Feature: cache timestamp.json to accelerate

[lucklove]

What problem does this PR solve?

We implemented a base function, ensureManifests(), which will fetch n.root.json and timestamp.json, and if the timestamp.json is a new one, fetch snapshot.json and {component}.json.

However, there are many places invoke ensureManifests() and TiUP will fetch timestamp.json and root.json many times even though there is no change on them, which cause TiUP run slowly.

What is changed and how it works?

Cache timestamp.json in memory so that TiUP will only fetch it once every time the user execute TiUP command.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release notes:

NONE

[codecov-io]

Codecov Report

Merging #1212 (b0205f7) into master (c9376f1) will decrease coverage by 4.63%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1212      +/-   ##
==========================================
- Coverage   52.43%   47.79%   -4.64%     
==========================================
  Files         289      288       -1     
  Lines       20563    20564       +1     
==========================================
- Hits        10782     9829     -953     
- Misses       8085     9021     +936     
- Partials     1696     1714      +18     

Flag	Coverage Δ
cluster	44.90% <83.33%> (+1.23%)	⬆️
dm	25.54% <83.33%> (-0.04%)	⬇️
integrate	47.79% <100.00%> (+0.96%)	⬆️
playground	3.09% <0.00%> (-0.01%)	⬇️
tiup	16.53% <100.00%> (+0.05%)	⬆️
unittest	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
cmd/mirror.go	48.71% <100.00%> (+0.11%)	⬆️
pkg/repository/v1_repository.go	51.25% <100.00%> (-11.76%)	⬇️
components/dm/ansible/worker.go	0.00% <0.00%> (-100.00%)	⬇️
pkg/meta/err.go	0.00% <0.00%> (-81.25%)	⬇️
pkg/telemetry/scrub.go	6.66% <0.00%> (-80.00%)	⬇️
pkg/cluster/api/error.go	0.00% <0.00%> (-80.00%)	⬇️
pkg/telemetry/telemetry.go	0.00% <0.00%> (-68.43%)	⬇️
pkg/utils/error.go	0.00% <0.00%> (-63.64%)	⬇️
components/dm/ansible/import.go	0.00% <0.00%> (-62.70%)	⬇️
pkg/cluster/executor/local.go	0.00% <0.00%> (-55.72%)	⬇️
... and 51 more

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[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• AstroProfundis

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[AstroProfundis]

/hold

unit tests are failing

[AstroProfundis]

/unhold

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 8ddf0f4