- investigate consistency guarantees through acquire-release
==> turns out we do not need a fence, but it is tantamount
to have a guard variable and actually load and check
the value to ensure we indeed get a happens-before
- elaborate design of the WorkForce
+ no shared control variables necessary
+ no ability to forcibly shut-down the WorkForce
+ rather, all control will be exerted through the return value
of the Work-Functor
...to show in test that indeed the actual time is retrieved on each activation,
we can assign a λ -- which is rigged to increase the time on each access
...turns out there is still a lot of leeway in the possible implementation,
and seemingly it is too early to decide which case to consider the default.
Thus I'll proceed with the drafted preliminary solution...
- on primary-chain, an inhibited Gate dispatches itself into future for re-check
- on Notification, activation happens if and only if this very notification opens the Gate
- provide a specifically wired requireDirectActivation() to allow enforcing a minimal start time
Solved by special treatment of a notification, which happens
to decrement the latch to zero: in this case, the chain is
dispatched, but also the Gate is locked permanently to block
any further activations scheduled or forwareded otherwise
essentially define a concept how to ''perform'' render activities in the Scheduler.
This entails to specify the operation patterns for the four known base cases
and to establish a setup for the implementation.
Further extensive testing with parameter variations,
using the test setup in `BlockFlow_test::storageFlow()`
- Tweaks to improve convergence under extreme overload;
sudden load peaks are now accomodated typically < 5 sec
- Make the test definition parametric, to simplify variations
- Extract the generic microbenchmark helper function
- Documentation
..using a simplistic implementation for now: scale down the
Epoch-stepping by 0.9 to increase capacity accordingly.
This is done on each separate overflow event, and will be
counterbalanced by the observation of Epoch fill ratio
performed later on clean-up of completed Epochs
Iteration should just yield an Reference to an Extent,
thereby hiding all details of the actual raw storage (char[]).
This can be achieved by usind a wrapper type around a pointer
into the managing vector; from this pointer we may convert
into a vector::iterator with the trick described here
https://stackoverflow.com/a/37101607/444796
Furthermore, continued planning of the Activity-Language,
basically clarified the complete usage scenario for now;
seems all implementable right away without further difficulties
- decision to favour small memory footprint
- rather use several Activity records to express invocation
- design Activity record as »POD with constructor«
- conceptually, Activity is polymorphic, but on implementation
level, this is "folded down" into union-based data storage,
layering accessor functions on top
- decision how to handle the Extent storage (by forced-cast)
- decision to place the administrative record directly into the Extent
TODO not clear yet how to handle the implicit limitation for future deadlines
using a simple yet performant data structure.
Not clear yet if this approach is sustainable
- assuming that no value initialisation happens for POD payload
- performance trade-off growth when in wrapped-state vs using a list
- define a simple record to represent the Activity
- define a handle with an ordering function
- low-level functions to...
+ accept such a handle
+ pick it from the entrace queue
+ pass it for priorisation into the PriQueue
+ dequeue the top priority element
after completing the recent clean-up and refactoring work,
the monad based framework for recursive tree expansion
can be abandoned and retracted.
This approach from functional programming leads to code,
which is ''cool to write'' yet ''hard to understand.''
A second design attempt was based on the pipeline and decorator pattern
and integrates the monadic expansion as a special case, used here to
discover the prerequisites for a render job. This turned out to be
more effective and prolific and became standard for several exploring
and backtracking algorithms in Lumiera.
- allow to configure the expected job runtime in the test spec
- remove link to EngineConfig and hard-wire the engine latency for now
... extended integration testing reveals two further bugs ;-)
... document deadline calculation
..this is now the third attempt, and it seems this one leads to a
clean solution for the type rebinding problem, while also allowing
to unit-test each step in isolation.
The idea is to layer a *templated* builder class on top,
but to slice it away in each step, re-assemble the pipeline
and decorate a new builder instance on top. The net result
is a tightly interconnected processing pipeline without
any spurious interspersed leftovers from the builder,
while all intermediate steps are fully operational
and can thus be unit-tested...
...which is build a »Job planning pipeline« step by step
in a test setup, and then factor that out as RenderDrive,
to supersede the existing CalcPlanContinuation and get
rid of the Monads this way...
Challenges
- there is a inconsistency with channel usage
- need to establish a way how to transport the output-Sink into the JobFunctor
- need a way to propagate the current frame number to the next planning chunk
The prototypical setup of data structures and test support components
is largely complete by now — with the exception of the `MockDispatcher`,
which will be completed while moving to the next steps pertaining the
setup of a frame dispatch pipeline.
* the existing `DummyJob` was augmented to allow verification of
association between Job and `JobTicket`
* the existing implementation of `JobTicket` was verified and augmented
to allow coverage of the whole usage cycle
* a `MockJobTicket` was implemented on top, which can be generated
from a symbolical test specification (rather than from the real
Fixture data structure)
* a complete `MockSegmentation` was developed, allowing to establish
all the aforementioned data structures without an actual backing
Render Engine. Moreover, `MockSegmentation` can be generated
from the aforementioned symbolic test specification.
