import { TracerProvider } from '@opentelemetry/api';
import { OldClassPlugin, OldPluginConfig } from '../../../types_plugin_only';
export declare enum HookState {
    UNINITIALIZED = 0,
    ENABLED = 1,
    DISABLED = 2
}
/**
 * Environment variable which will contain list of modules to not load corresponding plugins for
 * e.g.OTEL_NO_PATCH_MODULES=pg,https,mongodb
 */
export declare const ENV_PLUGIN_DISABLED_LIST = "OTEL_NO_PATCH_MODULES";
export interface Plugins {
    [pluginName: string]: OldPluginConfig;
}
/**
 * The PluginLoader class can load instrumentation plugins that use a patch
 * mechanism to enable automatic tracing for specific target modules.
 */
export declare class PluginLoader {
    readonly provider: TracerProvider;
    /** A list of loaded plugins. */
    plugins: OldClassPlugin[];
    /**
     * A field that tracks whether the require-in-the-middle hook has been loaded
     * for the first time, as well as whether the hook body is activated or not.
     */
    private _hookState;
    /** Constructs a new PluginLoader instance. */
    constructor(provider: TracerProvider);
    /**
     * Loads a list of plugins. Each plugin module should implement the core
     * {@link Plugin} interface and export an instance named as 'plugin'. This
     * function will attach a hook to be called the first time the module is
     * loaded.
     * @param Plugins an object whose keys are plugin names and whose
     *     {@link OldPluginConfig} values indicate several configuration options.
     */
    load(plugins: Plugins): PluginLoader;
    /** Unloads plugins. */
    unload(): PluginLoader;
}
/**
 * Adds a search path for plugin modules. Intended for testing purposes only.
 * @param searchPath The path to add.
 */
export declare function searchPathForTest(searchPath: string): void;