Implementation of redis locks (for single redis masters)

[mattrasband]

What do these changes do?

Provide an implementation of locking utilizing redis

Are there changes in behavior for the user?

Users now have a .lock method on the GenericCommandsMixin, but it's optional path.

Related issue number

#43

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
• If you provide code modification, please add yourself to CONTRIBUTORS.txt
  • The format is <Name> <Surname>.
  • Please keep alphabetical order, the file is sorted by names.
• Add a new news fragment into the CHANGES folder
  • name it <issue_id>.<type> (e.g. 588.bugfix)
  • if you don't have an issue_id change it to the pr id after creating the PR
  • ensure type is one of the following:
    • .feature: Signifying a new feature.
    • .bugfix: Signifying a bug fix.
    • .doc: Signifying a documentation improvement.
    • .removal: Signifying a deprecation or removal of public API.
    • .misc: A ticket has been closed, but it is not of interest to users.
  • Make sure to use full sentences with correct case and punctuation, for example: Fix issue with non-ascii contents in doctest text files.

[codecov]

Codecov Report

Merging #573 (5924033) into master (e8c33e3) will decrease coverage by 0.22%.
The diff coverage is 90.00%.

@@            Coverage Diff             @@
##           master     #573      +/-   ##
==========================================
- Coverage   96.86%   96.64%   -0.23%     
==========================================
  Files          57       57              
  Lines        8431     8051     -380     
  Branches      567      571       +4     
==========================================
- Hits         8167     7781     -386     
- Misses        188      191       +3     
- Partials       76       79       +3     

Impacted Files	Coverage Δ
tests/generic_commands_test.py	99.63% <83.33%> (-0.37%)	⬇️
aioredis/locks.py	93.93% <90.90%> (-6.07%)	⬇️
aioredis/commands/generic.py	100.00% <100.00%> (ø)
aioredis/errors.py	100.00% <100.00%> (ø)
tests/conftest.py	88.29% <0.00%> (-0.68%)	⬇️
tests/connection_commands_test.py	95.45% <0.00%> (-0.55%)	⬇️
tests/sentinel_failover_test.py	87.31% <0.00%> (-0.55%)	⬇️
aioredis/commands/__init__.py	95.18% <0.00%> (-0.33%)	⬇️
tests/pyreader_test.py	96.87% <0.00%> (-0.27%)	⬇️
aioredis/sentinel/pool.py	76.80% <0.00%> (-0.27%)	⬇️
... and 29 more

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[iMerica]

LGTM 👍

[mattrasband]

Updated to resolve conflicts/changes from master

[seandstewart]

@mrasband -

Thanks for the contribution! Would you be willing to rebase your changes off of master and resolve the merge conflicts?

You may be asked to sign a CLA after which I think we can move forward with merging it in!

[CLAassistant]

All committers have signed the CLA.

[mattrasband]

@seandstewart Yep, I will get to that sometime today or tomorrow!

[mattrasband]

This out of date enough I will close and reopen.