Initial upload of a GRPC implementation for Helidon

[rbair23]

This PR introduces a new module, pbj-grpc-helidon. This is a Helidon specific module (for version 4.0.8+) that provides the glue between HTTP2 (implemented by Helidon) and PBJ service endpoints (generated by PBJ based on a service definition in the protobuf schema files).

This PR does not introduce changes to the compiler to generate service interfaces or stubs. Rather, it assumes some other PR will do that, and it focuses on defining the runtime API and the Helidon module. Changes to the compiler will be done by #255.

In this PR:

• The build is upgraded to Java 21. The consensus node uses Java 21, as does Helidon.
• The module pbj-grpc-helidon is added
• The module pbj-grpc-helidon-config is added
• The interface ServiceInterface is added to pbj-runtime along with other gRPC interfaces

gRPC

gRPC is an HTTP2-based protocol for message passing. The specification and the documentation show how this is done. Both application/grpc+proto (protobuf based messages) and application/grpc+json (JSON-encoded protobuf) are supported.

A separate specification for web-grpc exists, but is not supported by this PR.

pbj-grpc-helidon

Public API in this module used directly by users include PbjRouting, and GrpcStatus.

Public API in this module used by Helidon directly include PbjProtocolSelector, PbjProtocolProvider, PbjProtocolConfigProvider, and PbjConfig.

All other entities are private to the module.

Design

Helidon uses the ServiceLoader to identify the ProtocolConfigProvider (used for configuration) and the Http2SubProtocolProvider to delegate HTTP2 calls to. Our implementation of Http2SubProtocolProvider, PbjProtocolProvider, is simply used to create (based on some provided configuration) the Http2SubProtocolSelector. This selector is where all the real works happens. For this module, that is PbjProtocolSelector.

If you look into the PbjProtocolSelector, you will find the subProtocol method. This method is called by Helidon. It is the main entry point for handling HTTP2 routes supported by this system. After some preliminary checks, it delegates to a "handler" (PbjErrorProtocolHandler or PbjProtocolHandler) to handle appropriate details (reading from and writing to HTTP2 streams).

The PbjProtocolHandler will delegate to a ServiceInterface to handle a particular method invocation, in such a way as to avoid all reflection. It provides a callback to the ServiceInterface through which the ServiceInterface can send start a request, stream messages, and close a request. The implementation of this callback handles all the glue with HTTP2.

That is, the classes in pbj-grpc-helidon are the glue between the HTTP code of Helidon (that knows nothing about gRPC or PBJ), and the PBJ ServiceInterfaces, which know nothing about HTTP2.

[jsync-swirlds]

A couple questions we should probably answer in the documentation for this PR:
What is the advantage of this approach over the existing Helidon gRPC implementation?
Could (or does) this work leverage the Helidon implementation to reduce the amount we must build ourselves?

[rbair23]

A couple questions we should probably answer in the documentation for this PR: What is the advantage of this approach over the existing Helidon gRPC implementation? Could (or does) this work leverage the Helidon implementation to reduce the amount we must build ourselves?

@jsync-swirlds, I'll add these to the issue itself (since it is more about the motivation rather than the solution)

[rbair23]

Could (or does) this work leverage the Helidon implementation to reduce the amount we must build ourselves?

I have put a message on their issue: helidon-io/helidon#5418. I will try to create a PR for Helidon that creates the right abstraction for us, such that our module could be truly minimal and hopefully avoid having to duplicate any work with what they're doing.

[github-actions]

JUnit Test Report

   66 files  +11     66 suites  +11   2m 18s ⏱️ -1s
1 244 tests +43  1 241 ✅ +42   3 💤 +1  0 ❌ ±0 
7 099 runs  +43  7 080 ✅ +42  19 💤 +1  0 ❌ ±0 

Results for commit 1aed82c. ± Comparison against base commit aa12028.

This pull request removes 8 and adds 50 tests. Note that renamed tests count towards both.

