xref: /xnu-8020.121.3/libsyscall/os/proc.h (revision fdd8201d7b966f0c3ea610489d29bd841d358941)
1*fdd8201dSApple OSS Distributions /*
2*fdd8201dSApple OSS Distributions  * Copyright (c) 2019 Apple Inc. All rights reserved.
3*fdd8201dSApple OSS Distributions  *
4*fdd8201dSApple OSS Distributions  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5*fdd8201dSApple OSS Distributions  *
6*fdd8201dSApple OSS Distributions  * This file contains Original Code and/or Modifications of Original Code
7*fdd8201dSApple OSS Distributions  * as defined in and that are subject to the Apple Public Source License
8*fdd8201dSApple OSS Distributions  * Version 2.0 (the 'License'). You may not use this file except in
9*fdd8201dSApple OSS Distributions  * compliance with the License. The rights granted to you under the License
10*fdd8201dSApple OSS Distributions  * may not be used to create, or enable the creation or redistribution of,
11*fdd8201dSApple OSS Distributions  * unlawful or unlicensed copies of an Apple operating system, or to
12*fdd8201dSApple OSS Distributions  * circumvent, violate, or enable the circumvention or violation of, any
13*fdd8201dSApple OSS Distributions  * terms of an Apple operating system software license agreement.
14*fdd8201dSApple OSS Distributions  *
15*fdd8201dSApple OSS Distributions  * Please obtain a copy of the License at
16*fdd8201dSApple OSS Distributions  * http://www.opensource.apple.com/apsl/ and read it before using this file.
17*fdd8201dSApple OSS Distributions  *
18*fdd8201dSApple OSS Distributions  * The Original Code and all software distributed under the License are
19*fdd8201dSApple OSS Distributions  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20*fdd8201dSApple OSS Distributions  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21*fdd8201dSApple OSS Distributions  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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23*fdd8201dSApple OSS Distributions  * Please see the License for the specific language governing rights and
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25*fdd8201dSApple OSS Distributions  *
26*fdd8201dSApple OSS Distributions  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27*fdd8201dSApple OSS Distributions  */
28*fdd8201dSApple OSS Distributions 
29*fdd8201dSApple OSS Distributions #ifndef __OS_PROC__
30*fdd8201dSApple OSS Distributions #define __OS_PROC__
31*fdd8201dSApple OSS Distributions 
32*fdd8201dSApple OSS Distributions #include <stddef.h>
33*fdd8201dSApple OSS Distributions #include <sys/cdefs.h>
34*fdd8201dSApple OSS Distributions #include <os/availability.h>
35*fdd8201dSApple OSS Distributions 
36*fdd8201dSApple OSS Distributions /*!
37*fdd8201dSApple OSS Distributions  * @header
38*fdd8201dSApple OSS Distributions  *
39*fdd8201dSApple OSS Distributions  * @preprocinfo
40*fdd8201dSApple OSS Distributions  * This is for functions that operate on the calling process alone.
41*fdd8201dSApple OSS Distributions  */
42*fdd8201dSApple OSS Distributions 
43*fdd8201dSApple OSS Distributions __BEGIN_DECLS
44*fdd8201dSApple OSS Distributions 
45*fdd8201dSApple OSS Distributions /*!
46*fdd8201dSApple OSS Distributions  * @function os_proc_available_memory
47*fdd8201dSApple OSS Distributions  *
48*fdd8201dSApple OSS Distributions  * @abstract
49*fdd8201dSApple OSS Distributions  * Return the number of bytes remaining, at the time of the call, before the
50*fdd8201dSApple OSS Distributions  * current process will hit its current dirty memory limit.
51*fdd8201dSApple OSS Distributions  *
52*fdd8201dSApple OSS Distributions  * @discussion
53*fdd8201dSApple OSS Distributions  * Developers can query this value efficiently whenever it is needed. The return
54*fdd8201dSApple OSS Distributions  * value is only a snapshot at the time of the call. Caching the result is not
55*fdd8201dSApple OSS Distributions  * advised. The result may be instantaneously invalidated by actions taken in
56*fdd8201dSApple OSS Distributions  * another thread or another framework.
57*fdd8201dSApple OSS Distributions  *
58*fdd8201dSApple OSS Distributions  * Memory limits can change during the app life cycle. Make sure to check accordingly.
59*fdd8201dSApple OSS Distributions  *
60*fdd8201dSApple OSS Distributions  * The size returned is not representative of the total memory of the device, it
61*fdd8201dSApple OSS Distributions  * is the current dirty memory limit minus the dirty memory footprint used at the
62*fdd8201dSApple OSS Distributions  * time of the query.
63*fdd8201dSApple OSS Distributions  *
64*fdd8201dSApple OSS Distributions  * This interface allows an app to efficiently consume all available memory resources.
65*fdd8201dSApple OSS Distributions  * Significant memory use, even under the current memory limit, may still cause
66*fdd8201dSApple OSS Distributions  * system-wide performance including the termination of other apps and system
67*fdd8201dSApple OSS Distributions  * processes. Take care to use the minimum amount of memory needed to satisfy the
68*fdd8201dSApple OSS Distributions  * user’s need.
69*fdd8201dSApple OSS Distributions  *
70*fdd8201dSApple OSS Distributions  * If you need more information than just the available memory, you can use task_info().
71*fdd8201dSApple OSS Distributions  * The information returned is equivalent to the task_vm_info.limit_bytes_remaining
72*fdd8201dSApple OSS Distributions  * field. task_info() is a more expensive call, and will return information such
73*fdd8201dSApple OSS Distributions  * as your phys_footprint, which is used to calculate the return of this function.
74*fdd8201dSApple OSS Distributions  *
75*fdd8201dSApple OSS Distributions  * Dirty memory contains data that must be kept in RAM (or the equivalent) even
76*fdd8201dSApple OSS Distributions  * when unused. It is memory that has been modified.
77*fdd8201dSApple OSS Distributions  *
78*fdd8201dSApple OSS Distributions  * @param none
79*fdd8201dSApple OSS Distributions  *
80*fdd8201dSApple OSS Distributions  * @result
81*fdd8201dSApple OSS Distributions  * The remaining bytes. 0 is returned if the calling process is not an app, or
82*fdd8201dSApple OSS Distributions  * the calling process exceeds its memory limit.
83*fdd8201dSApple OSS Distributions  */
84*fdd8201dSApple OSS Distributions 
85*fdd8201dSApple OSS Distributions     API_UNAVAILABLE(macos) API_AVAILABLE(ios(13.0), tvos(13.0), watchos(6.0), bridgeos(4.0))
86*fdd8201dSApple OSS Distributions extern
87*fdd8201dSApple OSS Distributions size_t os_proc_available_memory(void);
88*fdd8201dSApple OSS Distributions 
89*fdd8201dSApple OSS Distributions __END_DECLS
90*fdd8201dSApple OSS Distributions 
91*fdd8201dSApple OSS Distributions #endif
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