NAS-132019 / 25.04 / Remove DST gaps from chart reports

[bvasilenko]

Changes:

Screenshot attached to a ticket depicts the DST gap, which occurs when server's internal clock does a transition from time point 1:59 to time point 3:00 GMT+0100, and timezone info (GMT+0100) is lost, resulting in representational 1:01 hour gap

In pseudocode:

Actual:

> new Date(`Jan 01 2024 01:59:00`) - new Date(`Jan 01 2024 03:00:00`)
  -> -3660000

Expected:

> new Date(`Jan 01 2024 01:59:00 GMT+0000`) - new Date(`Jan 01 2024 03:00:00 GMT+0100`) 
  -> -60000

This PR removes DST gaps from reporting time series.

Testing:

To simulate DST, you need to add the addDstGaps method in the src/app/pages/reports-dashboard/reports.service.ts file and apply it to reportingData.data as shown below:

Replace the constant dstTimestamp with the value of the DST change time (in seconds!).

For example, 1732168676 <=> Thu Nov 21 2024 08:57:56 GMT+0300.

A gap of one hour should appear on the chart:

Using the removeDstGaps method should remove this gap.

addDstGaps method code:

addDstGaps(data: number[][]): number[][] {
    data.forEach((item) => {
      const dstTimestamp = new Date().getTime() / 1000 - 10 * 60; // Set DST time, e.g. 1732168676
      if (item[0] > dstTimestamp) {
        item[0] = item[0] + 3600;
      }
    });
    return data;
}

[bugclerk]

Jira URL: https://ixsystems.atlassian.net/browse/NAS-132019

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.37%. Comparing base (807b9d8) to head (f620f67).
Report is 11 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #11086      +/-   ##
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+ Coverage   82.30%   82.37%   +0.06%     
==========================================
  Files        1631     1632       +1     
  Lines       57286    57325      +39     
  Branches     5917     5915       -2     
==========================================
+ Hits        47152    47220      +68     
+ Misses      10134    10105      -29     

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[undsoft]

So if I understand the PR correctly, middleware returns timestamps that may jump from some value to another hour. If this is the case, then this is not a UI issue as timestamps don't care about DST.