include/libkern/OSMemoryNotification.h

   1 /*
   2  * Copyright (c) 2006 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #ifndef _OSMEMORYNOTIFICATION_H_
  25 #define _OSMEMORYNOTIFICATION_H_
  26
  27 #include <sys/cdefs.h>
  28
  29 /*
  30 **  OSMemoryNotification.h
  31 **
  32 **  Kernel-generated notification mechanism to alert registered tasks when physical memory
  33 **  pressure reaches certain thresholds. Notifications are triggered in both directions
  34 **  so clients can manage their memory usage more and less aggressively.
  35 **
  36 */
  37
  38 __BEGIN_DECLS
  39
  40 struct timeval;
  41
  42 /*
  43 ** Opaque type for notification object
  44 */
  45
  46 typedef struct _OSMemoryNotification * OSMemoryNotificationRef;
  47
  48 /*
  49 ** Threshold values for notifications
  50 */
  51
  52 typedef enum {
  53         OSMemoryNotificationLevelAny      = -1,
  54         OSMemoryNotificationLevelNormal   =  0,
  55         OSMemoryNotificationLevelWarning  =  1,
  56         OSMemoryNotificationLevelUrgent   =  2,
  57         OSMemoryNotificationLevelCritical =  3
  58 } OSMemoryNotificationLevel;
  59
  60 /*
  61 ** Creation routines. Returns the created OSMemoryNotificationRef in the note param.
  62 ** returns: 0 on success
  63 **          ENOMEM if insufficient memory or resources exists to create the notification object
  64 **          EINVAL if the threshold is not a valid notification level
  65 */
  66
  67 int OSMemoryNotificationCreate(OSMemoryNotificationRef *note);
  68
  69 /*
  70 ** returns: 0 on success
  71 **          EINVAL if the notification is not an initialized notification object
  72 */
  73
  74 int OSMemoryNotificationDestroy(OSMemoryNotificationRef note);
  75
  76 /*
  77 ** Block waiting for notification
  78 ** returns: 0 on success, with the level that triggered the notification in the level param
  79 **          EINVAL if the notification object is invalid
  80 **          ETIMEDOUT if abstime passes before notification occurs
  81 */
  82 int OSMemoryNotificationWait(OSMemoryNotificationRef note, OSMemoryNotificationLevel *level);
  83 int OSMemoryNotificationTimedWait(OSMemoryNotificationRef note, OSMemoryNotificationLevel *level, const struct timeval *abstime);
  84
  85 /*
  86 ** Simple polling interface to detect current memory pressure level
  87 */
  88
  89 OSMemoryNotificationLevel OSMemoryNotificationCurrentLevel(void);
  90
  91 /*
  92 ** External notify(3) string for manual notification setup
  93 */
  94
  95 extern const char *kOSMemoryNotificationName;
  96
  97 __END_DECLS
  98
  99 #endif /* _OSMEMORYNOTIFICATION_H_ */