| commit | 6b48eb4e083a4fbbe0559b2b3386afdcf46464d8 | [log] [tgz] |
|---|---|---|
| author | Kun Zhang <[email protected]> | Tue Nov 06 16:48:09 2018 -0800 |
| committer | GitHub <[email protected]> | Tue Nov 06 16:48:09 2018 -0800 |
| tree | 478ba236eae88852d11623b6a58a8f92cc469e5f | |
| parent | 80c973cbd508f4588db57630eb83be1242c95fb3 [diff] |
core: ChannelLogger (#5024) Introduce ChannelLogger, which is a utility provided to LoadBalancer implementations (potentially NameResolvers too) for recording events to channel trace. This is immediately required by client-side health checking (#4932, https://github.com/grpc/proposal/blob/master/A17-client-side-health-checking.md) to record an error about disabling health checking. It is also useful for any LoadBalancer implementations to record important information. ChannelLogger implementation is backed by the internal ChannelTracer/Channelz. Because Channelz limits the number of retained events, and events are lost once the process ends, I have expanded it to also log Java logger. This would provide a "last resort" in cases where there are too many events or off-line investigation is needed. All logs are prefixed with logId so that they can be easily associated with the involved Channel/Subchannel. To prevent log spamming, the logs are all at FINE level or below so that they are not visible by default. They are logged to ChannelLogger's logger, so that user can have precise control. There are also more verbose information that may not fit in ChannelTracer, but can be useful for debugging. It's desirable that these logs are associated with logId, but they currently manually include the logId, which is cumbersome and may result in inconsistency. For this use case, I added the DEBUG level for ChannelLogger, which formats the log in the same way as other levels, while not recorded to Channelz. I have converted most logging and channel tracer recording in the Channel implementation and LoadBalancers.
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.
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 the JARs. Or for Maven with non-Android, add to your pom.xml:
<dependency> <groupId>io.grpc</groupId> <artifactId>grpc-netty-shaded</artifactId> <version>1.16.1</version> </dependency> <dependency> <groupId>io.grpc</groupId> <artifactId>grpc-protobuf</artifactId> <version>1.16.1</version> </dependency> <dependency> <groupId>io.grpc</groupId> <artifactId>grpc-stub</artifactId> <version>1.16.1</version> </dependency>
Or for Gradle with non-Android, add to your dependencies:
compile 'io.grpc:grpc-netty-shaded:1.16.1' compile 'io.grpc:grpc-protobuf:1.16.1' compile 'io.grpc:grpc-stub:1.16.1'
For Android client, use grpc-okhttp instead of grpc-netty-shaded and grpc-protobuf-lite instead of grpc-protobuf:
compile 'io.grpc:grpc-okhttp:1.16.1' compile 'io.grpc:grpc-protobuf-lite:1.16.1' compile 'io.grpc:grpc-stub:1.16.1'
Development snapshots are available in Sonatypes's snapshot repository.
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:3.5.1-1:exe:${os.detected.classifier}</protocArtifact> <pluginId>grpc-java</pluginId> <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.16.1:exe:${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:0.8.5' } } protobuf { protoc { artifact = "com.google.protobuf:protoc:3.5.1-1" } plugins { grpc { artifact = 'io.grpc:protoc-gen-grpc-java:1.16.1' } } 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.
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.
If you are making changes to gRPC-Java, see the compiling instructions.
At a high level there are three distinct layers to the library: Stub, Channel, and Transport.
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.
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.
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: