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Add support for exponential backoff on retry
1 parent c3ab4a2 commit 3b9a125

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10 files changed

+238
-6
lines changed

10 files changed

+238
-6
lines changed

‎backoff.c

Lines changed: 79 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,79 @@
1+
#include "common.h"
2+
3+
#include <ext/standard/php_rand.h>
4+
#include <ext/standard/php_mt_rand.h>
5+
6+
#include "backoff.h"
7+
8+
zend_long default_backoff(struct Backoff *self, int retry_index) {
9+
zend_long backoff = retry_index ? self->base : (php_rand() % self->base);
10+
return MIN(self->cap, backoff);
11+
}
12+
13+
zend_long constant_backoff(struct Backoff *self, int retry_index) {
14+
zend_long backoff = self->base;
15+
return MIN(self->cap, backoff);
16+
}
17+
18+
zend_long uniform_backoff(struct Backoff *self, int retry_index) {
19+
zend_long backoff = php_rand() % self->base;
20+
return MIN(self->cap, backoff);
21+
}
22+
23+
zend_long exponential_backoff(struct Backoff *self, int retry_index) {
24+
zend_long pow = MIN(retry_index, 10);
25+
zend_long backoff = self->base * (1 << pow);
26+
return MIN(self->cap, backoff);
27+
}
28+
29+
zend_long full_jitter_backoff(struct Backoff *self, int retry_index) {
30+
zend_long pow = MIN(retry_index, 10);
31+
zend_long backoff = self->base * (1 << pow);
32+
zend_long cap = MIN(self->cap, backoff);
33+
return php_mt_rand_range(0, cap);
34+
}
35+
36+
zend_long equal_jitter_backoff(struct Backoff *self, int retry_index) {
37+
zend_long pow = MIN(retry_index, 10);
38+
zend_long backoff = self->base * (1 << pow);
39+
zend_long temp = MIN(self->cap, backoff) >> 1;
40+
return temp + php_mt_rand_range(0, temp);
41+
}
42+
43+
zend_long decorrelated_jitter_backoff(struct Backoff *self, int retry_index) {
44+
zend_long max_backoff = MAX(self->base, self->previous_backoff * 3);
45+
zend_long temp = php_mt_rand_range(self->base, max_backoff);
46+
self->previous_backoff = MIN(self->cap, temp);
47+
return self->previous_backoff;
48+
}
49+
50+
typedef zend_long (*backoff_algorithm)(struct Backoff *self, int retry_index);
51+
52+
static backoff_algorithm backoff_algorithms[BACKOFF_ALGORITHMS] = {
53+
default_backoff,
54+
constant_backoff,
55+
uniform_backoff,
56+
exponential_backoff,
57+
full_jitter_backoff,
58+
equal_jitter_backoff,
59+
decorrelated_jitter_backoff,
60+
};
61+
62+
struct Backoff make_default_backoff(long retry_interval) {
63+
struct Backoff self = {
64+
.algorithm = 0, // default backoff
65+
.base = retry_interval,
66+
.cap = retry_interval,
67+
.previous_backoff = 0
68+
};
69+
70+
return self;
71+
}
72+
73+
void backoff_reset(struct Backoff *self) {
74+
self->previous_backoff = 0;
75+
}
76+
77+
zend_long backoff_compute(struct Backoff *self, int retry_index) {
78+
return backoff_algorithms[self->algorithm](self, retry_index);
79+
}

‎backoff.h

Lines changed: 26 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,26 @@
1+
#ifndef REDIS_BACKOFF_H
2+
#define REDIS_BACKOFF_H
3+
4+
/* {{{ struct Backoff */
5+
struct Backoff {
6+
int algorithm; /* index of algorithm function, returns backoff in microseconds*/
7+
zend_long base; /* base backoff in microseconds */
8+
zend_long cap; /* max backoff in microseconds */
9+
zend_long previous_backoff; /* previous backoff in microseconds */
10+
};
11+
/* }}} */
12+
13+
zend_long default_backoff(struct Backoff *self, int retry_index);
14+
zend_long constant_backoff(struct Backoff *self, int retry_index);
15+
zend_long uniform_backoff(struct Backoff *self, int retry_index);
16+
zend_long exponential_backoff(struct Backoff *self, int retry_index);
17+
zend_long full_jitter_backoff(struct Backoff *self, int retry_index);
18+
zend_long equal_jitter_backoff(struct Backoff *self, int retry_index);
19+
zend_long decorrelated_jitter_backoff(struct Backoff *self, int retry_index);
20+
21+
struct Backoff make_default_backoff();
22+
23+
void backoff_reset(struct Backoff *self);
24+
zend_long backoff_compute(struct Backoff *self, int retry_index);
25+
26+
#endif

