enricobuehler
ab2bcc8e68
Field verdict on the depth-2 gate (M4 iPad Pro, 2752x2064@120): display stage 22-28 ms vs depth-1's 14 — a REGRESSION, not the predicted 5-8. Post-mortem: any bounded-FIFO pacing keeps a STANDING queue on the always-vsync-latch platforms. One burst fills every admitted slot and, with arrivals and latches then running at the same rate, occupancy never returns to zero — each gate slot costs one full refresh, permanently (the ladder fits exactly: arrival ~3 slots -> 30+ ms, depth 2 -> 22-28, depth 1 -> 14). A bounded FIFO caps the queue; nothing ever drains it. And depth 1 serializes presents on the on-glass callback's delivery lag, so neither rung can approach the sub-refresh floor. Stage-4 (PresentPacing.deadline) inverts drawable ownership instead: - A CAMetalDisplayLink on its own runloop thread vends ONE deadline-timed drawable per refresh (preferredFrameLatency 1) into a newest-wins LatestBox; an unpresented vend is replaced by the next (back to the pool). - The render thread pairs it with the newest decoded frame the moment either half arrives — the common case presents a frame INSTANTLY into an already- vended drawable, latching the upcoming refresh. No image queue can form and nothing waits on on-glass callbacks (they only feed the meters now). - A stashed drawable can lag a mid-session HDR reconfigure by one vend: encodePresent skips the mismatched-format vend (frame re-rings) instead of tripping Metal validation. - iOS/iPadOS defaults to stage-4; tvOS keeps stage-3 until its own A/B (PUNKTFUNK_PRESENTER=stage4); macOS resolves "stage4" back to its default (the sync-off/DCP-panic saga — deadline pacing lands there deliberately or not at all). Settings picker gains Stage 4 with the derived default marker. - Gate depth defaults to 1 everywhere again; PUNKTFUNK_GATE_DEPTH stays only to reproduce the standing-queue ladder on-device. - PUNKTFUNK_PRESENT_DEBUG gains latchMs p50/max (present-issue -> on-glass: standing queue reads ~n x period, healthy reads < 1 period) + noDrawable=. swift test (14/14) + full Punktfunk-iOS device build green. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
250 lines
13 KiB
Swift
250 lines
13 KiB
Swift
import XCTest
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#if canImport(Metal)
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import QuartzCore
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@testable import PunktfunkKit
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/// Present pacing: the stage-3 bounded in-flight `PresentGate`, the stage-4 `LatestBox`
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/// drawable hand-off, the stage-1/2/3/4 `PresenterChoice` resolution (setting +
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/// PUNKTFUNK_PRESENTER env override + the release-build stage-1 gate + the iOS/tvOS-only
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/// stage-4 gate), and the per-platform glass-gate depth.
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final class PresentPacingTests: XCTestCase {
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// MARK: - PresentGate
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/// The depth-1 invariant: one present in flight. A second acquire while pending must fail
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/// (the frame stays in the ring for the presented handler's re-signal); release reopens.
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func testGateAdmitsOneInFlightPresent() {
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let gate = PresentGate()
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XCTAssertTrue(gate.tryAcquire(now: 0), "an idle gate must admit the first present")
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XCTAssertFalse(gate.tryAcquire(now: 0.001), "a pending present must close the gate")
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gate.release()
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XCTAssertTrue(gate.tryAcquire(now: 0.002), "release must reopen the gate")
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XCTAssertEqual(gate.drainForced(), 0, "no stale present was force-cleared")
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}
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/// Depth 2 (the PUNKTFUNK_GATE_DEPTH ladder rung — no longer a default; see
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/// `SessionPresenter.gateDepth`'s standing-queue post-mortem): a second present may queue
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/// behind the flip scanning out — the bound only bites at the THIRD. One release (a glass
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/// callback) reopens exactly one slot.
