客户端方案

• 确定收集各类型golang runtime metrcis的收集工具
• 确定数据收集和数据上报的协作方式

float64(rtm.PauseNs[(rtm.NumGC+255)%256]) / float64(1000000),

syntax = "proto3";

package skywalking.v3;

option java_package = "org.apache.skywalking.apm.network.language.agent.v3";
option go_package = "github.com/easonyipj/skywalking-goapi/collect/language/agent/v3";

import "common/Common.proto";

// Define the Golang metrics report service.
service GolangMetricReportService {
  rpc collect (GolangMetricCollection) returns (Commands) {
  }
}

message GolangMetricCollection {
  repeated GolangMetric metrics = 1;
  string service = 2;
  string serviceInstance = 3;
}

message GolangMetric {
  int64 time = 1;
  int64 heapAlloc = 2;
  int64 stackInUse = 3;
  int64 gcNum = 4;
  float gcPauseTime = 5;
  int64 goroutineNum = 6;
  int64 threadNum = 7;
  float cpuUsedRate = 8;
  float memUsedRate = 9;
}

服务端方案

1. 启动时通过定义的OAL脚本动态生成Golang Metrics相关的类和对应的Dispatcher
2. 启动时自动检查Golang Metrics相关的表是否已创建，如果未创建则自动创建
3. 启动时注册gRPC handler 接收客户端的数据
4. 将数据进行处理后持久化
5. 接收前端的数据查询请求

服务端初始化

1. golang mertices相关的Source子类；
2. golang mertices相关的OAL脚本
3. 新增注册gRPC handler
4. 新增golang metrics的处理类GolangSourceDispatcher

详细方案如下：

1. skywalking OAP中的每个metric都对应一个org.apache.skywalking.oap.server.core.source.Source的子类和一个OAL脚本中的一行，因此需要先定义好Source类和OAL脚本；
   
   1. 1. 在oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/source中新增golang mertices相关的Source子类，用于保存相关的指标和生成对应的数据库表，以CPU指标为例，需新建下面的类，关键点：
         1. 继承Source
         2. @ScopeDeclaration中的id和scope()方法返回的id保持一致

            @ScopeDeclaration(id = SERVICE_INSTANCE_GOLANG_CPU, name = "ServiceInstanceGolangCPU", catalog = SERVICE_INSTANCE_CATALOG_NAME)
            @ScopeDefaultColumn.VirtualColumnDefinition(fieldName = "entityId", columnName = "entity_id", isID = true, type = String.class)
            public class ServiceInstanceGolangCPU extends Source {
                @Override
                public int scope() {
                    return DefaultScopeDefine.SERVICE_INSTANCE_JVM_CPU;
                }
            
                @Override
                public String getEntityId() {
                    return String.valueOf(id);
                }
            
                @Getter
                @Setter
                private String id;
                @Getter
                @Setter
                @ScopeDefaultColumn.DefinedByField(columnName = "name", requireDynamicActive = true)
                private String name;
                @Getter
                @Setter
                @ScopeDefaultColumn.DefinedByField(columnName = "service_name", requireDynamicActive = true)
                private String serviceName;
                @Getter
                @Setter
                @ScopeDefaultColumn.DefinedByField(columnName = "service_id")
                private String serviceId;
                @Getter
                @Setter
                private double usePercent;
            }

      2. 新增OAL脚本
      3. 在oap-server/server-starter/src/main/resources/oal中新增处理golang runtime mertics的的OAL文件

         instance_golang_cpu = from(ServiceInstanceJVMCPU.usePercent).doubleAvg();

      4. 在oap-server/oal-grammar/src/main/antlr4/org/apache/skywalking/oal/rt/grammar/OALLexer.g4和OALParser.g4中新增相关的关键字 
          
   2. 服务端初始化时，应该注册好gRPC handler，并且使用OAL脚本动态生成处理golang runtime mertics的类：
       
      1. 在apm-network模块的proto中新增上文文GolangMetric.proto，并执行编译命令./mvnw compile -Dmaven.test.skip=true
      2. 在oap-server/server-receiver-plugin新增处理golang mertices的plugin模块skywalking-golang-receiver-plugin，目录结构如下：

