- Add pointer member to thread. This is the current executing block.
- Add stackFrame member to thread. This is the current frame
information like procedure parameters.
This is a step potentially towards stack-less threads. With further
modifications we could have stack and stackFrames be null if a script
does not call a procedure.
A previous change fixed compatibility with Scratch 2 removing 3's
unintentional scope leaking. This furthers that change so that
procedures with no parameters will also not accidentally use values in
other procedure stacks.
Freeze promise waiting blocks into an array of reported values. Thaw
those reported values into parent values of matching blocks by id. If
the reporting block was waiting on a promise and reported a value
assign it to its parent value at that future time.
Turn the reporter tree execute walks into a sequence of block
functions. After calling a block function store the reported value in
the arguments object its depending block will use.
- Set the reported value on the thread. There is only ever one "just"
reported value, which is read and stored elsewhere after being
reported.
Use a private StackFrame class to help internally manage use of Stack
Frame values and memory. Create params, reported, and executionContext
on demand.
Store the thread's blocks at blockContainer letting execute quickly
determine the block source. Monitor threads are a monitor thread. They
do not become a target thread suddenly.
- Add stackFrame.justReported
Report the block result to a known key `justReported` instead of a
dynamic key on `reported`. Assuming blocks with a promised value are
relatively infrequent the most common recursive input flow immediately
reads the value "just" reported. In the assumed uncommon case of a
promised thread status, empty the already argValues assigned values
onto the currentStackFrame's reported member. In the next execute call
on this stackFrame, values assigned to reported are read back off onto
argValues, and execute will returned to the assumed common case. This
is a safe assumption since a thread in the promise state will not exit
that state until the next frame when javascript has a chance to call
the resolve handle, setting the thread's state back to another
executable state.
Using direct assignment to `justReported` saves building an object
dynamically. Instead of always building `reported` and `argValues` only
`argValues` is built until a promised state is reached. This also gives
a known time when `reported` is used, allowing cleanup of a
stackFrame's reported to only happen when it was used to persist
already reported values.
Problem:
When a clone is deleted, its thread is removed from the thread
list; but the index "i" in the execution for-loop will still +1,
making the next thread skipped.
Changes:
Added a flag "isKilled" on a thread;
Set the flag when a thread is removed from the thread list;
reduce the "i" counter if the thread of the current loop is removed.
This saves popping, destroying, recreating, and pushing the stack frame,
and then reassigning the warp mode attribute for every block to block
step in the execution.
Run-time Optimisation
The thread.stackFrames array is accessed all the time to retrieve the
'parent' stack frame. This is done using as index of [this.stack.length
- 1]. However, a lot of the time this evaluated to [-1]. Although this
results in null, which is fine, to get to this javascript actually
defers from a numeric array lookup to an object lookup using the string
"-1". This is roughly 100 times slower to compute and so a simple catch
for negative indexes is well worth the extra check.
* Provide property to Clone to distinguish "original" clones
* Provide method to clone a clone's properties
* Don't report clones in the UI target list
* Add target info to Thread
* Allow hats to skip clones (for green flag)
* Green flag skips clones
* Implement "create clone" and hat
* Pass the runtime to sprites and clones (for start hats)
* Clone disposal; trigger hats after drawable initializes.
* Separate stop threads for target; fix handling of stop button
* Remove extraneous `skipClones` property
* Add global clone limit
* Don't allow a non-clone to delete itself.
* Rename `cloneClone` -> `makeClone`
* Variable updates in runtime.js
* Synchronous drawable initialization (until we put it back to promises)
* Strip out old script glowing in thread management
* Add new tracking mechanism for glowing scripts
* Track parents and use them to determine script glows
* Use top-block for a thread if there's nothing on the stack
* Remove `console.log`
Thomas Weber