[Enhancement] Support display datacache's hit rate in app level

[Smith-Cruise]

Why I'm doing:

hit rate in curl -XGET http://127.0.0.1:4449/api/datacache/stat can't reflect the real hit rate in the user-end.

This makes it difficult for users to determine whether DataCache is truly effective.

What I'm doing:

Add stat metrics at the application level.

Using curl -XGET http://127.0.0.1:4449/api/datacache/app_stat to check it.

curl -XGET http://127.0.0.1:4449/api/datacache/app_stat
{
    "hit_bytes": 1262,
    "miss_bytes": 1262,
    "hit_rate": 0.5,
    "hit_bytes_last_minute": 0,
    "miss_bytes_last_minute": 0,
    "hit_rate_last_minute": 0.0
}

Algorithm: hit_rate = read_cache_bytes / (read_cache_bytes + read_network_bytes).

What type of PR is this:

• BugFix
• Feature
• Enhancement
• Refactor
• UT
• Doc
• Tool

Does this PR entail a change in behavior?

• Yes, this PR will result in a change in behavior.
• No, this PR will not result in a change in behavior.

If yes, please specify the type of change:

• Interface/UI changes: syntax, type conversion, expression evaluation, display information
• Parameter changes: default values, similar parameters but with different default values
• Policy changes: use new policy to replace old one, functionality automatically enabled
• Feature removed
• Miscellaneous: upgrade & downgrade compatibility, etc.

Checklist:

• I have added test cases for my bug fix or my new feature
• This pr needs user documentation (for new or modified features or behaviors)
  • I have added documentation for my new feature or new function
• This is a backport pr

Bugfix cherry-pick branch check:

• I have checked the version labels which the pr will be auto-backported to the target branch
  • 3.3
  • 3.2
  • 3.1
  • 3.0
  • 2.5

[GavinMar]

How about to move this class to another independent file? Because it actually save the upper layer statistics and has nothing to do with the underly block cache module. Also, it is unnecessary to include the bvar header to other modules which use block cache.

[Smith-Cruise]

changed

[github-actions]

[FE Incremental Coverage Report]

✅ pass : 0 / 0 (0%)

[github-actions]

[BE Incremental Coverage Report]

✅ pass : 36 / 36 (100.00%)

file detail

	path	covered_line	new_line	coverage	not_covered_line_detail
🔵	be/src/http/action/datacache_action.cpp	17	17	100.00%	[]
🔵	be/src/exec/hdfs_scanner.cpp	1	1	100.00%	[]
🔵	be/src/block_cache/block_cache_hit_rate_counter.hpp	18	18	100.00%	[]

[github-actions]

@Mergifyio backport branch-3.3

[mergify]

backport branch-3.3

✅ Backports have been created

• #48617 [Enhancement] Support display datacache's hit rate in app level (backport #48450) has been created for branch branch-3.3