feature: add Cap interface{}

[zhuliquan]

add Cap func for getting the capacity of the cache. it's helpful for computing usage ratio of cache

[hashicorp-cla]

All committers have signed the CLA.

[mgaffney]

This results in an infinite recursive call.

[zhuliquan]

This results in an infinite recursive call.

Thank for your reviewing, I have fix it

[mgaffney]

@zhuliquan can you update this PR to resolve the conflicts. Once that is done, I will merge it. Sorry for the delay.

[zhuliquan]

@zhuliquan can you update this PR to resolve the conflicts. Once that is done, I will merge it. Sorry for the delay.

Yes, I have resolved

[mgaffney]

Your branch still has conflicts. Can you rebase off of main instead of doing a merge from main?

[zhuliquan]

@zhuliquan can you update this PR to resolve the conflicts. Once that is done, I will merge it. Sorry for the delay.

I'am very confused, all tests is ok before. Three are some cases is wrong, when I rung go test -v ./...
error info as below:

--- FAIL: TestLRUWithPurge (0.32s)
    expirable_lru_test.go:257: length differs from expected
--- FAIL: TestLoadingExpired (0.12s)
    expirable_lru_test.go:405: length differs from expected
--- FAIL: ExampleLRU (0.12s)

[mgaffney]

I don't get those errors when I run the tests

[zhuliquan]

I don't get those errors when I run the tests

Case (TestLRUWithPurge) isn't ok until I add more wait time (i.g. 2000 * time.Millisecond). are there some bugs in expire operation?

golang-lru/expirable/expirable_lru_test.go

Line 247 in d582c45

time.Sleep(200 * time.Millisecond) // expire