‎common.h

Lines changed: 26 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -21,6 +21,8 @@
2121
#define NULL ((void *) 0)
2222
#endif
2323

24+
#include "backoff.h"
25+
2426
typedef enum {
2527
REDIS_SOCK_STATUS_FAILED = -1,
2628
REDIS_SOCK_STATUS_DISCONNECTED,
@@ -83,6 +85,10 @@ typedef enum _PUBSUB_TYPE {
8385
#define REDIS_OPT_REPLY_LITERAL 8
8486
#define REDIS_OPT_COMPRESSION_LEVEL 9
8587
#define REDIS_OPT_NULL_MBULK_AS_NULL 10
88+
#define REDIS_OPT_MAX_RETRIES 11
89+
#define REDIS_OPT_BACKOFF_ALGORITHM 12
90+
#define REDIS_OPT_BACKOFF_BASE 13
91+
#define REDIS_OPT_BACKOFF_CAP 14
8692

8793
/* cluster options */
8894
#define REDIS_FAILOVER_NONE 0
@@ -109,6 +115,24 @@ typedef enum {
109115
#define REDIS_SCAN_PREFIX 2
110116
#define REDIS_SCAN_NOPREFIX 3
111117

118+
/* BACKOFF_ALGORITHM options */
119+
#define BACKOFF_ALGORITHMS 7
120+
#define BACKOFF_ALGORITHM_DEFAULT 0
121+
#define BACKOFF_ALGORITHM_CONSTANT 1
122+
#define BACKOFF_ALGORITHM_UNIFORM 2
123+
#define BACKOFF_ALGORITHM_EXPONENTIAL 3
124+
#define BACKOFF_ALGORITHM_FULL_JITTER 4
125+
#define BACKOFF_ALGORITHM_EQUAL_JITTER 5
126+
#define BACKOFF_ALGORITHM_DECORRELATED_JITTER 6
127+
128+
zend_long default_backoff(struct Backoff *self, int retry_index);
129+
zend_long constant_backoff(struct Backoff *self, int retry_index);
130+
zend_long uniform_backoff(struct Backoff *self, int retry_index);
131+
zend_long exponential_backoff(struct Backoff *self, int retry_index);
132+
zend_long full_jitter_backoff(struct Backoff *self, int retry_index);
133+
zend_long equal_jitter_backoff(struct Backoff *self, int retry_index);
134+
zend_long decorrelated_jitter_backoff(struct Backoff *self, int retry_index);
135+
112136
/* GETBIT/SETBIT offset range limits */
113137
#define BITOP_MIN_OFFSET 0
114138
#define BITOP_MAX_OFFSET 4294967295U
@@ -267,6 +291,8 @@ typedef struct {
267291
double timeout;
268292
double read_timeout;
269293
long retry_interval;
294+
int max_retries;
295+
struct Backoff backoff;
270296
redis_sock_status status;
271297
int persistent;
272298
int watching;

‎config.m4

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -323,5 +323,5 @@ if test "$PHP_REDIS" != "no"; then
323323
fi
324324

325325
PHP_SUBST(REDIS_SHARED_LIBADD)
326-
PHP_NEW_EXTENSION(redis, redis.c redis_commands.c library.c redis_session.c redis_array.c redis_array_impl.c redis_cluster.c cluster_library.c redis_sentinel.c sentinel_library.c $lzf_sources, $ext_shared)
326+
PHP_NEW_EXTENSION(redis, redis.c redis_commands.c library.c redis_session.c redis_array.c redis_array_impl.c redis_cluster.c cluster_library.c redis_sentinel.c sentinel_library.c backoff.c $lzf_sources, $ext_shared)
327327
fi

‎config.w32

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -5,7 +5,7 @@ ARG_ENABLE("redis-session", "whether to enable sessions", "yes");
55
ARG_ENABLE("redis-igbinary", "whether to enable igbinary serializer support", "no");
66

77
if (PHP_REDIS != "no") {
8-
var sources = "redis.c redis_commands.c library.c redis_session.c redis_array.c redis_array_impl.c redis_cluster.c cluster_library.c redis_sentinel.c sentinel_library.c";
8+
var sources = "redis.c redis_commands.c library.c redis_session.c redis_array.c redis_array_impl.c redis_cluster.c cluster_library.c redis_sentinel.c sentinel_library.c backoff.c";
99
if (PHP_REDIS_SESSION != "no") {
1010
ADD_EXTENSION_DEP("redis", "session");
1111
ADD_FLAG("CFLAGS_REDIS", ' /D PHP_SESSION=1 ');

‎library.c

Lines changed: 6 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -301,7 +301,7 @@ redis_error_throw(RedisSock *redis_sock)
301301
PHP_REDIS_API int
302302
redis_check_eof(RedisSock *redis_sock, int no_throw)
303303
{
304-
int count;
304+
int retry_index;
305305
char *errmsg;
306306

307307
if (!redis_sock || !redis_sock->stream || redis_sock->status == REDIS_SOCK_STATUS_FAILED) {
@@ -333,16 +333,16 @@ redis_check_eof(RedisSock *redis_sock, int no_throw)
333333
errmsg = "Connection lost and socket is in MULTI/watching mode";
334334
} else {
335335
errmsg = "Connection lost";
336-
/* TODO: configurable max retry count */
337-
for (count = 0; count < 10; ++count) {
336+
backoff_reset(&redis_sock->backoff);
337+
for (retry_index = 0; retry_index < redis_sock->max_retries; ++retry_index) {
338338
/* close existing stream before reconnecting */
339339
if (redis_sock->stream) {
340340
redis_sock_disconnect(redis_sock, 1);
341341
}
342342
// Wait for a while before trying to reconnect
343343
if (redis_sock->retry_interval) {
344344
// Random factor to avoid having several (or many) concurrent connections trying to reconnect at the same time
345-
long retry_interval = (count ? redis_sock->retry_interval : (php_rand() % redis_sock->retry_interval));
345+
zend_long retry_interval = backoff_compute(&redis_sock->backoff, retry_index);
346346
usleep(retry_interval);
347347
}
348348
/* reconnect */
@@ -2150,6 +2150,8 @@ redis_sock_create(char *host, int host_len, int port,
21502150
redis_sock->host = zend_string_init(host, host_len, 0);
21512151
redis_sock->status = REDIS_SOCK_STATUS_DISCONNECTED;
21522152
redis_sock->retry_interval = retry_interval * 1000;
2153+
redis_sock->max_retries = 10;
2154+
redis_sock->backoff = make_default_backoff(retry_interval);
21532155
redis_sock->persistent = persistent;
21542156

21552157
if (persistent && persistent_id != NULL) {

‎package.xml

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -88,6 +88,8 @@ http://pear.php.net/dtd/package-2.0.xsd">
8888
<file role='doc' name='arrays.markdown'/>
8989
<file role='doc' name='cluster.markdown'/>
9090
<file role='doc' name='sentinel.markdown'/>
91+
<file role='src' name='backoff.c'/>
92+
<file role='src' name='backoff.h'/>
9193
<file role='src' name='cluster_library.c'/>
9294
<file role='src' name='cluster_library.h'/>
9395
<file role='src' name='common.h'/>

