xds: implement lb policy backend metric api (#5639)

* implemented utility methods to create ClientStreamTracer.Factory with OrcaReportListener installed for retrieving per-request ORCA data

* added unit tests

* use delegatesTo instead of spy

* implemented OrcaReportingHelper delegating to some original Helper for load balancing policies accessing OOB metric reports

* added unit tests for out-of-band ORCA metric accessing API in a separate test class

* rebase to master, resolve the breaking change of StreamInfo class being final with builder

* trashed hashCode/equal for OrcaReportingConfig

* changed log level and channel trace event level to ERROR as required by design doc

* added OrcaReportingHelperWrapper layer to allow updating report interval at any time

* reverse the naming of parent/child helper, child helper is the outer-most helper in the wrapping structure

* changed orca listener interface to use separate listener interfaces for per-request and out-of-band cases

* added more comprehensive unit tests

* added test case for per-request reporting that parent creates its own stream tracer

* fixed bug of directly assign reporting config, which would cause it be mutated later

* separate test cases for updating reporting config at different time

* fixed lint style error

* polish comments

* minor polish in unit tests

* refactor OrcaUtil class into OrcaOobUtil and OrcaPerRequestUtil and get rid of static methods for easier user testing

* hide BackoffPolicyProvider and Stopwatch supplier in OrcaOobUtil's public API

* add javadoc for getInstance() methods

* ensure the same Subchannel instance created by the helper that has corresponding OrcaOobReportListener registered are passed to the listener callback

* removed costNames foe OrcaReportingConfig

* removed redundant checks

* reformated the OrcaOobUtilTest class to put helper methods in the bottom

* fixed impl with changes made on Subchannel (SubchannelStateListener now ties with Subchannel)

* fixed comments

* added usage examples in javadoc for OrcaUtils

* add method comments for OrcaUtil's listener API threading

* make fields in OrcaReportingConfig final

* fixed OrcaOobUtilTest for calling setOrcaReportingConfig inside syncContext

* added ExperimentalApi annotation for Orca utils
4 files changed
tree: fab6984e43242798f929ba78c58ba9c944a6b883
  1. .github/
  2. all/
  3. alts/
  4. android/
  5. android-interop-testing/
  6. api/
  7. auth/
  8. benchmarks/
  9. bom/
  10. buildscripts/
  11. compiler/
  12. context/
  13. core/
  14. cronet/
  15. documentation/
  16. examples/
  17. gae-interop-testing/
  18. gradle/
  19. grpclb/
  20. interop-testing/
  21. netty/
  22. okhttp/
  23. protobuf/
  24. protobuf-lite/
  25. services/
  26. stub/
  27. testing/
  28. testing-proto/
  29. xds/
  30. .bazelignore
  31. .gitattributes
  32. .gitignore
  33. .travis.yml
  34. AUTHORS
  35. BUILD.bazel
  36. build.gradle
  37. codecov.yml
  38. COMPILING.md
  39. CONTRIBUTING.md
  40. gradlew
  41. gradlew.bat
  42. java_grpc_library.bzl
  43. LICENSE
  44. NOTICE.txt
  45. README.md
  46. RELEASING.md
  47. repositories.bzl
  48. run-test-client.sh
  49. run-test-server.sh
  50. SECURITY.md
  51. settings.gradle
  52. WORKSPACE
README.md

gRPC-Java - An RPC library and framework

gRPC-Java works with JDK 7. gRPC-Java clients are supported on Android API levels 14 and up (Ice Cream Sandwich and later). Deploying gRPC servers on an Android device is not supported.

TLS usage typically requires using Java 8, or Play Services Dynamic Security Provider on Android. Please see the Security Readme.

Join the chat at https://gitter.im/grpc/grpc Build Status Coverage Status

Getting Started

For a guided tour, take a look at the quick start guide or the more explanatory gRPC basics.

The examples and the Android example are standalone projects that showcase the usage of gRPC.

