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--
-- Test resource cleanup
--
-- This feature was ... by discussion on the Lua list about exceptions.
-- The idea is to always run a certain block at exit, whether due to success
-- or error. Normally, 'pcall' would be used for such but as Lua already
-- does that, simply giving a 'cleanup=function' parameter is a logical
-- thing to do. -- AKa 22-Jan-2009
--
local lanes = require "lanes"
lanes.configure{with_timers=false}
local finally = lanes.finally
local FN = "finalizer-test.tmp"
local cleanup
local function lane(error_)
set_finalizer(cleanup)
local st,err = pcall(finally, cleanup) -- should cause an error because called from a lane
assert(not st, "finally() should have thrown an error")
io.stderr:write("finally() raised error '", err, "'\n")
local f,err = io.open(FN,"w")
if not f then
error( "Could not create "..FN..": "..err)
end
f:write( "Test file that should get removed." )
io.stderr:write( "File "..FN.." created\n" )
-- don't forget to close the file immediately, else we won't be able to delete it until f is collected
f:close()
if error_ then
io.stderr:write("Raising ", tostring(error_), "\n")
error(error_, 0) -- exception here; the value needs NOT be a string
end
-- no exception
io.stderr:write("Lane completed\n")
return true
end
--
-- This is called at the end of the lane; whether succesful or not.
-- Gets the 'error()' argument as argument ('nil' if normal return).
--
cleanup = function(err)
io.stderr:write "------------------------ In Worker Finalizer -----------------------\n"
-- An error in finalizer will override an error (or success) in the main
-- chunk.
--
--error( "This is important!" )
if err then
io.stderr:write( "Cleanup after error: "..tostring(err).."\n" )
else
io.stderr:write( "Cleanup after normal return\n" )
end
local _,err2 = os.remove(FN)
io.stderr:write( "file removal result: ", tostring(err2), "\n")
assert(not err2) -- if this fails, it will be shown in the calling script
-- as an error from the lane itself
io.stderr:write( "Removed file "..FN.."\n" )
end
-- we need error_trace_level above "minimal" to get a stack trace out of h:join()
local lgen = lanes.gen("*", { name = 'auto', error_trace_level = "basic" }, lane)
local do_test = function(error_)
io.stderr:write "======================== Launching the lane! =======================\n"
local h = lgen(error_)
local _,err,stack = h:join() -- wait for the lane (no automatic error propagation)
if err then
assert(stack, "no stack trace on error, check 'error_trace_level'")
io.stderr:write( "Lane error: "..tostring(err).."\n" )
io.stderr:write( "\t", table.concat(stack,"\t\n"), "\n" )
else
io.stderr:write( "Done\n" )
end
end
do_test(nil)
-- do return end
do_test("An error")
local on_exit = function()
finally(nil)
io.stderr:write "=========================In Lanes Finalizer! =======================\n"
local f = io.open(FN,"r")
if f then
error( "CLEANUP DID NOT WORK: "..FN.." still exists!" )
else
io.stderr:write(FN .. " was successfully removed\n")
end
io.stderr:write "Finished!\n"
end
-- this function is called after script exit, when the state is closed
lanes.finally(on_exit)
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