‎redis.c

Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -775,6 +775,22 @@ static void add_class_constants(zend_class_entry *ce, int is_cluster) {
775775
zend_declare_class_constant_stringl(ce, "LEFT", 4, "left", 4);
776776
zend_declare_class_constant_stringl(ce, "RIGHT", 5, "right", 5);
777777
}
778+
779+
/* retry/backoff options*/
780+
zend_declare_class_constant_long(ce, ZEND_STRL("OPT_MAX_RETRIES"), REDIS_OPT_MAX_RETRIES);
781+
782+
zend_declare_class_constant_long(ce, ZEND_STRL("OPT_BACKOFF_ALGORITHM"), REDIS_OPT_BACKOFF_ALGORITHM);
783+
zend_declare_class_constant_long(ce, ZEND_STRL("BACKOFF_ALGORITHM_DEFAULT"), BACKOFF_ALGORITHM_DEFAULT);
784+
zend_declare_class_constant_long(ce, ZEND_STRL("BACKOFF_ALGORITHM_CONSTANT"), BACKOFF_ALGORITHM_CONSTANT);
785+
zend_declare_class_constant_long(ce, ZEND_STRL("BACKOFF_ALGORITHM_UNIFORM"), BACKOFF_ALGORITHM_UNIFORM);
786+
zend_declare_class_constant_long(ce, ZEND_STRL("BACKOFF_ALGORITHM_EXPONENTIAL"), BACKOFF_ALGORITHM_EXPONENTIAL);
787+
zend_declare_class_constant_long(ce, ZEND_STRL("BACKOFF_ALGORITHM_FULL_JITTER"), BACKOFF_ALGORITHM_FULL_JITTER);
788+
zend_declare_class_constant_long(ce, ZEND_STRL("BACKOFF_ALGORITHM_EQUAL_JITTER"), BACKOFF_ALGORITHM_EQUAL_JITTER);
789+
zend_declare_class_constant_long(ce, ZEND_STRL("BACKOFF_ALGORITHM_DECORRELATED_JITTER"), BACKOFF_ALGORITHM_DECORRELATED_JITTER);
790+
791+
zend_declare_class_constant_long(ce, ZEND_STRL("OPT_BACKOFF_BASE"), REDIS_OPT_BACKOFF_BASE);
792+
793+
zend_declare_class_constant_long(ce, ZEND_STRL("OPT_BACKOFF_CAP"), REDIS_OPT_BACKOFF_CAP);
778794
}
779795

780796
static ZEND_RSRC_DTOR_FUNC(redis_connections_pool_dtor)

‎redis_commands.c

Lines changed: 37 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -4308,6 +4308,14 @@ void redis_getoption_handler(INTERNAL_FUNCTION_PARAMETERS,
43084308
RETURN_LONG(redis_sock->null_mbulk_as_null);
43094309
case REDIS_OPT_FAILOVER:
43104310
RETURN_LONG(c->failover);
4311+
case REDIS_OPT_MAX_RETRIES:
4312+
RETURN_LONG(redis_sock->max_retries);
4313+
case REDIS_OPT_BACKOFF_ALGORITHM:
4314+
RETURN_LONG(redis_sock->backoff.algorithm);
4315+
case REDIS_OPT_BACKOFF_BASE:
4316+
RETURN_LONG(redis_sock->backoff.base / 1000);
4317+
case REDIS_OPT_BACKOFF_CAP:
4318+
RETURN_LONG(redis_sock->backoff.cap / 1000);
43114319
default:
43124320
RETURN_FALSE;
43134321
}
@@ -4441,6 +4449,35 @@ void redis_setoption_handler(INTERNAL_FUNCTION_PARAMETERS,
44414449
RETURN_TRUE;
44424450
}
44434451
break;
4452+
case REDIS_OPT_MAX_RETRIES:
4453+
val_long = zval_get_long(val);
4454+
if(val_long >= 0) {
4455+
redis_sock->max_retries = val_long;
4456+
RETURN_TRUE;
4457+
}
4458+
break;
4459+
case REDIS_OPT_BACKOFF_ALGORITHM:
4460+
val_long = zval_get_long(val);
4461+
if(val_long >= 0 &&
4462+
val_long < BACKOFF_ALGORITHMS) {
4463+
redis_sock->backoff.algorithm = val_long;
4464+
RETURN_TRUE;
4465+
}
4466+
break;
4467+
case REDIS_OPT_BACKOFF_BASE:
4468+
val_long = zval_get_long(val);
4469+
if(val_long >= 0) {
4470+
redis_sock->backoff.base = val_long * 1000;
4471+
RETURN_TRUE;
4472+
}
4473+
break;
4474+
case REDIS_OPT_BACKOFF_CAP:
4475+
val_long = zval_get_long(val);
4476+
if(val_long >= 0) {
4477+
redis_sock->backoff.cap = val_long * 1000;
4478+
RETURN_TRUE;
4479+
}
4480+
break;
44444481
EMPTY_SWITCH_DEFAULT_CASE()
44454482
}
44464483
RETURN_FALSE;

