ActionScheduler will now use ActionListener instead of tokio::watch

[allada]

This will enable the underlying scheduler to intercept the Drop call allowing easier cleanups of actively listened actions.

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This change is 

[allada]

+@zbirenbaum

Reviewable status: 0 of 1 LGTMs obtained, and pending CI: vale (waiting on @zbirenbaum)

[zbirenbaum]

Reviewable status: 0 of 1 LGTMs obtained, and 4 discussions need to be resolved

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nativelink-scheduler/src/cache_lookup_scheduler.rs line 224 at r1 (raw file):

                        };
                        let Some(pending_txs) = maybe_pending_txs else {
                            return; // Noone is waiting for this action anymore.

nit: Nobody

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nativelink-scheduler/src/cache_lookup_scheduler.rs line 251 at r1 (raw file):

            let maybe_pending_txs = {
                let mut cache_check_actions = cache_check_actions.lock();

Comment and rename cache_check_actions

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nativelink-scheduler/src/cache_lookup_scheduler.rs line 255 at r1 (raw file):

            };
            let Some(pending_txs) = maybe_pending_txs else {
                return; // Noone is waiting for this action anymore.

nit: Nobody

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nativelink-scheduler/src/cache_lookup_scheduler.rs line 275 at r1 (raw file):

                )
            })?
            .err_tip(|| "While passing through CacheLookupScheduler::add_action")

"In CacheLookupScheduler::add_action"

[allada]

Reviewable status: 0 of 1 LGTMs obtained, and 2 discussions need to be resolved (waiting on @zbirenbaum)

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nativelink-scheduler/src/cache_lookup_scheduler.rs line 224 at r1 (raw file):

Previously, zbirenbaum (Zach Birenbaum) wrote…

nit: Nobody

Done.

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nativelink-scheduler/src/cache_lookup_scheduler.rs line 251 at r1 (raw file):

Previously, zbirenbaum (Zach Birenbaum) wrote…

Comment and rename cache_check_actions

Done.

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nativelink-scheduler/src/cache_lookup_scheduler.rs line 255 at r1 (raw file):

Previously, zbirenbaum (Zach Birenbaum) wrote…

nit: Nobody

Done.

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nativelink-scheduler/src/cache_lookup_scheduler.rs line 275 at r1 (raw file):

Previously, zbirenbaum (Zach Birenbaum) wrote…

"In CacheLookupScheduler::add_action"

Done.

[zbirenbaum]

Reviewable status: complete! 1 of 1 LGTMs obtained