[Kotlin Sync] Monitoring > Cluster Monitoring (#65)

Author: rachel-mack

source/includes/monitoring_JMX.kt

@@ -0,0 +1,36 @@
+import com.mongodb.kotlin.client.MongoClient
+import org.bson.Document
+import com.mongodb.MongoClientSettings
+import com.mongodb.ConnectionString
+import com.mongodb.management.JMXConnectionPoolListener
+
+fun main() {
+    val uri = "<connection string uri>"
+
+// Instantiate your JMX listener
+    val connectionPoolListener = JMXConnectionPoolListener()
+
+// Include the listener in your client settings
+    val settings = MongoClientSettings.builder()
+        .applyConnectionString(ConnectionString(uri))
+        .applyToConnectionPoolSettings {
+            it.addConnectionPoolListener(connectionPoolListener)
+        }
+        .build()
+
+    try {
+// Connect to your database
+        val mongoClient = MongoClient.create(settings)
+        val database = mongoClient.getDatabase("sample_mflix")
+        val collection = database.getCollection<Document>("movies")
+        collection.find().firstOrNull()
+        collection.find().firstOrNull()
+        println("Navigate to JConsole to see your connection pools...")
+
+// Pause execution
+        Thread.sleep(Long.MAX_VALUE)
+        mongoClient.close()
+    } catch (e: Exception) {
+        e.printStackTrace()
+    }
+}

source/includes/monitoring_counter.kt

@@ -0,0 +1,45 @@
+import com.mongodb.kotlin.client.MongoClient
+import org.bson.Document
+import com.mongodb.event.*
+import com.mongodb.MongoClientSettings
+import com.mongodb.ConnectionString
+
+class CommandCounter : CommandListener {
+    private val commands = mutableMapOf<String, Int>()
+
+    override fun commandSucceeded(event: CommandSucceededEvent) {
+        val commandName = event.commandName
+        val count = commands[commandName] ?: 0
+        commands[commandName] = count + 1
+        println(commands.toString())
+    }
+
+    override fun commandFailed(event: CommandFailedEvent) {
+        println("Failed execution of command '${event.commandName}' with id ${event.requestId}")
+    }
+}
+
+
+fun main() {
+    val uri = "<connection string uri>"
+
+// Instantiate your new listener
+    val commandCounter = CommandCounter()
+
+// Include the listener in your client settings
+    val settings = MongoClientSettings.builder()
+        .applyConnectionString(ConnectionString(uri))
+        .addCommandListener(commandCounter)
+        .build()
+
+// Connect to your database
+    val mongoClient = MongoClient.create(settings)
+    val database = mongoClient.getDatabase("sample_mflix")
+    val collection = database.getCollection<Document>("movies")
+
+// Run some commands to test the counter
+    collection.find().firstOrNull()
+    collection.find().firstOrNull()
+
+    mongoClient.close()
+}

source/includes/monitoring_librarian.kt

@@ -0,0 +1,40 @@
+import com.mongodb.kotlin.client.MongoClient
+import org.bson.Document
+import com.mongodb.event.*
+import com.mongodb.MongoClientSettings
+import com.mongodb.ConnectionString
+
+class ConnectionPoolLibrarian : ConnectionPoolListener {
+    override fun connectionCheckedOut(event: ConnectionCheckedOutEvent) {
+        println("Let me get you the connection with id ${event.connectionId.localValue}...")
+    }
+    override fun connectionCheckOutFailed(event: ConnectionCheckOutFailedEvent) {
+        println("Something went wrong! Failed to checkout connection.")
+    }
+}
+
+
+fun main() {
+    val uri = "<connection string uri>"
+
+// Instantiate your new listener
+val cpListener = ConnectionPoolLibrarian()
+
+// Include the listener in your client settings
+    val settings = MongoClientSettings.builder()
+        .applyConnectionString(ConnectionString(uri))
+        .applyToConnectionPoolSettings({
+            it.addConnectionPoolListener(cpListener)
+            })
+        .build()
+
+// Connect to your database        
+    val mongoClient = MongoClient.create(settings)
+    val database = mongoClient.getDatabase("sample_mflix")
+    val collection = database.getCollection<Document>("movies")
+
+// Run some commands to test the counter
+    collection.find().firstOrNull()
+
+    mongoClient.close()
+}

source/includes/monitoring_writable.kt

@@ -0,0 +1,49 @@
+import com.mongodb.kotlin.client.MongoClient
+import org.bson.Document
+import com.mongodb.event.*
+import com.mongodb.MongoClientSettings
+import com.mongodb.ConnectionString
+
+class IsWriteable : ClusterListener {
+    private var isWritable = false
+
+    override fun clusterDescriptionChanged(event: ClusterDescriptionChangedEvent) {
+        if (!isWritable) {
+            if (event.newDescription.hasWritableServer()) {
+                isWritable = true
+                println("Able to write to cluster")
+            }
+        } else {
+            if (!event.newDescription.hasWritableServer()) {
+                isWritable = false
+                println("Unable to write to cluster")
+            }
+        }
+    }
+}
+
+
+fun main() {
+    val uri = "<connection string uri>"
+
+// Instantiate your new listener
+    val clusterListener = IsWriteable()
+
+// Include the listener in your client settings
+    val settings = MongoClientSettings.builder()
+        .applyConnectionString(ConnectionString(uri))
+        .applyToClusterSettings { builder ->
+            builder.addClusterListener(clusterListener)
+        }
+        .build()
+
+// Connect to your database
+    val mongoClient = MongoClient.create(settings)
+    val database = mongoClient.getDatabase("sample_mflix")
+    val collection = database.getCollection<Document>("movies")
+
+// Run a command to trigger a ClusterDescriptionChangedEvent event
+    collection.find().firstOrNull()
+
+    mongoClient.close()
+}

source/index.txt

@@ -23,6 +23,7 @@
    Specialized Data Formats </data-formats>
    Builders </builders>
    Run a Command </run-command>
+   Monitoring </monitoring>
    Security </security>
    In-Use Encryption </security/encrypt-fields>
    Compatibility </compatibility>