‎tests/RedisTest.php

Lines changed: 44 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -5398,6 +5398,50 @@ public function testScanPrefix() {
53985398
$this->assertTrue(count($arr_all_keys) == 0);
53995399
}
54005400

5401+
public function testMaxRetriesOption() {
5402+
$maxRetriesExpected = 5;
5403+
$this->redis->setOption(Redis::OPT_MAX_RETRIES, $maxRetriesExpected);
5404+
$maxRetriesActual=$this->redis->getOption(Redis::OPT_MAX_RETRIES);
5405+
$this->assertEquals($maxRetriesActual, $maxRetriesExpected);
5406+
}
5407+
5408+
public function testBackoffOptions() {
5409+
$this->redis->setOption(Redis::OPT_MAX_RETRIES, 5);
5410+
$this->assertEquals($this->redis->getOption(Redis::OPT_MAX_RETRIES), 5);
5411+
5412+
$this->$redis->setOption(Redis::OPT_BACKOFF_ALGORITHM, Redis::BACKOFF_ALGORITHM_DEFAULT);
5413+
$this->assertEquals($this->$redis->getOption(Redis::OPT_BACKOFF_ALGORITHM), Redis::BACKOFF_ALGORITHM_DEFAULT);
5414+
5415+
$this->$redis->setOption(Redis::OPT_BACKOFF_ALGORITHM, Redis::BACKOFF_ALGORITHM_CONSTANT);
5416+
$this->assertEquals($this->$redis->getOption(Redis::OPT_BACKOFF_ALGORITHM), Redis::BACKOFF_ALGORITHM_CONSTANT);
5417+
5418+
$this->$redis->setOption(Redis::OPT_BACKOFF_ALGORITHM, Redis::BACKOFF_ALGORITHM_UNIFORM);
5419+
$this->assertEquals($this->$redis->getOption(Redis::OPT_BACKOFF_ALGORITHM), Redis::BACKOFF_ALGORITHM_UNIFORM);
5420+
5421+
$this->$redis -> setOption(Redis::OPT_BACKOFF_ALGORITHM, Redis::BACKOFF_ALGORITHM_EXPONENTIAL);
5422+
$this->assertEquals($this->$redis->getOption(Redis::OPT_BACKOFF_ALGORITHM), Redis::BACKOFF_ALGORITHM_EXPONENTIAL);
5423+
5424+
$this->$redis->setOption(Redis::OPT_BACKOFF_ALGORITHM, Redis::BACKOFF_ALGORITHM_FULL_JITTER);
5425+
$this->assertEquals($this->$redis->getOption(Redis::OPT_BACKOFF_ALGORITHM), Redis::BACKOFF_ALGORITHM_FULL_JITTER);
5426+
5427+
$this->$redis->setOption(Redis::OPT_BACKOFF_ALGORITHM, Redis::BACKOFF_ALGORITHM_DECORRELATED_JITTER);
5428+
$this->assertEquals($this->$redis->getOption(Redis::OPT_BACKOFF_ALGORITHM), Redis::BACKOFF_ALGORITHM_DECORRELATED_JITTER);
5429+
5430+
$this->assertFalse($this->$redis->setOption(Redis::OPT_BACKOFF_ALGORITHM, 55555));
5431+
5432+
$this->$redis->setOption(Redis::OPT_BACKOFF_BASE, 500);
5433+
$this->assertEquals($this->$redis->getOption(Redis::OPT_BACKOFF_BASE), 500);
5434+
5435+
$this->$redis->setOption(Redis::OPT_BACKOFF_BASE, 750);
5436+
$this->assertEquals($this->$redis->getOption(Redis::OPT_BACKOFF_BASE), 750);
5437+
5438+
$this->$redis->setOption(Redis::OPT_BACKOFF_CAP, 500);
5439+
$this->assertEquals($this->$redis->getOption(Redis::OPT_BACKOFF_CAP), 500);
5440+
5441+
$this->$redis->setOption(Redis::OPT_BACKOFF_CAP, 750);
5442+
$this->assertEquals($this->$redis->getOption(Redis::OPT_BACKOFF_CAP), 750);
5443+
}
5444+
54015445
public function testHScan() {
54025446
if (version_compare($this->version, "2.8.0") < 0) {
54035447
$this->markTestSkipped();

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