Let profiled code track frames and arguments called by incrementing a
counter for a frame id or frame id and argument. This replaces the same
counting by recording the call as part of a history of calls and
returns. Updating the array for all calls counted takes enough time to
bias the profiled run towards less overall executions.
Check that a reporting block is the last operation as part of some
parent block. The last operation is the block itself which may report
values for stack clicks and monitor updates if it meets other
requirements.
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.
Block args set by fields are static and never change. Inputs that do
change are always set onto args. With these two assumptions we can
reuse the same objects for each execution of the same block instead of
constantly creating them and letting them be garbage collected.
Use a private StackFrame class to help internally manage use of Stack
Frame values and memory. Create params, reported, and executionContext
on demand.
Explain how BlocksExecuteCache helps speed up execute by storing values from
Blocks and one-time derived values on an object that is released when Blocks is
edited in the editor. The one time created cache object for a block then
simplifies the complexity of later javascript operations to use these stored
values.
Add a Blocks cache available only to execute. This cache lets execute
get a blocks inputs, fields, opcode, and mutation in one request and an
object execute can further modify to store derivative values it use
this and every later execute iteration to perform its duties quicker.
Before calling execute, if a thread's target is null, retire that
thread.
This saves repeatedly checking if the thread's target is null in
recursive calls where even if scratch-gui or blocks, or some other
related library set the target to null, that will not happen during
block execution. It will happen at some time outside of the sequencer
letting the sequencer check once instead of execute checking at every
recursive level.
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.
When execute calls itself to step into the next stack level, pass
RECURSIVE to the recursiveCall level. This argument provides
opportunity to recursed calls in execute to reduce the time needed for
some checks.
- Reduce time for checking around setting
thread.requestScriptGlowInFrame
- Call thread.pushReportedValue at end of execute when in a recursive
call
A boolean check is faster than a type lookup, command blocks will only
be executed in non-recursive calls. This saves a minor amount of time
for any result reporting blocks like blocks that get variables or add
two inputs together.
If the block is not returning a promise and execute is a recursed call,
that implies that the block is neither a hat or that the thread is not
at the top. That reduces handleReport to pushReportedValue. Using the
recursiveCall argument the final block calling handleReport can
shortcut the extra work in handleReport and reduce it to immediately
calling pushReportedValue.
- 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.
blockUtility as an object literal inside execute creates 11 objects,
one for the object, and 10 for the function closures. As a separate
object and allocated once, setting its sequencer and thread members,
block functions can share the same util object. Extract blockUtility to
cut down on allocations.
`handleReport` inside `src/engine/execute.js`'s `execute` method needs
to allocate a closure to be able to refer to the higher scoped
variables. `execute` is called frequently that this has a noticable
impact on memory allocation and later collection. Extract handleReport
and add arguments to prevent the allocation.
Testing with implicitly casted `value` and `value.then` is deoptimizing
isPromise, which deoptimizes execute. In this case deoptimizing means
that the JavaScript VM cannot compile the functions into a form that
can be run faster.