, 1
com.hedera.pbj.runtime.ProtoWriterToolsTest ‑ [1] FLOAT, com.hedera.pbj.runtime.ProtoWriterToolsTest$$Lambda/0x00007f45fc30ab00@4ae49387, [0.1, 0.5, 100.0], 12, com.hedera.pbj.runtime.ProtoWriterToolsTest$$Lambda/0x00007f45fc30ad18@6abb7b7d
com.hedera.pbj.runtime.ProtoWriterToolsTest ‑ [1] STRING, com.hedera.pbj.runtime.ProtoWriterToolsTest$$Lambda/0x00007f45fc31d098@4db728df, [string 1, testing here, testing there], com.hedera.pbj.runtime.ProtoWriterToolsTest$$Lambda/0x00007f45fc31d2b0@b0d3e7
com.hedera.pbj.runtime.ProtoWriterToolsTest ‑ [2] BYTES, com.hedera.pbj.runtime.ProtoWriterToolsTest$$Lambda/0x00007f45fc31d4c8@7cdfa824, [010203, ff7f0f, 42da07370bff], com.hedera.pbj.runtime.ProtoWriterToolsTest$$Lambda/0x00007f45fc31d6e0@18db3b3c
com.hedera.pbj.runtime.ProtoWriterToolsTest ‑ [2] DOUBLE, com.hedera.pbj.runtime.ProtoWriterToolsTest$$Lambda/0x00007f45fc30af30@7f2c995b, [0.1, 0.5, 100.0, 1.7653472635472653E240], 32, com.hedera.pbj.runtime.ProtoWriterToolsTest$$Lambda/0x00007f45fc30b148@101c15ad
com.hedera.pbj.runtime.ProtoWriterToolsTest ‑ [3] BOOL, com.hedera.pbj.runtime.ProtoWriterToolsTest$$Lambda/0x00007f45fc30b360@6068ebb2, [true, false, false, true, true, true], 6, com.hedera.pbj.runtime.ProtoWriterToolsTest$$Lambda/0x00007f45fc30b578@5a466dd
com.hedera.pbj.runtime.ProtoWriterToolsTest ‑ [4] ENUM, com.hedera.pbj.runtime.ProtoWriterToolsTest$$Lambda/0x00007f45fc30b790@1ed9d173, [Mock for EnumWithProtoMetadata, hashCode: 347436335, Mock for EnumWithProtoMetadata, hashCode: 1592970214, Mock for EnumWithProtoMetadata, hashCode: 644718663], 3, com.hedera.pbj.runtime.ProtoWriterToolsTest$$Lambda/0x00007f45fc30b9a8@298e002d
com.hedera.pbj.runtime.Utf8ToolsTest ‑ [4] 

com.hedera.pbj.grpc.helidon.PbjTest$BidiStreamingTests ‑ streamingBidi()
com.hedera.pbj.grpc.helidon.PbjTest$CompressionTests ‑ [1] gzip
com.hedera.pbj.grpc.helidon.PbjTest$CompressionTests ‑ [2] deflate
com.hedera.pbj.grpc.helidon.PbjTest$CompressionTests ‑ [3] random
com.hedera.pbj.grpc.helidon.PbjTest$CompressionTests ‑ identityIfNotSpecified()
com.hedera.pbj.grpc.helidon.PbjTest$CompressionTests ‑ identityIfSpecified()
com.hedera.pbj.grpc.helidon.PbjTest$ConcurrencyTests ‑ manyConcurrentUnaryCalls()
com.hedera.pbj.grpc.helidon.PbjTest$ContentTypeTests ‑ [1] application/grpc+proto
com.hedera.pbj.grpc.helidon.PbjTest$ContentTypeTests ‑ [2] application/grpc
com.hedera.pbj.grpc.helidon.PbjTest$ContentTypeTests ‑ contentTypeCanBeCustom()
…

♻️ This comment has been updated with latest results.

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
❌ -3.59% (target: -1.00%)	✅ 6.70%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (6da76df)	4361	1977	45.33%
Head commit (d5f5caa)	4779 (+418)	1995 (+18)	41.75% (-3.59%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#259)	537	36	6.70%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

See your quality gate settings    Change summary preferences

---

_{🚀 Don’t miss a bit, follow what’s new on Codacy.}

_{Codacy stopped sending the deprecated coverage status on June 5th, 2024. Learn more}

[github-actions]

Integration Test Report

    289 files  ±0      289 suites  ±0   9m 13s ⏱️ +33s
103 729 tests ±0  103 729 ✅ ±0  0 💤 ±0  0 ❌ ±0 
103 957 runs  ±0  103 957 ✅ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit 1aed82c. ± Comparison against base commit aa12028.

This pull request removes 3 and adds 3 tests. Note that renamed tests count towards both.

com.hedera.pbj.intergration.test.ParserNeverWrapsTest ‑ [1] com.hedera.pbj.intergration.test.ParserNeverWrapsTest$$Lambda/0x00007f05fc49f2d0@67c22d78
com.hedera.pbj.intergration.test.ParserNeverWrapsTest ‑ [2] com.hedera.pbj.intergration.test.ParserNeverWrapsTest$$Lambda/0x00007f05fc49f508@46fb22b5
com.hedera.pbj.intergration.test.ParserNeverWrapsTest ‑ [3] com.hedera.pbj.intergration.test.ParserNeverWrapsTest$$Lambda/0x00007f05fc49f740@4902c6e9

com.hedera.pbj.intergration.test.ParserNeverWrapsTest ‑ [1] com.hedera.pbj.intergration.test.ParserNeverWrapsTest$$Lambda/0x00007fea644e2008@a5f66be
com.hedera.pbj.intergration.test.ParserNeverWrapsTest ‑ [2] com.hedera.pbj.intergration.test.ParserNeverWrapsTest$$Lambda/0x00007fea644e2240@7978a822
com.hedera.pbj.intergration.test.ParserNeverWrapsTest ‑ [3] com.hedera.pbj.intergration.test.ParserNeverWrapsTest$$Lambda/0x00007fea644e2478@7eafc404

♻️ This comment has been updated with latest results.