awesome/widgets/awesompd/asyncshell.lua

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