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Implement consistent hashing algorithm for RedisArray

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This commit is contained in:
Pavlo Yatsukhnenko
2018-12-20 15:04:13 +02:00
parent 3e7e1c833d
commit bb32e6f3a0
7 changed files with 117 additions and 20 deletions
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redis_array_impl.c
+81 -5
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@@ -24,6 +24,7 @@
#include "SAPI.h"
#include "ext/standard/url.h"
#include "ext/standard/crc32.h"
#include "ext/standard/md5.h"
#define PHPREDIS_INDEX_NAME "__phpredis_array_index__"
@@ -173,9 +174,10 @@ RedisArray *ra_load_array(const char *name TSRMLS_DC) {
zval z_params_connect_timeout;
zval z_params_read_timeout;
zval z_params_lazy_connect;
zval z_params_consistent;
RedisArray *ra = NULL;
zend_bool b_index = 0, b_autorehash = 0, b_pconnect = 0;
zend_bool b_index = 0, b_autorehash = 0, b_pconnect = 0, consistent = 0;
long l_retry_interval = 0;
zend_bool b_lazy_connect = 0;
double d_connect_timeout = 0, read_timeout = 0.0;
@@ -312,9 +314,20 @@ RedisArray *ra_load_array(const char *name TSRMLS_DC) {
}
}
/* find consistent option */
array_init(&z_params_consistent);
if ((iptr = INI_STR("redis.arrays.consistent")) != NULL) {
sapi_module.treat_data(PARSE_STRING, estrdup(iptr), &z_params_consistent TSRMLS_CC);
}
if ((z_data = zend_hash_str_find(Z_ARRVAL(z_params_consistent), name, name_len)) != NULL) {
if (Z_TYPE_P(z_data) == IS_STRING && strncmp(Z_STRVAL_P(z_data), "1", 1) == 0) {
consistent = 1;
}
}
/* create RedisArray object */
ra = ra_make_array(hHosts, &z_fun, &z_dist, hPrev, b_index, b_pconnect, l_retry_interval, b_lazy_connect, d_connect_timeout, read_timeout TSRMLS_CC);
ra = ra_make_array(hHosts, &z_fun, &z_dist, hPrev, b_index, b_pconnect, l_retry_interval, b_lazy_connect, d_connect_timeout, read_timeout, consistent TSRMLS_CC);
if (ra) {
ra->auto_rehash = b_autorehash;
if(ra->prev) ra->prev->auto_rehash = b_autorehash;
@@ -332,14 +345,55 @@ RedisArray *ra_load_array(const char *name TSRMLS_DC) {
zval_dtor(&z_params_connect_timeout);
zval_dtor(&z_params_read_timeout);
zval_dtor(&z_params_lazy_connect);
zval_dtor(&z_params_consistent);
zval_dtor(&z_dist);
zval_dtor(&z_fun);
return ra;
}
static int
ra_points_cmp(const void *v1, const void *v2)
{
const ContinuumPoint *p1 = v1, *p2 = v2;
return p1->value < p2->value ? - 1 : p1->value > p2->value;
}
static Continuum *
ra_make_continuum(zend_string **hosts, int nb_hosts)
{
int i, j, k, len, idx = 0;
char host[HOST_NAME_MAX];
unsigned char digest[16];
PHP_MD5_CTX ctx;
Continuum *c;
c = ecalloc(1, sizeof(*c));
c->nb_points = nb_hosts * 160; /* 40 hashes, 4 numbers per hash = 160 points per server */
c->points = ecalloc(c->nb_points, sizeof(*c->points));
for (i = 0; i < nb_hosts; ++i) {
for (j = 0; j < 40; ++j) {
len = snprintf(host, sizeof(host), "%.*s-%u", ZSTR_LEN(hosts[i]), ZSTR_VAL(hosts[i]), j);
PHP_MD5Init(&ctx);
PHP_MD5Update(&ctx, host, len);
PHP_MD5Final(digest, &ctx);
for (k = 0; k < 4; ++k) {
c->points[idx].index = i;
c->points[idx++].value = (digest[3 + k * 4] << 24)
| (digest[2 + k * 4] << 16)
| (digest[1 + k * 4] << 8)
| (digest[k * 4]);
}
}
}
qsort(c->points, c->nb_points, sizeof(*c->points), ra_points_cmp);
return c;
}
RedisArray *
ra_make_array(HashTable *hosts, zval *z_fun, zval *z_dist, HashTable *hosts_prev, zend_bool b_index, zend_bool b_pconnect, long retry_interval, zend_bool b_lazy_connect, double connect_timeout, double read_timeout TSRMLS_DC) {
ra_make_array(HashTable *hosts, zval *z_fun, zval *z_dist, HashTable *hosts_prev, zend_bool b_index, zend_bool b_pconnect, long retry_interval, zend_bool b_lazy_connect, double connect_timeout, double read_timeout, zend_bool consistent TSRMLS_DC) {
int i, count;
RedisArray *ra;
@@ -357,6 +411,7 @@ ra_make_array(HashTable *hosts, zval *z_fun, zval *z_dist, HashTable *hosts_prev
ra->pconnect = b_pconnect;
ra->connect_timeout = connect_timeout;
ra->read_timeout = read_timeout;
ra->continuum = NULL;
if (ra_load_hosts(ra, hosts, retry_interval, b_lazy_connect TSRMLS_CC) == NULL || !ra->count) {
for (i = 0; i < ra->count; ++i) {
@@ -368,7 +423,7 @@ ra_make_array(HashTable *hosts, zval *z_fun, zval *z_dist, HashTable *hosts_prev
efree(ra);
return NULL;
}
ra->prev = hosts_prev ? ra_make_array(hosts_prev, z_fun, z_dist, NULL, b_index, b_pconnect, retry_interval, b_lazy_connect, connect_timeout, read_timeout TSRMLS_CC) : NULL;
ra->prev = hosts_prev ? ra_make_array(hosts_prev, z_fun, z_dist, NULL, b_index, b_pconnect, retry_interval, b_lazy_connect, connect_timeout, read_timeout, consistent TSRMLS_CC) : NULL;
/* init array data structures */
ra_init_function_table(ra);
@@ -377,6 +432,11 @@ ra_make_array(HashTable *hosts, zval *z_fun, zval *z_dist, HashTable *hosts_prev
ZVAL_ZVAL(&ra->z_fun, z_fun, 1, 0);
ZVAL_ZVAL(&ra->z_dist, z_dist, 1, 0);
/* init continuum */
if (consistent) {
ra->continuum = ra_make_continuum(ra->hosts, ra->count);
}
return ra;
}
@@ -480,7 +540,23 @@ ra_find_node(RedisArray *ra, const char *key, int key_len, int *out_pos TSRMLS_D
}
/* get position on ring */
pos = (int)((ret ^ 0xffffffff) * ra->count / 0xffffffff);
if (ra->continuum) {
int left = 0, right = ra->continuum->nb_points;
while (left < right) {
i = (int)((left + right) / 2);
if (ra->continuum->points[i].value < ret) {
left = i + 1;
} else {
right = i;
}
}
if (right == ra->continuum->nb_points) {
right = 0;
}
pos = ra->continuum->points[right].index;
} else {
pos = (int)((ret ^ 0xffffffff) * ra->count / 0xffffffff);
}
} else {
pos = ra_call_distributor(ra, key, key_len TSRMLS_CC);
if (pos < 0 || pos >= ra->count) {