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func testGateDepthTwoAdmitsTwoInFlightPresents() {
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let gate = PresentGate(capacity: 2)
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XCTAssertTrue(gate.tryAcquire(now: 0))
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XCTAssertTrue(gate.tryAcquire(now: 0.001), "depth 2 must admit a queued second flip")
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XCTAssertFalse(gate.tryAcquire(now: 0.002), "the third present must wait for glass")
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gate.release()
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XCTAssertTrue(gate.tryAcquire(now: 0.003), "one glass callback frees one slot")
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XCTAssertFalse(gate.tryAcquire(now: 0.004))
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XCTAssertEqual(gate.drainForced(), 0)
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}
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/// Depth 2 staleness anchors to the OLDEST in-flight present: a full gate stays closed while
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/// the oldest is live, force-opens once it ages out, and the younger present keeps its slot.
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func testGateDepthTwoForceOpensOnTheOldestStalePresent() {
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let gate = PresentGate(capacity: 2)
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XCTAssertTrue(gate.tryAcquire(now: 10))
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XCTAssertTrue(gate.tryAcquire(now: 10.05))
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XCTAssertFalse(gate.tryAcquire(now: 10 + PresentGate.staleAfter - 0.01))
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XCTAssertTrue(gate.tryAcquire(now: 10 + PresentGate.staleAfter + 0.01))
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XCTAssertEqual(gate.drainForced(), 1)
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// The 10.05 present is still live, so the gate is full again right after the force-open.
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XCTAssertFalse(gate.tryAcquire(now: 10 + PresentGate.staleAfter + 0.02))
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}
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/// The lost-handler insurance: a present whose handler never fires (the macOS "presents
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/// aren't damage" hazard class) must not freeze the stream — past `staleAfter` the gate
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/// force-opens and counts the event for the PUNKTFUNK_PRESENT_DEBUG `forced` stat.
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func testGateForceOpensAfterStaleTimeout() {
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let gate = PresentGate()
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XCTAssertTrue(gate.tryAcquire(now: 10))
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// Within the stale window the gate stays closed.
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XCTAssertFalse(gate.tryAcquire(now: 10 + PresentGate.staleAfter - 0.01))
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// Past it, the pending present is presumed lost: reopen, and count the force-clear.
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XCTAssertTrue(gate.tryAcquire(now: 10 + PresentGate.staleAfter + 0.01))
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XCTAssertEqual(gate.drainForced(), 1)
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XCTAssertEqual(gate.drainForced(), 0, "drain resets the counter")
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}
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/// Release is idempotent (a late stale-path double-release must be harmless), and an
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/// acquire-then-release with no present (empty ring after arming) leaves the gate clean.
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func testGateReleaseIsIdempotent() {
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let gate = PresentGate()
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XCTAssertTrue(gate.tryAcquire(now: 0))
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gate.release()
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gate.release() // the stale-cleared present's handler firing late
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XCTAssertTrue(gate.tryAcquire(now: 0.001))
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XCTAssertEqual(gate.drainForced(), 0)
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}
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// MARK: - LatestBox (stage-4's drawable hand-off)
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/// Newest-wins hand-off: `put` replaces (an unpresented older drawable returns to the
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/// layer's pool by release), `take` empties the slot.
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func testLatestBoxNewestWins() {
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let box = LatestBox<Int>()
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XCTAssertNil(box.take())
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box.put(1)
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box.put(2)
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XCTAssertEqual(box.take(), 2, "a fresher put replaces the unpresented value")
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XCTAssertNil(box.take(), "take empties the slot")
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}
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/// `putBack` fills only an EMPTY slot: the render thread returning a drawable it took but
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/// didn't present must never clobber a fresher one the link vended in between.
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func testLatestBoxPutBackNeverClobbersAFresherPut() {
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let box = LatestBox<Int>()
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box.put(1)
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let stale = box.take()
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XCTAssertEqual(stale, 1)
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box.putBack(stale!)
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XCTAssertEqual(box.take(), 1, "putBack into a still-empty slot restores the value")
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box.put(2)
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let taken = box.take()
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box.put(3) // the link vends a fresher drawable while the render thread holds `taken`
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box.putBack(taken!)
