标签：文件中 mem 描述 数位 mod dict efault https memcpy
syntax: value, flags = ngx.shared.DICT:get(key)
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*
requires: resty.core.shdict or resty.core检索 ngx.shared.DICT 共享内存中 key 对应的值。如果 key 不存在或者超时，则返回 nil。
如果发生错误，返回 nil 和错误描述字符串。
在插入字典后，返回的值具有原始数据类型，如 Lua boolean，number，或者 string。
该方法的第一个参数是字典自身，如下：
local cats = ngx.shared.cats
local value, flags = cats.get(cats, "Mary")或者用如下方法调用：
local cats = ngx.shared.cats
local value, flags = cats:get("Marry")如果用户标志 flag 为 0（默认），则不返回任何标志值。
local value_type = ffi_new("int[1]")
local user_flags = ffi_new("int[1]")
local num_value = ffi_new("double[1]")
local is_stale = ffi_new("int[1]")
local str_value_buf = ffi_new("unsigned char *[1]")
local errmsg = base.get_errmsg_ptr()
local function shdict_get(zone, key)
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
local size = get_string_buf_size() -- 4096
local buf = get_string_buf(size)
str_value_buf[0] = buf -- str_value_buf = ffi_new("unsigned char *[1]")
local value_len = get_size_ptr()
value_len[0] = size
local rc = C.ngx_http_lua_ffi_shdict_get(zone, key, key_len, value_type,
str_value_buf, value_len,
num_value, user_flags, 0,
is_stale, errmsg)
if rc ~= 0 then
if errmsg[0] then
return nil, ffi_str(errmsg[0])
end
error("failed to get the key")
end
local typ = value_type[0]
if typ == 0 then -- LUA_TNIL
return nil
end
local flags = tonumber(user_flags[0])
local val
if typ == 4 then -- LUA_TSTRING
if str_value_buf[0] ~= buf then
-- ngx.say("len: ", tonumber(value_len[0]))
buf = str_value_buf[0]
val = ffi_str(buf, value_len[0])
C.free(buf)
else
val = ffi_str(buf, value_len[0])
end
elseif typ == 3 then -- LUA_TNUMBER
val = tonumber(num_value[0])
elseif typ == 1 then -- LUA_TBOOLEAN
val = (tonumber(buf[0]) ~= 0)
else
error("unknown value type: " .. typ)
end
if flags ~= 0 then
return val, flags
end
return val
end这两个函数位于 resty.core.base.lua 文件中:
local ffi = require = ‘ffi‘
local ffi_new = ffi.new
local str_buf_size = 4096
local str_buf
local size_ptr
local FREE_LIST_REF = 0
local c_buf_type = ffi.typeof("char[?]")
local errmsg
function _M.get_errmsg_ptr()
if not errmsg then
errmsg = ffi_new("char *[1]")
end
return errmsg
end
function _M.get_string_buf_size()
return str_buf_size
end
function _M.get_string_buf(size, must_alloc)
-- ngx.log(ngx.ERR, "str buf size: ", str_buf_size)
if size > str_buf_size or must_alloc then
return ffi_new(c_buf_type, size)
end
if not str_buf then
str_buf = ffi_new(c_buf_type, str_buf_size)
end
return str_buf
end
function _M.get_size_ptr()
if not size_ptr then
size_ptr = ffi_new("size_t[1]")
end
return size_ptr
endint
ngx_http_lua_ffi_shdict_get(ngx_shm_zone_t *zone, u_char *key,
size_t key_len, int *value_type, u_char **str_value_buf,
size_t *str_value_len, double *num_value, int *user_flags,
int get_stale, int *is_stale, char **err)
{
ngx_str_t name;
uint32_t hash;
ngx_int_t rc;
ngx_http_lua_shdict_ctx_t *ctx;
ngx_http_lua_shdict_node_t *sd;
ngx_str_t value;
if (zone == NULL) {
return NGX_ERROR;
}
*err = NULL;
ctx = zone->data;
name = ctx->name;
hash = ngx_crc32_short(key, key_len);
#if (NGX_DEBUG)
ngx_log_debug3(NGX_LOG_DEBUG_HTTP, ctx->log, 0,
"fetching key \"%*s\" in shared dict \"%V\"", key_len,
key, &name);
end
ngx_shmtx_lock(&ctx->shpool->mutex);
#if 1
if (!get_stale) {
/* 删除共享内存中过期的 1~2 个项 */
ngx_http_lua_shdict_expire(ctx, 1);
}
end
rc = ngx_http_lua_shdict_lookup(zone, hash, key, key_len, &sd);
dd("shdict lookup returns %d", (int) rc);
if (rc == NGX_DECLINED || (rc == NGX_DONE && !get_stale)) {
ngx_shmtx_unlock(&ctx->shpool->mutex);
*value_type = LUA_TNIL;
return NGX_OK;
}
/* rc == NGX_OK || (rc == NGX_DONE && get_stale) */
*value_type = sd->value_type;
dd("data: ", sd->data);
dd("key len: %d", (int) sd->key_len);
value.data = sd->data + sd->key_len;
value.len = (size_t) sd->value_len;
if (*str_value_len < (size_t) value.len) {
if (*value_type == SHDICT_TBOOLEAN) {
ngx_shmtx_unlock(&ctx->shpool->mutex);
return NGX_ERROR;
}
if (*value_type == SHDICT_TSTRING) {
*str_value_buf = malloc(value.len);
if (*str_value_buf == NULL) {
ngx_shmtx_unlock(&ctx->shpool->mutex);
return NGX_ERROR;
}
}
}
switch (*value_type) {
case SHDICT_TSTRING:
*str_value_len = value.len;
ngx_memcpy(*str_value_buf, value.data, value.len);
break;
case SHDCIT_TNUMBER:
if (value.len != sizeof(double)) {
ngx_shmtx_unlock(&ctx->shpool->mutex);
ngx_log_error(NGX_LOG_ERR, ngx_cycle->log, 0,
"bad lua number value size found for key %*s "
"in shared_dict %V: %z", key_len, key,
&name, value.len);
return NGX_ERROR;
}
*str_value_len = value.len;
ngx_memcpy(num_value, value.data, sizeof(double));
break;
case SHDICT_TBOOLEAN:
if (value.len != sizeof(u_char)) {
ngx_shmtx_unlock(&ctx->shpool->mutex);
ngx_log_error(NGX_LOG_ERR, ngx_cycle->log, 0,
"bad lua boolean value size found for key %*s "
"in shared_dict %V: %z", key_len, key, &name,
value.len);
return NGX_ERROR;
}
ngx_memcpy(*str_value_buf, value.data, value.len);
break;
case SHDICT_TLIST:
ngx_shmtx_unlock(&ctx->shpool->mutex);
*err = "value is a list";
return NGX_ERROR;
default:
ngx_shmtx_unlock(&ctx->shpool->mutex);
ngx_log_error(NGX_LOG_ERR, ngx_cycle->log, 0,
"bad value type found for key %*s in "
"shared_dict %V: %d", key_len, key, &name,
*value_type);
return NGX_ERROR;
}
*user_flags = sd->user_flags;
dd("user flags: %d", *user_flags);
ngx_shmtx_unlock(&ctx->shpool->mutex);
if (get_stale) {
/* always return value, flags, stale */
/* 为 true 表示已经过期了 */
*is_stale = (rc == NGX_DONE);
return NGX_OK;
}
return NGX_OK;
}标签：文件中 mem 描述 数位 mod dict efault https memcpy
原文地址：https://www.cnblogs.com/jimodetiantang/p/9439907.html
