add a test to illustrate rate-limit application

[krichprollsch]

Test result for lightpanda-io/browser#3266

server      http://127.0.0.2:33221/page
runs        200 navigations x 2 phases, 15000ms pause between them
browser     ../../browser/zig-out/bin/lightpanda



========================================================================================
SUMMARY
========================================================================================

  mode      phase  reqs  span (s)  req/s  gap p50  gap p95  gap max  client p50
  --------  -----  ----  --------  -----  -------  -------  -------  ----------
  off           1   200      0.77  257.4      3.2      5.3     92.9         3.2
                2   200      0.64  309.2      3.1      3.8      5.9         3.1
  fixed100      1   200     19.00   10.5     99.8    100.7    100.8        99.8
                2   200     19.00   10.5     99.9    100.7    100.9        99.9
  adaptive      1   200     16.06   12.4     99.2    100.6    100.7        99.1
                2   200     16.06   12.4     99.2    100.6    100.7        98.7

  gap = time between two consecutive requests as seen by the server (ms)
  client p50 = median page.goto() duration as seen by puppeteer (ms)


----------------------------------------------------------------------------------------
1. SERVER POV -- requests received over time (all modes)
----------------------------------------------------------------------------------------

           requests received
      400 |                       o                                       aaa     fff
          |                      oo                                    aaaa    ffff  
          |                      o                                  aaaa    ffff     
          |                      o                               aaaa    ffff        
      306 |                      o                            aaa     ffff           
          |                      o                         aaa    ffff               
          |                      o                      aaaa   ffff                  
          |                      o                     aa   ffff                     
      212 | o                    a   f                a   fff                        
          | o                 aaaaffff                                               
          | o              aaaaffff                                                  
          | o          aaaaaffff                                                     
      118 | o       aaaaffff                                                         
          |oo    aaaaffff                                                            
          |o   aaaffff                                                               
          |o aaafff                                                                  
     23.5 |aaaf                                                                      
        0 |a                                                                         
          +--------------------------------------------------------------------------
           0.001           13.3               26.5              39.8             53.0
           elapsed (s)

           o disabled (--http-nav-delay 0)   f fixed 100ms (--http-nav-delay 100)   a adaptive (default, no flag)

  The flat part in the middle of each line is the pause. A line that bends
  to the right is slowing down; adaptive bends, then starts steep again
  after the pause because its pressure cooled down.


----------------------------------------------------------------------------------------
2. SERVER POV -- spacing between requests: disabled (--http-nav-delay 0)
----------------------------------------------------------------------------------------

           gap since previous request (ms)
     92.9 |  o                                 :                                     
          |                                    :                                     
          |                                    :                                     
          |                                    :                                     
     64.3 |                                    :                                     
          |                                    :                                     
          |                                    :                                     
          |                                    :                                     
     35.7 |                                    :                                     
          |                                    :                                     
          |                                    :                                     
          |                                    :                                     
     7.14 |o o o oo       o  o   oo  o  oo o   :ooo o  ooo o    o o      o   o       
        0 |ooooooooooooooooooooooooooooo ooooooo oooooooooooooooooooooooooooooooooooo
          +--------------------------------------------------------------------------
           2                102                201               301              400
           request number   (":" = the 15000ms pause)

  end of phase 1: 3ms spacing
  start of phase 2 after 15000ms idle: 4ms spacing


----------------------------------------------------------------------------------------
2. SERVER POV -- spacing between requests: fixed 100ms (--http-nav-delay 100)
----------------------------------------------------------------------------------------

           gap since previous request (ms)
      101 |  fffffffffffffffffffffffffffffffffff  fffffffffffffffffffffffffffffffffff
          |  f                                 :                                     
          |                                    :                                     
          |  f                                 :                                     
     69.9 |                                    : f                                   
          |                                    :                                     
          |                                    :                                     
          |                                    :                                     
     38.8 |                                    :                                     
          |                                    :                                     
          |                                    :                                     
          |                                    :                                     
     7.76 |                                    :f                                    
        0 |ff                                  :ff                                   
          +--------------------------------------------------------------------------
           2                102                201               301              400
           request number   (":" = the 15000ms pause)

  end of phase 1: 100ms spacing
  start of phase 2 after 15000ms idle: 4ms spacing


----------------------------------------------------------------------------------------
2. SERVER POV -- spacing between requests: adaptive (default, no flag)
----------------------------------------------------------------------------------------

           gap since previous request (ms)
      101 |                  aaaaaaaaaaaaaaaaaaa                  aaaaaaaaaaaaaaaaaaa
          |  a                                 :                                     
          |                                    :                                     
          |         aaaaaaaaaa                 :         aaaaaaaaa                   
     69.7 |                                    :                                     
          |     aaaaa                          :    aaaaaa                           
          |                                    :                                     
          |                                    :                                     
     38.7 |   aa                               :  aaa                                
          |  a                                 :                                     
          |                                    :  a                                  
          |                                    :                                     
     7.75 |                                    :a                                    
        0 |aaa                                 :aa                                   
          +--------------------------------------------------------------------------
           2                102                201               301              400
           request number   (":" = the 15000ms pause)

  end of phase 1: 100ms spacing
  start of phase 2 after 15000ms idle: 5ms spacing
  browser logged "navigation delayed" 1 time(s)


----------------------------------------------------------------------------------------
3. CLIENT POV -- page.goto() duration (all modes)
----------------------------------------------------------------------------------------

           goto() duration (ms)
      103 |  ffffffffffffffffaaaaaaaaaaaaaaaaaaa: ffffffffffffffffaaaaaaaaaaaaaaaaaaa
          |   fffffffffffffffaaaaaaaaaaaaaaaaaaa: fffff ffff fffffaaaaaaaaaaaaaaaaaaa
          |  a                                  :                                    
          |  f      aaaaaaaaaa                  :        aaaaaaaaaa                  
     75.7 |         a   a a                     :               a                    
          |                                     :f                                   
          |     aaaaa                           :   aaaaaa                           
          |                                     :    a                               
     48.1 |                                     :                                    
          |   aaa                               : aaa                                
          |                                     :                                    
          |   a                                 : a                                  
     20.6 |                                     :                                    
          |                                     :                                    
          |afaoo ooo      o  o oooo  o  ooo oo  aaooo  ooo o   oo oo  o ooo  o   o   
        0 |aaaoooooooooooooooooooooooooooooooooofaooooooooooooooooooooooooooooooooooo
          +--------------------------------------------------------------------------
           1                101                201               300              400
           navigation number   (":" = the 15000ms pause)

           o disabled (--http-nav-delay 0)   f fixed 100ms (--http-nav-delay 100)   a adaptive (default, no flag)

  The client waits inside page.goto(): the rate limiter holds the request
  before it goes on the wire, so the delay shows up as navigation time.