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[etc/awesome.git] / asyncshell.lua
1
2 --[[
3                                                   
4      Licensed under GNU General Public License v2 
5       * (c) 2013, Alexander Yakushev              
6                                                   
7 --]]
8
9 -- Asynchronous io.popen for Awesome WM.
10 -- How to use...
11 -- ...asynchronously:
12 -- asyncshell.request('wscript -Kiev', function(f) wwidget.text = f:read("*l") end)
13 -- ...synchronously
14 -- widget:set_text(asyncshell.demand('wscript -Kiev', 5):read("*l") or "Error")
15
16 -- This is more cpu demanding, but makes things faster.
17
18 local spawn = require('awful.util').spawn
19
20 asyncshell               = {}
21 asyncshell.request_table = {}
22 asyncshell.id_counter    = 0
23 asyncshell.folder        = "/tmp/asyncshell"
24 asyncshell.file_template = asyncshell.folder .. '/req'
25
26 -- Create a directory for asynchell response files
27 os.execute("mkdir -p " .. asyncshell.folder)
28
29 -- Returns next tag - unique identifier of the request
30 local function next_id()
31    asyncshell.id_counter = (asyncshell.id_counter + 1) % 100000
32    return asyncshell.id_counter
33 end
34
35 -- Sends an asynchronous request for an output of the shell command.
36 -- @param command Command to be executed and taken output from
37 -- @param callback Function to be called when the command finishes
38 -- @return Request ID
39 function asyncshell.request(command, callback)
40    local id = next_id()
41    local tmpfname = asyncshell.file_template .. id
42    asyncshell.request_table[id] = { callback = callback }
43    local req =
44       string.format("sh -c '%s > %s; " ..
45                     'echo "asyncshell.deliver(%s)" | ' ..
46                     "awesome-client' 2> /dev/null",
47                     string.gsub(command, "'", "'\\''"), tmpfname,
48                     id, tmpfname)
49    spawn(req, false)
50    return id
51 end
52
53 -- Calls the remembered callback function on the output of the shell
54 -- command.
55 -- @param id Request ID
56 -- @param output The output file of the shell command to be delievered
57 function asyncshell.deliver(id)
58    if asyncshell.request_table[id] and
59       asyncshell.request_table[id].callback then
60       local output = io.open(asyncshell.file_template .. id, 'r')
61       asyncshell.request_table[id].callback(output)
62    end
63 end
64
65 -- Sends a synchronous request for an output of the command. Waits for
66 -- the output, but if the given timeout expires returns nil.
67 -- @param command Command to be executed and taken output from
68 -- @param timeout Maximum amount of time to wait for the result
69 -- @return File handler on success, nil otherwise
70 function asyncshell.demand(command, timeout)
71    local id = next_id()
72    local tmpfname = asyncshell.file_template .. id
73    local f = io.popen(string.format("(%s > %s; echo asyncshell_done) & " ..
74                                     "(sleep %s; echo asynchell_timeout)",
75                                     command, tmpfname, timeout))
76    local result = f:read("*line")
77    if result == "asyncshell_done" then
78       return io.open(tmpfname)
79    end
80 end
81
82 return asyncshell