IGNITE-29107 Add ClientConnector metrics for current and max active compute tasks

docs/_docs/monitoring-metrics/new-metrics-system.adoc

@@ -419,6 +419,7 @@ The metrics belong to the `snapshot` register, see link:monitoring-metrics/new-m
 Metrics related to JDBC/ODBC or thin client connections.
 
 * `ActiveSessionsCount`, `thin.ActiveSessions`, `jdbc.ActiveSessions`, `odbc.ActiveSessions` - The number of active connections, total and per client type (`client.connector` register, see link:monitoring-metrics/new-metrics#ignite-thin-client-connector[Ignite Thin Client Connector]).
+* `ActiveComputeTasksOnBusiestConnection`, `MaxComputeTasksPerConnection` - The number of currently running compute tasks on the busiest thin client connection and the configured per-connection limit of concurrently running compute tasks; their ratio shows how close connections are to the limit (`client.connector` register, see link:monitoring-metrics/new-metrics#ignite-thin-client-connector[Ignite Thin Client Connector]).
 * The link:monitoring-metrics/system-views#client_connections[CLIENT_CONNECTIONS] system view lists every connection with its user and addresses.
 * `Connections` - Attribute of the `ClientProcessorMXBean` MBean, not available in the metric registers. A list of strings, each string containing information about a connection:
 

docs/_docs/monitoring-metrics/new-metrics.adoc

@@ -459,11 +459,13 @@ Register name: `client.connector`
 [cols="2,1,3",opts="header"]
 |===
 |Name | Type | Description
+|ActiveComputeTasksOnBusiestConnection | integer | Number of currently running compute tasks on the busiest thin client connection.
 |ActiveSessionsCount | integer | Active TCP sessions count.
 |AffinityKeyRequestsHits | long | The number of affinity-aware cache key requests that were sent to the primary node.
 |AffinityKeyRequestsMisses | long | The number of affinity-aware cache key requests that were sent not to the primary node.
 |AffinityQueryRequestsHits | long | The number of affinity-aware query requests that were sent to the primary node.
 |AffinityQueryRequestsMisses | long | The number of affinity-aware query requests that were sent not to the primary node.
+|MaxComputeTasksPerConnection | integer | Maximum number of concurrently running compute tasks allowed per thin client connection (0 if compute is disabled for thin clients).
 |RejectedSessionsAuthenticationFailed | integer | TCP sessions count that were rejected due to failed authentication.
 |RejectedSessionsTimeout | integer | TCP sessions count that were rejected due to handshake timeout.
 |RejectedSessionsTotal | integer | Total number of rejected TCP connections.

modules/core/src/main/java/org/apache/ignite/internal/processors/odbc/ClientListenerProcessor.java

@@ -40,13 +40,15 @@
 import org.apache.ignite.configuration.IgniteConfiguration;
 import org.apache.ignite.configuration.OdbcConfiguration;
 import org.apache.ignite.configuration.SqlConnectorConfiguration;
+import org.apache.ignite.configuration.ThinClientConfiguration;
 import org.apache.ignite.internal.GridKernalContext;
 import org.apache.ignite.internal.processors.GridProcessorAdapter;
 import org.apache.ignite.internal.processors.configuration.distributed.DistributedBooleanProperty;
 import org.apache.ignite.internal.processors.configuration.distributed.DistributedThinClientConfiguration;
 import org.apache.ignite.internal.processors.metric.MetricRegistryImpl;
 import org.apache.ignite.internal.processors.odbc.jdbc.JdbcConnectionContext;
 import org.apache.ignite.internal.processors.odbc.odbc.OdbcConnectionContext;
+import org.apache.ignite.internal.processors.platform.client.ClientConnectionContext;
 import org.apache.ignite.internal.systemview.ClientConnectionAttributeViewWalker;
 import org.apache.ignite.internal.systemview.ClientConnectionViewWalker;
 import org.apache.ignite.internal.util.GridSpinBusyLock;
@@ -71,6 +73,7 @@
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import static org.apache.ignite.configuration.ThinClientConfiguration.DFLT_MAX_ACTIVE_COMPUTE_TASKS_PER_CONNECTION;
 import static org.apache.ignite.internal.cluster.DistributedConfigurationUtils.newConnectionEnabledProperty;
 import static org.apache.ignite.internal.processors.metric.GridMetricManager.CLIENT_CONNECTOR_METRICS;
 import static org.apache.ignite.internal.processors.metric.impl.MetricUtils.metricName;
@@ -100,6 +103,12 @@ public class ClientListenerProcessor extends GridProcessorAdapter {
     /** */
     public static final String METRIC_ACTIVE = "ActiveSessions";
 
+    /** Active compute tasks on the busiest thin client connection metric name. */
+    public static final String METRIC_ACTIVE_COMPUTE_TASKS = "ActiveComputeTasksOnBusiestConnection";
+
+    /** Max active compute tasks per connection (configured limit) metric name. */
+    public static final String METRIC_MAX_COMPUTE_TASKS = "MaxComputeTasksPerConnection";
+
     /** Default client connector configuration. */
     public static final ClientConnectorConfiguration DFLT_CLI_CFG = new ClientConnectorConfigurationEx();
 
@@ -350,6 +359,36 @@ private void registerClientMetrics(MetricRegistry mreg) {
                 "Number of active sessions for the " + cliTypeName + " client."
             );
         }
+
+        mreg.register(
+            METRIC_ACTIVE_COMPUTE_TASKS,
+            () -> {
+                int res = 0;
+
+                for (GridNioSession ses : srv.sessions()) {
+                    ClientListenerConnectionContext connCtx = ses.meta(CONN_CTX_META_KEY);
+
+                    if (connCtx instanceof ClientConnectionContext)
+                        res = Math.max(res, ((ClientConnectionContext)connCtx).activeTasksCount());
+                }
+
+                return res;
+            },
+            "Number of currently running compute tasks on the busiest thin client connection."
+        );
+
+        ThinClientConfiguration thinCfg = cliConnCfg.getThinClientConfiguration();
+
+        int maxComputeTasks = thinCfg == null
+            ? DFLT_MAX_ACTIVE_COMPUTE_TASKS_PER_CONNECTION
+            : thinCfg.getMaxActiveComputeTasksPerConnection();
+
+        mreg.register(
+            METRIC_MAX_COMPUTE_TASKS,
+            () -> maxComputeTasks,
+            "Maximum number of concurrently running compute tasks allowed per thin client connection " +
+                "(0 if compute is disabled for thin clients)."
+        );
     }
 
     /**

modules/core/src/main/java/org/apache/ignite/internal/processors/platform/client/ClientConnectionContext.java

@@ -367,4 +367,12 @@ public void decrementActiveTasksCount() {
 
         assert cnt >= 0 : "Unexpected active tasks count: " + cnt;
     }
+
+    /**
+     * @return Number of active compute tasks for this connection. Never exceeds the configured limit: the counter may
+     * temporarily exceed it while a rejected task is being rolled back in {@link #incrementActiveTasksCount()}.
+     */
+    public int activeTasksCount() {
+        return Math.min(activeTasksCnt.get(), maxActiveComputeTasks);
+    }
 }