Low-resolution timers on Windows

[tsandall]

It seems the timers we're using through the Go standard library are not high enough resolution for some the operations that we keep track of. This results in metrics being returned from OPA or emitted in the decision logs that are set to zero. Perhaps there's an alternative timer API we should be calling for Windows systems.

Example from iterating over 10, 100, 1000 element array:

PS C:\Users\torin> .\Downloads\opa_windows_amd64.exe eval '{1|numbers.range(1,10)[_]}' --metrics
{
  "result": [
    {
      "expressions": [
        {
          "value": [
            1
          ],
          "text": "{1|numbers.range(1,10)[_]}",
          "location": {
            "row": 1,
            "col": 1
          }
        }
      ]
    }
  ],
  "metrics": {
    "timer_rego_query_compile_ns": 10200,
    "timer_rego_query_eval_ns": 0,
    "timer_rego_query_parse_ns": 502300
  }
}
PS C:\Users\torin> .\Downloads\opa_windows_amd64.exe eval '{1|numbers.range(1,100)[_]}' --metrics
{
  "result": [
    {
        }
      ]
    }
  ],
  "metrics": {
    "timer_rego_query_compile_ns": 0,
    "timer_rego_query_eval_ns": 18000,
    "timer_rego_query_parse_ns": 0
  }
}
PS C:\Users\torin> .\Downloads\opa_windows_amd64.exe eval '{1|numbers.range(1,1000)[_]}' --metrics
{
  "result": [
    {
      "expressions": [
        {
          "value": [
            1
          ],
          "text": "{1|numbers.range(1,1000)[_]}",
          "location": {
            "row": 1,
            "col": 1
          }
        }
      ]
    }
  ],
  "metrics": {
    "timer_rego_query_compile_ns": 0,
    "timer_rego_query_eval_ns": 1016000,
    "timer_rego_query_parse_ns": 508700
  }
}

[stale]

This issue has been automatically marked as inactive because it has not had any activity in the last 30 days.

[philipaconrad]

MacOS and Windows seem to have situations where the timer resolution can be coarser or finer than anticipated, especially when power management is involved.

Additional Context:

• runtime: windows system clock resolution issue golang/go#8687
• runtime: time.Now clock resolution unexpectedly low on Windows XP. golang/go#11313
• runtime: osRelax reduces precision of short sleeps golang/go#20937 (Might be worth looking into for a workaround?)
• runtime: Interferes with Windows timer frequency golang/go#28255
• time: Sleep(1 * time.Nanosecond) pauses at least 1.9ms on Windows 10 or Windows 7 golang/go#29485
• Related blog post, documenting behavior changes in the Windows 10 timer system: https://randomascii.wordpress.com/2020/10/04/windows-timer-resolution-the-great-rule-change/

[stale]

This issue has been automatically marked as inactive because it has not had any activity in the last 30 days.