Annotation of win32/apache22/srclib/apr/include/apr_shm.h, revision 1.1
1.1 ! moko 1: /* Licensed to the Apache Software Foundation (ASF) under one or more
! 2: * contributor license agreements. See the NOTICE file distributed with
! 3: * this work for additional information regarding copyright ownership.
! 4: * The ASF licenses this file to You under the Apache License, Version 2.0
! 5: * (the "License"); you may not use this file except in compliance with
! 6: * the License. You may obtain a copy of the License at
! 7: *
! 8: * http://www.apache.org/licenses/LICENSE-2.0
! 9: *
! 10: * Unless required by applicable law or agreed to in writing, software
! 11: * distributed under the License is distributed on an "AS IS" BASIS,
! 12: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
! 13: * See the License for the specific language governing permissions and
! 14: * limitations under the License.
! 15: */
! 16:
! 17: #ifndef APR_SHM_H
! 18: #define APR_SHM_H
! 19:
! 20: /**
! 21: * @file apr_shm.h
! 22: * @brief APR Shared Memory Routines
! 23: */
! 24:
! 25: #include "apr.h"
! 26: #include "apr_pools.h"
! 27: #include "apr_errno.h"
! 28:
! 29: #ifdef __cplusplus
! 30: extern "C" {
! 31: #endif /* __cplusplus */
! 32:
! 33: /**
! 34: * @defgroup apr_shm Shared Memory Routines
! 35: * @ingroup APR
! 36: * @{
! 37: */
! 38:
! 39: /**
! 40: * Private, platform-specific data struture representing a shared memory
! 41: * segment.
! 42: */
! 43: typedef struct apr_shm_t apr_shm_t;
! 44:
! 45: /**
! 46: * Create and make accessable a shared memory segment.
! 47: * @param m The shared memory structure to create.
! 48: * @param reqsize The desired size of the segment.
! 49: * @param filename The file to use for shared memory on platforms that
! 50: * require it.
! 51: * @param pool the pool from which to allocate the shared memory
! 52: * structure.
! 53: * @remark A note about Anonymous vs. Named shared memory segments:
! 54: * Not all plaforms support anonymous shared memory segments, but in
! 55: * some cases it is prefered over other types of shared memory
! 56: * implementations. Passing a NULL 'file' parameter to this function
! 57: * will cause the subsystem to use anonymous shared memory segments.
! 58: * If such a system is not available, APR_ENOTIMPL is returned.
! 59: * @remark A note about allocation sizes:
! 60: * On some platforms it is necessary to store some metainformation
! 61: * about the segment within the actual segment. In order to supply
! 62: * the caller with the requested size it may be necessary for the
! 63: * implementation to request a slightly greater segment length
! 64: * from the subsystem. In all cases, the apr_shm_baseaddr_get()
! 65: * function will return the first usable byte of memory.
! 66: *
! 67: */
! 68: APR_DECLARE(apr_status_t) apr_shm_create(apr_shm_t **m,
! 69: apr_size_t reqsize,
! 70: const char *filename,
! 71: apr_pool_t *pool);
! 72:
! 73: /**
! 74: * Remove named resource associated with a shared memory segment,
! 75: * preventing attachments to the resource, but not destroying it.
! 76: * @param filename The filename associated with shared-memory segment which
! 77: * needs to be removed
! 78: * @param pool The pool used for file operations
! 79: * @remark This function is only supported on platforms which support
! 80: * name-based shared memory segments, and will return APR_ENOTIMPL on
! 81: * platforms without such support. Removing the file while the shm
! 82: * is in use is not entirely portable, caller may use this to enhance
! 83: * obscurity of the resource, but be prepared for the the call to fail,
! 84: * and for concurrent attempts to create a resource of the same name
! 85: * to also fail. The pool cleanup of apr_shm_create (apr_shm_destroy)
! 86: * also removes the named resource.
! 87: */
! 88: APR_DECLARE(apr_status_t) apr_shm_remove(const char *filename,
! 89: apr_pool_t *pool);
! 90:
! 91: /**
! 92: * Destroy a shared memory segment and associated memory.
! 93: * @param m The shared memory segment structure to destroy.
! 94: */
! 95: APR_DECLARE(apr_status_t) apr_shm_destroy(apr_shm_t *m);
! 96:
! 97: /**
! 98: * Attach to a shared memory segment that was created
! 99: * by another process.
! 100: * @param m The shared memory structure to create.
! 101: * @param filename The file used to create the original segment.
! 102: * (This MUST match the original filename.)
! 103: * @param pool the pool from which to allocate the shared memory
! 104: * structure for this process.
! 105: */
! 106: APR_DECLARE(apr_status_t) apr_shm_attach(apr_shm_t **m,
! 107: const char *filename,
! 108: apr_pool_t *pool);
! 109:
! 110: /**
! 111: * Detach from a shared memory segment without destroying it.
! 112: * @param m The shared memory structure representing the segment
! 113: * to detach from.
! 114: */
! 115: APR_DECLARE(apr_status_t) apr_shm_detach(apr_shm_t *m);
! 116:
! 117: /**
! 118: * Retrieve the base address of the shared memory segment.
! 119: * NOTE: This address is only usable within the callers address
! 120: * space, since this API does not guarantee that other attaching
! 121: * processes will maintain the same address mapping.
! 122: * @param m The shared memory segment from which to retrieve
! 123: * the base address.
! 124: * @return address, aligned by APR_ALIGN_DEFAULT.
! 125: */
! 126: APR_DECLARE(void *) apr_shm_baseaddr_get(const apr_shm_t *m);
! 127:
! 128: /**
! 129: * Retrieve the length of a shared memory segment in bytes.
! 130: * @param m The shared memory segment from which to retrieve
! 131: * the segment length.
! 132: */
! 133: APR_DECLARE(apr_size_t) apr_shm_size_get(const apr_shm_t *m);
! 134:
! 135: /**
! 136: * Get the pool used by this shared memory segment.
! 137: */
! 138: APR_POOL_DECLARE_ACCESSOR(shm);
! 139:
! 140: /** @} */
! 141:
! 142: #ifdef __cplusplus
! 143: }
! 144: #endif
! 145:
! 146: #endif /* APR_SHM_T */
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