Support Feature Flags for Breaking Changes

[demirkayaender]

What changed?
Note: ignore go.mod changes for now. They will be fixed once the client changes are in

Shipping WorkflowExecutionAlreadyCompletedError broke some customers' workflow logic since it was changing previous contract between their workflow and cadence server. With this change, they can enable the new feature only when they are ready.

Changes need to go in with the following orders

• IDL changes: Add IDL changes to support feature flags cadence-idl#73
• Client-side changes: Support Client Feature flags cadence-go-client#1103
• Server-side changes: Support Feature Flags for Breaking Changes #4257
• Samples changes: Add feature flags samples cadence-samples#45

Ignore go.mod/sum changes for now, I will update them once IDL and client changes are in.

Why?
Without this change, shipping new features will break customer workflows.

How did you test it?
go test -run TestIntegrationSuite github.com/uber/cadence/host -testify.m TestSignalWorkflow$ -v

Potential risks

Release notes

Documentation Changes

[coveralls]

Pull Request Test Coverage Report for Build 4ee32b95-34fc-43c4-aa78-52a472cee6c7

• 94 of 142 (66.2%) changed or added relevant lines in 14 files are covered.
• 117 unchanged lines in 15 files lost coverage.
• Overall coverage decreased (-0.03%) to 60.243%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
tools/cli/workflowCommands.go	16	17	94.12%
common/types/mapper/thrift/errors.go	0	4	0.0%
tools/cli/workflowBatchCommands.go	0	4	0.0%
common/types/errors.go	0	5	0.0%
common/types/shared.go	0	5	0.0%
common/client/versionChecker.go	30	37	81.08%
common/types/mapper/proto/errors.go	0	8	0.0%
common/types/mapper/thrift/shared.go	0	14	0.0%

Files with Coverage Reduction	New Missed Lines	%
common/persistence/executionStore.go	2	75.75%
common/persistence/statsComputer.go	2	96.43%
common/task/weightedRoundRobinTaskScheduler.go	2	89.12%
service/history/execution/mutable_state_builder.go	2	70.02%
service/history/queue/timer_queue_processor.go	2	58.77%
common/cache/lru.go	3	90.73%
common/persistence/cassandra/cassandraPersistence.go	3	54.09%
common/archiver/filestore/historyArchiver.go	4	80.54%
common/types/mapper/thrift/shared.go	4	70.58%
service/history/queue/timer_queue_processor_base.go	4	78.83%

Totals
Change from base Build 4d95b83b-a240-498f-8680-2d4571e321f7:	-0.03%
Covered Lines:	88961
Relevant Lines:	147671

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💛 - Coveralls

[JuanPalacios]

Is this feature included in the java client?

[demirkayaender]

Yes, java client supports it. Here's an example usage: https://github.com/uber/cadence-java-samples/blob/e3a0e310435d51c7152b2c904eef960d22fa4f5a/src/main/java/com/uber/cadence/samples/hello/HelloSignal.java#L103