backends

Module nuspace.system.backends.

Backends: what executes plane runs. Polymorphic fabrics the kernel never looks inside.

A plane names its backend (props.backend), a plane run records it, and the kernel reaches it by that name through BackendRef. A new backend is a Backend subclass registered by name at open, with no kernel edit.

• base: the fabric, its ref, its interactions, and the worker records every backend writes through them.
• pool: the books both process backends keep over nustd.mp_pool.
• async_: async, one worker per plane run.
• mp: mp, one worker per cell run.

base

Module nuspace.system.backends.base.

The backend fabric: what every backend is, how the kernel reaches one, what it records.

A backend executes plane runs. Each is a fabric, one instance per name, bound on the host's context at open under Backend tagged with its name. The kernel reads one with BackendRef(name), the name off the plane run's record, and speaks to it only through the interactions here, so it never asks what kind it holds:

StartRun(ref, run)             a plane run begins            -> made
PlaceCell(ref, run, cr)        where a cell run goes          -> [worker, made]
RunCell (kernel)               its body run there, to its end -> "" or why it was lost
EndCell(ref, run, cr)          a cell run is over             -> [worker let go]
KillRun(ref, run)              the plane run is over          -> [worker let go]

made is [[worker, handle], ...], the workers a call brought up. A worker is whatever unit the backend runs cells on (a process here, anything later), its handle a str only the backend reads.

Workers are records the backends write and everybody reads (start, placed, lost, end_cell, kill): the terms here pair each interaction with its record writes, so no backend is ever half recorded. The kernel only composes released into the commit that ends a plane run, so its workers end with it, and ended into reconcile's, for what a gone host left up.

EndCell

aend_cell. Yields the workers let go. Shielded.

EndCell(backend, run_id, cell_run_id)

Path nuspace.system.backends.EndCell. Kind ScalarAction, sort scalar_action, cardinality scalar. Arity 3 (3 required).

Arguments

Undocumented: yields, example.

KillRun

akill. Yields the workers let go. Shielded.

KillRun(backend, run_id)

Path nuspace.system.backends.KillRun. Kind ScalarAction, sort scalar_action, cardinality scalar. Arity 2 (2 required).

Arguments

Undocumented: yields, example.

PlaceCell

aplace. Yields [worker, made].

PlaceCell(backend, run_id, cell_run_id)

Path nuspace.system.backends.PlaceCell. Kind ScalarAction, sort scalar_action, cardinality scalar. Arity 3 (3 required).

Arguments

Undocumented: yields, example.

StartRun

astart. Yields the workers brought up.

StartRun(backend, run_id)

Path nuspace.system.backends.StartRun. Kind ScalarAction, sort scalar_action, cardinality scalar. Arity 2 (2 required).

Arguments

Undocumented: yields, example.

BackendRef

The Backend bound under name on the context.

BackendRef(name)

Path nuspace.system.backends.BackendRef. Kind Ref, sort ref, cardinality scalar.

Where none is, it yields a stand-in carrying the name, which every interaction refuses with UnknownBackendError naming it.

Methods

.fabric()

What executes plane runs. Subclass it, register the subclass by name at open.

Every method is async and runs in the host. Worker ids are minted by the backend (mint_ordered_id("w")), and each method says which workers it brought up or let go, so the record writes around it stay generic.

A backend's bookkeeping (its handles, which cell run is where) is its own. The kernel keeps none of it.

Undocumented: yields, example.

Inherited methods

From nu.context.fabric.refs.FabricRef:

Undocumented: example.

end_cell

EndCell, and the workers it let go recorded ended exit_.

backends.end_cell(backend, run_id, cell_run_id, exit_)

Path nuspace.system.backends.end_cell. Defined on nuspace.system.backends.base, bound as a function. Builds nu.Nu.

Arguments

Undocumented: example.

ended

A worker's end, written once, and out of workers_running. No bracket.

backends.ended(worker_id, exit_, error='')

Path nuspace.system.backends.ended. Defined on nuspace.system.backends.base, bound as a function. Builds nu.Nu.

Out of both: its run's and the kernel's, in the same commit.

Arguments

Undocumented: example.

kill

KillRun, and the workers it let go recorded ended exit_.

backends.kill(backend, run_id, exit_)

Path nuspace.system.backends.kill. Defined on nuspace.system.backends.base, bound as a function. Builds nu.Nu.

Arguments

Undocumented: example.

lost

A worker that died by itself, recorded ended failed with why. No bracket.

backends.lost(worker_id, why)

Path nuspace.system.backends.lost. Defined on nuspace.system.backends.base, bound as a function. Builds nu.Nu.

For the commit that ends the cell run it took with it (RunCell yielded why). Written once: with async, every cell run on the worker reports the same death, and the first one writes it.

Arguments

Undocumented: example.

placed

The cell run's worker and the workers place brought up, recorded. One commit.

backends.placed(backend, run_id, cell_run_id, place)

Path nuspace.system.backends.placed. Defined on nuspace.system.backends.base, bound as a function. Builds nu.Nu.

Arguments

Undocumented: example.

released

Every live worker of a plane run ended exit_. No bracket.

backends.released(run_id, exit_)

Path nuspace.system.backends.released. Defined on nuspace.system.backends.base, bound as a function. Builds nu.Nu.

For the commit that ends the run: its workers' records end with it, so nothing is left to write once the kernel lets go of the run, however it is cancelled. The backend's own kill follows, and finds them ended.

Walks the run's workers_running, its live workers, never its workers: with mp that is a worker per cell run ever.

Arguments

Undocumented: example.

require_backend

Unwrap a BackendRef's value.

backends.require_backend(value)

Path nuspace.system.backends.require_backend. Defined on nuspace.system.backends.base, bound as a function. Builds Backend.

Arguments

Undocumented: example.

start

StartRun, and the workers it brought up recorded. One commit for the records.

backends.start(backend, run_id)

Path nuspace.system.backends.start. Defined on nuspace.system.backends.base, bound as a function. Builds nu.Nu.

Arguments

Undocumented: example.

nuspace.system.backends

Module nuspace.system.backends.

Backends: what executes plane runs. Polymorphic fabrics the kernel never looks inside.

A plane names its backend (props.backend), a plane run records it, and the kernel reaches it by that name through BackendRef. A new backend is a Backend subclass registered by name at open, with no kernel edit.

• base: the fabric, its ref, its interactions, and the worker records every backend writes through them.
• pool: the books both process backends keep over nustd.mp_pool.
• async_: async, one worker per plane run.
• mp: mp, one worker per cell run.

provided

Every backend bound on the context under its name: BACKENDS, then backends.

backends.provided(backends=None)

Path nuspace.system.backends.provided. Defined on nuspace.system.backends, bound as a function. Builds nu.With.

Goes inside the pool and its shelf, which the process backends take from.

Arguments

Undocumented: example.