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asyncContextManager.ts
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asyncContextManager.ts
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/*
* Copyright The OpenTelemetry 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.
*/
export interface AsyncContext {
/**
* Get a value from the context.
*
* @param key key which identifies a context value
*/
getValue(key: symbol): unknown;
/**
* Create a new context which inherits from this context and has
* the given key set to the given value.
*
* @param key context key for which to set the value
* @param value value to set for the given key
*/
setValue(key: symbol, value: unknown): AsyncContext;
/**
* Return a new context which inherits from this context but does
* not contain a value for the given key.
*
* @param key context key for which to clear a value
*/
deleteValue(key: symbol): AsyncContext;
}
export interface AsyncContextManager {
/**
* Get the current active context
*/
active(): AsyncContext;
/**
* Run the fn callback with object set as the current active context
* @param context Any object to set as the current active context
* @param fn A callback to be immediately run within a specific context
* @param thisArg optional receiver to be used for calling fn
* @param args optional arguments forwarded to fn
*/
with<A extends unknown[], F extends (...args: A) => ReturnType<F>>(
context: AsyncContext,
fn: F,
thisArg?: ThisParameterType<F>,
...args: A
): ReturnType<F>;
/**
* Bind an object as the current context (or a specific one)
* @param [context] Optionally specify the context which you want to assign
* @param target Any object to which a context need to be set
*/
bind<T>(context: AsyncContext, target: T): T;
/**
* Enable context management
*/
enable(): this;
/**
* Disable context management
*/
disable(): this;
}
class AsyncBaseContext implements AsyncContext {
private _currentContext!: Map<symbol, unknown>;
/**
* Construct a new context which inherits values from an optional parent context.
*
* @param parentContext a context from which to inherit values
*/
constructor(parentContext?: Map<symbol, unknown>) {
// for minification
// eslint-disable-next-line @typescript-eslint/no-this-alias
const self = this;
self._currentContext = parentContext ? new Map(parentContext) : new Map();
self.getValue = (key: symbol) => self._currentContext.get(key);
self.setValue = (key: symbol, value: unknown): AsyncContext => {
const context = new AsyncBaseContext(self._currentContext);
context._currentContext.set(key, value);
return context;
};
self.deleteValue = (key: symbol): AsyncContext => {
const context = new AsyncBaseContext(self._currentContext);
context._currentContext.delete(key);
return context;
};
}
/**
* Get a value from the context.
*
* @param key key which identifies a context value
*/
public getValue!: (key: symbol) => unknown;
/**
* Create a new context which inherits from this context and has
* the given key set to the given value.
*
* @param key context key for which to set the value
* @param value value to set for the given key
*/
public setValue!: (key: symbol, value: unknown) => AsyncContext;
/**
* Return a new context which inherits from this context but does
* not contain a value for the given key.
*
* @param key context key for which to clear a value
*/
public deleteValue!: (key: symbol) => AsyncContext;
}
/** The root context is used as the default parent context when there is no active context */
export const ASYNC_ROOT_CONTEXT: AsyncContext = new AsyncBaseContext();
export class NoopContextManager implements AsyncContextManager {
active(): AsyncContext {
return ASYNC_ROOT_CONTEXT;
}
with<A extends unknown[], F extends (...args: A) => ReturnType<F>>(
_context: AsyncContext,
fn: F,
thisArg?: ThisParameterType<F>,
...args: A
): ReturnType<F> {
return fn.call(thisArg, ...args);
}
bind<T>(_context: AsyncContext, target: T): T {
return target;
}
enable(): this {
return this;
}
disable(): this {
return this;
}
}