When creating a peripheral or custom Lua object, one must implement two
methods:
- getMethodNames(): String[] - Returns the name of the methods
- callMethod(int, ...): Object[] - Invokes the method using an index in
the above array.
This has a couple of problems:
- It's somewhat unwieldy to use - you need to keep track of array
indices, which leads to ugly code.
- Functions which yield (for instance, those which run on the main
thread) are blocking. This means we need to spawn new threads for
each CC-side yield.
We replace this system with a few changes:
- @LuaFunction annotation: One may annotate a public instance method
with this annotation. This then exposes a peripheral/lua object
method.
Furthermore, this method can accept and return a variety of types,
which often makes functions cleaner (e.g. can return an int rather
than an Object[], and specify and int argument rather than
Object[]).
- MethodResult: Instead of returning an Object[] and having blocking
yields, functions return a MethodResult. This either contains an
immediate return, or an instruction to yield with some continuation
to resume with.
MethodResult is then interpreted by the Lua runtime (i.e. Cobalt),
rather than our weird bodgey hacks before. This means we no longer
spawn new threads when yielding within CC.
- Methods accept IArguments instead of a raw Object array. This has a
few benefits:
- Consistent argument handling - people no longer need to use
ArgumentHelper (as it doesn't exist!), or even be aware of its
existence - you're rather forced into using it.
- More efficient code in some cases. We provide a Cobalt-specific
implementation of IArguments, which avoids the boxing/unboxing when
handling numbers and binary strings.
OK, so let's get this out of the way, there's some actual changes mixed
in here too. I'm really sorry:
- Turtles can now not be renamed with unnamed item tags (previously it
would clear the name, this seemed a little unideal).
- commands.getBlock(s)Data will also include NBT.
Now, onto the horror story which is these inspection changes:
- Make a lot of methods static
- Typo fixes
- Make utility classes final + private constructor
- Lots of reformatting (ifs -> ternary, invert control flow, etc...)
- ???
- Profit!
I'm so going to regret this - can pretty much guarantee this is going to
break something.
Oh goodness, when will it end?
- Computer errors are shown in red.
- Lua machine operations provide whether they succeeded, and an
optional error message (reason bios failed to load, timeout error,
another Lua error), which is then shown to the user.
- Clear the Cobalt "thrown soft abort" flag when resuming, rather than
every n instructions.
- Computers will clear their "should start" flag once the time has
expired, irrespective of whether it turned on or not. Before
computers would immediately restart after shutting down if the flag
had been set much earlier.
Errors within the Lua machine are displayed in a more friendly
- TimeoutState uses nanoseconds rather than milliseconds. While this is
slightly less efficient on Windows, it's a) not the bottleneck of Lua
execution and b) we need a monotonic counter, otherwise we could
fail to terminate computers if the time changes.
- Add an exception handler to all threads.
- Document several classes a little better - I'm not sure how useful
all of these are, but _hopefully_ it'll make the internals a little
more accessible.
- Instead of setting soft/hard timeouts on the ILuaMachine, we instead
provide it with a TimeoutState instance. This holds the current abort
flags, which can then be polled within debug hooks.
This means the Lua machine has to do less state management, but also
allows a more flexible implementation of aborts.
- Soft aborts are now handled by the TimeoutState - we track when the
task was started, and now only need to check we're more than 7s since
then.
Note, these timers work with millisecond granularity, rather than
nano, as this invokes substantially less overhead.
- Instead of having n runners being observed with n managers, we now
have n runners and 1 manager (or Monitor).
The runners are now responsible for pulling work from the queue. When
the start to execute a task, they set the time execution commenced.
The monitor then just checks each runner every 0.1s and handles hard
aborts (or killing the thread if need be).
- Rename unload -> close to be a little more consistent
- Make pollAndResetChanged be atomic, so we don't need to aquire a lock
- Get the computer queue from the task owner, rather than a separate
argument.
ILuaAPI has been moved to dan200.computercraft.api.lua. One creates
a new API by registering an instance of ILuaAPIFactory. This takes an
instance of IComputerSystem and returns such an API.
IComputerSystem is an extension of IComputerAccess, with methods to
access additional information about the the computer, such as its label
and filesystem.
