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node_modules/@azure/msal-node/src/retry/ExponentialRetryStrategy.ts

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+/*
+ * Copyright (c) Microsoft Corporation. All rights reserved.
+ * Licensed under the MIT License.
+ */
+
+export class ExponentialRetryStrategy {
+    // Minimum backoff time in milliseconds
+    private minExponentialBackoff: number;
+    // Maximum backoff time in milliseconds
+    private maxExponentialBackoff: number;
+    // Maximum backoff time in milliseconds
+    private exponentialDeltaBackoff: number;
+
+    constructor(
+        minExponentialBackoff: number,
+        maxExponentialBackoff: number,
+        exponentialDeltaBackoff: number
+    ) {
+        this.minExponentialBackoff = minExponentialBackoff;
+        this.maxExponentialBackoff = maxExponentialBackoff;
+        this.exponentialDeltaBackoff = exponentialDeltaBackoff;
+    }
+
+    /**
+     * Calculates the exponential delay based on the current retry attempt.
+     *
+     * @param {number} currentRetry - The current retry attempt number.
+     * @returns {number} - The calculated exponential delay in milliseconds.
+     *
+     * The delay is calculated using the formula:
+     * - If `currentRetry` is 0, it returns the minimum backoff time.
+     * - Otherwise, it calculates the delay as the minimum of:
+     *   - `(2^(currentRetry - 1)) * deltaBackoff`
+     *   - `maxBackoff`
+     *
+     * This ensures that the delay increases exponentially with each retry attempt,
+     * but does not exceed the maximum backoff time.
+     */
+    public calculateDelay(currentRetry: number): number {
+        // Attempt 1
+        if (currentRetry === 0) {
+            return this.minExponentialBackoff;
+        }
+
+        // Attempt 2+
+        const exponentialDelay = Math.min(
+            Math.pow(2, currentRetry - 1) * this.exponentialDeltaBackoff,
+            this.maxExponentialBackoff
+        );
+
+        return exponentialDelay;
+    }
+}