Dubbo Metrics and Observability

This project has three main modules: indicator collection, local aggregation and indicator push. 1.indicator collection : Define MetricsCollector under the common package to collect various internal indicators of Dubbo, and count the basic indicators (total number of requests, total number of successes, total number of failures, number of requests being processed, number of threads, request response time) when the service is invoked. 2.local aggregation : The result of index collection is used as the basic index, and the sliding window algorithm is used to calculate some quantile indexes. This function is controlled by XML label and is disabled by default. 3.indicator push : Encapsulate collected and aggregated indicators and push them to a third-party server in a specific way.