1 #include "common.h"
2
3 #include <ext/standard/php_rand.h>
4
5 #if PHP_VERSION_ID >= 70100
6 #include <ext/standard/php_mt_rand.h>
7 #else
php_mt_rand_range(zend_long min,zend_long max)8 static zend_long php_mt_rand_range(zend_long min, zend_long max) {
9 zend_long number = php_rand();
10 RAND_RANGE(number, min, max, PHP_RAND_MAX);
11 return number;
12 }
13 #endif
14
15 #include "backoff.h"
16
random_range(zend_ulong min,zend_ulong max)17 static zend_ulong random_range(zend_ulong min, zend_ulong max) {
18 if (max < min) {
19 return php_mt_rand_range(max, min);
20 }
21
22 return php_mt_rand_range(min, max);
23 }
24
redis_default_backoff(struct RedisBackoff * self,unsigned int retry_index)25 static zend_ulong redis_default_backoff(struct RedisBackoff *self, unsigned int retry_index) {
26 zend_ulong backoff = retry_index ? self->base : random_range(0, self->base);
27 return MIN(self->cap, backoff);
28 }
29
redis_constant_backoff(struct RedisBackoff * self,unsigned int retry_index)30 static zend_ulong redis_constant_backoff(struct RedisBackoff *self, unsigned int retry_index) {
31 zend_ulong backoff = self->base;
32 return MIN(self->cap, backoff);
33 }
34
redis_uniform_backoff(struct RedisBackoff * self,unsigned int retry_index)35 static zend_ulong redis_uniform_backoff(struct RedisBackoff *self, unsigned int retry_index) {
36 zend_ulong backoff = random_range(0, self->base);
37 return MIN(self->cap, backoff);
38 }
39
redis_exponential_backoff(struct RedisBackoff * self,unsigned int retry_index)40 static zend_ulong redis_exponential_backoff(struct RedisBackoff *self, unsigned int retry_index) {
41 zend_ulong pow = MIN(retry_index, 10);
42 zend_ulong backoff = self->base * (1 << pow);
43 return MIN(self->cap, backoff);
44 }
45
redis_full_jitter_backoff(struct RedisBackoff * self,unsigned int retry_index)46 static zend_ulong redis_full_jitter_backoff(struct RedisBackoff *self, unsigned int retry_index) {
47 zend_ulong pow = MIN(retry_index, 10);
48 zend_ulong backoff = self->base * (1 << pow);
49 zend_ulong cap = MIN(self->cap, backoff);
50 return random_range(0, cap);
51 }
52
redis_equal_jitter_backoff(struct RedisBackoff * self,unsigned int retry_index)53 static zend_ulong redis_equal_jitter_backoff(struct RedisBackoff *self, unsigned int retry_index) {
54 zend_ulong pow = MIN(retry_index, 10);
55 zend_ulong backoff = self->base * (1 << pow);
56 zend_ulong temp = MIN(self->cap, backoff);
57 return temp / 2 + random_range(0, temp) / 2;
58 }
59
redis_decorrelated_jitter_backoff(struct RedisBackoff * self,unsigned int retry_index)60 static zend_ulong redis_decorrelated_jitter_backoff(struct RedisBackoff *self, unsigned int retry_index) {
61 self->previous_backoff = random_range(self->base, self->previous_backoff * 3);
62 return MIN(self->cap, self->previous_backoff);
63 }
64
65 typedef zend_ulong (*redis_backoff_algorithm)(struct RedisBackoff *self, unsigned int retry_index);
66
67 static redis_backoff_algorithm redis_backoff_algorithms[REDIS_BACKOFF_ALGORITHMS] = {
68 redis_default_backoff,
69 redis_decorrelated_jitter_backoff,
70 redis_full_jitter_backoff,
71 redis_equal_jitter_backoff,
72 redis_exponential_backoff,
73 redis_uniform_backoff,
74 redis_constant_backoff,
75 };
76
redis_initialize_backoff(struct RedisBackoff * self,unsigned long retry_interval)77 void redis_initialize_backoff(struct RedisBackoff *self, unsigned long retry_interval) {
78 self->algorithm = 0; // default backoff
79 self->base = retry_interval;
80 self->cap = retry_interval;
81 self->previous_backoff = 0;
82 }
83
redis_backoff_reset(struct RedisBackoff * self)84 void redis_backoff_reset(struct RedisBackoff *self) {
85 self->previous_backoff = 0;
86 }
87
redis_backoff_compute(struct RedisBackoff * self,unsigned int retry_index)88 zend_ulong redis_backoff_compute(struct RedisBackoff *self, unsigned int retry_index) {
89 return redis_backoff_algorithms[self->algorithm](self, retry_index);
90 }
91