Add queue middleware

[adrianlungu]

Hoping this middleware might be useful for others, I'm submitting this PR that adds a Queue Middleware.

Basically, it creates a queue of size x and a worker pool of size y so no more than y requests can be processed at any given time while x requests can stack up in the queue.

[aldas]

just some quick remarks:

• It would be better if you return errors instead of using c.Error(). It would allow middlewares up in chain to react on errors
• what happens when next middleware/handler panics - will semaphores be released eventually?

[adrianlungu]

Good points!

I've adjusted the code, now errors should properly return upwards the chain, and semaphores should be released through the defer mechanism. Also added a test case for panics to test that everything's working as expected.

[codecov[bot]]

Codecov Report

Merging #1882 (cb70c01) into master (2acb24a) will increase coverage by 0.12%. The diff coverage is 87.87%.

@@            Coverage Diff             @@
##           master    #1882      +/-   ##
==========================================
+ Coverage   90.21%   90.34%   +0.12%     
==========================================
  Files          31       32       +1     
  Lines        2770     2806      +36     
==========================================
+ Hits         2499     2535      +36     
- Misses        173      175       +2     
+ Partials       98       96       -2     

Impacted Files	Coverage Δ
middleware/queue.go	87.87% <87.87%> (ø)
middleware/jwt.go	79.80% <0.00%> (ø)
middleware/rate_limiter.go	100.00% <0.00%> (ø)
bind.go	89.41% <0.00%> (+0.19%)	:arrow_up:
middleware/recover.go	93.75% <0.00%> (+12.50%)	:arrow_up:

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[adrianlungu]

Thanks @pafuent , I've updated the code, hope the tests go well this time 🤞

[adrianlungu]

Is there anything else I should look into for this MR to get merged ?

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed within a month if no further activity occurs. Thank you for your contributions.

[adrianlungu]

Any update on this ?