refine a bit and add session limit

Author: SylvainJuge

instrumentation/jmx-metrics/library/src/main/resources/jmx/rules/wildfly.yaml

@@ -12,11 +12,18 @@ rules:
         metric: created
         type: counter
         desc: The number of sessions created
-      # wildfly.session.count
+      # wildfly.session.active.count
       activeSessions:
-        metric: count
+        metric: active.count
         type: updowncounter
         desc: The number of active sessions
+      # wildfly.session.active.limit
+      maxActiveSessions:
+        metric: active.limit
+        type: updowncounter
+        desc: The maximum number of active sessions
+        # discard negative values used to indicate absence of limit
+        dropNegativeValues: true
       # wildfly.session.expired
       expiredSessions:
         metric: expired
@@ -39,7 +46,7 @@ rules:
       requestCount:
         metric: request.count
         unit: "{request}"
-        desc: The number of requests received
+        desc: The number of requests served
       # wildfly.request.duration.sum
       processingTime:
         metric: request.duration.sum

instrumentation/jmx-metrics/library/src/test/java/io/opentelemetry/instrumentation/jmx/rules/WildflyTest.java

@@ -77,13 +77,21 @@ private static MetricsVerifier createMetricsVerifier() {
                     .hasUnit("{session}")
                     .hasDataPointsWithOneAttribute(deploymentAttribute))
         .add(
-            "wildfly.session.count",
+            "wildfly.session.active.count",
             metric ->
                 metric
                     .isUpDownCounter()
                     .hasDescription("The number of active sessions")
                     .hasUnit("{session}")
                     .hasDataPointsWithOneAttribute(deploymentAttribute))
+        .add(
+            "wildfly.session.active.limit",
+            metric ->
+                metric
+                    .isUpDownCounter()
+                    .hasDescription("The maximum number of active sessions")
+                    .hasUnit("{session}")
+                    .hasDataPointsWithOneAttribute(deploymentAttribute))
         .add(
             "wildfly.session.expired",
             metric ->
@@ -106,7 +114,7 @@ private static MetricsVerifier createMetricsVerifier() {
             metric ->
                 metric
                     .isCounter()
-                    .hasDescription("The number of requests received")
+                    .hasDescription("The number of requests served")
                     .hasUnit("{request}")
                     .hasDataPointsWithAttributes(serverListenerAttributes))
         .add(

instrumentation/jmx-metrics/library/wildfly.md

@@ -4,14 +4,15 @@ Here is the list of metrics based on MBeans exposed by Wildfly.
 
 | Metric Name                             | Type          | Attributes                                                 | Description                                                     |
 |-----------------------------------------|---------------|------------------------------------------------------------|-----------------------------------------------------------------|
-| wildfly.network.io                      | Counter       | wildfly.server, network.io.direction                       | Total number of bytes transferred                               |
+| wildfly.network.io                      | Counter       | wildfly.server, wildfly.listener, network.io.direction     | Total number of bytes transferred                               |
 | wildfly.error.count                     | Counter       | wildfly.server, wildfly.listener                           | The number of requests that have resulted in a 5xx response     |
-| wildfly.request.count                   | Counter       | wildfly.server, wildfly.listener                           | The number of requests this listener has served                 |
+| wildfly.request.count                   | Counter       | wildfly.server, wildfly.listener                           | The number of requests served                                   |
 | wildfly.request.duration.sum            | Counter       | wildfly.server, wildfly.listener                           | The total amount of time spent processing requests              |
 | wildfly.session.expired                 | Counter       | wildfly.deployment                                         | The number of expired sessions                                  |
 | wildfly.session.rejected                | Counter       | wildfly.deployment                                         | The number of rejected sessions                                 |
 | wildfly.session.created                 | Counter       | wildfly.deployment                                         | The number of sessions created                                  |
-| wildfly.session.count                   | UpDownCounter | wildfly.deployment                                         | The number of active sessions                                   |
+| wildfly.session.active.count            | UpDownCounter | wildfly.deployment                                         | The number of active sessions                                   |
+| wildfly.session.active.limit            | UpDownCounter | wildfly.deployment                                         | The maximum supported number of active sessions                 |
 | wildfly.db.client.connection.count      | UpDownCounter | db.client.connection.pool.name, db.client.connection.state | The number of open physical database connections                |
 | wildfly.db.client.connection.wait.count | Counter       | db.client.connection.pool.name                             | The number of connection requests that had to wait to obtain it |
 | wildfly.transaction.inflight            | UpDownCounter |                                                            | The number of in-flight transactions                            |

instrumentation/jmx-metrics/testing-webapp/src/main/webapp/WEB-INF/jboss-web.xml

@@ -0,0 +1,4 @@
+<jboss-web>
+  <!-- add an explicit limit for sessions, otherwise negative value is filtered out -->
+  <max-active-sessions>42</max-active-sessions>
+</jboss-web>