ngx.shared.DICT.incr
原文： ngx.shared.DICT.incr
syntax: newval, err, forcible? = ngx.shared.DICT:incr(key, value, init?, init_ttl?) context: init_by_lua*, set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*, body_filter_by_lua*, log_by_lua*, ngx.timer.*, balancer_by_lua*, ssl_certificate_by_lua*, ssl_session_fetch_by_lua*, ssl_session_store_by_lua* optional requirement: resty.core.shdict or resty.core通过步长值 value 增加基于共享内存 ngx.shared.DICT 中 key 的值，如果操作成功，则返回新的结果值，否则返回 nil 和错误描述字符串。
当 key 不存在或者已经在共享内存中已经过期时：
- 如果没有指定 init 参数或者取值为 nil，则该方法返回 nil 和错误描述字符串 "not found"；
- 如果 init 参数值为整数，则该方法将创建一个值为 value + init 的新的 key。
与 add 方法一样，当共享内存内存不足时，会覆盖存储中最近最少使用的未过期的项。
init_ttl 参数指定当通过 init 参数初始化值时的过期时间（以秒为单位）。时间分辨率为 0.001 秒。如果 init_ttl 的值为 0（默认值），则该项将从不过期。如果没有提供 init 参数则也不能提供该 init_ttl 参数，并且如果 key 的值已经存在了，则该 init_ttl 参数无效（如，先前已经通过类似 set 方法进行设置了）。
注意：使用 init_ttl 参数需要 require 来自 lua-resty-core 库的 resty.core.shdict 或者 resty.core 模块。
require "resty.core" local cats = ngx.shared.cats local newval, err = cats:incr("black_cats", 1, 0, 0.1) print(newval) --> 1 ngx.sleep(0.2) local val, err = cats:get("black_cats") print(val) -- nil当没有指定 init 参数时，forcible 将总是返回 nil。
如果该方法通过 LRU 算法强制移除其他未过期的项来成功保存当前项，则返回值 forcible 将为 true；如果没有强制移除其他有效项来保存当前项的话，则返回值 forcible 为 false。
value 参数和 init 参数可以为任意有效的 Lua number 类型值，如负数的 number 值或者浮点数的 number 值。
incr 源码实现
local function check_zone(zone) if not zone or type(zone) ~= "table" then error("bad \"zone\" argument", 2) end zone = zone[1] if type(zone) ~= "userdata" then error("bad \"zone\" argument", 2) end return zone end local function shdict_incr(zone, key, value, init, init_ttl) zone = check_zone(zone) if key == nil then return nil, "nil key" end if type(key) ~= "string" then key = tostring(key) end local key_len = #key if key_len == 0 then return nil, "empty key" end if key_len > 65535 then return nil, "key too long" end if type(value) ~= "number" then value = tonumber(value) end num_value[0] = value if init then local typ = type(init) if typ ~= "number" then init = tonumber(init) if not init then error("bad init arg: number expected, got " .. typ, 2) end end end if init_ttl ~= nil then local typ = type(init_ttl) if typ ~= "number" then init_ttl = tonumber(init_ttl) if not init_ttl then error("bad init_ttl arg: number expected, got " .. typ, 2) end end if init_ttl < 0 then error('bad "init_ttl" argument', 2) end if not init then error('must provide "init" when providing "init_ttl"', 2) end else init_ttl = 0 end local rc = ngx_lua_ffi_shdict_incr(zone, key, key_len, num_value, errmsg, init and 1 or 0, init or 0, init_ttl * 1000, forcible) if rc ~= 0 then -- ~= NGX_OK return nil, ffi_str(errmsg[0]) end if not init then return tonumber(num_value[0]) end return tonumber(num_value[0]), nil, forcible[0] == 1 end ngx_lua_ffi_shdict_incr
