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Merged
aywrite merged 1 commit into from
Oct 12, 2026
Merged

Let a depth under way run past the share to a hard limit #399

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12 changes: 6 additions & 6 deletions arche-core/src/engine/tests.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1130,7 +1130,7 @@ mod search {
fn already_spent() -> Limits {
Limits::starting_at(
time::Instant::now() - time::Duration::from_secs(1),
Some(Clock::Share(time::Duration::from_millis(1))),
Some(Clock::share(time::Duration::from_millis(1))),
u64::MAX,
)
}
Expand Down Expand Up @@ -1528,7 +1528,7 @@ mod search {
None,
Limits::starting_at(
time::Instant::now() - time::Duration::from_secs(1),
Some(Clock::Share(time::Duration::from_millis(1))),
Some(Clock::share(time::Duration::from_millis(1))),
1_000_000,
),
);
Expand All @@ -1543,7 +1543,7 @@ mod search {
let options = SearchParameters::new(
None,
Limits::starting_now(
Some(Clock::Share(time::Duration::from_secs(10))),
Some(Clock::share(time::Duration::from_secs(10))),
Some(limit),
),
);
Expand Down Expand Up @@ -1730,7 +1730,7 @@ mod search {
let mut e = engine(Board::new());
let params = SearchParameters::new(
None,
Limits::starting_now(Some(Clock::Share(time::Duration::from_millis(50))), None),
Limits::starting_now(Some(Clock::share(time::Duration::from_millis(50))), None),
);
let outcome = e.iterative_deepening_search(params, |_, _, _, _| {});
assert!(matches!(outcome, SearchOutcome::Aborted(Some(_))));
Expand All @@ -1742,7 +1742,7 @@ mod search {
// itself has not. The fraction belongs to Limits; this asserts the
// deepening loop asks it, and only of a share of a game clock
for (kind, depths) in [
(Clock::Share as fn(time::Duration) -> Clock, vec![1]),
(Clock::share as fn(time::Duration) -> Clock, vec![1]),
(Clock::Fixed as fn(time::Duration) -> Clock, vec![1, 2]),
] {
let mut e = engine(Board::new());
Expand Down Expand Up @@ -1778,7 +1778,7 @@ mod search {
Some(2),
Limits::starting_at(
time::Instant::now() - time::Duration::from_millis(gone),
Some(Clock::Share(time::Duration::from_secs(1))),
Some(Clock::share(time::Duration::from_secs(1))),
u64::MAX,
),
);
Expand Down
76 changes: 61 additions & 15 deletions arche-core/src/limits.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -55,8 +55,7 @@ const UNSETTLED_PERMILLE: u128 = 500;
const TABLE_ANSWERED_PERMILLE: u128 = 100;

/// The line after a depth that chose another move than the depth before
/// it, whatever its nodes say. Still under the deadline, which stays the
/// share.
/// it, whatever its nodes say. Still under the share.
const CHANGED_PERCENT: u128 = 65;

/// How a completed depth spent its nodes at the root, which is what the
Expand Down Expand Up @@ -99,17 +98,36 @@ impl RootNodes {
/// exactly that much thinking and there is nothing to save it for.
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum Clock {
/// A share of a running game clock, worked out from what is left of it.
Share(Duration),
/// A share of a running game clock, worked out from what is left of it,
/// and the limit a depth begun inside the share may run on to.
Share { share: Duration, limit: Duration },
/// A time the caller named, spent as named.
Fixed(Duration),
}

impl Clock {
/// A share with no room past it.
pub fn share(share: Duration) -> Self {
Clock::Share {
share,
limit: share,
}
}

/// What the move is planned to take: the share, or the time named. The
/// soft line is read against it.
pub fn budget(self) -> Duration {
match self {
Clock::Share { share, .. } => share,
Clock::Fixed(budget) => budget,
}
}

/// How long the search may run, whichever kind of clock this is.
pub fn deadline(self) -> Duration {
match self {
Clock::Share(budget) | Clock::Fixed(budget) => budget,
Clock::Share { limit, .. } => limit,
Clock::Fixed(budget) => budget,
}
}
}
Expand Down Expand Up @@ -172,7 +190,7 @@ impl Limits {
match self.clock {
// nanoseconds in a u128: multiplying the durations themselves
// panics on a clock large enough to overflow
Some(Clock::Share(budget)) => {
Some(Clock::Share { share: budget, .. }) => {
self.started.elapsed().as_nanos() * 100
< budget.as_nanos() * last.soft_line_percent()
}
Expand Down Expand Up @@ -248,7 +266,7 @@ mod tests {
fn already_spent() -> Limits {
Limits::starting_at(
Instant::now() - Duration::from_secs(1),
Some(Clock::Share(Duration::from_millis(1))),
Some(Clock::share(Duration::from_millis(1))),
u64::MAX,
)
}
Expand Down Expand Up @@ -300,7 +318,7 @@ mod tests {

