Delete the entry for the waiter when the timeout is reached

When the lock times out the promise rejects, and the calling code will do "something sensible". Something sensible
could be to retry later -- but that actually requires the lock to be able to be acquired again. Right now this is
not possible, because the failed `tryToAcquire` is still inside the waiting queue -- and will never release the lock.

src/utils/lock.js

@@ -39,10 +39,12 @@ module.exports = class Lock {
       }
 
       this[PRIVATE.WAITING].add(tryToAcquire)
-      timeoutId = setTimeout(
-        () => reject(new KafkaJSLockTimeout(this[PRIVATE.TIMEOUT_ERROR_MESSAGE]())),
-        this[PRIVATE.TIMEOUT]
-      )
+      timeoutId = setTimeout(() => {
+        // The message should contain the number of waiters _including_ this one
+        const error = new KafkaJSLockTimeout(this[PRIVATE.TIMEOUT_ERROR_MESSAGE]())
+        this[PRIVATE.WAITING].delete(tryToAcquire)
+        reject(error)
+      }, this[PRIVATE.TIMEOUT])
     })
   }
 

src/utils/lock.spec.js

@@ -40,6 +40,26 @@ describe('Utils > Lock', () => {
     ).rejects.toHaveProperty('message', 'Timeout while acquiring lock (2 waiting locks)')
   })
 
+  it('allows lock to be acquired after timeout', async () => {
+    const lock = new Lock({ timeout: 60 })
+    const resource = jest.fn()
+    const callResource = async () => {
+      await lock.acquire()
+      try {
+        resource(Date.now())
+        await sleep(100)
+      } finally {
+        lock.release()
+      }
+    }
+
+    await expect(
+      Promise.all([callResource(), callResource(), callResource()])
+    ).rejects.toHaveProperty('message', 'Timeout while acquiring lock (2 waiting locks)')
+
+    await expect(callResource()).resolves.toBeUndefined()
+  })
+
   describe('with a description', () => {
     it('throws an error with the configured description if the lock cannot be acquired within a period', async () => {
       const lock = new Lock({ timeout: 60, description: 'My test mock' })