+/*
+ * Hash a variable to choose an upstream server.
+ *
+ * Copyright (C) Evan Miller
+ *
+ * This module can be distributed under the same terms as Nginx itself.
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_http.h>
+
+#define ngx_bitvector_index(index) index / (8 * sizeof(uintptr_t))
+#define ngx_bitvector_bit(index) (uintptr_t) 1 << index % (8 * sizeof(uintptr_t))
+
+typedef struct {
+ struct sockaddr *sockaddr;
+ socklen_t socklen;
+ ngx_str_t name;
+} ngx_http_upstream_hash_peer_t;
+
+typedef struct {
+ ngx_uint_t number;
+ ngx_http_upstream_hash_peer_t peer[0];
+} ngx_http_upstream_hash_peers_t;
+
+typedef struct {
+ ngx_http_upstream_hash_peers_t *peers;
+ ngx_uint_t hash;
+ ngx_str_t current_key;
+ ngx_str_t original_key;
+ ngx_uint_t try_i;
+ uintptr_t tried[1];
+} ngx_http_upstream_hash_peer_data_t;
+
+
+static ngx_int_t ngx_http_upstream_init_hash_peer(ngx_http_request_t *r,
+ ngx_http_upstream_srv_conf_t *us);
+static ngx_int_t ngx_http_upstream_get_hash_peer(ngx_peer_connection_t *pc,
+ void *data);
+static void ngx_http_upstream_free_hash_peer(ngx_peer_connection_t *pc,
+ void *data, ngx_uint_t state);
+static char *ngx_http_upstream_hash(ngx_conf_t *cf, ngx_command_t *cmd,
+ void *conf);
+static char *ngx_http_upstream_hash_again(ngx_conf_t *cf, ngx_command_t *cmd,
+ void *conf);
+static ngx_int_t ngx_http_upstream_init_hash(ngx_conf_t *cf,
+ ngx_http_upstream_srv_conf_t *us);
+static ngx_uint_t ngx_http_upstream_hash_crc32(u_char *keydata, size_t keylen);
+
+
+static ngx_command_t ngx_http_upstream_hash_commands[] = {
+ { ngx_string("hash"),
+ NGX_HTTP_UPS_CONF|NGX_CONF_TAKE1,
+ ngx_http_upstream_hash,
+ 0,
+ 0,
+ NULL },
+
+ { ngx_string("hash_again"),
+ NGX_HTTP_UPS_CONF|NGX_CONF_TAKE1,
+ ngx_http_upstream_hash_again,
+ 0,
+ 0,
+ NULL },
+
+ ngx_null_command
+};
+
+
+static ngx_http_module_t ngx_http_upstream_hash_module_ctx = {
+ NULL, /* preconfiguration */
+ NULL, /* postconfiguration */
+
+ NULL, /* create main configuration */
+ NULL, /* init main configuration */
+
+ NULL, /* create server configuration */
+ NULL, /* merge server configuration */
+
+ NULL, /* create location configuration */
+ NULL /* merge location configuration */
+};
+
+
+ngx_module_t ngx_http_upstream_hash_module = {
+ NGX_MODULE_V1,
+ &ngx_http_upstream_hash_module_ctx, /* module context */
+ ngx_http_upstream_hash_commands, /* module directives */
+ NGX_HTTP_MODULE, /* module type */
+ NULL, /* init master */
+ NULL, /* init module */
+ NULL, /* init process */
+ NULL, /* init thread */
+ NULL, /* exit thread */
+ NULL, /* exit process */
+ NULL, /* exit master */
+ NGX_MODULE_V1_PADDING
+};
+
+
+static ngx_int_t
+ngx_http_upstream_init_hash(ngx_conf_t *cf, ngx_http_upstream_srv_conf_t *us)
+{
+ ngx_uint_t i, j, n;
+ ngx_http_upstream_server_t *server;
+ ngx_http_upstream_hash_peers_t *peers;
+
+ us->peer.init = ngx_http_upstream_init_hash_peer;
+
+ if (!us->servers) {
+
+ return NGX_ERROR;
+ }
+
+ server = us->servers->elts;
+
+ for (n = 0, i = 0; i < us->servers->nelts; i++) {
+ n += server[i].naddrs;
+ }
+
+ peers = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_hash_peers_t)
+ + sizeof(ngx_http_upstream_hash_peer_t) * n);
+
+ if (peers == NULL) {
+ return NGX_ERROR;
+ }
+
+ peers->number = n;
+
+ /* one hostname can have multiple IP addresses in DNS */
+ for (n = 0, i = 0; i < us->servers->nelts; i++) {
+ for (j = 0; j < server[i].naddrs; j++, n++) {
+ peers->peer[n].sockaddr = server[i].addrs[j].sockaddr;
+ peers->peer[n].socklen = server[i].addrs[j].socklen;
+ peers->peer[n].name = server[i].addrs[j].name;
+ }
+ }
+
+ us->peer.data = peers;
+
+ return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_upstream_init_hash_peer(ngx_http_request_t *r,
+ ngx_http_upstream_srv_conf_t *us)
+{
+ ngx_http_upstream_hash_peer_data_t *uhpd;
+
+ ngx_str_t val;
+
+ if (ngx_http_script_run(r, &val, us->lengths, 0, us->values) == NULL) {
+ return NGX_ERROR;
+ }
+
+ uhpd = ngx_pcalloc(r->pool, sizeof(ngx_http_upstream_hash_peer_data_t)
+ + sizeof(uintptr_t) *
+ ((ngx_http_upstream_hash_peers_t *)us->peer.data)->number /
+ (8 * sizeof(uintptr_t)));