#[test]
fn nothing_is_armed_until_a_depth_has_been_answered() {
let limits = Limits::starting_at(Instant::now(), Some(Clock::Share(Duration::ZERO)), 10);
let limits = Limits::starting_at(Instant::now(), Some(Clock::share(Duration::ZERO)), 10);
let first = limits.for_iteration(false, 0);
assert!(!first.expired(1_000_000), "depth one was stoppable");
}
Expand Down Expand Up @@ -332,11 +350,11 @@ mod tests {
// any scheduling stall that long
let soft = Duration::from_millis(SOFT_LIMIT_PERCENT as u64 * 10);
assert!(
a_second_of(Clock::Share, soft - Duration::from_millis(50))
a_second_of(Clock::share, soft - Duration::from_millis(50))
.worth_another_iteration(answered())
);
assert!(
!a_second_of(Clock::Share, soft + Duration::from_millis(50))
!a_second_of(Clock::share, soft + Duration::from_millis(50))
.worth_another_iteration(answered())
);
}
Expand Down Expand Up @@ -383,15 +401,15 @@ mod tests {
fn the_root_moves_the_line_an_iteration_is_begun_under() {
// each elapsed share sits at least five points from every line it
// is read against, since the call reads the clock again
let at = |percent: u64| a_second_of(Clock::Share, Duration::from_millis(percent * 10));
let at = |percent: u64| a_second_of(Clock::share, Duration::from_millis(percent * 10));
// a settled root gives up where the line before it did not
assert!(at(38).worth_another_iteration(answered()));
assert!(!at(38).worth_another_iteration(Some(took(950))));
// a contested root carries on where the line before it gave up
assert!(!at(52).worth_another_iteration(answered()));
assert!(at(52).worth_another_iteration(Some(took(400))));
assert!(!at(52).worth_another_iteration(Some(took(50))));
// and a changed move further still, short of the deadline
// and a changed move further still, short of the share
let changed = RootNodes {
changed: true,
..took(950)
Expand All @@ -405,7 +423,35 @@ mod tests {
// an elapsed share that a clock budget would refuse is still begun
let late = Duration::from_millis(990);
assert!(a_second_of(Clock::Fixed, late).worth_another_iteration(answered()));
assert!(!a_second_of(Clock::Share, late).worth_another_iteration(answered()));
assert!(!a_second_of(Clock::share, late).worth_another_iteration(answered()));
}

#[test]
fn a_depth_under_way_runs_past_the_share_to_its_limit() {
// a second and a half into a share of a second that may run to two
let limits = Limits::starting_at(
Instant::now() - Duration::from_millis(1_500),
Some(Clock::Share {
share: Duration::from_secs(1),
limit: Duration::from_secs(2),
}),
u64::MAX,
);
assert!(!limits.expired(0), "the share was read as the deadline");
assert!(
!limits.worth_another_iteration(answered()),
"a depth was begun past the share"
);
}

#[test]
fn every_iteration_keeps_the_limit_past_the_share() {
let clock = Clock::Share {
share: Duration::from_secs(1),
limit: Duration::from_secs(3),
};
let limits = Limits::starting_now(Some(clock), None);
assert_eq!(limits.for_iteration(true, 5_000).clock(), Some(clock));
}

#[test]
Expand All @@ -428,7 +474,7 @@ mod tests {
let started = Instant::now() - Duration::from_secs(1);
let limits = Limits::starting_at(
started,
Some(Clock::Share(Duration::from_secs(2))),
Some(Clock::share(Duration::from_secs(2))),
u64::MAX,
);
// the second iteration does not start the two seconds again
Expand All @@ -437,7 +483,7 @@ mod tests {

#[test]
fn a_search_with_no_node_limit_never_takes_one_from_the_deepening() {
let limits = Limits::starting_now(Some(Clock::Share(Duration::from_secs(1))), None);
let limits = Limits::starting_now(Some(Clock::share(Duration::from_secs(1))), None);
assert_eq!(limits.node_budget(), u64::MAX);
assert_eq!(limits.for_iteration(true, 5_000).node_budget(), u64::MAX);
}
Expand Down
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