* as part of this work, an algorithm to split an existing Segmentation
and to splice in new segments was developed and verified
By reasoning and analysis I conclude that the differentiation into
multiple channels is likely misplaced in JobTicket; it belongs ratther
into the Segment and should provide a suitable JobTicket for each ModelPort
Handling of prerequisites also needs to be reshaped entirely after
switching to a pipeline builder for the Job-planning pipeline; as
preliminary access point, just add an iterator over the immediate
prerequisites, thereby shifting the exploration mechanism entirely
out of the JobTicket implementation
Testcase: A simple Sementation with a single and bounded Segment
As aside, figured out how to unpack an iterator such as to
tie a fixed number of references through a structural binding:
auto const& [s1,s2,s3] = seqTuple<3> (mockSegs.eachSeg());
There are 12 distinct cases regarding the orientation of two intervals;
The Segmentation::splitSplice() operation shall insert a new Segment
and adjust / truncate / expand / split / delete existing segments
such as to retain the *Invariant* (seamless segmentation covering
the complete time axis)
- introduce a new entity: RenderDrive
- it supersedes the CalcPlanCalculation, but is managed by CalcStream
- moreover, the RenderDrive will house a IterTreeExplorer-Pipeline
- define the concerns and relationships more clearly (see Drawing)
- prerequisite to disentangle the Job-planning "mechanics"
- decision: the Monad-style iteration framework will be abandoned
- the job-planning will be recast in terms of the iter-tree-explorer
- job-planning and frame dispatch will be disentangled
- the Scheduler will deliberately offer a high-level interface
- on this high-level, Scheduler will support dependency management
- the low-level implementation of the Scheduler will be based on Activity verbs
The drawing code extracts style information from some "virtual"
widgets, which serve as logical placeholder for the actual nested
structure of tracks.
For sake of demonstration, I used rather obvious colours and
also all kinds of margin and padding; a screenshot was added
with annotations to indicate where some specific style settings
are utilised from the drawing code
- pick up all relevant values from CSS
- also control the width of the StaveBracket
- observe the given overall height
Moreover, complete documentation drawing in Inkscape
and add a page to the TiddlyWiki, describing the principles
underlying this design and construction.
It is now tied to the start of ZoomWindow::overallSpan(),
thereby defining the (technical) pixel coordinates within the window
and for drawing on the canvas to be always positive. Whenever ZoomWindow
re-calibrates, it's change signal will trigger, causing the
TimelineLayout to perform a new DisplayEvaluationPass,
which in turn prompts all embedded widgets to readjust
their positions accordingly.
Writing this specification unveiled a limitation of our internal
time base implementation, which is a 64bit microsecond grid.
As it turns out, any grid based time representation will always
be not precise enough to handle some relevant time specifications,
which are defined by a divisor. Most notably this affects the precise
display of frame duration in the GUI, and even more relevant,
the sample accurate editing of sound in the timeline.
Thus I decided to perform the internal computation in ZoomWindow
as rational numbers, based on boost::rational
Note: implementation stubbed only, test fails
...as it turns out, this code basically works already when the
widget is not(yet) realized:
- when a widget is hidden, it responds with size=0
- when a widget is shown, it reponds with proper or at least
preliminary size requirement, irrespective if already drawn
After injecting the diff, the widgets are created and then adjusted
in several steps; however, this code all executes from within a single
call to the UI-bus, and thus just piles up a sequence of realize()
and resize() messages, which are only executed later, in case the
Application-UI as a whole is visible on screen.
*Remaining Problems*:
- size-constraint code not working correct in all cases
- dragging works only on the buttons, not on the background
devise a more fine grained algorithm for adapting the display of IDLabel
to a situation with size constrained layout, e.g. for a time calibrated canvas.
We still do not implement the shortening of ID labels (see #1242),
since doing so would be surprisingly expensive. But at least we
do proceed in several steps now
- first attempt to reduce the name-ID (for now: hide it)
- if this doesn't suffice, also hide the menu
- and as a last resort, hide the icon and thus make the IDLabel empty
as it turns out, this is a self-contained separate concern,
and thus this arrangement of two icons plus a caption shall
now manage itself as a custom widget.
And while touching this subject, I have also reconsidered
the purpose and arrangement of those icons and completed
the specification with some decisions...
- context menus will be left-click, selection right-click (Blender!)
- we will always show those two icons, just allocate different graphics
- when there is no expander, the 2nd icon will just serve to open the menu
- so the button is almost redundant in that case (except when dragging)
identify the various dimensions, which require flexibility
to support the intended use cases; try to come up with a
design draft, allowing to settle on a preliminary version
soon, while not hampering further development later on.
Obviously this is a very deep and challenging topic,
and we're far from even remotely addressing it adequately;
we just need to get to the point to use this drafted version
as building block, since these usages will then push us further
into the right direction...
Investigate how the GTK implementation allocates size extension
to widgets and child widgets; identify possible extensions points
and work out a solution strategy to make GTK observe our specific
size constraints, which are derived from a time calibrated canvas.
The flexible custom styling yet needs to be definied.
Just adding a stock icon and a standard sized label field for now.
Widget can be constructed and successfully attached to a track.
Complete the investigation and turn the solution into a generic
mix-in-template, which can be used in flexible ways to support
this qualifier notation.
Moreover, recapitulate requirements for the ElementBoxWidget
