Add unique tokens counter

[akhomchenko]

Closes #515

Overview:

Unique tokens are saved to store and their count is exposed by metrics reporter at custom endpoint.

Details:

• store is cache-like structure with 2 implementations:
  • in-memory is based on ES6 Map
  • redis is based on Redis sorted set where key is token and score is timestamp in ms

TODO:

• [ ] - separate issue for oauth middleware?

[coveralls]

Coverage decreased (-0.3%) to 89.127% when pulling d736c07feb72cd95505f104f7200e482df27cdb4 on feature/distinct-tokens-middleware into 5fce443f96bf29556ad52579bbebd1f2c27e9f2e on master.

[coveralls]

Coverage decreased (-0.3%) to 89.127% when pulling 84e7058af0f73c760687b126cc7d32b61cfa7348 on feature/distinct-tokens-middleware into 5fce443f96bf29556ad52579bbebd1f2c27e9f2e on master.

[coveralls]

Coverage decreased (-0.3%) to 89.127% when pulling 84e7058af0f73c760687b126cc7d32b61cfa7348 on feature/distinct-tokens-middleware into 5fce443f96bf29556ad52579bbebd1f2c27e9f2e on master.

[akhomchenko]

Is blocked by #517

[coveralls]

Coverage decreased (-0.3%) to 89.127% when pulling 4ca9e3a895e22aa3323fd6a0e0e94c2d605b07f9 on feature/distinct-tokens-middleware into 5fce443f96bf29556ad52579bbebd1f2c27e9f2e on master.

[coveralls]

Coverage decreased (-0.3%) to 89.127% when pulling f42a14e2ec2ea8ca3c2d0158197b06f17dd4c2db on feature/distinct-tokens-middleware into 5fce443f96bf29556ad52579bbebd1f2c27e9f2e on master.

[akhomchenko]

@prayerslayer I need to update the code to work on node v5. So you can postpone the review.

[coveralls]

Coverage decreased (-0.3%) to 89.127% when pulling d187a5ca060ec4b389f80ffa09629d637e897b00 on feature/distinct-tokens-middleware into 5fce443f96bf29556ad52579bbebd1f2c27e9f2e on master.

[akhomchenko]

@prayerslayer code is ready for a review

[prayerslayer]

@gagoman Done with review, I'd really like to change where the unique tokens middleware is used.

[coveralls]

Coverage decreased (-0.3%) to 89.145% when pulling ddc3524f6499f7ac96726e270d193174c7a8b966 on feature/distinct-tokens-middleware into 5fce443f96bf29556ad52579bbebd1f2c27e9f2e on master.

[prayerslayer]

👍

[akhomchenko]

👍