Blackjack dealer

Fast blackjack dealer

Build with cargo, starts up on port 1337 by default.

Endpoints

• /shuffle - returns a shuffled deck ()
• /fouraces - returns a shuffled deck, but with the four aces on top of the deck
• /bothblackjack - returns a deck with blackjack for both players. Dealer wins
• /playerblackjack - returns a deck with blackjack for the player
• /dealerblackjack - returns a deck with blackjack for the dealer
• /dealerbust - returns a deck where dealer will bust
• /playerbust - returns a deck where player will bust
• /tie21 - Both players draw 21 - - This should cause dealer to lose, since they always draw until they have higher than player -
• /custom?cards=[cards] - Use this with the shorthand expected from the candidate to put the cards in the cards argument on top, so /custom?cards=SA,SK,HA,HK would give player Ace of Spades (SA) and King of Spades (SK), and dealer Ace of Hearts (HA) and King of Hearts (HK)

Backing endpoints

• /metrics - Prometheus metrics for requests and process
• /health - returns 200 OK

Benchmarking

We're using k6 for benchmarking. This repo includes a k6benchmark.js file which can run on the server running this application or modified to access the URL where the application is deployed.

We've also included Criterion benchmarks, these can be run with

$ cargo bench

Basic usage of k6

• For benchmarking the shuffle endpoint

$ k6 run --vus 50 --duration 30s k6benchmark.js

k6 results (on a Ryzen 9 5900X (12C/24T)) built with --release for /shuffle

scenarios: (100.00%) 1 scenario, 50 max VUs, 40s max duration (incl. graceful stop):
* default: 50 looping VUs for 10s (gracefulStop: 30s)


running (10.0s), 00/50 VUs, 1974808 complete and 0 interrupted iterations
default ✓ [======================================] 50 VUs  10s

     data_received..................: 2.8 GB  279 MB/s
     data_sent......................: 172 MB  17 MB/s
     http_req_blocked...............: avg=1.18µs   min=330ns   med=850ns    max=4.71ms  p(90)=1.34µs   p(95)=1.74µs
     http_req_connecting............: avg=2ns      min=0s      med=0s       max=305.9µs p(90)=0s       p(95)=0s
     http_req_duration..............: avg=186.04µs min=28.63µs med=155.04µs max=7.07ms  p(90)=312.72µs p(95)=386.81µs
       { expected_response:true }...: avg=186.04µs min=28.63µs med=155.04µs max=7.07ms  p(90)=312.72µs p(95)=386.81µs
     http_req_failed................: 0.00%   ✓ 0             ✗ 1974808
     http_req_receiving.............: avg=15.78µs  min=3.86µs  med=10.99µs  max=6.72ms  p(90)=15.95µs  p(95)=18.47µs
     http_req_sending...............: avg=5.96µs   min=2.04µs  med=4.44µs   max=6.64ms  p(90)=6.53µs   p(95)=7.94µs
     http_req_tls_handshaking.......: avg=0s       min=0s      med=0s       max=0s      p(90)=0s       p(95)=0s
     http_req_waiting...............: avg=164.28µs min=16.71µs med=137.58µs max=5.36ms  p(90)=288.71µs p(95)=355.72µs
     http_reqs......................: 1974808 197459.999801/s
     iteration_duration.............: avg=245.73µs min=47.12µs med=180.94µs max=28.53ms p(90)=353.19µs p(95)=448.45µs
     iterations.....................: 1974808 197459.999801/s
     vus............................: 0       min=0           max=50
     vus_max........................: 50      min=50          max=50

k6 results (on a hetzner CPX11 (2VCPU, 2GB RAM)) built with --release for /shuffle

scenarios: (100.00%) 1 scenario, 50 max VUs, 40s max duration (incl. graceful stop):

• default: 50 looping VUs for 10s (gracefulStop: 30s)

running (10.0s), 00/50 VUs, 107538 complete and 0 interrupted iterations default ✗ [======================================] 50 VUs 10s

 data_received..................: 198 MB 20 MB/s
 data_sent......................: 9.4 MB 935 kB/s
 http_req_blocked...............: avg=3.4µs   min=552ns   med=1.39µs  max=5.31ms  p(90)=2.61µs  p(95)=3.63µs
 http_req_connecting............: avg=1.05µs  min=0s      med=0s      max=4.63ms  p(90)=0s      p(95)=0s
 http_req_duration..............: avg=4.57ms  min=55.96µs med=3.59ms  max=49.76ms p(90)=9.28ms  p(95)=12.14ms
   { expected_response:true }...: avg=4.57ms  min=55.96µs med=3.59ms  max=49.76ms p(90)=9.28ms  p(95)=12.14ms
 http_req_failed................: 0.00%  ✓ 0            ✗ 107538
 http_req_receiving.............: avg=56.17µs min=6.74µs  med=20.91µs max=34.14ms p(90)=80.49µs p(95)=101.03µs
 http_req_sending...............: avg=23.65µs min=2.92µs  med=7.91µs  max=22.52ms p(90)=15.11µs p(95)=51.58µs
 http_req_tls_handshaking.......: avg=0s      min=0s      med=0s      max=0s      p(90)=0s      p(95)=0s
 http_req_waiting...............: avg=4.49ms  min=33.36µs med=3.52ms  max=49.65ms p(90)=9.17ms  p(95)=11.93ms
 http_reqs......................: 107538 10750.424771/s
 iteration_duration.............: avg=4.63ms  min=83.71µs med=3.64ms  max=49.8ms  p(90)=9.37ms  p(95)=12.25ms
 iterations.....................: 107538 10750.424771/s
 vus............................: 50     min=50         max=50
 vus_max........................: 50     min=50         max=50