Pool class

tshemsedinov · tshemsedinov · commit dcbed2a98a3e · 2021-09-21T02:32:32.000+03:00
diff --git a/JavaScript/8-class.js b/JavaScript/8-class.js
@@ -0,0 +1,31 @@
+'use strict';
+
+class Pool {
+  constructor() {
+    this.items = [];
+    this.current = 0;
+  }
+
+  next() {
+    const item = this.items[this.current];
+    this.current++;
+    if (this.current === this.items.length) this.current = 0;
+    return item;
+  }
+
+  add(item) {
+    if (this.items.includes(item)) throw new Error('Pool: add duplicates');
+    this.items.push(item);
+  }
+}
+
+// Usage
+
+const pool = new Pool();
+pool.add({ item: 1 });
+pool.add({ item: 2 });
+pool.add({ item: 3 });
+
+for (let i = 0; i < 10; i++) {
+  console.log(pool.next());
+}
diff --git a/JavaScript/9-exclusive.js b/JavaScript/9-exclusive.js
@@ -0,0 +1,62 @@
+'use strict';
+
+class Pool {
+  constructor() {
+    this.items = [];
+    this.free = [];
+    this.current = 0;
+    this.size = 0;
+    this.available = 0;
+  }
+
+  next() {
+    if (this.available === 0) return null;
+    let item = null;
+    let free = false;
+    do {
+      item = this.items[this.current];
+      free = this.free[this.current];
+      this.current++;
+    } while (!item || !free);
+    if (this.current === this.size) this.current = 0;
+    return item;
+  }
+
+  add(item) {
+    if (this.items.includes(item)) throw new Error('Pool: add duplicates');
+    this.size++;
+    this.available++;
+    this.items.push(item);
+    this.free.push(true);
+  }
+
+  capture() {
+    const item = this.next();
+    if (!item) return null;
+    const index = this.items.indexOf(item);
+    this.free[index] = false;
+    this.available--;
+    return item;
+  }
+
+  release(item) {
+    const index = this.items.indexOf(item);
+    if (index < 0) throw new Error('Pool: release unexpected item');
+    if (this.free[index]) throw new Error('Pool: release not captured');
+    this.free[index] = true;
+    this.available++;
+  }
+}
+
+// Usage
+
+const pool = new Pool();
+pool.add({ item: 1 });
+pool.add({ item: 2 });
+const last = { item: 3 };
+pool.add(last);
+
+for (let i = 0; i < 10; i++) {
+  console.log(pool.capture());
+  if (i === 5) pool.release(last);
+}
