Fix partially completed commutative chains

Previously when the lowest operation completed, the entire commutative chain would be squashed and deleted. Instead only the completed operations until the next lowest uncompleted operation should be squashed.
urql-graphql · Mar 3, 2020 · 4c81797 · 4c81797
1 parent 1359234
commit 4c81797
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Showing 2 changed files with 49 additions and 4 deletions.
diff --git a/exchanges/graphcache/src/store/data.test.ts b/exchanges/graphcache/src/store/data.test.ts
@@ -278,4 +278,39 @@ describe('commutative changes', () => {
     InMemoryData.initDataState(data, null);
     expect(InMemoryData.readRecord('Query', 'index')).toBe(1);
   });
+
+  it('continues applying optimistic layers even if the first one completes', () => {
+    InMemoryData.reserveLayer(data, 1);
+    InMemoryData.reserveLayer(data, 2);
+    InMemoryData.reserveLayer(data, 3);
+    InMemoryData.reserveLayer(data, 4);
+
+    InMemoryData.initDataState(data, 1);
+    InMemoryData.writeRecord('Query', 'index', 1);
+    InMemoryData.clearDataState();
+
+    InMemoryData.initDataState(data, null);
+    expect(InMemoryData.readRecord('Query', 'index')).toBe(1);
+
+    InMemoryData.initDataState(data, 3);
+    InMemoryData.writeRecord('Query', 'index', 3);
+    InMemoryData.clearDataState();
+
+    InMemoryData.initDataState(data, null);
+    expect(InMemoryData.readRecord('Query', 'index')).toBe(3);
+
+    InMemoryData.initDataState(data, 4);
+    InMemoryData.writeRecord('Query', 'index', 4);
+    InMemoryData.clearDataState();
+
+    InMemoryData.initDataState(data, null);
+    expect(InMemoryData.readRecord('Query', 'index')).toBe(4);
+
+    InMemoryData.initDataState(data, 2);
+    InMemoryData.writeRecord('Query', 'index', 2);
+    InMemoryData.clearDataState();
+
+    InMemoryData.initDataState(data, null);
+    expect(InMemoryData.readRecord('Query', 'index')).toBe(4);
+  });
 });
diff --git a/exchanges/graphcache/src/store/data.ts b/exchanges/graphcache/src/store/data.ts
@@ -101,10 +101,20 @@ export const clearDataState = () => {
     // and is the "first" one and hence blocking all others, we squash all
     // results and empty the list of commutative keys
     if (blockingKey === optimisticKey) {
-      for (let i = data.optimisticOrder.length - 1; i >= commutativeIndex; i--)
-        squashLayer(data.optimisticOrder[i]);
-      data.optimisticOrder.length = commutativeIndex;
-      data.commutativeKeys.clear();
+      const squash: number[] = [];
+      const orderSize = data.optimisticOrder.length;
+      // Collect all completed, commutative layers until and excluding the first
+      // pending one that overrides the others
+      for (let i = commutativeIndex; i < orderSize; i++) {
+        const layerKey = data.optimisticOrder[i];
+        if (!data.refLock[layerKey]) break;
+        squash.unshift(layerKey);
+      }
+
+      // Apply all completed, commutative layers
+      for (let i = 0, l = squash.length; i < l; i++) {
+        squashLayer(squash[i]);
+      }
     }
   }