import { KobpServiceContext } from '..';
export interface TracerConfig {
    /**
     * By default tracer will always prefers `x-tracerId` explicitly provided in the request header.
     * If not provided. It will fallback to use `traceIdMaker()` to create one.
     *
     * Default to `x-traceId`
     */
    requestTraceHeaderKey: string;
    /**
     * Default to `<timestamp(radix:32)> + '.' + <random(4bytes).hex>.substr(4)`
     */
    traceIdMaker: (currentKey: string) => string;
}
/**
 * Tracer Usage
 *
 * Extends this class. And initialize this with beforeFork middlewares
 *
 * Example:
 * ```ts
 *
 * class CustomTracer extends Tracer {
 *    ** my own functions **
 * }
 *
 * makeServer(
 *    ...,
 *    {
 *        middlewareBeforeFork: (app) => {
 *            app.use((ctx, next) => {
 *                ctx.tracer = new CustomTracer(ctx)
 *                await next()
 *            })
 *        },
 *        middlewareAfterFork: (app) => {
 *          app.use(Tracer.attach('tracer'))
 *        }
 *    }
 * )
 * ```
 */
export declare class Tracer {
    /**
     * Access this parameter to customize the Tracer behavior
     */
    static _config: TracerConfig;
    /**
     * Update tracer's configuration. You should call this only once.
     *
     * @param config
     */
    static config(config: Partial<TracerConfig>): void;
    readonly traceId: string;
    readonly context: KobpServiceContext;
    /**
     *
     * will be called automatically when the context is created
     */
    constructor(ctx: KobpServiceContext);
}