Reimplement retry with incremental backoff

[blowmage]

This implements the simplified retry mechanics. It splits apart the old RetryOptions object and places retry_codes and retry_settings directly on CallOptions. This was done to allow users to configure only the settings they want to change, without having to specify all settings.

RetrySettings is a replacement for BackoffSettings. It provides a simpler set of values to configure the incremental backoff. It also allows users to only specify the values they want to change, not every value.

CallOptions#kwargs has been removed.

[refs #150, fixes #163, refs #165]

[codecov[bot]]

Codecov Report

Merging #172 into master will decrease coverage by 0.6%. The diff coverage is 89.65%.

@@            Coverage Diff             @@
##           master     #172      +/-   ##
==========================================
- Coverage   98.28%   97.67%   -0.61%     
==========================================
  Files          18       22       +4     
  Lines        1165     1292     +127     
==========================================
+ Hits         1145     1262     +117     
- Misses         20       30      +10

Impacted Files	Coverage Δ
test/google/gax/paged_enumerable/enum_test.rb	100% <ø> (ø)	:arrow_up:
test/google/gax/util_test.rb	100% <ø> (ø)	:arrow_up:
test/google/gax/operation_test.rb	100% <ø> (ø)	:arrow_up:
...oogle/gax/paged_enumerable/invalid_request_test.rb	100% <ø> (ø)	:arrow_up:
lib/google/gax/settings.rb	100% <ø> (ø)	:arrow_up:
test/google/gax/error_test.rb	100% <ø> (ø)	:arrow_up:
...ogle/gax/paged_enumerable/invalid_response_test.rb	79.48% <ø> (-1.47%)	:arrow_down:
...ax/paged_enumerable/valid_request_response_test.rb	100% <ø> (ø)	:arrow_up:
lib/google/gax/errors.rb	100% <100%> (ø)	:arrow_up:
test/google/gax/api_callable_test.rb	97.53% <100%> (ø)
... and 9 more

---

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[codecov[bot]]

Codecov Report

Merging #172 into master will decrease coverage by 0.6%. The diff coverage is 89.65%.

@@            Coverage Diff             @@
##           master     #172      +/-   ##
==========================================
- Coverage   98.28%   97.67%   -0.61%     
==========================================
  Files          18       22       +4     
  Lines        1165     1292     +127     
==========================================
+ Hits         1145     1262     +117     
- Misses         20       30      +10

Impacted Files	Coverage Δ
test/google/gax/paged_enumerable/enum_test.rb	100% <ø> (ø)	:arrow_up:
test/google/gax/util_test.rb	100% <ø> (ø)	:arrow_up:
test/google/gax/operation_test.rb	100% <ø> (ø)	:arrow_up:
...oogle/gax/paged_enumerable/invalid_request_test.rb	100% <ø> (ø)	:arrow_up:
lib/google/gax/settings.rb	100% <ø> (ø)	:arrow_up:
test/google/gax/error_test.rb	100% <ø> (ø)	:arrow_up:
...ogle/gax/paged_enumerable/invalid_response_test.rb	79.48% <ø> (-1.47%)	:arrow_down:
...ax/paged_enumerable/valid_request_response_test.rb	100% <ø> (ø)	:arrow_up:
lib/google/gax/errors.rb	100% <100%> (ø)	:arrow_up:
test/google/gax/api_callable_test.rb	97.53% <100%> (ø)
... and 9 more

---

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[codecov-io]

Codecov Report

Merging #172 into master will decrease coverage by 57.2%. The diff coverage is 33.89%.

@@             Coverage Diff             @@
##           master     #172       +/-   ##
===========================================
- Coverage   98.28%   41.08%   -57.21%     
===========================================
  Files          18        6       -12     
  Lines        1165      185      -980     
===========================================
- Hits         1145       76     -1069     
- Misses         20      109       +89

Impacted Files	Coverage Δ
lib/google/gax/errors.rb	64% <0%> (-36%)	:arrow_down:
lib/google/gax.rb	20% <100%> (-80%)	:arrow_down:
lib/google/gax/api_callable.rb	25.92% <20%> (-70.08%)	:arrow_down:
lib/google/gax/retry_settings.rb	30.76% <30.76%> (ø)
lib/google/gax/retry_manager.rb	42.85% <42.85%> (ø)
lib/google/gax/grpc.rb	35.29% <0%> (-58.83%)	:arrow_down:
lib/google/gax/operation.rb
test/google/gax/grpc_test.rb
... and 6 more

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[codecov-io]

Codecov Report

Merging #172 into master will increase coverage by 0.27%. The diff coverage is 99.41%.

@@            Coverage Diff             @@
##           master     #172      +/-   ##
==========================================
+ Coverage   98.28%   98.55%   +0.27%     
==========================================
  Files          18       25       +7     
  Lines        1165     1452     +287     
==========================================
+ Hits         1145     1431     +286     
- Misses         20       21       +1

Impacted Files	Coverage Δ
lib/google/gax/operation.rb	100% <ø> (ø)	:arrow_up:
test/google/gax/util_test.rb	100% <ø> (ø)	:arrow_up:
lib/google/gax/grpc.rb	94.11% <ø> (ø)	:arrow_up:
test/google/gax/error_test.rb	100% <ø> (ø)	:arrow_up:
test/google/gax/paged_enumerable/enum_test.rb	100% <ø> (ø)	:arrow_up:
lib/google/gax/settings.rb	100% <ø> (ø)	:arrow_up:
...ogle/gax/paged_enumerable/invalid_response_test.rb	79.48% <ø> (-1.47%)	:arrow_down:
test/google/gax/operation_test.rb	100% <ø> (ø)	:arrow_up:
...oogle/gax/paged_enumerable/invalid_request_test.rb	100% <ø> (ø)	:arrow_up:
...ax/paged_enumerable/valid_request_response_test.rb	100% <ø> (ø)	:arrow_up:
... and 18 more

---

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Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 64712da...d9f381f. Read the comment docs.