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 #define ONE_SECOND_IN_NS INT64_C(1000000000)
47
48 #define OS_TIMEOUT_INFINITE 0xffffffffffffffffull
49
50 /*
51 * Get the current time in nanoseconds from an unknown base.
52 */
53 int64_t
54 os_time_get_nano(void);
55
56
57 /*
58 * Get the current time in microseconds from an unknown base.
59 */
60 static inline int64_t
os_time_get(void)61 os_time_get(void)
62 {
63 return os_time_get_nano() / 1000;
64 }
65
66
67 static inline struct tm *
os_localtime(const time_t * timer,struct tm * buf)68 os_localtime(const time_t *timer, struct tm *buf)
69 {
70 #ifdef _WIN32
71 return localtime_s(buf, timer) ? NULL : buf;
72 #else
73 return localtime_r(timer, buf);
74 #endif
75 }
76
77
78 /*
79 * Sleep.
80 */
81 void
82 os_time_sleep(int64_t usecs);
83
84
85 /*
86 * Helper function for detecting time outs, taking in account overflow.
87 *
88 * Returns true if the current time has elapsed beyond the specified interval.
89 */
90 static inline bool
os_time_timeout(int64_t start,int64_t end,int64_t curr)91 os_time_timeout(int64_t start,
92 int64_t end,
93 int64_t curr)
94 {
95 if (start <= end)
96 return !(start <= curr && curr < end);
97 else
98 return !((start <= curr) || (curr < end));
99 }
100
101
102 /**
103 * Convert a relative timeout in nanoseconds into an absolute timeout,
104 * in other words, it returns current time + timeout.
105 * os_time_get_nano() must be monotonic.
106 * OS_TIMEOUT_INFINITE is passed through unchanged. If the calculation
107 * overflows, OS_TIMEOUT_INFINITE is returned.
108 */
109 int64_t
110 os_time_get_absolute_timeout(uint64_t timeout);
111
112
113 /**
114 * Wait until the variable at the given memory location is zero.
115 *
116 * \param var variable
117 * \param timeout timeout in ns, can be anything from 0 (no wait) to
118 * OS_TIMEOUT_INFINITE (wait forever)
119 * \return true if the variable is zero
120 */
121 bool
122 os_wait_until_zero(volatile int *var, uint64_t timeout);
123
124
125 /**
126 * Wait until the variable at the given memory location is zero.
127 * The timeout is the absolute time when the waiting should stop. If it is
128 * less than or equal to the current time, it only returns the status and
129 * doesn't wait. OS_TIMEOUT_INFINITE waits forever. This requires that
130 * os_time_get_nano is monotonic.
131 *
132 * \param var variable
133 * \param timeout the time in ns when the waiting should stop
134 * \return true if the variable is zero
135 */
136 bool
137 os_wait_until_zero_abs_timeout(volatile int *var, int64_t timeout);
138
139 #ifdef __cplusplus
140 }
141 #endif
142
143 #endif /* _OS_TIME_H_ */
144