Obliterate expansion utilities and feature flag (microsoft#22574)

Adds some utilities and properties needed for obliterate endpoint expansion. Split out from microsoft#22552
tylerbutler · Sep 19, 2024 · c98abac · c98abac
1 parent 78cc3c9
commit c98abac
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diff --git a/packages/dds/merge-tree/api-report/merge-tree.legacy.alpha.api.md b/packages/dds/merge-tree/api-report/merge-tree.legacy.alpha.api.md
@@ -379,6 +379,7 @@ export interface IMergeTreeOptions {
     catchUpBlobName?: string;
     mergeTreeEnableObliterate?: boolean;
     mergeTreeEnableObliterateReconnect?: boolean;
+    mergeTreeEnableSidedObliterate?: boolean;
     mergeTreeReferencesCanSlideToEndpoint?: boolean;
     // (undocumented)
     mergeTreeSnapshotChunkSize?: number;
@@ -418,6 +419,7 @@ export interface IMoveInfo {
     movedSeq: number;
     movedSeqs: number[];
     moveDst?: ReferencePosition;
+    prevObliterateByInserter?: ObliterateInfo;
     wasMovedOnInsert: boolean;
 }
 

diff --git a/packages/dds/merge-tree/src/mergeTree.ts b/packages/dds/merge-tree/src/mergeTree.ts
@@ -197,6 +197,17 @@ export interface IMergeTreeOptions {
 	 * @defaultValue `false`
 	 */
 	mergeTreeEnableObliterateReconnect?: boolean;
+
+	/**
+	 * Enables support for obliterate endpoint expansion.
+	 * When enabled, obliterate operations can have sidedness specified for their endpoints.
+	 * If an endpoint is externally anchored
+	 * (aka the start is after a given position, or the end is before a given position),
+	 * then concurrent inserts adjacent to the exclusive endpoint of an obliterated range will be included in the obliteration
+	 *
+	 * @defaultValue `false`
+	 */
+	mergeTreeEnableSidedObliterate?: boolean;
 }
 export function errorIfOptionNotTrue(
 	options: IMergeTreeOptions | undefined,

diff --git a/packages/dds/merge-tree/src/mergeTreeNodes.ts b/packages/dds/merge-tree/src/mergeTreeNodes.ts
@@ -160,6 +160,13 @@ export interface IMoveInfo {
 	 * calculations
 	 */
 	wasMovedOnInsert: boolean;
+
+	/**
+	 * If a segment is inserted into an obliterated range,
+	 * but the newest obliteration of that range was by the inserting client,
+	 * then the segment is not obliterated because it is aware of the latest obliteration.
+	 */
+	prevObliterateByInserter?: ObliterateInfo;
 }
 
 export function toMoveInfo(maybe: Partial<IMoveInfo> | undefined): IMoveInfo | undefined {

diff --git a/packages/dds/merge-tree/src/sequencePlace.ts b/packages/dds/merge-tree/src/sequencePlace.ts
@@ -87,3 +87,19 @@ export function endpointPosAndSide(
 		endPos,
 	};
 }
+
+/**
+ * Returns the given place in InteriorSequencePlace form.
+ */
+export function normalizePlace(place: SequencePlace): InteriorSequencePlace {
+	if (typeof place === "number") {
+		return { pos: place, side: Side.Before };
+	}
+	if (place === "start") {
+		return { pos: -1, side: Side.After };
+	}
+	if (place === "end") {
+		return { pos: -1, side: Side.Before };
+	}
+	return place;
+}