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XCTAssertEqual(box.take(), 3, "the fresher vend wins over the stale return")
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}
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// MARK: - PresenterChoice
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/// The platform default: deadline-paced stage-4 on iOS/iPadOS (the vsync-latching platform
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/// where any bounded-FIFO pacing keeps a standing queue), glass stage-3 on tvOS (proven —
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/// stage-4 A/Bs first), arrival stage-2 on macOS (sync-off presents don't queue). No
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/// selection / garbage falls back to it.
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func testPresenterChoiceFallsBackToPlatformDefault() {
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#if os(iOS)
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XCTAssertEqual(PresenterChoice.platformDefault, .stage4)
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#elseif os(tvOS)
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XCTAssertEqual(PresenterChoice.platformDefault, .stage3)
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#else
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XCTAssertEqual(PresenterChoice.platformDefault, .stage2)
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#endif
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XCTAssertEqual(
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PresenterChoice.resolve(setting: nil, env: nil, allowStage1: true),
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PresenterChoice.platformDefault)
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XCTAssertEqual(
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PresenterChoice.resolve(setting: "garbage", env: nil, allowStage1: true),
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PresenterChoice.platformDefault)
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XCTAssertEqual(
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PresenterChoice.resolve(setting: "stage2", env: nil, allowStage1: true), .stage2)
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}
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func testPresenterChoiceResolvesStage3FromSettingAndEnv() {
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XCTAssertEqual(
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PresenterChoice.resolve(setting: "stage3", env: nil, allowStage1: true), .stage3)
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// The env override wins over the persisted setting (A/B without touching settings)…
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XCTAssertEqual(
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PresenterChoice.resolve(setting: "stage2", env: "stage3", allowStage1: true), .stage3)
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XCTAssertEqual(
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PresenterChoice.resolve(setting: "stage3", env: "stage2", allowStage1: true), .stage2)
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// …but an EMPTY env var is "unset", not an override.
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XCTAssertEqual(
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PresenterChoice.resolve(setting: "stage3", env: "", allowStage1: true), .stage3)
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}
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/// "stage4" (deadline pacing) resolves only on iOS/tvOS. On macOS — whose present path is
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/// entangled with the sync-off/DCP-panic saga — a synced-over "stage4" value maps back to
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/// the platform default instead of engaging an unvalidated pacing.
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func testPresenterChoiceGatesStage4ToVsyncLatchPlatforms() {
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#if os(macOS)
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XCTAssertNil(PresenterChoice.explicit(setting: "stage4", env: nil, allowStage1: true))
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XCTAssertEqual(
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PresenterChoice.resolve(setting: "stage4", env: nil, allowStage1: true), .stage2)
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XCTAssertEqual(
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PresenterChoice.resolve(setting: nil, env: "stage4", allowStage1: true), .stage2)
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#else
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XCTAssertEqual(
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PresenterChoice.explicit(setting: "stage4", env: nil, allowStage1: true), .stage4)
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XCTAssertEqual(
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PresenterChoice.resolve(setting: nil, env: "stage4", allowStage1: true), .stage4)
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// The env override wins over the persisted setting, both directions.
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XCTAssertEqual(
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PresenterChoice.resolve(setting: "stage4", env: "stage3", allowStage1: true), .stage3)
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XCTAssertEqual(
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PresenterChoice.resolve(setting: "stage2", env: "stage4", allowStage1: true), .stage4)
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#endif
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}
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/// Stage-1 (the freeze-prone system-layer diagnostic) resolves only where allowed (DEBUG
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/// builds); a leftover "stage1" value in a release build maps back to the platform default.
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func testPresenterChoiceGatesStage1() {
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XCTAssertEqual(
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PresenterChoice.resolve(setting: "stage1", env: nil, allowStage1: true), .stage1)
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XCTAssertEqual(
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PresenterChoice.resolve(setting: "stage1", env: nil, allowStage1: false),
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PresenterChoice.platformDefault)
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XCTAssertEqual(
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PresenterChoice.resolve(setting: nil, env: "stage1", allowStage1: false),
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PresenterChoice.platformDefault)
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}
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/// `explicit` is nil exactly when `resolve` would fall back to the platform default — the
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/// distinction the codec-conditional pacing default rides on.
