org.apache.tomcat.jni
Class Shm
public
class
Shm
extends Object
Shm
Version: $Revision: 467222 $, $Date: 2006-10-24 05:17:11 +0200 (Tue, 24 Oct 2006) $
Author: Mladen Turk
Method Summary |
static long | attach(String filename, long pool)
Attach to a shared memory segment that was created
by another process. |
static long | baseaddr(long m)
Retrieve the base address of the shared memory segment.
|
static ByteBuffer | buffer(long m)
Retrieve new ByteBuffer base address of the shared memory segment.
|
static long | create(long reqsize, String filename, long pool)
Create and make accessable a shared memory segment.
|
static int | destroy(long m)
Destroy a shared memory segment and associated memory. |
static int | detach(long m)
Detach from a shared memory segment without destroying it. |
static int | remove(String filename, long pool)
Remove shared memory segment associated with a filename.
|
static long | size(long m)
Retrieve the length of a shared memory segment in bytes. |
public static long attach(String filename, long pool)
Attach to a shared memory segment that was created
by another process.
Parameters: filename The file used to create the original segment.
(This MUST match the original filename.) pool the pool from which to allocate the shared memory
structure for this process.
Returns: The created shared memory structure.
public static long baseaddr(long m)
Retrieve the base address of the shared memory segment.
NOTE: This address is only usable within the callers address
space, since this API does not guarantee that other attaching
processes will maintain the same address mapping.
Parameters: m The shared memory segment from which to retrieve
the base address.
Returns: address, aligned by APR_ALIGN_DEFAULT.
public static ByteBuffer buffer(long m)
Retrieve new ByteBuffer base address of the shared memory segment.
NOTE: This address is only usable within the callers address
space, since this API does not guarantee that other attaching
processes will maintain the same address mapping.
Parameters: m The shared memory segment from which to retrieve
the base address.
Returns: address, aligned by APR_ALIGN_DEFAULT.
public static long create(long reqsize, String filename, long pool)
Create and make accessable a shared memory segment.
A note about Anonymous vs. Named shared memory segments:
Not all plaforms support anonymous shared memory segments, but in
some cases it is prefered over other types of shared memory
implementations. Passing a NULL 'file' parameter to this function
will cause the subsystem to use anonymous shared memory segments.
If such a system is not available, APR_ENOTIMPL is returned.
A note about allocation sizes:
On some platforms it is necessary to store some metainformation
about the segment within the actual segment. In order to supply
the caller with the requested size it may be necessary for the
implementation to request a slightly greater segment length
from the subsystem. In all cases, the apr_shm_baseaddr_get()
function will return the first usable byte of memory.
Parameters: reqsize The desired size of the segment. filename The file to use for shared memory on platforms that
require it. pool the pool from which to allocate the shared memory
structure.
Returns: The created shared memory structure.
public static int destroy(long m)
Destroy a shared memory segment and associated memory.
Parameters: m The shared memory segment structure to destroy.
public static int detach(long m)
Detach from a shared memory segment without destroying it.
Parameters: m The shared memory structure representing the segment
to detach from.
public static int remove(String filename, long pool)
Remove shared memory segment associated with a filename.
This function is only supported on platforms which support
name-based shared memory segments, and will return APR_ENOTIMPL on
platforms without such support.
Parameters: filename The filename associated with shared-memory segment which
needs to be removed pool The pool used for file operations
public static long size(long m)
Retrieve the length of a shared memory segment in bytes.
Parameters: m The shared memory segment from which to retrieve
the segment length.
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