Jeff Massung wrote:
That said, there are areas where LiveCode could - itself - benefit from
multi-threading that isn't exposed to the end user. One example of this is
in access to the internet, file, or various OS accesses. Being able to issue
a large disk read/write and get a callback when done, and either a revamp or
serious bug fix/cleaning of libURL. Or being able to wait on a particular
event to be completed/happen. These alone would help considerably.
One small step in that direction, from the LiveCode 4.5 Release
Notes.pdf (which is unfortunately buried deep inside the app bundle on
OS X virtually guaranteeing no Mac customer will ever see it):
Engine changes
Non-blocking DNS resolution
The open socket command no longer blocks on DNS resolution.
Instead, if resolution is required the command will return
immediately and the DNS lookup will happen in the background.
If resolution fails, then a socketError message is sent in
the same was as if connection fails.
For applications using hostNameToAddress directly, its syntax
has been augmented:
hostnameToAddress(hostname, [ callback ])
If the callback parameter is specified then the call will
return immediately and upon completion of the lookup, the
callback will be invoked with the resolved address as a
parameter.
Another nifty new thing including in that unfortunately hidden document is:
Slave process improvements
A number of issues with the open process command and the engine
itself have, up until now, conspired to make it difficult (if
not impossible!) to either run a slave process, or use the
engine as slave on all platforms.
These issues have been resolved in this version, thus making it
straightforward to run another process and poll for input and
output over stdin/stdout.
The typical form for this is along the following lines:
local sSlaveProcess
command startSlave pProcess
open process sSlaveProcess for text update
send “monitorSlave” to me in 50 millisecs
end startSlave
command monitorSlave
repeat forever
# Loop until there are no more lines to read.
read from process sSlaveProcess for 1 line in 0 millisecs
if the result is empty then
# The slave has sent us something, so process it and loop for
# (potentially) more data. else if the result is “timeout” then
# There is nothing waiting for us, so exit repeat
exit repeat
else if the result is “eof” then
# The slave has terminated, so do any final processing and
# finish monitoring.
close process sSlaveProcess
exit monitorSlave
else
# Some error has occurred!
exit monitorSlave
end if
end repeat
send “monitorSlave” to me in 50 millisecs
end monitorSlave
--
Richard Gaskin
Fourth World
LiveCode training and consulting: http://www.fourthworld.com
Webzine for LiveCode developers: http://www.LiveCodeJournal.com
LiveCode Journal blog: http://LiveCodejournal.com/blog.irv
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