feat: add batch process metrics

doc/plugins/prometheus.md

@@ -125,6 +125,7 @@ Or you can goto [Grafana official](https://grafana.com/grafana/dashboards/11719)
 * `Bandwidth`: Total Bandwidth (egress/ingress) flowing through apisix. This metric is available per service and as a sum across all services.
 * `etcd reachability`: A gauge type with a value of 0 or 1, representing if etcd can be reached by a apisix or not.
 * `Connections`: Various Nginx connection metrics like active, reading, writing, and number of accepted connections.
+* `Batch process entries`: A gauge type, when we use plugins such as: sys logger, http logger, sls logger, tcp logger, udp logger and zipkin, the surplus entries which not sended will be statistics in the metrics.
 
 Here is the original metric data of apisix:
 
@@ -138,6 +139,14 @@ apisix_bandwidth{type="egress",service="foo.com"} 2379
 apisix_bandwidth{type="ingress",service="127.0.0.2"} 83
 apisix_bandwidth{type="ingress",service="bar.com"} 76
 apisix_bandwidth{type="ingress",service="foo.com"} 988
+# HELP apisix_batch_process_entries batch process remaining entries
+# TYPE apisix_batch_process_entries gauge
+apisix_batch_process_entries{name="http-logger",route_id="9",server_addr="127.0.0.1"} 1
+apisix_batch_process_entries{name="sls-logger",route_id="9",server_addr="127.0.0.1"} 1
+apisix_batch_process_entries{name="tcp-logger",route_id="9",server_addr="127.0.0.1"} 1
+apisix_batch_process_entries{name="udp-logger",route_id="9",server_addr="127.0.0.1"} 1
+apisix_batch_process_entries{name="sys-logger",route_id="9",server_addr="127.0.0.1"} 1
+apisix_batch_process_entries{name="zipkin_report",route_id="9",server_addr="127.0.0.1"} 1
 # HELP apisix_etcd_reachable Config server etcd reachable from Apisix, 0 is unreachable
 # TYPE apisix_etcd_reachable gauge
 apisix_etcd_reachable 1

doc/zh-cn/plugins/prometheus.md

@@ -123,7 +123,7 @@ plugin_attr:
 * `Bandwidth`: 流经apisix的总带宽(可分出口带宽和入口带宽). 每个服务指标或者是所有服务指标的总和都可以统计到。
 * `etcd reachability`: apisix 连接 etcd 的可用性，用 0 和 1来表示。
 * `Connections`: 各种的 Nginx 连接指标，如 active（正处理的活动连接数），reading（nginx 读取到客户端的 Header 信息数），writing（nginx 返回给客户端的 Header 信息数），已建立的连接数。.
-
+* `Batch process entries`: 批处理未发送数据统计，当你使用了批处理发送插件，比如：sys logger, http logger, sls logger, tcp logger, udp logger and zipkin, 那么你将会在此指标中看到当前尚未发送的数据量。
 这里是apisix的原始的指标数据集:
 
 ```
@@ -136,6 +136,14 @@ apisix_bandwidth{type="egress",service="foo.com"} 2379
 apisix_bandwidth{type="ingress",service="127.0.0.2"} 83
 apisix_bandwidth{type="ingress",service="bar.com"} 76
 apisix_bandwidth{type="ingress",service="foo.com"} 988
+# HELP apisix_batch_process_entries batch process remaining entries
+# TYPE apisix_batch_process_entries gauge
+apisix_batch_process_entries{name="http-logger",route_id="9",server_addr="127.0.0.1"} 1
+apisix_batch_process_entries{name="sls-logger",route_id="9",server_addr="127.0.0.1"} 1
+apisix_batch_process_entries{name="tcp-logger",route_id="9",server_addr="127.0.0.1"} 1
+apisix_batch_process_entries{name="udp-logger",route_id="9",server_addr="127.0.0.1"} 1
+apisix_batch_process_entries{name="sys-logger",route_id="9",server_addr="127.0.0.1"} 1
+apisix_batch_process_entries{name="zipkin_report",route_id="9",server_addr="127.0.0.1"} 1
 # HELP apisix_etcd_reachable Config server etcd reachable from Apisix, 0 is unreachable
 # TYPE apisix_etcd_reachable gauge
 apisix_etcd_reachable 1