1978510 - Update async generator implementation to the latest spec

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P3)

Description

[Tooru Fujisawa [:arai]]

In the same way as bug 1724123, we need to update the implementation to match the latest spec again.

Comment 1

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 1: Update spec step comments, with FIXME comments for mismatching parts. r?mgaudet!

Comment 2

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 2: Move early-return out of AsyncGeneratorDrainQueue. r?mgaudet!

Handling the special states is not AsyncGeneratorDrainQueue's responsibility,
and also some consumers already filter out those states.

Comment 3

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 3: Simplify the loop in AsyncGeneratorDrainQueue. r?mgaudet!

Comment 4

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 4: Split the branches for AsyncGeneratorDrainQueue caller to match the spec. r?mgaudet!

"completed" state has two separate internal states.

One is where there's no request in the queue.
This maps to the updated spec's "completed" state.

The other is where there are some requests in the queue, and those requests
are going to be drained in upcoming AsyncGeneratorDrainQueue.
This maps to the updated spec's "draining-queue" state.

In the former case, if .next/.throw/.return is called, a new request for them
will be immediately processed.

In the latter case, if .next/.throw/.return is called before draining the
existing requests, which means those calls are performed inside
AsyncGeneratorDrainQueue, as a side-effect of promise handling.
Those calls will enqueue the request and then perform another
AsyncGeneratorDrainQueue, and all requests will be processed there.

This is actually the same situation as just enqueueing and not performing
another AsyncGeneratorDrainQueue. The next patch will remove the
AsyncGeneratorDrainQueue call.

Comment 5

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 5: Do not re-enter AsyncGeneratorDrainQueue in completed state. r?mgaudet!

The AsyncGeneratorDrainQueue call for the completed+non-empty-queue happens
only as a part of side-effect of promise handling which is performed
during AsyncGeneratorDrainQueue.

The requests will be handled by the outer AsyncGeneratorDrainQueue.

Comment 6

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 6: Inline AsyncGeneratorDrainQueue. r?mgaudet!

This patch just inlines the AsyncGeneratorDrainQueue code to each consumer,
with slight modification for the return statements.

The subsequent patches will simplify each case.

Comment 7

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 7: Remove unused branches. r?mgaudet!

Each consumer has specific situation, where the loop and some branches can be
removed.

Comment 8

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 8: Move setSuspendedYield call to each branch. r?mgaudet!

This is unobservable change.

This makes the else-branch match the updated spec.
The then-branch's state transition is not part of the spec, but the state
will be overwritten immediately.

Comment 9

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 9: Add AsyncGeneratorUnwrapYieldResumption. r?mgaudet!

This makes one of AsyncGeneratorUnwrapYieldResumption consumer to match the
updated spec.

The other consumer will be rewritten in later patch.

Comment 10

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 10: Move comments for AsyncGeneratorYield. r?mgaudet!

Comment 11

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 11: Remove unnecessary state transition. r?mgaudet!

The state is going to immediately be overwritten to either:

• AwaitingYieldReturn if completionKind is Return, or
• Executing otherwise

Comment 12

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 12: Optimize out enqueue+dequeue. r?mgaudet!

The request enqueued in the "Completed+empty-queue" case will be immediately
dequeued and processed.
This patch removes the queue+dequeue and let each case directly pass the
completeion.

Comment 13

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 13: Use AsyncGeneratorUnwrapYieldResumption in AsyncGeneratorReturn. r?mgaudet!

This is another consumer of AsyncGeneratorUnwrapYieldResumption,
which is added in earlier patch.

Comment 14

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 14: Move comments for AsyncGeneratorNext/AsyncGeneratorReturn/AsyncGeneratorThrow. r?mgaudet!

Comment 15

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 15: Remove suspended-start and suspended-yield cases from AsyncGeneratorDrainQueue. r?mgaudet!

Now all consumers of AsyncGeneratorDrainQueue sets the state to "completed"
before entering AsyncGeneratorDrainQueue, and
"suspended-start" and "suspended-yield" states don't reach there,
even with side-effects.

Comment 16

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 16: Update the [[AsyncGeneratorState]] variants. r?mgaudet!

This modifies the existing states in the following ways:

• Completed (empty queue) -> Completed
• Completed (non-empty queue) -> DrainingQueue
• AwaitingYieldReturn -> Executing_AwaitingYieldReturn
• AwaitingReturn -> DrainingQueue_AwaitingReturn

The latter 2 are not part of the updated spec, but they're our
implementation-defined state, to reflect the state during the Await calls.

