issue-1774: Function to retrieve info about client connections was added

Author: testisnullus

session.go

@@ -780,6 +780,95 @@ func (s *Session) MapExecuteBatchCAS(batch *Batch, dest map[string]interface{})
 	return applied, iter, iter.err
 }
 
+// connectionType is a custom type that represents the different stages
+// of a client connection in a Cassandra cluster. It is used to filter and categorize
+// connections based on their current state.
+type connectionType string
+
+const (
+	Ready      connectionType = "ready"
+	Connecting connectionType = "connecting"
+	Idle       connectionType = "idle"
+	Closed     connectionType = "closed"
+	Failed     connectionType = "failed"
+)
+
+// ClientConnection represents a client connection to a Cassandra node. It holds detailed
+// information about the connection, including the client address, connection stage, driver details,
+// and various configuration options.
+type ClientConnection struct {
+	Address         string
+	Port            int
+	ConnectionStage string
+	DriverName      string
+	DriverVersion   string
+	Hostname        string
+	KeyspaceName    *string
+	ProtocolVersion int
+	RequestCount    int
+	SSLCipherSuite  *string
+	SSLEnabled      bool
+	SSLProtocol     *string
+	Username        string
+}
+
+// RetrieveClientConnections retrieves a list of client connections from the
+// `system_views.clients` table based on the specified connection type. The function
+// queries the Cassandra database for connections with a given `connection_stage` and
+// scans the results into a slice of `ClientConnection` structs. It handles nullable
+// fields and returns the list of connections or an error if the operation fails.
+func (s *Session) RetrieveClientConnections(connectionType connectionType) ([]*ClientConnection, error) {
+	const stmt = `
+		SELECT address, port, connection_stage, driver_name, driver_version, 
+		       hostname, keyspace_name, protocol_version, request_count, 
+		       ssl_cipher_suite, ssl_enabled, ssl_protocol, username 
+		FROM system_views.clients 
+		WHERE connection_stage = ?`
+
+	iter := s.control.query(stmt, connectionType)
+	if iter.NumRows() == 0 {
+		return nil, ErrConnectionsDoNotExist
+	}
+	defer iter.Close()
+
+	var connections []*ClientConnection
+	for {
+		conn := &ClientConnection{}
+
+		// Variables to hold nullable fields
+		var keyspaceName, sslCipherSuite, sslProtocol *string
+
+		if !iter.Scan(
+			&conn.Address,
+			&conn.Port,
+			&conn.ConnectionStage,
+			&conn.DriverName,
+			&conn.DriverVersion,
+			&conn.Hostname,
+			&keyspaceName,
+			&conn.ProtocolVersion,
+			&conn.RequestCount,
+			&sslCipherSuite,
+			&conn.SSLEnabled,
+			&sslProtocol,
+			&conn.Username,
+		) {
+			if err := iter.Close(); err != nil {
+				return nil, err
+			}
+			break
+		}
+
+		conn.KeyspaceName = keyspaceName
+		conn.SSLCipherSuite = sslCipherSuite
+		conn.SSLProtocol = sslProtocol
+
+		connections = append(connections, conn)
+	}
+
+	return connections, nil
+}
+
 type hostMetrics struct {
 	// Attempts is count of how many times this query has been attempted for this host.
 	// An attempt is either a retry or fetching next page of results.
@@ -2259,16 +2348,17 @@ func (e Error) Error() string {
 }
 
 var (
-	ErrNotFound             = errors.New("not found")
-	ErrUnavailable          = errors.New("unavailable")
-	ErrUnsupported          = errors.New("feature not supported")
-	ErrTooManyStmts         = errors.New("too many statements")
-	ErrUseStmt              = errors.New("use statements aren't supported. Please see https://github.com/gocql/gocql for explanation.")
-	ErrSessionClosed        = errors.New("session has been closed")
-	ErrNoConnections        = errors.New("gocql: no hosts available in the pool")
-	ErrNoKeyspace           = errors.New("no keyspace provided")
-	ErrKeyspaceDoesNotExist = errors.New("keyspace does not exist")
-	ErrNoMetadata           = errors.New("no metadata available")
+	ErrNotFound              = errors.New("not found")
+	ErrUnavailable           = errors.New("unavailable")
+	ErrUnsupported           = errors.New("feature not supported")
+	ErrTooManyStmts          = errors.New("too many statements")
+	ErrUseStmt               = errors.New("use statements aren't supported. Please see https://github.com/gocql/gocql for explanation.")
+	ErrSessionClosed         = errors.New("session has been closed")
+	ErrNoConnections         = errors.New("gocql: no hosts available in the pool")
+	ErrNoKeyspace            = errors.New("no keyspace provided")
+	ErrKeyspaceDoesNotExist  = errors.New("keyspace does not exist")
+	ErrConnectionsDoNotExist = errors.New("connections do not exist")
+	ErrNoMetadata            = errors.New("no metadata available")
 )
 
 type ErrProtocol struct{ error }