skywalking源码分析第二十二篇一agent端实战之JDBC插件

文章目录

• ​​源码分析一插件定义​​
• ​​源码分析一方法拦截器定义​​
• ​​总结​​

源码分析一插件定义

• StatementInstrumentation插件拦截StatementImpl相关方法进行增强
• jdbc含包含其他众多插件
• 其中CONSTRUCTOR_INTERCEPTOR并非skywalking源码,其为笔者私有定制,用于全链路压测场景

public class StatementInstrumentation extends AbstractMysqlInstrumentation {
    private static final String SERVICE_METHOD_INTERCEPTOR =  org.apache.skywalking.apm.plugin.jdbc.mysql.Constants.STATEMENT_EXECUTE_METHODS_INTERCEPTOR;
    public static final String MYSQL8_STATEMENT_CLASS_NAME = "com.mysql.cj.jdbc.StatementImpl";
    private static final String CONSTRUCTOR_INTERCEPTOR = "org.apache.skywalking.apm.plugin.jdbc.mysql.v8.StatementCreateInterceptor";

    @Override public ConstructorInterceptPoint[] getConstructorsInterceptPoints() {
        return new ConstructorInterceptPoint[]{ new ConstructorInterceptPoint() {
            @Override
            public ElementMatcher<MethodDescription> getConstructorMatcher() {
                return any();
            }

            @Override
            public String getConstructorInterceptor() {
                return CONSTRUCTOR_INTERCEPTOR;
            }
        }};
    }

    @Override public InstanceMethodsInterceptPoint[] getInstanceMethodsInterceptPoints() {
        return new InstanceMethodsInterceptPoint[] {
            new InstanceMethodsInterceptPoint() {
                @Override public ElementMatcher<MethodDescription> getMethodsMatcher() {
                    return named("execute")
                        .or(named("executeQuery"))
                        .or(named("executeUpdate"))
                        .or(named("executeLargeUpdate"))
                        .or(named("executeBatchInternal"))
                        .or(named("executeUpdateInternal"))
                        .or(named("executeQuery"))
                        .or(named("executeBatch"));
                }

                @Override public String getMethodsInterceptor() {
                    return SERVICE_METHOD_INTERCEPTOR;
                }

                @Override public boolean isOverrideArgs() {
                    return false;
                }
            }
        };
    }
    
    @Override protected ClassMatch enhanceClass() {
        return byName(MYSQL8_STATEMENT_CLASS_NAME);
    }
}

源码分析一方法拦截器定义

• 设置数据库span的相关kv键值对
• 包含sql语句等

public class StatementExecuteMethodsInterceptor implements InstanceMethodsAroundInterceptor {
    @Override
    public final void beforeMethod(EnhancedInstance objInst, Method method, Object[] allArguments,
        Class<?>[] argumentsTypes,
        MethodInterceptResult result) throws Throwable {
        StatementEnhanceInfos cacheObject = (StatementEnhanceInfos)objInst.getSkyWalkingDynamicField();
        ConnectionInfo connectInfo = cacheObject.getConnectionInfo();
        if (connectInfo != null) {
            // 创建Exitspan
            AbstractSpan span = ContextManager.createExitSpan(buildOperationName(connectInfo, method.getName(), cacheObject.getStatementName()), connectInfo.getDatabasePeer());
            Tags.DB_TYPE.set(span, "sql");
            // 设置数据库名称
            Tags.DB_INSTANCE.set(span, connectInfo.getDatabaseName());
            String sql = "";
            if (allArguments.length > 0) {
                sql = (String)allArguments[0];
            }

            为span设置sql语句
            Tags.DB_STATEMENT.set(span, sql);
            span.setComponent(connectInfo.getComponent());

            SpanLayer.asDB(span);
        }
    }

    @Override
    public final Object afterMethod(EnhancedInstance objInst, Method method, Object[] allArguments,
        Class<?>[] argumentsTypes,
        Object ret) throws Throwable {
        StatementEnhanceInfos cacheObject = (StatementEnhanceInfos)objInst.getSkyWalkingDynamicField();
        if (cacheObject.getConnectionInfo() != null) {
            // 将TracerContext.activeSpanStack中的span弹栈加入Segment
            ContextManager.stopSpan();
        }
        return ret;
    }

   

    private String buildOperationName(ConnectionInfo connectionInfo, String methodName, String statementName) {
        return connectionInfo.getDBType() + "/JDBI/" + statementName + "/" + methodName;
    }
}

总结

• jdbc插件众多,本文分析的Statement是一个重点,其创建的span持有sql语句,查询参数等信息