforms it is necessary to store some metainformation
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* about the segment within the actual segment. In order to supply
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* the caller with the requested size it may be necessary for the
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* implementation to request a slightly greater segment length
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* from the subsystem. In all cases, the apr_shm_baseaddr_get()
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* function will return the first usable byte of memory.
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* @param reqsize The desired size of the segment.
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* @param filename The file to use for shared memory on platforms that
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* require it.
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* @param pool the pool from which to allocate the shared memory
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* structure.
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* @return The created shared memory structure.
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* @throws Error An error occurred
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*/
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public static native long create(long reqsize, String filename, long pool)
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throws Error;
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/**
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* Remove shared memory segment associated with a filename.
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* <br>
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* This function is only supported on platforms which support
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* name-based shared memory segments, and will return APR_ENOTIMPL on
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* platforms without such support.
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* @param filename The filename associated with shared-memory segment which
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* needs to be removed
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* @param pool The pool used for file operations
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* @return the operation status
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*/
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public static native int remove(String filename, long pool);
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/**
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* Destroy a shared memory segment and associated memory.
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* @param m The shared memory segment structure to destroy.
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* @return the operation status
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*/
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public static native int destroy(long m);
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/**
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* Attach to a shared memory segment that was created
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* by another process.
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* @param filename The file used to create the original segment.
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* (This MUST match the original filename.)
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* @param pool the pool from which to allocate the shared memory
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* structure for this process.
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* @return The created shared memory structure.
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* @throws Error An error occurred
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*/
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public static native long attach(String filename, long pool)
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throws Error;
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/**
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* Detach from a shared memory segment without destroying it.
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* @param m The shared memory structure representing the segment
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* to detach from.
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* @return the operation status
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*/
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public static native int detach(long m);
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/**
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* Retrieve the base address of the shared memory segment.
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* NOTE: This address is only usable within the callers address
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* space, since this API does not guarantee that other attaching
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* processes will maintain the same address mapping.
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* @param m The shared memory segment from which to retrieve
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* the base address.
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* @return address, aligned by APR_ALIGN_DEFAULT.
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*/
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public static native long baseaddr(long m);
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/**
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* Retrieve the length of a shared memory segment in bytes.
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* @param m The shared memory segment from which to retrieve
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* the segment length.
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* @return the length of the segment
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*/
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public static native long size(long m);
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/**
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* Retrieve new ByteBuffer base address of the shared memory segment.
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* NOTE: This address is only usable within the callers address
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* space, since this API does not guarantee that other attaching
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* processes will maintain the same address mapping.
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* @param m The shared memory segment from which to retrieve
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* the base address.
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* @return address, aligned by APR_ALIGN_DEFAULT.
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*/
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public static native ByteBuffer buffer(long m);
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}
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