What is the method for implementing Exponential Backoff retry using Kotlin coroutines?

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Here is an example of implementing Exponential Backoff retry using Kotlin coroutines:

suspend fun <T> retryWithExponentialBackoff(
    maxRetries: Int,
    initialDelayMillis: Long,
    factor: Float = 2.0f,
    block: suspend () -> T
): T {
    var currentDelayMillis = initialDelayMillis

    repeat(maxRetries) { retryCount ->
        try {
            return block()
        } catch (e: Exception) {
            if (retryCount == maxRetries - 1) {
                throw e
            }
            delay(currentDelayMillis)
            currentDelayMillis *= factor
        }
    }

    // This should not happen
    throw IllegalStateException("Should have already returned from block()")
}

This function takes parameters for the maximum number of retries, initial delay, and a factor for the delay multiplier (defaults to 2.0). It takes a suspend lambda block that contains the code to retry.

The function then uses a repeat loop to try the block and catch any exceptions. If the maximum number of retries is reached, it throws the last exception.

If there is an exception, the function delays for the current exponential delay and then increases the delay time by multiplying it by the factor. The delay function is a coroutine function that will not block the thread.

The function uses the suspend keyword to make the function a coroutine, allowing it to suspend and resume when making the delay.