Comment 17

[Tooru Fujisawa [:arai]]

Attachment: Bug 1978510 - Part 17: Update SMDOC for async generator. r?mgaudet!

Comment 18

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/2a6521c849ca
https://hg.mozilla.org/integration/autoland/rev/e16f2e94fafb
Part 1: Update spec step comments, with FIXME comments for mismatching parts. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/8c329787536d
https://hg.mozilla.org/integration/autoland/rev/d41df4292f15
Part 2: Move early-return out of AsyncGeneratorDrainQueue. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/5bf90680fdf9
https://hg.mozilla.org/integration/autoland/rev/3777ca63a7d2
Part 3: Simplify the loop in AsyncGeneratorDrainQueue. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/c31f0f55cb32
https://hg.mozilla.org/integration/autoland/rev/a381c7ee6bf3
Part 4: Split the branches for AsyncGeneratorDrainQueue caller to match the spec. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/bdbc3398e150
https://hg.mozilla.org/integration/autoland/rev/93f5b5332d86
Part 5: Do not re-enter AsyncGeneratorDrainQueue in completed state. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/fc2ff6359aad
https://hg.mozilla.org/integration/autoland/rev/9044d687cf06
Part 6: Inline AsyncGeneratorDrainQueue. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/7c91b971f88a
https://hg.mozilla.org/integration/autoland/rev/69a84ced2945
Part 7: Remove unused branches. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/f872a5fb3bad
https://hg.mozilla.org/integration/autoland/rev/13b3d1aadb36
Part 8: Move setSuspendedYield call to each branch. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/fcf093b9e195
https://hg.mozilla.org/integration/autoland/rev/b1a0f12ba781
Part 9: Add AsyncGeneratorUnwrapYieldResumption. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/b4a22b5cd912
https://hg.mozilla.org/integration/autoland/rev/0670b4a44063
Part 10: Move comments for AsyncGeneratorYield. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/802690f99d03
https://hg.mozilla.org/integration/autoland/rev/aafd77ab2a2c
Part 11: Remove unnecessary state transition. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/52749339e160
https://hg.mozilla.org/integration/autoland/rev/ff097c4cc4de
Part 12: Optimize out enqueue+dequeue. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/d2bd290d337a
https://hg.mozilla.org/integration/autoland/rev/b36d99d371a1
Part 13: Use AsyncGeneratorUnwrapYieldResumption in AsyncGeneratorReturn. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/7eb33617b89a
https://hg.mozilla.org/integration/autoland/rev/70a42de5f414
Part 14: Move comments for AsyncGeneratorNext/AsyncGeneratorReturn/AsyncGeneratorThrow. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/01d1f1193939
https://hg.mozilla.org/integration/autoland/rev/75536f7a0080
Part 15: Remove suspended-start and suspended-yield cases from AsyncGeneratorDrainQueue. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/9d7c1fb671dc
https://hg.mozilla.org/integration/autoland/rev/ce5019292a43
Part 16: Update the [[AsyncGeneratorState]] variants. r=mgaudet
https://github.com/mozilla-firefox/firefox/commit/580d0755219f
https://hg.mozilla.org/integration/autoland/rev/940a04fd8ade
Part 17: Update SMDOC for async generator. r=mgaudet

Comment 19

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/e16f2e94fafb
https://hg.mozilla.org/mozilla-central/rev/d41df4292f15
https://hg.mozilla.org/mozilla-central/rev/3777ca63a7d2
https://hg.mozilla.org/mozilla-central/rev/a381c7ee6bf3
https://hg.mozilla.org/mozilla-central/rev/93f5b5332d86
https://hg.mozilla.org/mozilla-central/rev/9044d687cf06
https://hg.mozilla.org/mozilla-central/rev/69a84ced2945
https://hg.mozilla.org/mozilla-central/rev/13b3d1aadb36
https://hg.mozilla.org/mozilla-central/rev/b1a0f12ba781
https://hg.mozilla.org/mozilla-central/rev/0670b4a44063
https://hg.mozilla.org/mozilla-central/rev/aafd77ab2a2c
https://hg.mozilla.org/mozilla-central/rev/ff097c4cc4de
https://hg.mozilla.org/mozilla-central/rev/b36d99d371a1
https://hg.mozilla.org/mozilla-central/rev/70a42de5f414
https://hg.mozilla.org/mozilla-central/rev/75536f7a0080
https://hg.mozilla.org/mozilla-central/rev/ce5019292a43
https://hg.mozilla.org/mozilla-central/rev/940a04fd8ade