+ if (uhpd == NULL) {
+ return NGX_ERROR;
+ }
+
+ r->upstream->peer.data = uhpd;
+
+ uhpd->peers = us->peer.data;
+
+ r->upstream->peer.free = ngx_http_upstream_free_hash_peer;
+ r->upstream->peer.get = ngx_http_upstream_get_hash_peer;
+ r->upstream->peer.tries = us->retries + 1;
+
+ /* must be big enough for the retry keys */
+ if ((uhpd->current_key.data = ngx_pcalloc(r->pool, NGX_ATOMIC_T_LEN + val.len)) == NULL) {
+ return NGX_ERROR;
+ }
+
+ ngx_memcpy(uhpd->current_key.data, val.data, val.len);
+ uhpd->current_key.len = val.len;
+ uhpd->original_key = val;
+
+ ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+ "upstream_hash: hashing \"%V\"", &val);
+
+ uhpd->hash = ngx_http_upstream_hash_crc32(val.data, val.len);
+
+ return NGX_OK;
+}
+
+
+static ngx_int_t
+ngx_http_upstream_get_hash_peer(ngx_peer_connection_t *pc, void *data)
+{
+ ngx_http_upstream_hash_peer_data_t *uhpd = data;
+ ngx_http_upstream_hash_peer_t *peer;
+ ngx_uint_t peer_index;
+
+ ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
+ "upstream_hash: get upstream request hash peer try %ui", pc->tries);
+
+ pc->cached = 0;
+ pc->connection = NULL;
+
+ peer_index = uhpd->hash % uhpd->peers->number;
+
+ peer = &uhpd->peers->peer[peer_index];
+
+ ngx_log_debug2(NGX_LOG_DEBUG_HTTP, pc->log, 0,
+ "upstream_hash: chose peer %ui w/ hash %ui", peer_index, uhpd->hash);
+
+ pc->sockaddr = peer->sockaddr;
+ pc->socklen = peer->socklen;
+ pc->name = &peer->name;
+
+ return NGX_OK;
+}
+
+/* retry implementation is PECL memcache compatible */
+static void
+ngx_http_upstream_free_hash_peer(ngx_peer_connection_t *pc, void *data,
+ ngx_uint_t state)
+{
+ ngx_http_upstream_hash_peer_data_t *uhpd = data;
+ ngx_uint_t current;
+
+ ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
+ "upstream_hash: free upstream hash peer try %ui", pc->tries);
+
+ if (state & (NGX_PEER_FAILED|NGX_PEER_NEXT)
+ && --pc->tries)
+ {
+ current = uhpd->hash % uhpd->peers->number;
+
+ uhpd->tried[ngx_bitvector_index(current)] |= ngx_bitvector_bit(current);
+
+ do {
+ uhpd->current_key.len = ngx_sprintf(uhpd->current_key.data, "%d%V",
+ ++uhpd->try_i, &uhpd->original_key) - uhpd->current_key.data;
+ ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
+ "upstream_hash: hashing \"%V\"", &uhpd->current_key);
+ uhpd->hash += ngx_http_upstream_hash_crc32(uhpd->current_key.data,
+ uhpd->current_key.len);
+ current = uhpd->hash % uhpd->peers->number;
+ } while ((uhpd->tried[ngx_bitvector_index(current)] & ngx_bitvector_bit(current))
+ && --pc->tries);
+ }
+}
+
+/* bit-shift, bit-mask, and non-zero requirement are for libmemcache compatibility */
+static ngx_uint_t
+ngx_http_upstream_hash_crc32(u_char *keydata, size_t keylen)
+{
+ ngx_uint_t crc32 = (ngx_crc32_short(keydata, keylen) >> 16) & 0x7fff;
+ return crc32 ? crc32 : 1;
+}
+
+static char *
+ngx_http_upstream_hash(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+ ngx_http_upstream_srv_conf_t *uscf;
+ ngx_http_script_compile_t sc;
+ ngx_str_t *value;
+ ngx_array_t *vars_lengths, *vars_values;
+
+ value = cf->args->elts;
+
+ ngx_memzero(&sc, sizeof(ngx_http_script_compile_t));
+
+ vars_lengths = NULL;
+ vars_values = NULL;
+
+ sc.cf = cf;
+ sc.source = &value[1];
+ sc.lengths = &vars_lengths;
+ sc.values = &vars_values;
+ sc.complete_lengths = 1;
+ sc.complete_values = 1;
+
+ if (ngx_http_script_compile(&sc) != NGX_OK) {
+ return NGX_CONF_ERROR;
+ }
+
+ uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module);
+
+ uscf->peer.init_upstream = ngx_http_upstream_init_hash;
+
+ uscf->flags = NGX_HTTP_UPSTREAM_CREATE;
+
+ uscf->values = vars_values->elts;
+ uscf->lengths = vars_lengths->elts;
+
+ return NGX_CONF_OK;
+}
+
+static char *
+ngx_http_upstream_hash_again(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+ ngx_http_upstream_srv_conf_t *uscf;
+ ngx_int_t n;
+
+ ngx_str_t *value;
+
+ uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module);
+
+ value = cf->args->elts;
+
+ n = ngx_atoi(value[1].data, value[1].len);
+
+ if (n == NGX_ERROR || n < 0) {
+ return "invalid number";
+ }
+
+ uscf->retries = n;
+
+ return NGX_CONF_OK;
+}
projects / nginx.git / commitdiff