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func testPresenterChoiceExplicitIsNilWithoutASelection() {
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XCTAssertNil(PresenterChoice.explicit(setting: nil, env: nil, allowStage1: true))
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XCTAssertNil(PresenterChoice.explicit(setting: "garbage", env: nil, allowStage1: true))
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XCTAssertNil(PresenterChoice.explicit(setting: "stage1", env: nil, allowStage1: false))
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XCTAssertEqual(
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PresenterChoice.explicit(setting: "stage2", env: nil, allowStage1: true), .stage2)
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XCTAssertEqual(
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PresenterChoice.explicit(setting: nil, env: "stage3", allowStage1: true), .stage3)
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}
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// MARK: - Session pacing (the macOS PyroWave swapID-panic mitigation)
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/// macOS PyroWave sessions under the DEFAULT stage-2 choice must get glass pacing (the
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/// one-in-flight gate is the "mismatched swapID's" kernel-panic mitigation); an EXPLICIT
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/// stage-2 pick must stay a faithful arrival-pacing A/B. Elsewhere the default is unchanged.
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func testPacingDefaultsPyroWaveToGlassOnMacOS() {
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#if os(macOS)
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XCTAssertEqual(
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SessionPresenter.pacing(for: .stage2, explicit: nil, codec: .pyrowave), .glass,
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"defaulted macOS PyroWave must serialize presents (swapID-panic mitigation)")
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XCTAssertEqual(
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SessionPresenter.pacing(for: .stage2, explicit: .stage2, codec: .pyrowave), .arrival,
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"an explicit stage-2 pick must keep arrival pacing (honest A/B)")
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#else
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XCTAssertEqual(
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SessionPresenter.pacing(for: .stage2, explicit: nil, codec: .pyrowave), .arrival)
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#endif
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// Non-PyroWave defaults keep arrival pacing under stage-2 everywhere.
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XCTAssertEqual(
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SessionPresenter.pacing(for: .stage2, explicit: nil, codec: .hevc), .arrival)
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// Stage-3 means glass regardless of codec or how it was chosen.
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XCTAssertEqual(
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SessionPresenter.pacing(for: .stage3, explicit: .stage3, codec: .hevc), .glass)
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XCTAssertEqual(
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SessionPresenter.pacing(for: .stage3, explicit: nil, codec: .pyrowave), .glass)
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// Stage-4 means deadline regardless of codec or how it was chosen.
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XCTAssertEqual(
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SessionPresenter.pacing(for: .stage4, explicit: nil, codec: .hevc), .deadline)
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XCTAssertEqual(
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SessionPresenter.pacing(for: .stage4, explicit: .stage4, codec: .pyrowave), .deadline)
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}
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// MARK: - Glass-gate depth
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/// The in-flight present budget is 1 EVERYWHERE: any deeper gate keeps a standing queue —
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/// the 2026-07 iPad depth-2 experiment regressed display latency 14→22–28 ms (see
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/// `SessionPresenter.gateDepth`'s post-mortem). macOS additionally pins the env lever (glass
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/// there is the swapID-panic mitigation — strict serialization is its point);
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/// PUNKTFUNK_GATE_DEPTH still reproduces the standing-queue ladder on iOS/tvOS.
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/// Out-of-range/garbage values are ignored.
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func testGateDepthPlatformDefaultsAndEnvOverride() {
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#if os(macOS)
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XCTAssertEqual(SessionPresenter.gateDepth(env: nil), 1)
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XCTAssertEqual(SessionPresenter.gateDepth(env: "2"), 1, "macOS is pinned to 1")
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#else
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XCTAssertEqual(
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SessionPresenter.gateDepth(env: nil), 1,
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"any depth >1 is a standing queue — one refresh of display latency per slot")
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XCTAssertEqual(SessionPresenter.gateDepth(env: "2"), 2, "the on-device ladder lever")
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#endif
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XCTAssertEqual(
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SessionPresenter.gateDepth(env: "0"), SessionPresenter.gateDepth(env: nil),
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"out-of-range env values fall back to the platform depth")
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XCTAssertEqual(
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SessionPresenter.gateDepth(env: "garbage"), SessionPresenter.gateDepth(env: nil))
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}
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}
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#endif
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