1 /*
2 * librdkafka - Apache Kafka C library
3 *
4 * Copyright (c) 2018 Magnus Edenhill
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright notice,
11 * this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright notice,
13 * this list of conditions and the following disclaimer in the documentation
14 * and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #ifndef _RDINTERVAL_H_
30 #define _RDINTERVAL_H_
31
32 #include "rd.h"
33
34 typedef struct rd_interval_s {
35 rd_ts_t ri_ts_last; /* last interval timestamp */
36 rd_ts_t ri_fixed; /* fixed interval if provided interval is 0 */
37 int ri_backoff; /* back off the next interval by this much */
38 } rd_interval_t;
39
40
rd_interval_init(rd_interval_t * ri)41 static RD_INLINE RD_UNUSED void rd_interval_init (rd_interval_t *ri) {
42 memset(ri, 0, sizeof(*ri));
43 }
44
45
46
47 /**
48 * Returns the number of microseconds the interval has been over-shot.
49 * If the return value is >0 (i.e., time for next intervalled something) then
50 * the time interval is updated to the current time.
51 *
52 * The current time can be provided in 'now', or if this is set to 0 the time
53 * will be gathered automatically.
54 *
55 * If 'interval_us' is set to 0 the fixed interval will be used, see
56 * 'rd_interval_fixed()'.
57 *
58 * If this is the first time rd_interval() is called after an _init() or
59 * _reset() or the \p immediate parameter is true, then a positive value
60 * will be returned immediately even though the initial interval has not
61 * passed.
62 */
63 #define rd_interval(ri,interval_us,now) rd_interval0(ri,interval_us,now,0)
64 #define rd_interval_immediate(ri,interval_us,now) \
65 rd_interval0(ri,interval_us,now,1)
rd_interval0(rd_interval_t * ri,rd_ts_t interval_us,rd_ts_t now,int immediate)66 static RD_INLINE RD_UNUSED rd_ts_t rd_interval0 (rd_interval_t *ri,
67 rd_ts_t interval_us,
68 rd_ts_t now,
69 int immediate) {
70 rd_ts_t diff;
71
72 if (!now)
73 now = rd_clock();
74 if (!interval_us)
75 interval_us = ri->ri_fixed;
76
77 if (ri->ri_ts_last || !immediate) {
78 diff = now - (ri->ri_ts_last + interval_us + ri->ri_backoff);
79 } else
80 diff = 1;
81 if (unlikely(diff > 0)) {
82 ri->ri_ts_last = now;
83 ri->ri_backoff = 0;
84 }
85
86 return diff;
87 }
88
89
90 /**
91 * Reset the interval to zero, i.e., the next call to rd_interval()
92 * will be immediate.
93 */
rd_interval_reset(rd_interval_t * ri)94 static RD_INLINE RD_UNUSED void rd_interval_reset (rd_interval_t *ri) {
95 ri->ri_ts_last = 0;
96 ri->ri_backoff = 0;
97 }
98
99 /**
100 * Reset the interval to 'now'. If now is 0, the time will be gathered
101 * automatically.
102 */
rd_interval_reset_to_now(rd_interval_t * ri,rd_ts_t now)103 static RD_INLINE RD_UNUSED void rd_interval_reset_to_now (rd_interval_t *ri,
104 rd_ts_t now) {
105 if (!now)
106 now = rd_clock();
107
108 ri->ri_ts_last = now;
109 ri->ri_backoff = 0;
110 }
111
112 /**
113 * Back off the next interval by `backoff_us` microseconds.
114 */
rd_interval_backoff(rd_interval_t * ri,int backoff_us)115 static RD_INLINE RD_UNUSED void rd_interval_backoff (rd_interval_t *ri,
116 int backoff_us) {
117 ri->ri_backoff = backoff_us;
118 }
119
120 /**
121 * Expedite (speed up) the next interval by `expedite_us` microseconds.
122 * If `expedite_us` is 0 the interval will be set to trigger
123 * immedately on the next rd_interval() call.
124 */
rd_interval_expedite(rd_interval_t * ri,int expedite_us)125 static RD_INLINE RD_UNUSED void rd_interval_expedite (rd_interval_t *ri,
126 int expedite_us) {
127 if (!expedite_us)
128 ri->ri_ts_last = 0;
129 else
130 ri->ri_backoff = -expedite_us;
131 }
132
133 /**
134 * Specifies a fixed interval to use if rd_interval() is called with
135 * `interval_us` set to 0.
136 */
rd_interval_fixed(rd_interval_t * ri,rd_ts_t fixed_us)137 static RD_INLINE RD_UNUSED void rd_interval_fixed (rd_interval_t *ri,
138 rd_ts_t fixed_us) {
139 ri->ri_fixed = fixed_us;
140 }
141
142 /**
143 * Disables the interval (until rd_interval_init()/reset() is called).
144 * A disabled interval will never return a positive value from
145 * rd_interval().
146 */
rd_interval_disable(rd_interval_t * ri)147 static RD_INLINE RD_UNUSED void rd_interval_disable (rd_interval_t *ri) {
148 /* Set last beat to a large value a long time in the future. */
149 ri->ri_ts_last = 6000000000000000000LL; /* in about 190000 years */
150 }
151
152 /**
153 * Returns true if the interval is disabled.
154 */
rd_interval_disabled(const rd_interval_t * ri)155 static RD_INLINE RD_UNUSED int rd_interval_disabled (const rd_interval_t *ri) {
156 return ri->ri_ts_last == 6000000000000000000LL;
157 }
158
159 #endif /* _RDINTERVAL_H_ */
160