/**
 * An interface representing distributed pacing and rate limiting algorithms.
 */
export interface Pacer {
    /** Human readable name of the pacer, used when composing multiple pacers. */
    readonly key: string;
    /**
     * Calling this method signals the pacer that we want to send a request. The
     * method predicts the delay on which the worker needs to await before
     * actually sending the request.
     */
    pace(weight?: number): Promise<PacerOutcome>;
    /**
     * Implements rare limiting use case (i.e. on receiver side), when the
     * requests which go out of qps & maxBurst quote are rejected instead of being
     * delayed. For rate limiting, we use the same algorithm which handles bursts
     * in pace() method.
     */
    rateLimit(weight?: number): Promise<PacerOutcome>;
}
/**
 * A result of the pace() or rateLimit() work.
 */
export interface PacerOutcome {
    /** For pacing use case, how much time a worker needs to wait before sending
     * the request. For rate limiting use case, when can the client retry the
     * request and expect it not being rate limited. */
    delayMs: number;
    /** Debug information about why that `delayMs` value was returned. */
    reason: string;
}
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