1 /**************************************************************************
2 *
3 * Copyright 2008-2010 VMware, Inc.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27
28 /**
29 * @file
30 * OS independent time-manipulation functions.
31 *
32 * @author Jose Fonseca <jfonseca@vmware.com>
33 */
34
35 #ifndef _OS_TIME_H_
36 #define _OS_TIME_H_
37
38 #include <stdbool.h>
39 #include <stdint.h>
40 #include <time.h>
41
42 #ifdef __cplusplus
43 extern "C" {
44 #endif
45
46 /* must be equal to PIPE_TIMEOUT_INFINITE */
47 #define OS_TIMEOUT_INFINITE 0xffffffffffffffffull
48
49 /*
50 * Get the current time in nanoseconds from an unknown base.
51 */
52 int64_t
53 os_time_get_nano(void);
54
55
56 /*
57 * Get the current time in microseconds from an unknown base.
58 */
59 static inline int64_t
os_time_get(void)60 os_time_get(void)
61 {
62 return os_time_get_nano() / 1000;
63 }
64
65
66 static inline struct tm *
os_localtime(const time_t * timer,struct tm * buf)67 os_localtime(const time_t *timer, struct tm *buf)
68 {
69 #ifdef _WIN32
70 return localtime_s(buf, timer) ? NULL : buf;
71 #else
72 return localtime_r(timer, buf);
73 #endif
74 }
75
76
77 /*
78 * Sleep.
79 */
80 void
81 os_time_sleep(int64_t usecs);
82
83
84 /*
85 * Helper function for detecting time outs, taking in account overflow.
86 *
87 * Returns true if the current time has elapsed beyond the specified interval.
88 */
89 static inline bool
os_time_timeout(int64_t start,int64_t end,int64_t curr)90 os_time_timeout(int64_t start,
91 int64_t end,
92 int64_t curr)
93 {
94 if (start <= end)
95 return !(start <= curr && curr < end);
96 else
97 return !((start <= curr) || (curr < end));
98 }
99
100
101 /**
102 * Convert a relative timeout in nanoseconds into an absolute timeout,
103 * in other words, it returns current time + timeout.
104 * os_time_get_nano() must be monotonic.
105 * OS_TIMEOUT_INFINITE is passed through unchanged. If the calculation
106 * overflows, OS_TIMEOUT_INFINITE is returned.
107 */
108 int64_t
109 os_time_get_absolute_timeout(uint64_t timeout);
110
111
112 /**
113 * Wait until the variable at the given memory location is zero.
114 *
115 * \param var variable
116 * \param timeout timeout in ns, can be anything from 0 (no wait) to
117 * OS_TIMEOUT_INFINITE (wait forever)
118 * \return true if the variable is zero
119 */
120 bool
121 os_wait_until_zero(volatile int *var, uint64_t timeout);
122
123
124 /**
125 * Wait until the variable at the given memory location is zero.
126 * The timeout is the absolute time when the waiting should stop. If it is
127 * less than or equal to the current time, it only returns the status and
128 * doesn't wait. OS_TIMEOUT_INFINITE waits forever. This requires that
129 * os_time_get_nano is monotonic.
130 *
131 * \param var variable
132 * \param timeout the time in ns when the waiting should stop
133 * \return true if the variable is zero
134 */
135 bool
136 os_wait_until_zero_abs_timeout(volatile int *var, int64_t timeout);
137
138 #ifdef __cplusplus
139 }
140 #endif
141
142 #endif /* _OS_TIME_H_ */
143