feat(flag-evaluation): optimize ANY_OF and NOT_ANY_OFF operators (#413)

Expose a new evaluation interface which lets us optimize the ANY_OF and
NOT_ANY_OFF operators. This works through the use of a one-time
pre-evaluation step which converts lists used in ANY_OF and NOT_ANY_OFF
evaluation to sets for quicker lookups.

Author: roncohen

packages/flag-evaluation/src/index.ts

@@ -116,6 +116,7 @@ export interface ContextFilter {
   field: string;
   operator: ContextFilterOperator;
   values?: string[];
+  valueSet?: Set<string>;
 }
 
 /**
@@ -286,6 +287,7 @@ export function evaluate(
   fieldValue: string,
   operator: ContextFilterOperator,
   values: string[],
+  valueSet?: Set<string>,
 ): boolean {
   const value = values[0];
 
@@ -331,9 +333,11 @@ export function evaluate(
     case "IS_NOT":
       return fieldValue !== value;
     case "ANY_OF":
-      return values.includes(fieldValue);
+      return valueSet ? valueSet.has(fieldValue) : values.includes(fieldValue);
     case "NOT_ANY_OF":
-      return !values.includes(fieldValue);
+      return valueSet
+        ? !valueSet.has(fieldValue)
+        : !values.includes(fieldValue);
     case "IS_TRUE":
       return fieldValue == "true";
     case "IS_FALSE":
@@ -362,6 +366,7 @@ function evaluateRecursively(
         context[filter.field],
         filter.operator,
         filter.values || [],
+        filter.valueSet,
       );
     case "rolloutPercentage": {
       if (!(filter.partialRolloutAttribute in context)) {
@@ -463,3 +468,47 @@ export function evaluateFeatureRules<T extends RuleValue>({
     missingContextFields,
   };
 }
+
+export function newEvaluator<T extends RuleValue>(rules: Rule<T>[]) {
+  function translateRule(rule: RuleFilter): RuleFilter {
+    if (rule.type === "group") {
+      return {
+        ...rule,
+        filters: rule.filters.map(translateRule),
+      };
+    }
+
+    if (
+      rule.type === "context" &&
+      (rule.operator === "ANY_OF" || rule.operator === "NOT_ANY_OF")
+    ) {
+      return {
+        ...rule,
+        valueSet: new Set(rule.values ?? []),
+      };
+    }
+
+    return { ...rule };
+  }
+
+  const translatedRules = rules.map((rule) => {
+    const { filter } = rule;
+    const translatedFilter = translateRule(filter);
+
+    return {
+      ...rule,
+      filter: translatedFilter,
+    };
+  });
+
+  return function evaluateOptimized(
+    context: Record<string, unknown>,
+    featureKey: string,
+  ) {
+    return evaluateFeatureRules({
+      context,
+      featureKey,
+      rules: translatedRules,
+    });
+  };
+}

packages/flag-evaluation/test/index.test.ts

@@ -6,6 +6,7 @@ import {
   EvaluationParams,
   flattenJSON,
   hashInt,
+  newEvaluator,
   unflattenJSON,
 } from "../src";
 
@@ -239,6 +240,115 @@ describe("evaluate feature targeting integration ", () => {
       ruleEvaluationResults: [false],
     });
   });
+
+  it("evaluates optimized rule evaluations correctly", async () => {
+    const res = newEvaluator([
+      {
+        value: true,
+        filter: {
+          type: "group",
+          operator: "and",
+          filters: [
+            {
+              type: "context",
+              field: "company.id",
+              operator: "IS",
+              values: ["company1"],
+            },
+            {
+              type: "rolloutPercentage",
+              key: "flag",
+              partialRolloutAttribute: "company.id",
+              partialRolloutThreshold: 99999,
+            },
+            {
+              type: "group",
+              operator: "or",
+              filters: [
+                {
+                  type: "context",
+                  field: "company.id",
+                  operator: "ANY_OF",
+                  values: ["company2"],
+                },
+                {
+                  type: "negation",
+                  filter: {
+                    type: "context",
+                    field: "company.id",
+                    operator: "IS",
+                    values: ["company3"],
+                  },
+                },
+              ],
+            },
+            {
+              type: "negation",
+              filter: {
+                type: "constant",
+                value: false,
+              },
+            },
+          ],
+        },
+      },
+    ])(
+      {
+        "company.id": "company1",
+      },
+      "feature",
+    );
+
+    expect(res).toEqual({
+      value: true,
+      context: {
+        "company.id": "company1",
+      },
+      featureKey: "feature",
+      missingContextFields: [],
+      reason: "rule #0 matched",
+      ruleEvaluationResults: [true],
+    });
+  });
+
+  it.each([
+    {
+      context: { "company.id": "company1" },
+      expected: true,
+    },
+    {
+      context: { "company.id": "company2" },
+      expected: true,
+    },
+    {
+      context: { "company.id": "company3" },
+      expected: false,
+    },
+  ])(
+    "%#: evaluates optimized rule evaluations correctly",
+    async ({ context, expected }) => {
+      const evaluator = newEvaluator([
+        {
+          value: true,
+          filter: {
+            type: "group",
+            operator: "and",
+            filters: [
+              {
+                type: "context",
+                field: "company.id",
+                operator: "ANY_OF",
+                values: ["company1", "company2"],
+              },
+            ],
+          },
+        },
+      ]);
+
+      const res = evaluator(context, "feature");
+      expect(res.value ?? false).toEqual(expected);
+    },
+  );
 });
 
 describe("operator evaluation", () => {