wip: [do not review] improve hnsw iterator

[zhengbuqian]

by adding unvisited invalid nodes in initial search to pending visit candidates

/kind improvement issue: #500

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: zhengbuqian

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• ~~OWNERS~~ [zhengbuqian]

Approvers can indicate their approval by writing /approve in a comment Approvers can cancel approval by writing /approve cancel in a comment

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 71.14%. Comparing base (3c46f4c) to head (b7a6a77). Report is 68 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##           main     #528       +/-   ##
=========================================
+ Coverage      0   71.14%   +71.14%     
=========================================
  Files         0       67       +67     
  Lines         0     4401     +4401     
=========================================
+ Hits          0     3131     +3131     
- Misses        0     1270     +1270     

see 67 files with indirect coverage changes

[zhengbuqian]

/hold