Fix move and override

Author: julienmalard

src/ordered-keyvalue.ts

@@ -95,14 +95,29 @@ export const OrderedKeyValueApi = ({
   const put = async (
     key: string,
     value: DagCborEncodable,
-    position = -1,
+    position?: number,
   ): Promise<string> => {
     // Somewhat inefficient, I suppose, but we need to know which entries are already present.
     const entries = await itAll(iterator());
-    const entryValue: { value: DagCborEncodable; position: number } = {
+
+    // Avoid overwriting existing position; default to end of list (findIndex gives -1)
+    let scaledPosition: number | undefined = undefined;
+    if (position === undefined) {
+      scaledPosition = entries.find((e) => e.key === key)?.position;
+    }
+    if (scaledPosition === undefined) {
+      scaledPosition = await getScalePosition({
+        entries,
+        key,
+        position: position ?? -1,
+      });
+    }
+
+    const entryValue = {
       value,
-      position: await getScalePosition({ entries, key, position }),
+      position: scaledPosition,
     };
+
     return database.addOperation({ op: "PUT", key, value: entryValue });
   };
 
@@ -143,30 +158,33 @@ export const OrderedKeyValueApi = ({
     unknown
   > {
     let count = 0;
-    const keys: { [key: string]: true } = {};
-    const positions: { [key: string]: number } = {};
+
+    // `true` indicates a `PUT` operation; `number` indicates a `MOVE` operation
+    const keys: { [key: string]: true | number } = {};
 
     for await (const entry of database.log.traverse()) {
       const { op, key, value } = entry.payload;
+      if (typeof key !== "string") continue;
 
-      if (!key || keys[key]) continue;
-
-      if (op === "PUT") {
+      if (op === "PUT" && keys[key] !== true) {
         const hash = entry.hash;
-        const putValue = value as { value: unknown; position?: number };
+        const putValue = value as { value: unknown; position: number };
 
+        const position =
+          typeof keys[key] === "number"
+            ? (keys[key] as number)
+            : putValue.position;
         keys[key] = true;
         count++;
 
         yield {
           key,
           value: putValue.value,
-          position: positions[key] ?? putValue.position ?? -1,
+          position,
           hash,
         };
-      } else if (op === "MOVE") {
-        if (positions[key] !== undefined || keys[key]) continue;
-        positions[key] = value as number;
+      } else if (op === "MOVE" && !keys[key]) {
+        keys[key] = value as number;
       } else if (op === "DEL") {
         keys[key] = true;
       }

test/ordered-keyvalue.spec.ts

@@ -227,6 +227,7 @@ describe("OrderedKeyValue Database", () => {
       const hash = await db.put(key, value);
       const hash2 = await db.put(key2, value2);
       await db.move(key, 1);
+
       const actual = await db.all();
 
       expect(actual).to.deep.equal([
@@ -309,24 +310,29 @@ describe("OrderedKeyValue Database", () => {
     });
 
     it("move and override a key concurrently", async () => {
-      const value = "value1";
-      const valueMod = "value1a";
-      const key = "key1";
+      const key1 = "key1";
+      const value1 = "value1";
 
-      const value2 = "value2";
       const key2 = "key2";
+      const value2 = "value2";
+      const value2Mod = "value2a";
 
-      await db.put(key, value);
-      const hash2 = await db.put(key2, value2);
-      await db.move(key, 1);
+      const key3 = "key3";
+      const value3 = "value3";
 
-      const hash = await db.put(key, valueMod);
+      const hash1 = await db.put(key1, value1);
+      await db.put(key2, value2);
+      const hash3 = await db.put(key3, value3);
+      await db.move(key1, 1);
+
+      const hash2 = await db.put(key2, value2Mod);
 
       const actual = await db.all();
 
       expect(actual).to.deep.equal([
-        { value: value2, key: key2, hash: hash2 },
-        { value: valueMod, key, hash },
+        { value: value2Mod, key: key2, hash: hash2 },
+        { value: value1, key: key1, hash: hash1 },
+        { value: value3, key: key3, hash: hash3 },
       ]);
     });