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|
-- Light Unix I/O for Lua
-- Copyright 2012 Rob Kendrick <rjek+luxio@rjek.com>
--
-- Distributed under the same terms as Lua itself (MIT).
--
-- High-level functions for using POSIX message queues. Delicate.
local l = require "luxio"
assert(l._ABI == 0, "luxio ABI mismatch")
local sio = require "luxio.simple"
local serialise = require("luxio.serialise").serialise
local lua_version = tonumber(_VERSION:match "Lua (%d.%d)")
local function err(txt, errno)
return nil, ("%s: %s"):format(txt, l.strerror(errno)), errno
end
local mq_check_mt
local function mq_meta_gc(o)
if not o.closed then
l.mq_close(o.desc)
end
end
local mq_mt = {
send = function(o, msg, prio)
mq_check_mt(o)
local r, errno = l.mq_send(o.desc, msg, prio)
if r < 0 then
return err("mq_send", errno)
end
return true
end,
receive = function(o)
mq_check_mt(o)
local r, errno, msg, prio = l.mq_receive(o.desc)
if r < 0 then
return err("mq_receive", errno)
end
return msg, prio
end,
close = function(o)
mq_check_mt(o)
local r, errno = l.mq_close(o.desc)
if r < 0 then
return err("mq_close", errno)
end
o.closed = true
return true
end,
push = function(o, data, prio)
mq_check_mt(o)
local payload = serialise(data)
local r, errno, attr = l.mq_getattr(o.desc)
if r < 0 then
return err("mq_getattr", errno)
end
if #payload > attr.mq_msgsize then
return nil, "payload serialisation too large"
end
r, errno = l.mq_send(o.desc, payload, prio or 0)
if r < 0 then
return err("mq_send", errno)
end
return true
end,
pull = function(o)
mq_check_mt(o)
local r, errno, data, prio = l.mq_receive(o.desc)
if r < 0 then
return err("mq_receive", errno)
end
local f, err = loadstring("return " .. data)
if f == nil then
return nil, "payload error: " .. err
end
local ok, result = pcall(f)
if not ok then
return nil, "payload error: ".. result
end
return result
end,
__tostring = function(x)
return ("message queue: %s %s (%d)%s"):format(
x.rw_mode, x.path, x.desc, x.closed and " closed" or "")
end,
__gc = mq_meta_gc
}
mq_mt.__index = mq_mt
if lua_version == 5.1 then
mq_wrap_mt = function(t)
t.proxy = newproxy(true)
getmetatable(t.proxy).__gc = function()
mq_meta_gc(t)
end
setmetatable(t, mq_mt)
end
else
mq_wrap_mt = function(t)
setmetatable(t, mq_mt)
end
end
mq_check_mt = function(x)
if getmetatable(x) ~= mq_mt then
error "object passed is not an MQ object"
end
if x.closed then
error "MQ passed has been closed"
end
end
local rw_mode_map = {
r = l.O_RDONLY,
w = l.O_WRONLY,
rw = l.O_RDWR
}
local function open(path, rw, mode)
-- Opens a message queue. rw is one of "r", "w", or "rw".
-- If mode is specified, it will also try to create it.
local rw_mode = rw_mode_map[rw] or error "unknown read/write mode"
local mq, errno
if mode then
mode = sio.tomode(mode)
mq, errno = l.mq_open(path, l.bit.bor(rw_mode, l.O_CREAT), mode)
else
mq, errno = l.mq_open(path, rw_mode)
end
if mq < 0 then
return err("mq_open", errno)
end
local t = { path = path, desc = mq, rw_mode = rw }
mq_wrap_mt(t)
return t
end
local function unlink(path)
local r, errno = l.mq_unlink(path)
if r < 0 then
return err("mq_unlink", errno)
end
return true
end
return { open = open, unlink = unlink }
|
