Define a `DLocker` interface for distributed locker

[ahrtr]

Also updated the contrib/lock example to demo how to use the DLocker.

For more background, please refer to the article by Martin Kleppmann.

• It should be an improvement to help users better use etcd as a distributed lock.
• It's also backward compatible. It won't break any existing applications

[k8s-ci-robot]

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This pull-request has been approved by: ahrtr

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[codecov-commenter]

Codecov Report

:x: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 68.78%. Comparing base (18eb5c6) to head (bddc7a9). :warning: Report is 2026 commits behind head on main.

:warning: Current head bddc7a9 differs from pull request most recent head 9786c9e

Please upload reports for the commit 9786c9e to get more accurate results.

Files with missing lines	Patch %	Lines
client/v3/concurrency/mutex.go	0.00%	3 Missing :warning:

Additional details and impacted files

Files with missing lines	Coverage Δ
client/v3/concurrency/mutex.go	63.75% <0.00%> (+2.71%)	:arrow_up:

... and 16 files with indirect coverage changes

@@            Coverage Diff             @@
##             main   #18779      +/-   ##
==========================================
+ Coverage   68.74%   68.78%   +0.04%     
==========================================
  Files         420      420              
  Lines       35512    35515       +3     
==========================================
+ Hits        24411    24430      +19     
+ Misses       9671     9659      -12     
+ Partials     1430     1426       -4     

---

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[ivanvc]

/test pull-etcd-verify

I want to check if it was a flake in govet.

[ahrtr]

/test pull-etcd-integration-1-cpu-amd64

[k8s-ci-robot]

PR needs rebase.

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[github-actions[bot]]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed after 21 days if no further activity occurs. Thank you for your contributions.

[k8s-ci-robot]

@ahrtr: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-etcd-markdown-lint	9786c9e1c208ff63a96ea22c9ddc9de7da3dfebb	link	true	/test pull-etcd-markdown-lint
ci-etcd-robustness-release36-amd64	9786c9e1c208ff63a96ea22c9ddc9de7da3dfebb	link	true	/test ci-etcd-robustness-release36-amd64
ci-etcd-robustness-release35-amd64	9786c9e1c208ff63a96ea22c9ddc9de7da3dfebb	link	true	/test ci-etcd-robustness-release35-amd64
ci-etcd-robustness-release34-amd64	9786c9e1c208ff63a96ea22c9ddc9de7da3dfebb	link	true	/test ci-etcd-robustness-release34-amd64
pull-etcd-govulncheck-main	9786c9e1c208ff63a96ea22c9ddc9de7da3dfebb	link	true	/test pull-etcd-govulncheck-main
pull-etcd-govulncheck	9786c9e1c208ff63a96ea22c9ddc9de7da3dfebb	link	true	/test pull-etcd-govulncheck

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[github-actions[bot]]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed after 21 days if no further activity occurs. Thank you for your contributions.