-- Copyright (C) Yichun Zhang (agentzh) -- Copyright (C) cuiweixie -- I hereby assign copyright in this code to the lua-resty-core project, -- to be licensed under the same terms as the rest of the code. local ffi = require 'ffi' local base = require "resty.core.base" local FFI_OK = base.FFI_OK local FFI_ERROR = base.FFI_ERROR local FFI_DECLINED = base.FFI_DECLINED local ffi_new = ffi.new local ffi_str = ffi.string local ffi_gc = ffi.gc local C = ffi.C local type = type local error = error local tonumber = tonumber local getfenv = getfenv local get_string_buf = base.get_string_buf local get_size_ptr = base.get_size_ptr local setmetatable = setmetatable local co_yield = coroutine._yield local ERR_BUF_SIZE = 128 local errmsg = base.get_errmsg_ptr() ffi.cdef[[ struct ngx_http_lua_sema_s; typedef struct ngx_http_lua_sema_s ngx_http_lua_sema_t; int ngx_http_lua_ffi_sema_new(ngx_http_lua_sema_t **psem, int n, char **errmsg); int ngx_http_lua_ffi_sema_post(ngx_http_lua_sema_t *sem, int n); int ngx_http_lua_ffi_sema_count(ngx_http_lua_sema_t *sem); int ngx_http_lua_ffi_sema_wait(ngx_http_request_t *r, ngx_http_lua_sema_t *sem, int wait_ms, unsigned char *errstr, size_t *errlen); void ngx_http_lua_ffi_sema_gc(ngx_http_lua_sema_t *sem); ]] local psem = ffi_new("ngx_http_lua_sema_t *[1]") local _M = { version = base.version } local mt = { __index = _M } function _M.new(n) n = tonumber(n) or 0 if n < 0 then return error("no negative number") end local ret = C.ngx_http_lua_ffi_sema_new(psem, n, errmsg) if ret == FFI_ERROR then return nil, ffi_str(errmsg[0]) end local sem = psem[0] ffi_gc(sem, C.ngx_http_lua_ffi_sema_gc) return setmetatable({ sem = sem }, mt) end function _M.wait(self, seconds) if type(self) ~= "table" or type(self.sem) ~= "cdata" then return error("not a semaphore instance") end local r = getfenv(0).__ngx_req if not r then return error("no request found") end local milliseconds = tonumber(seconds) * 1000 if milliseconds < 0 then return error("no negative number") end local cdata_sem = self.sem local err = get_string_buf(ERR_BUF_SIZE) local errlen = get_size_ptr() errlen[0] = ERR_BUF_SIZE local ret = C.ngx_http_lua_ffi_sema_wait(r, cdata_sem, milliseconds, err, errlen) if ret == FFI_ERROR then return nil, ffi_str(err, errlen[0]) end if ret == FFI_OK then return true end if ret == FFI_DECLINED then return nil, "timeout" end -- Note: we cannot use the tail-call form here since we -- might need the current function call's activation -- record to hold the reference to our semaphore object -- to prevent it from getting GC'd prematurely. local ok, err = co_yield() return ok, err end function _M.post(self, n) if type(self) ~= "table" or type(self.sem) ~= "cdata" then return error("not a semaphore instance") end local cdata_sem = self.sem local num = n and tonumber(n) or 1 if num < 1 then return error("no negative number") end -- always return NGX_OK C.ngx_http_lua_ffi_sema_post(cdata_sem, num) return true end function _M.count(self) if type(self) ~= "table" or type(self.sem) ~= "cdata" then return error("not a semaphore instance") end return C.ngx_http_lua_ffi_sema_count(self.sem) end return _M