DVWindowPerformance class

What the windowing layer measures, and what it finds in the measurements.

The specification's performance contract for Multi-Window names five measurements -- open() to ready (real and virtual), tear-out handover, shared-store write rate and coalescing ratio, store size and spill count, and restore-on-launch duration -- and four diagnostics. This is where they live. The manager, the shared store and the tab workspace record into it; the running application publishes it beside its live window list, and dartvel analyze performance reads it from there.

Time comes from nowMicros rather than a stopwatch so a test can hand in a clock and know the duration between two reads, instead of asserting on whatever the runner's scheduler happened to allow.

Constructors

DVWindowPerformance({int nowMicros()?, Duration frameBudget = const Duration(milliseconds: 16), Duration startupBudget = const Duration(milliseconds: 500), int minimumSamples = 3})

Properties

burstWrites → Map<String, int>: Per key, how many writes landed within frameBudget of the previous write to the same key -- writes coalescing has to absorb.
no setter
coalescingRatio → double: The share of writes coalescing absorbed: 0 when every write was flushed, approaching 1 when nearly all of them collapsed into one.
no setter
degradationsByRoute → Map<String, DVRouteDegradations>: Opens and degradations per call site. The call site is the route: that is what a window is identified by, and what a developer can find.
no setter
findings → List<DVWindowPerformanceFinding>: What the measurements say is wrong. Each subject appears once: a call site that always degrades is one finding, not a thousand log lines.
no setter
frameBudget → Duration: One frame at 60Hz: what a close of owned windows, or a burst of writes to one key, is measured against.
final
hashCode → int: The hash code for this object.
no setterinherited
minimumSamples → int: How many opens a call site needs before "always degrades" is a finding rather than a coincidence.
final
opens → List<DVWindowOpenSample>: Every open() that made a window, real or virtual, in order.
no setter
ownedCloses → List<DVOwnedCloseSample>: Every close of a window that owned others.
no setter
restores → List<DVWorkspaceRestoreSample>: Every workspace restore.
no setter
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
spillCount → int: Values that left the preference store for file storage.
no setter
startupBudget → Duration: What a workspace restore on launch is measured against.
final
storeFlushes → int: Writes that reached the backend after coalescing.
no setter
storeSizeBytes → int: Encoded bytes currently stored, across every key, spilled or not.
no setter
storeWrites → int: Calls to set on the shared store.
no setter
tearOuts → List<DVWindowTearOutSample>: Every tear-out, from the gesture to the new window being ready.
no setter

Methods

mark() → int: A point in time, for callers that measure a span.
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
recordOpen({required String route, required bool virtual, required Duration elapsed, String? code}) → void
recordOpenFrom(int mark, {required String route, required bool virtual, String? code}) → void
recordOwnedCloseFrom(int mark, {required String owner, required int owned}) → void
recordRestoreFrom(int mark, {required String name, required int tabs}) → void
recordStoreFlush(String key, {required int? bytes, bool spilled = false}) → void: bytes is null when the key was removed.
recordStoreWrite(String key) → void
recordTearOutFrom(int mark, {required String route}) → void
toJson() → Map<String, Object?>
toString() → String: A string representation of this object.
inherited

Operators

operator ==(Object other) → bool: The equality operator.
inherited

Static Properties

current ↔ DVWindowPerformance: The recorder everything reports into. DVWindowManager.reset installs a fresh one so one test's samples are not the next test's findings.
getter/setter pair