         ├── skywalking-golang-receiver-plugin
         │   ├── pom.xml
         │   └── src
         │       ├── main
         │       │   ├── java
         │       │   │   └── org
         │       │   │       └── apache
         │       │   │           └── skywalking
         │       │   │               └── oap
         │       │   │                   └── server
         │       │   │                       └── receiver
         │       │   │                           └── golang
         │       │   │                               ├── module
         │       │   │                               │   └── GolangModule.java 
         │       │   │                               └── provider
         │       │   │                                   ├── GolangModuleProvider.java
         │       │   │                                   ├── GolangOALDefine.java
         │       │   │                                   └── handler
         │       │   │                                       └── GolangMetricReportServiceHandler.java
         │       │   └── resources
         │       │       └── services
         │       │           ├── org.apache.skywalking.oap.server.library.module.ModuleDefine
         │       │           └── org.apache.skywalking.oap.server.library.module.ModuleProvider
         │       └── test
         │           └── java

          
         1. 新增接收gRPC请求的handler GolangMetricReportServiceHandler，负责解析数据并初步封装，然后调用golang metrics的处理类GolangSourceDispatcher的sendMetric方法
         2. 新增相应的OALDefine - GolangOALDefine.java，需要在构造方法中传入对应OAL脚本的名称和source类所在的位置，以生成相关的表，示例如下

            public class GolangOALDefine extends OALDefine {
                public static final GolangOALDefine INSTANCE = new GolangOALDefine();
            
                private GolangOALDefine() {
                    super(
                            "oal/golang.oal",
                            "org.apache.skywalking.oap.server.core.source"
                    );
                }
            }

         3. 新增相应的GolangModule和GolangModuleProvider，并在resources/META-INF/services目录下的配置文件指定实现类的全路径名（同时在oap-server/server-starter/pom.xml中补充新增的skywalking-golang-receiver-plugin依赖，便于进行跨包SPI；在application.yml中新增），便于启动时通过SPI机制加载这些类，GolangModuleProvider中完成对gRPC handelr-GolangMetricReportServiceHandler的注册和OAL脚本的解析（动态生成类并且自动生成相关数据库表）

            
            public class GolangModuleProvider extends ModuleProvider {
            
                @Override
                public String name() {
                    return "default";
                }
            
                @Override
                public Class<? extends ModuleDefine> module() {
                    return GolangModule.class;
                }
            
                @Override
                public ModuleConfig createConfigBeanIfAbsent() {
                    return null;
                }
            
                @Override
                public void prepare() throws ServiceNotProvidedException, ModuleStartException {
            
                }
            
                @Override
                public void start() throws ServiceNotProvidedException, ModuleStartException {
                    getManager().find(CoreModule.NAME)
                            .provider()
                            .getService(OALEngineLoaderService.class)
                            .load(GolangOALDefine.INSTANCE);
                    GRPCHandlerRegister grpcHandlerRegister = getManager().find(SharingServerModule.NAME)
                            .provider()
                            .getService(GRPCHandlerRegister.class);
                    GolangMetricReportServiceHandler golangMetricReportServiceHandler = new GolangMetricReportServiceHandler(getManager());
                    grpcHandlerRegister.addHandler(golangMetricReportServiceHandler);
                }
            
                @Override
                public void notifyAfterCompleted() throws ServiceNotProvidedException, ModuleStartException {
            
                }
            
                @Override
                public String[] requiredModules() {
                    return new String[] {
                            CoreModule.NAME,
                            SharingServerModule.NAME
                    };
                }
            }

 数据接收和处理

1. 在oap-server/analyzer/agent-analyzer/src/main/java/org/apache/skywalking/oap/server/analyzer/provider中新增GolangSourceDispatcher，用于接受gRPC handler的信息，使用source包中的实体类封装这些信息，并调用sourceReceiver.receive方法

   ├── agent-analyzer
   │   ├── pom.xml
   │   ├── src
   │   │   ├── main
   │   │   │   ├── java
   │   │   │   │   └── org
   │   │   │   │       └── apache
   │   │   │   │           └── skywalking
   │   │   │   │               └── oap
   │   │   │   │                   └── server
   │   │   │   │                       └── analyzer
   │   │   │   │                           ├── module
   │   │   │   │                           │   └── AnalyzerModule.java
   │   │   │   │                           └── provider
   │   │   │   │                               ├── AnalyzerModuleConfig.java
   │   │   │   │                               ├── AnalyzerModuleProvider.java
   │   │   │   │                               ├── golang
   │   │   │   │                               │   └── GolangSourceDispatcher.java
   │   │   │   │                               ├── jvm
   │   │   │   │                               │   └── JVMSourceDispatcher.java