Implement unregister method for probes

Before this change, it was possible to disable a probe by
registering an empty probe with the same name, but this is neither
obvious nor documented. This commit adds a `probes.unregister()`
method that removes a probe in a more explicit manner.

packages/nodejs/.changesets/implement-unregister-method-for-probes.md

@@ -0,0 +1,7 @@
+---
+bump: "patch"
+type: "add"
+---
+
+Implement unregister method for probes. You can now call the
+`probes.unregister(name)` method to unregister a probe by name.

packages/nodejs/src/__tests__/probes.test.ts

@@ -21,6 +21,16 @@ describe("Probes", () => {
     probes.register("test_metric", fn)
     jest.runOnlyPendingTimers()
     expect(fn).toHaveBeenCalled()
+    expect(probes.count).toEqual(1)
+  })
+
+  it("unregisters a probe", () => {
+    const fn = jest.fn()
+    probes.register("test_metric", fn)
+    probes.unregister("test_metric")
+    jest.runOnlyPendingTimers()
+    expect(fn).not.toHaveBeenCalled()
+    expect(probes.count).toEqual(0)
   })
 
   describe("v8 probe", () => {

packages/nodejs/src/interfaces/probes.ts

@@ -13,6 +13,11 @@ export interface Probes {
    */
   register(name: string, fn: () => void): this
 
+  /**
+   * Unregisters an existing minutely probe.
+   */
+  unregister(name: string): this
+
   /**
    * Unregisters all probes and clears the timers.
    */

packages/nodejs/src/probes/index.ts

@@ -31,12 +31,25 @@ export class BaseProbes extends EventEmitter implements Probes {
     return this.on(name, fn)
   }
 
+  public unregister(name: string): this {
+    const timer = this.#timers.get(name)
+
+    if (typeof timer !== "undefined") {
+      clearInterval(timer)
+      this.#timers.delete(name)
+      this.removeAllListeners(name)
+    }
+
+    return this
+  }
+
   /**
    * Unregisters all probes and clears the timers.
    */
   public clear(): this {
     this.#timers.forEach(t => clearInterval(t))
     this.#timers = new Map()
+    this.removeAllListeners()
     return this
   }
 }