Slight adjustment to rpc-provider LRU (#4198)

packages/rpc-provider/src/lru.spec.ts

@@ -11,6 +11,7 @@ describe('LRUCache', (): void => {
     keys.forEach((k) => lru.set(k, `${k}${k}${k}`));
 
     expect(lru.keys().join(', ')).toEqual(keys.reverse().join(', '));
+    expect(lru.length === lru.lengthData && lru.length === lru.lengthRefs).toBe(true);
 
     keys.forEach((k) => expect(lru.get(k)).toEqual(`${k}${k}${k}`));
   });
@@ -22,6 +23,7 @@ describe('LRUCache', (): void => {
     keys.forEach((k) => lru.set(k, `${k}${k}${k}`));
 
     expect(lru.keys().join(', ')).toEqual(keys.slice(2).reverse().join(', '));
+    expect(lru.length === lru.lengthData && lru.length === lru.lengthRefs).toBe(true);
 
     keys.slice(2).forEach((k) => expect(lru.get(k)).toEqual(`${k}${k}${k}`));
   });
@@ -33,17 +35,21 @@ describe('LRUCache', (): void => {
     keys.forEach((k) => lru.set(k, `${k}${k}${k}`));
 
     expect(lru.entries()).toEqual([['5', '555'], ['4', '444'], ['3', '333'], ['2', '222']]);
+    expect(lru.length === lru.lengthData && lru.length === lru.lengthRefs).toBe(true);
 
     lru.get('3');
 
     expect(lru.entries()).toEqual([['3', '333'], ['5', '555'], ['4', '444'], ['2', '222']]);
+    expect(lru.length === lru.lengthData && lru.length === lru.lengthRefs).toBe(true);
 
     lru.set('4', '4433');
 
     expect(lru.entries()).toEqual([['4', '4433'], ['3', '333'], ['5', '555'], ['2', '222']]);
+    expect(lru.length === lru.lengthData && lru.length === lru.lengthRefs).toBe(true);
 
     lru.set('6', '666');
 
     expect(lru.entries()).toEqual([['6', '666'], ['4', '4433'], ['3', '333'], ['5', '555']]);
+    expect(lru.length === lru.lengthData && lru.length === lru.lengthRefs).toBe(true);
   });
 });

packages/rpc-provider/src/lru.ts

@@ -22,17 +22,26 @@ export class LRUCache {
   readonly #refs: Map<string, LRUNode> = new Map();
 
   #length = 0;
-  #head: LRUNode = new LRUNode('head');
-  #tail: LRUNode = new LRUNode('tail');
+  #head: LRUNode;
+  #tail: LRUNode;
 
   constructor (capacity = DEFAULT_CAPACITY) {
     this.capacity = capacity;
+    this.#head = this.#tail = new LRUNode('<empty>');
   }
 
   get length (): number {
     return this.#length;
   }
 
+  get lengthData (): number {
+    return this.#data.size;
+  }
+
+  get lengthRefs (): number {
+    return this.#refs.size;
+  }
+
   entries (): [string, unknown][] {
     const keys = this.keys();
     const entries = new Array<[string, unknown]>(keys.length);
@@ -49,7 +58,7 @@ export class LRUCache {
   keys (): string[] {
     const keys: string[] = [];
 
-    if (this.length) {
+    if (this.#length) {
       let curr = this.#head;
 
       while (curr !== this.#tail) {
@@ -67,7 +76,7 @@ export class LRUCache {
     const data = this.#data.get(key);
 
     if (data) {
-      this.#toFront(key);
+      this.#toHead(key);
 
       return data as T;
     }
@@ -77,7 +86,7 @@ export class LRUCache {
 
   set <T> (key: string, value: T): void {
     if (this.#data.has(key)) {
-      this.#toFront(key);
+      this.#toHead(key);
     } else {
       const node = new LRUNode(key);
 
@@ -96,7 +105,6 @@ export class LRUCache {
         this.#refs.delete(this.#tail.key);
 
         this.#tail = this.#tail.prev;
-        this.#tail.next = this.#head;
       } else {
         this.#length += 1;
       }
@@ -105,7 +113,7 @@ export class LRUCache {
     this.#data.set(key, value);
   }
 
-  #toFront (key: string): void {
+  #toHead (key: string): void {
     const ref = this.#refs.get(key);
 
     if (ref && ref !== this.#head) {