1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
#include "common.h"
#include <ext/standard/php_rand.h>
#if PHP_VERSION_ID >= 70100
#include <ext/standard/php_mt_rand.h>
#else
static zend_long php_mt_rand_range(zend_long min, zend_long max) {
zend_long number = php_rand();
RAND_RANGE(number, min, max, PHP_RAND_MAX);
return number;
}
#endif
#include "backoff.h"
static zend_ulong random_range(zend_ulong min, zend_ulong max) {
if (max < min) {
return php_mt_rand_range(max, min);
}
return php_mt_rand_range(min, max);
}
static zend_ulong redis_default_backoff(struct RedisBackoff *self, unsigned int retry_index) {
zend_ulong backoff = retry_index ? self->base : random_range(0, self->base);
return MIN(self->cap, backoff);
}
static zend_ulong redis_constant_backoff(struct RedisBackoff *self, unsigned int retry_index) {
zend_ulong backoff = self->base;
return MIN(self->cap, backoff);
}
static zend_ulong redis_uniform_backoff(struct RedisBackoff *self, unsigned int retry_index) {
zend_ulong backoff = random_range(0, self->base);
return MIN(self->cap, backoff);
}
static zend_ulong redis_exponential_backoff(struct RedisBackoff *self, unsigned int retry_index) {
zend_ulong pow = MIN(retry_index, 10);
zend_ulong backoff = self->base * (1 << pow);
return MIN(self->cap, backoff);
}
static zend_ulong redis_full_jitter_backoff(struct RedisBackoff *self, unsigned int retry_index) {
zend_ulong pow = MIN(retry_index, 10);
zend_ulong backoff = self->base * (1 << pow);
zend_ulong cap = MIN(self->cap, backoff);
return random_range(0, cap);
}
static zend_ulong redis_equal_jitter_backoff(struct RedisBackoff *self, unsigned int retry_index) {
zend_ulong pow = MIN(retry_index, 10);
zend_ulong backoff = self->base * (1 << pow);
zend_ulong temp = MIN(self->cap, backoff);
return temp / 2 + random_range(0, temp) / 2;
}
static zend_ulong redis_decorrelated_jitter_backoff(struct RedisBackoff *self, unsigned int retry_index) {
self->previous_backoff = random_range(self->base, self->previous_backoff * 3);
return MIN(self->cap, self->previous_backoff);
}
typedef zend_ulong (*redis_backoff_algorithm)(struct RedisBackoff *self, unsigned int retry_index);
static redis_backoff_algorithm redis_backoff_algorithms[REDIS_BACKOFF_ALGORITHMS] = {
redis_default_backoff,
redis_decorrelated_jitter_backoff,
redis_full_jitter_backoff,
redis_equal_jitter_backoff,
redis_exponential_backoff,
redis_uniform_backoff,
redis_constant_backoff,
};
void redis_initialize_backoff(struct RedisBackoff *self, unsigned long retry_interval) {
self->algorithm = 0; // default backoff
self->base = retry_interval;
self->cap = retry_interval;
self->previous_backoff = 0;
}
void redis_backoff_reset(struct RedisBackoff *self) {
self->previous_backoff = 0;
}
zend_ulong redis_backoff_compute(struct RedisBackoff *self, unsigned int retry_index) {
return redis_backoff_algorithms[self->algorithm](self, retry_index);
}
|