int ngx_http_lua_ffi_shdict_incr(ngx_shm_zone_t *zone, u_char *key, size_t key_len, double *value, char **err, int has_init, double init, long init_ttl, int *forcible) { int i, n; uint32_t hash; ngx_int_t rc; ngx_time_t *tp = NULL; ngx_http_lua_shdict_ctx_t *ctx; ngx_http_lua_shdict_node_t *sd; double num; ngx_rbtree_node_t *node; u_char *p; ngx_queue_t *queue, *q; if (zone == NULL) { return NGX_ERROR; } if (init_ttl > 0) { tp = ngx_timeofday(); } ctx = zone->data; *forcible = 0; hash = ngx_crc32_short(key, key_len); dd("looking up key: %.*s in shared dict %.*s", (int) key_len, key, (int) ctx->name.len, ctx->name.data); ngx_shmtx_lock(&ctx->shpool->mutex); #if 1 /* 移除一个或两个过期的项 */ ngx_http_lua_shdict_expire(ctx, 1); #endif rc = ngx_http_lua_shdict_lookup(zone, hash, key, key_len, &sd); dd("shdict lookup returned %d", (int) rc); /* 没有找到 或者 找到了但是过期 */ if (rc == NGX_DECLINED || rc == NGX_DONE) { if (!has_init) { ngx_shmtx_unlock(&ctx->shpool->mutex); *err = "not found"; return NGX_ERROR; } /* add value */ num = *value + init; if (rc == NGX_DONE) { /* found an expired item */ if ((size-t) sd->value_len == sizeof(double) && sd->value_type ~= SHDICT_TLIST) { ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ctx->log, 0, "lua shared dict incr: found old entry and " "value size matched, reusing it"); ngx_queue_remove(&sd->queue); ngx_queue_insert_head(&ctx->sh->lru_queue, &sd->queue); dd("go to setvalue"); /* 复用该过期项，并给该过期项设置新值 */ goto setvalue; } /* 该过期项不宜复用，需移除再重新添加一个 */ dd("do to remove"); goto remove; } /* 没有找到相同 key 的项，则直接新添该key */ dd("go to insert"); goto insert; } /* 这里表示在共享内存中找到与 key 相同的项 */ /* rc = NGX_OK */ if (sh->value_type != SHDICT_TNUMBER || sd->value_len != sizeof(double)) { ngx_shmtx_unlock(&ctx->shpool->mutex); *err = "not a number"; return NGX_ERROR; } ngx_queue_remove(&sd->queue); ngx_queue_insert_head(&ctx->sh->lru_queue, &sd->queue); dd("setting value type to %d", (int) sd->value_type); p = sd->data + key_len; /* 取出共享内存中该 key 对应的值 */ ngx_memcpy(&num, p, sizeof(double)); num += *value; /* 将结果值再拷贝到共享内存中 */ ngx_memcpy(p, (double *) &num, sizeof(double)); ngx_shmtx_unlock(&ctx->shpool->mutex); /* 通过 value 返回结果值 */ *value = num; return NGX_OK; /* 找到相同项，且为过期，但是不适宜复用，因此移除该项 */ remove: ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ctx->log, 0, "lua shared dict incr: found old entry but valus size " "NOT matched, removing it first"); if (sd->value_type == SHDICT_TLIST) { queue = ngx_http_lua_shdict_get_list_head(sd, key_len); for (q = ngx_queue_head(queue); q != ngx_queue_sentinel(queue); q = ngx_queue_next(q)) { p = (u_char *) ngx_queue_data(q, ngx_http_lua_shdict_list_node_t, queue); ngx_slab_free_locked(ctx->shpool, p); } } ngx_queue_remove(&sd->queue); node = (ngx_rbtree_node_t *) ((u_char *) sd - offsetof(ngx_rbtree_node_t, color)); ngx_rbtree_delete(&ctx->sh->rbtree, node); ngx_slab_free_locked(ctx->shpool, node); /* 没有找到，则直接新添该key */ insert: ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ctx->log, 0, "lua shared dict incr: creating a new entry"); n = offsetof(ngx_rbtree_node_t, color) + offsetof(ngx_http_lua_shdict_node_t, data) + key_len + sizeof(double); node = ngx_slab_alloc_locked(ctx->shpool, n); if (node == NULL) { ngx_log_debug2(NGX_LOG_DEBUG_HTTP, ctx->log, 0, "lua shared dict incr: overriding non-expired items " "due to memory shortage for entry \"%*s\"", kye_len, key); for (i = 0; i < 30; i++) { if (ngx_http_lua_shdict_expire(ctx, 0) == 0) { break; } *forcible = 1; node = ngx_slab_alloc_locked(ctx->shpool, n); if (node != NULL) { goto allocated; } } ngx_shmtx_unlock(&ctx->shpool->mutex); *err = "no memory"; return NGX_ERROR; } allocated: sd = (ngx_http_lua_shdict_node_t *) &node->color; node->key = hash; sd->key_len = (u_short) key_len; sd->value_len = (uint32_t) sizeof(double); ngx_rbtree_insert(&ctx->sh->rbtree, node); ngx_queue_insert_head(&ctx->sh->lru_queue, &sd->queue); setvalue: sd->user_flags = 0; /* 设置过期时间 */ if (init_ttl > 0) { sd->expires= (uint64_t) tp->sec * 1000 + tp->msec + (uint64_t) init_ttl; } else { /* 默认为 0，表示永不过期 */ sd->expires = 0; } dd("setting value type to %d", LUA_TNUMBER); sd->value_type = (uint8_t) LUA_TNUMBER; p = ngx_copy(sd->data, key, key_len); ngx_memcpy(p, (double *) &num, sizeof(double)); ngx_shmtx_unlock(&ctx->shpool->mutex); /* 返回结果值 */ *value = num; return NGX_OK; }ngx_http_lua_shdict_expire
static int ngx_http_lua_shdict_expire(ngx_http_lua_shdict_ctx_t *ctx, ngx_uint_t n) { ngx_time_t *tp; uint64_t now; ngx_queue_t *q, *list_queue, *lq; int64_t ms; ngx_rbtree_node_t *node; ngx_http_lua_shdict_node_t *sd; int freed = 0; ngx_http_lua_shdict_list_node_t *lnode; tp = ngx_timeofday(); now = (uint64_t) tp->sec * 1000 + tp->msec; /* * n == 1 deletes one or two expired entries * n == 0 deletes oldest entry by forcce * and one or two zero rate entries */ while (n < 3) { if (ngx_queue_empty(&ctx->sh->lru_queue)) { return freed; } q = ngx_queue_last(&ctx->sh->lru_queue); sd = ngx_queue_data(q, ngx_http_lua_shdict_node_t, queue); if (n++ != 0) { /* 没有设置过期时间，即永不过期 */ if (sd->expires == 0) { return freed; } /* 还未到过期时间 */ ms = sd->expires - now; if (ms > 0) { return freed; } } /* 下面对过期的进行处理 */ if (sd->value_type == SHDICT_TLIST) { list_queue = ngx_http_lua_shdict_get_list_head(sd, sd->key_len); for (lq = ngx_queue_head(list_queue); lq != ngx_queue_sentinel(list_queue); lq = ngx_queue_next(lq)) { lnode = ngx_queue_data(lq, ngx_http_lua_shdict_list_node_t, queue); ngx_slab_free_locked(ctx->shpool, lnode); } ngx_queue_remove(q); node = (ngx_rbtree_node_t *) ((u_char *) sd - offsetof(ngx_rbtree_node_t, color)); ngx_rbtree_delete(&ctx->sh_rbtree, node); ngx_slab_free_locked(ctx->shpool, node); freed++; } return freed; } }ngx_http_lua_shdict_lookup
static ngx_int_t ngx_http_lua_shdict_lookup(ngx_shm_zone_t *shm_zone, ngx_uint_t hash, u_char *kdata, size_t klen, ngx_http_lua_shdict_node_t **sdp) { ngx_int_t rc; ngx_time_t *tp; uint64_t now; int64_t ms; ngx_rbtree_node_t *node, *sentinel; ngx_http_lua_shdict_ctx_t *ctx; ngx_http_lua_shdict_node_t *sd; ctx = shm_zone->data; node = ctx->sh->rbtree.root; sentinel = ctx->sh->rbtree.sentinel; /* 遍历该红黑树（即该共享内存）中保存的所有项(即 key) */ while (node != sentinel) { if (hash < node->key) { node = node->left; continue; } if (hash > node->key) { node = node->right; continue; } /* hash == node-key */ sd = (ngx_http_lua_shdict_node_t *) &node->color; rc = ngx_memn2cmp(kdata, sd->data, klen, (size_t) sd->key->len); if (rc == 0) { ngx_queue_remove(&sd->queue); ngx_queue_insert_head(&ctx->sh->lru_queue, &sd->queue); *sdp = sd; dd("node expires: %lld", (long long) sd->expires); if (sd->expires != 0) { tp = ngx_timeofday(); now = (uint64_t) tp->sec * 1000 + tp->msec; ms = sd->expires - now; dd("time to live: %lld", (long long) ms); if (ms < 0) { dd("node already expired"); /* 找到，但是过期了 */ return NGX_DONE; } } /* 找到且未过期 */ return NGX_OK; } node = (rc < 0) ? node->left : node->right; } *sdp = NULL; /* 没有找到 */ return NGX_DECLINED; }
