remove stale_readers, it's obsolete now

packages/svelte/src/internal/client/reactivity/batch.js

@@ -330,16 +330,6 @@ export class Batch {
 	 */
 	fork_effects = null;
 
-	/**
-	 * Reactions that observed the pre-write world of this batch via its active
-	 * overlay while it was pending, mapped to the values they saw. When this
-	 * batch commits, readers whose observed values differ from the committed
-	 * ones re-run with the real values.
-	 * Lazily initialised for perf reasons
-	 * @type {Map<Reaction, Map<Value, any>> | null}
-	 */
-	stale_readers = null;
-
 	/**
 	 * `true` while this batch is flushing its effects and is provably terminal —
 	 * solitary, with no pending async work and nothing scheduled. Such a batch
@@ -720,14 +710,6 @@ export class Batch {
 		this.#scheduled.push(...other.#scheduled);
 		other.#scheduled = [];
 
-		// TODO could a newer value have been observed by this and other is older?
-		this.stale_readers = transfer_map(
-			this.stale_readers,
-			other.stale_readers,
-			(observed, seen) => /** @type {Map<Value, any>} */ (transfer_map(observed, seen))
-		);
-		other.stale_readers = null;
-
 		if (other.waiting !== null) {
 			var waiting = (this.waiting ??= { batches: new Set(), reactions: new Map() });
 
@@ -1207,51 +1189,6 @@ export class Batch {
 				});
 			}
 		}
-
-		if (this.stale_readers === null) return;
-
-		var readers = this.stale_readers;
-		this.stale_readers = null;
-
-		var batch = Batch.ensure();
-
-		for (const [reader, seen] of readers) {
-			var flags = reader.f;
-
-			if ((flags & (DESTROYED | INERT | DIRTY)) !== 0) continue;
-
-			// Only re-run readers that are actually affected by the commit: a
-			// reader observed specific values through this batch's overlay. If
-			// each of those matches the committed value (the write was reverted,
-			// or a derived recomputed to an equal value), or the reader no
-			// longer depends on it, the reader's world didn't change
-			var status = CLEAN;
-
-			for (const [signal, value] of seen) {
-				if (reader.deps === null || !includes.call(reader.deps, signal)) continue;
-
-				if ((signal.f & (DIRTY | MAYBE_DIRTY)) !== 0) {
-					// a derived that hasn't been revalidated with the committed
-					// values yet — the reader's own validation will recompute it
-					// (with equality applying) via `is_dirty`
-					status = MAYBE_DIRTY;
-				} else if (signal.v !== value) {
-					status = DIRTY;
-					break;
-				}
-			}
-
-			if (status === CLEAN) continue;
-
-			set_signal_status(reader, status);
-
-			if ((flags & DERIVED) !== 0) {
-				// invalidate anything that depends on the derived
-				mark_reactions(/** @type {Derived} */ (reader), MAYBE_DIRTY, null);
-			} else {
-				batch.schedule(/** @type {Effect} */ (reader));
-			}
-		}
 	}
 
 	/**
@@ -1749,10 +1686,8 @@ function mark_committed_reactions(value, batch, marked, status) {
 			var owner = effect.batch && effect.batch.resolved();
 
 			var superseded = batch.fork_effects?.get(effect);
-			var stale =
-				batch.stale_readers?.has(effect) === true || owner?.stale_readers?.has(effect) === true;
 
-			if (superseded === undefined || stale) {
+			if (superseded === undefined) {
 				if ((reaction.f & DIRTY) === 0) {
 					set_signal_status(reaction, status);
 				}

packages/svelte/src/internal/client/runtime.js

@@ -725,7 +725,7 @@ export function get(signal) {
 			active_batch.values !== null &&
 			(owner = claimed_by_other(derived)) !== null
 		) {
-			if (is_unseen_read(derived, owner, first_read) && entangle(derived)) {
+			if (is_unseen_read(derived, first_read) && entangle(derived)) {
 				// a read with no history can entangle the two batches instead, so
 				// that they commit together — the derived is now part of this
 				// batch's world and behaves normally (below)
@@ -794,13 +794,6 @@ export function get(signal) {
 				} else if (!untracking) {
 					override_owner = override_owner.resolved();
 
-					var seen = override_owner.stale_readers?.get(active_reaction);
-
-					// a reader keeps seeing the value it first observed while the owner is pending
-					if (seen !== undefined && seen.has(signal)) {
-						return seen.get(signal);
-					}
-
 					var override_value = override[0];
 
 					if (
@@ -829,14 +822,6 @@ export function get(signal) {
 						override_value = signal.v;
 					}
 
-					var readers = (override_owner.stale_readers ??= new Map());
-
-					if (seen === undefined) {
-						readers.set(active_reaction, (seen = new Map()));
-					}
-
-					seen.set(signal, override_value);
-
 					return override_value;
 				}
 			}
@@ -858,11 +843,10 @@ export function get(signal) {
  * nor observed a value for it while the owner batch was pending. (Reads outside
  * a reaction never have history.)
  * @param {Value} signal
- * @param {Batch} owner
  * @param {boolean} first_read whether a post-`await` read just added `signal` to the reaction's deps
  * @returns {boolean}
  */
-function is_unseen_read(signal, owner, first_read) {
+function is_unseen_read(signal, first_read) {
 	if (active_reaction === null) return true;
 	if (untracking) return false;
 
@@ -874,8 +858,7 @@ function is_unseen_read(signal, owner, first_read) {
 		return false;
 	}
 
-	var seen = owner.resolved().stale_readers?.get(active_reaction);
-	return seen === undefined || !seen.has(signal);
+	return true;
 }
 
 /**