storage: simplify mirror implementation

[imeoer]

Nydusd uses a registry backend which generates a surge of blob requests without
auth tokens on initial startup. This caused mirror backends (e.g. dragonfly)
to process very slowly, the commit fixes this problem.

It implements waiting for the first blob request to complete before making other
blob requests, this ensures the first request caches a valid registry auth token,
and subsequent concurrent blob requests can reuse the cached token.

This change is worthwhile to reduce concurrent token requests, it also makes the
behavior consistent with containerd, which first requests the image manifest and
caches the token before concurrently requesting blobs.

Relevant Issue (if applicable)

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Details

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Types of changes

What types of changes does your PullRequest introduce? Put an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation Update (if none of the other choices apply)

Checklist

Go over all the following points, and put an x in all the boxes that apply.

• I have updated the documentation accordingly.
• I have added tests to cover my changes.

[codecov]

Codecov Report

Merging #1375 (dc83210) into master (be52ebd) will increase coverage by 0.09%.
The diff coverage is 49.69%.

@@            Coverage Diff             @@
##           master    #1375      +/-   ##
==========================================
+ Coverage   46.17%   46.26%   +0.09%     
==========================================
  Files         122      122              
  Lines       37913    37970      +57     
  Branches    37913    37970      +57     
==========================================
+ Hits        17506    17567      +61     
+ Misses      19489    19481       -8     
- Partials      918      922       +4     

Impacted Files	Coverage Δ
api/src/config.rs	70.52% <ø> (-0.04%)	⬇️
storage/src/backend/object_storage.rs	32.07% <0.00%> (+4.20%)	⬆️
storage/src/backend/connection.rs	43.00% <18.75%> (+0.45%)	⬆️
storage/src/backend/registry.rs	34.20% <53.42%> (+7.27%)	⬆️
storage/src/backend/http_proxy.rs	75.14% <100.00%> (-0.64%)	⬇️

... and 3 files with indirect coverage changes

[anolis-bot]

@imeoer , the title has been updated, so a new test job has been submitted. Please wait in patience. The test job url: https://tone.openanolis.cn/ws/nrh4nnio/test_result/85389

[anolis-bot]

@imeoer , the code has been updated, so a new test job has been submitted. Please wait in patience. The test job url: https://tone.openanolis.cn/ws/nrh4nnio/test_result/85390

[anolis-bot]

@imeoer , the code has been updated, so a new test job has been submitted. Please wait in patience. The test job url: https://tone.openanolis.cn/ws/nrh4nnio/test_result/85391

[anolis-bot]

@imeoer , The CI test is completed, please check result:

Test Case		Test Result
build rust golang image		✅ SUCCESS
compile nydusd		✅ SUCCESS
compile ctr remote		✅ SUCCESS
compile nydus snapshotter		✅ SUCCESS
run container with rafs		✅ SUCCESS
run container with zran		✅ SUCCESS
run container with rafs and compile linux		✅ SUCCESS

Congratulations, your test job passed!

[anolis-bot]

@imeoer , The CI test is completed, please check result:

Test Case		Test Result
build rust golang image		✅ SUCCESS
compile nydusd		✅ SUCCESS
compile ctr remote		✅ SUCCESS
compile nydus snapshotter		✅ SUCCESS
run container with rafs		✅ SUCCESS
run container with zran		✅ SUCCESS
run container with rafs and compile linux		✅ SUCCESS

Congratulations, your test job passed!

[anolis-bot]

@imeoer , the title has been updated, so a new test job has been submitted. Please wait in patience. The test job url: https://tone.openanolis.cn/ws/nrh4nnio/test_result/85392

[anolis-bot]

@imeoer , the title has been updated, so a new test job has been submitted. Please wait in patience. The test job url: https://tone.openanolis.cn/ws/nrh4nnio/test_result/85393

[anolis-bot]

@imeoer , The CI test is completed, please check result:

Test Case		Test Result
build rust golang image		✅ SUCCESS
compile nydusd		✅ SUCCESS
compile ctr remote		✅ SUCCESS
compile nydus snapshotter		✅ SUCCESS
run container with rafs		✅ SUCCESS
run container with zran		✅ SUCCESS
run container with rafs and compile linux		✅ SUCCESS

Congratulations, your test job passed!

[anolis-bot]

@imeoer , The CI test is completed, please check result:

Test Case		Test Result
build rust golang image		✅ SUCCESS
compile nydusd		✅ SUCCESS
compile ctr remote		✅ SUCCESS
compile nydus snapshotter		✅ SUCCESS
run container with rafs		✅ SUCCESS
run container with zran		✅ SUCCESS
run container with rafs and compile linux		✅ SUCCESS

Congratulations, your test job passed!

[anolis-bot]

@imeoer , The CI test is completed, please check result:

Test Case		Test Result
build rust golang image		✅ SUCCESS
compile nydusd		✅ SUCCESS
compile ctr remote		✅ SUCCESS
compile nydus snapshotter		✅ SUCCESS
run container with rafs		✅ SUCCESS
run container with zran		✅ SUCCESS
run container with rafs and compile linux		✅ SUCCESS

Congratulations, your test job passed!

[anolis-bot]

@imeoer , The CI test is completed, please check result:

Test Case		Test Result
build rust golang image		✅ SUCCESS
compile nydusd		✅ SUCCESS
compile ctr remote		✅ SUCCESS
compile nydus snapshotter		✅ SUCCESS
run container with rafs		✅ SUCCESS
run container with zran		✅ SUCCESS
run container with rafs and compile linux		✅ SUCCESS

Congratulations, your test job passed!

[anolis-bot]

@imeoer , the code has been updated, so a new test job has been submitted. Please wait in patience. The test job url: https://tone.openanolis.cn/ws/nrh4nnio/test_result/85533

[anolis-bot]

@imeoer , The CI test is completed, please check result:

Test Case		Test Result
build rust golang image		✅ SUCCESS
compile nydusd		❌ FAIL

Sorry, your test job failed. Please get the details in the link.

[anolis-bot]

@imeoer , the code has been updated, so a new test job has been submitted. Please wait in patience. The test job url: https://tone.openanolis.cn/ws/nrh4nnio/test_result/85559

[anolis-bot]

@imeoer , The CI test is completed, please check result:

Test Case		Test Result
build rust golang image		✅ SUCCESS
compile nydusd		✅ SUCCESS
compile ctr remote		✅ SUCCESS
compile nydus snapshotter		✅ SUCCESS
run container with rafs		✅ SUCCESS
run container with zran		✅ SUCCESS
run container with rafs and compile linux		✅ SUCCESS

Congratulations, your test job passed!

[sctb512]

LGTM

[imeoer]

Merge it first, will update nydus-snapshotter later.

[imeoer]

@jiangliu PTAL.