Download

Download the JARs. Or for Maven with non-Android, add to your pom.xml:

<dependency>
  <groupId>io.grpc</groupId>
  <artifactId>grpc-netty-shaded</artifactId>
  <version>1.21.0</version>
</dependency>
<dependency>
  <groupId>io.grpc</groupId>
  <artifactId>grpc-protobuf</artifactId>
  <version>1.21.0</version>
</dependency>
<dependency>
  <groupId>io.grpc</groupId>
  <artifactId>grpc-stub</artifactId>
  <version>1.21.0</version>
</dependency>

Or for Gradle with non-Android, add to your dependencies:

compile 'io.grpc:grpc-netty-shaded:1.21.0'
compile 'io.grpc:grpc-protobuf:1.21.0'
compile 'io.grpc:grpc-stub:1.21.0'

For Android client, use grpc-okhttp instead of grpc-netty-shaded and grpc-protobuf-lite instead of grpc-protobuf:

compile 'io.grpc:grpc-okhttp:1.21.0'
compile 'io.grpc:grpc-protobuf-lite:1.21.0'
compile 'io.grpc:grpc-stub:1.21.0'

Development snapshots are available in Sonatypes's snapshot repository.

Generated Code

For protobuf-based codegen, you can put your proto files in the src/main/proto and src/test/proto directories along with an appropriate plugin.

For protobuf-based codegen integrated with the Maven build system, you can use protobuf-maven-plugin (Eclipse and NetBeans users should also look at os-maven-plugin's IDE documentation):

<build>
  <extensions>
    <extension>
      <groupId>kr.motd.maven</groupId>
      <artifactId>os-maven-plugin</artifactId>
      <version>1.5.0.Final</version>
    </extension>
  </extensions>
  <plugins>
    <plugin>
      <groupId>org.xolstice.maven.plugins</groupId>
      <artifactId>protobuf-maven-plugin</artifactId>
      <version>0.5.1</version>
      <configuration>
        <protocArtifact>com.google.protobuf:protoc:3.7.1:exe:${os.detected.classifier}</protocArtifact>
        <pluginId>grpc-java</pluginId>
        <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.21.0:exe:${os.detected.classifier}</pluginArtifact>
      </configuration>
      <executions>
        <execution>
          <goals>
            <goal>compile</goal>
            <goal>compile-custom</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

For protobuf-based codegen integrated with the Gradle build system, you can use protobuf-gradle-plugin:

apply plugin: 'com.google.protobuf'

buildscript {
  repositories {
    mavenCentral()
  }
  dependencies {
    classpath 'com.google.protobuf:protobuf-gradle-plugin:0.8.8'
  }
}

protobuf {
  protoc {
    artifact = "com.google.protobuf:protoc:3.7.1"
  }
  plugins {
    grpc {
      artifact = 'io.grpc:protoc-gen-grpc-java:1.21.0'
    }
  }
  generateProtoTasks {
    all()*.plugins {
      grpc {}
    }
  }
}

The prebuilt protoc-gen-grpc-java binary uses glibc on Linux. If you are compiling on Alpine Linux, you may want to use the Alpine grpc-java package which uses musl instead.

API Stability

APIs annotated with @Internal are for internal use by the gRPC library and should not be used by gRPC users. APIs annotated with @ExperimentalApi are subject to change in future releases, and library code that other projects may depend on should not use these APIs.

We recommend using the grpc-java-api-checker (an Error Prone plugin) to check for usages of @ExperimentalApi and @Internal in any library code that depends on gRPC. It may also be used to check for @Internal usage or unintended @ExperimentalApi consumption in non-library code.

How to Build

If you are making changes to gRPC-Java, see the compiling instructions.

High-level Components

At a high level there are three distinct layers to the library: Stub, Channel, and Transport.

Stub

The Stub layer is what is exposed to most developers and provides type-safe bindings to whatever datamodel/IDL/interface you are adapting. gRPC comes with a plugin to the protocol-buffers compiler that generates Stub interfaces out of .proto files, but bindings to other datamodel/IDL are easy and encouraged.

Channel

The Channel layer is an abstraction over Transport handling that is suitable for interception/decoration and exposes more behavior to the application than the Stub layer. It is intended to be easy for application frameworks to use this layer to address cross-cutting concerns such as logging, monitoring, auth, etc.

Transport

The Transport layer does the heavy lifting of putting and taking bytes off the wire. The interfaces to it are abstract just enough to allow plugging in of different implementations. Note the transport layer API is considered internal to gRPC and has weaker API guarantees than the core API under package io.grpc.

gRPC comes with three Transport implementations:

  1. The Netty-based transport is the main transport implementation based on Netty. It is for both the client and the server.
  2. The OkHttp-based transport is a lightweight transport based on OkHttp. It is mainly for use on Android and is for client only.
  3. The in-process transport is for when a server is in the same process as the client. It is useful for testing, while also being safe for production use.