/**
 * Copyright 2018, OpenCensus Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import { BasePlugin, PluginInternalFiles, SpanContext, SpanKind, TagMap } from '@opencensus/core';
import * as grpcTypes from 'grpc';
/** The metadata key under which span context is stored as a binary value. */
export declare const GRPC_TRACE_KEY = "grpc-trace-bin";
/** The metadata key under which TagMap is stored as a binary value. */
export declare const GRPC_TAGS_KEY = "grpc-tags-bin";
export declare type GrpcModule = typeof grpcTypes;
export declare type SendUnaryDataCallback = (error: grpcTypes.ServiceError | null, value?: any, trailer?: grpcTypes.Metadata, flags?: grpcTypes.writeFlags) => void;
/** gRPC instrumentation plugin for Opencensus */
export declare class GrpcPlugin extends BasePlugin {
    /** Span grpc attributes */
    static readonly ATTRIBUTE_GRPC_KIND = "grpc.kind";
    static readonly ATTRIBUTE_GRPC_METHOD = "grpc.method";
    static readonly ATTRIBUTE_GRPC_STATUS_CODE = "grpc.status_code";
    static readonly ATTRIBUTE_GRPC_ERROR_NAME = "grpc.error_name";
    static readonly ATTRIBUTE_GRPC_ERROR_MESSAGE = "grpc.error_message";
    protected readonly internalFileList: PluginInternalFiles;
    /** Constructs a new GrpcPlugin instance. */
    constructor();
    /** Patches gRPC incoming and outcoming request functions. */
    protected applyPatch(): any;
    /** Unpatches all gRPC patched function. */
    protected applyUnpatch(): void;
    /**
     * Returns a function that patches the gRPC server register function in order
     * to create trace spans for gRPC service methods.
     * @returns function that returns a patch for server.register function
     */
    private getPatchServer;
    /**
     * Handler Unary and Client Stream Calls
     */
    private clientStreamAndUnaryHandler;
    /**
     * Handler Server Stream and Bidirectional Stream Calls
     */
    private serverStreamAndBidiHandler;
    /**
     * Returns a function that patches the gRPC makeClientConstructor in order
     * to patch all client methods.
     * @returns  function that returns a patch for makeClientConstructor.
     */
    private getPatchClient;
    /**
     * This function starts a span (child or root) immediately before the
     * client method is invoked, and ends it either in a callback or stream
     * event handler, depending on the method type.
     */
    private getPatchedClientMethods;
    /**
     * This method handels the client remote call
     */
    private makeGrpcClientRemoteCall;
    /**
     * Gets a metadata form args, creates a new one if not found.
     *
     *  Code snippet inspired by:
     *  https://github.com/GoogleCloudPlatform/cloud-trace-nodejs/blob/src/plugins/plugin-grpc.ts#L96)
     */
    private getMetadata;
    /**
     * Convert Grpc Status to Span Status
     *
     * At this current version of Opencensus Specs they are the same.
     */
    static convertGrpcStatusToSpanStatus(statusCode: grpcTypes.status): number;
    /**
     * Returns a span context on a Metadata object if it exists and is
     * well-formed, or null otherwise.
     * @param metadata The Metadata object from which span context should be
     *     retrieved.
     */
    static getSpanContext(metadata: grpcTypes.Metadata): SpanContext | null;
    /**
     * Sets a span context on a Metadata object if it exists.
     * @param metadata The Metadata object to which a span context should be
     *     added.
     * @param spanContext The span context.
     */
    static setSpanContext(metadata: grpcTypes.Metadata, spanContext: SpanContext): void;
    /**
     * Returns a TagMap on a Metadata object if it exists and is well-formed, or
     * null otherwise.
     * @param metadata The Metadata object from which TagMap should be retrieved.
     */
    static getTagContext(metadata: grpcTypes.Metadata): TagMap | null;
    /**
     * Sets a TagMap context on a Metadata object if it exists.
     * @param metadata The Metadata object to which a TagMap should be added.
     * @param TagMap The TagMap.
     */
    static setTagContext(metadata: grpcTypes.Metadata, tagMap: TagMap): void;
    /** Method to record stats for client and server. */
    static recordStats(kind: SpanKind, tags: TagMap, argsOrValue: {}, reqOrRes: {}, ms: number): void;
}
declare const plugin: GrpcPlugin;
export { plugin };