Send TCP metrics for bytes sent and received to server

It would be good to send `tcp.bytesReceived` and `tcp.bytesSend`
metrics in the metrics blob to the server, so that, someone can
track how much traffic is passing between the server and the client.

I have manually tested the stats exported to Prometheus and verified
that these two new stats are displayed there correctly.

hazelcast/reactor.py

@@ -344,6 +344,8 @@ def __init__(self):
                 loop.shutdown()
             loop = _BasicLoop(self.map)
         self._loop = loop
+        self.bytes_sent = 0
+        self.bytes_received = 0
 
     def start(self):
         self._loop.start()
@@ -421,9 +423,11 @@ def handle_read(self):
         try:
             while True:
                 data = self.recv(receive_buffer_size)
+                bytes_received = len(data)
+                self._reactor.bytes_received += bytes_received
                 reader.read(data)
                 self.last_read_time = time.time()
-                if len(data) < receive_buffer_size:
+                if bytes_received < receive_buffer_size:
                     break
         except socket.error as err:
             if err.args[0] not in _RETRYABLE_ERROR_CODES:
@@ -461,7 +465,7 @@ def handle_write(self):
             buf.truncate(0)
 
         try:
-            sent = self.send(bytes_)
+            bytes_sent = self.send(bytes_)
         except socket.error as err:
             if err.args[0] in _RETRYABLE_ERROR_CODES:
                 # Couldn't write the bytes but we should
@@ -474,9 +478,9 @@ def handle_write(self):
             # No exception is thrown during the send
             self.last_write_time = time.time()
             self.sent_protocol_bytes = True
-
-            if sent < len(bytes_):
-                write_queue.appendleft(bytes_[sent:])
+            self._reactor.bytes_sent += bytes_sent
+            if bytes_sent < len(bytes_):
+                write_queue.appendleft(bytes_[bytes_sent:])
 
     def handle_close(self):
         _logger.warning("Connection closed by server")

hazelcast/statistics.py

@@ -25,6 +25,8 @@
 _NEAR_CACHE_DESCRIPTOR_PREFIX = "nearcache"
 _NEAR_CACHE_DESCRIPTOR_DISCRIMINATOR = "name"
 
+_TCP_METRICS_PREFIX = "tcp"
+
 
 class Statistics(object):
     def __init__(
@@ -130,7 +132,7 @@ def _register_system_gauge(self, gauge_name, gauge_fn, value_type=ValueType.LONG
             self._registered_system_gauges[gauge_name] = (gauge_fn, value_type)
         except Exception as e:
             _logger.debug(
-                "Unable to register the system related gauge %s. Error: %s" % (gauge_name, e)
+                "Unable to register the system related gauge %s. Error: %s", gauge_name, e
             )
 
     def _register_process_gauge(self, gauge_name, gauge_fn, value_type=ValueType.LONG):
@@ -141,7 +143,7 @@ def _register_process_gauge(self, gauge_name, gauge_fn, value_type=ValueType.LON
             self._registered_process_gauges[gauge_name] = (gauge_fn, value_type)
         except Exception as e:
             _logger.debug(
-                "Unable to register the process related gauge %s. Error: %s" % (gauge_name, e)
+                "Unable to register the process related gauge %s. Error: %s", gauge_name, e
             )
 
     def _collect_and_send_stats(self):
@@ -157,6 +159,7 @@ def _collect_and_send_stats(self):
         self._add_client_attributes(attributes, connection)
         self._add_near_cache_metrics(attributes, compressor)
         self._add_system_and_process_metrics(attributes, compressor)
+        self._add_tcp_metrics(compressor)
         self._send_stats(
             collection_timestamp, "".join(attributes), compressor.generate_blob(), connection
         )
@@ -180,7 +183,7 @@ def _add_system_and_process_metrics(self, attributes, compressor):
                     attributes, compressor, gauge_name, value, value_type
                 )
             except:
-                _logger.exception("Error while collecting '%s'." % gauge_name)
+                _logger.exception("Error while collecting '%s'.", gauge_name)
 
         if not self._registered_process_gauges:
             # Do not create the process object if no process-related
@@ -195,7 +198,7 @@ def _add_system_and_process_metrics(self, attributes, compressor):
                     attributes, compressor, gauge_name, value, value_type
                 )
             except:
-                _logger.exception("Error while collecting '%s'." % gauge_name)
+                _logger.exception("Error while collecting '%s'.", gauge_name)
 
     def _add_system_or_process_metric(self, attributes, compressor, gauge_name, value, value_type):
         # We don't have any metrics that do not have prefix.
@@ -342,9 +345,26 @@ def _add_near_cache_metric(
             self._add_attribute(attributes, metric, value, nc_name_with_prefix)
         except:
             _logger.exception(
-                "Error while collecting %s metric for near cache '%s'" % (metric, nc_name)
+                "Error while collecting %s metric for near cache '%s'.", metric, nc_name
             )
 
+    def _add_tcp_metrics(self, compressor):
+        self._add_tcp_metric(compressor, "bytesSend", self._reactor.bytes_sent)
+        self._add_tcp_metric(compressor, "bytesReceived", self._reactor.bytes_received)
+
+    def _add_tcp_metric(
+        self, compressor, metric, value, value_type=ValueType.LONG, unit=ProbeUnit.BYTES
+    ):
+        descriptor = MetricDescriptor(
+            metric=metric,
+            prefix=_TCP_METRICS_PREFIX,
+            unit=unit,
+        )
+        try:
+            self._add_metric(compressor, descriptor, value, value_type)
+        except:
+            _logger.exception("Error while collecting '%s.%s'.", _TCP_METRICS_PREFIX, metric)
+
     def _add_metric(self, compressor, descriptor, value, value_type):
         if value_type == ValueType.LONG:
             compressor.add_long(descriptor, value)

tests/integration/backward_compatible/client_test.py

@@ -1,10 +1,11 @@
 import time
+import unittest
 
-from tests.base import HazelcastTestCase
+from tests.base import HazelcastTestCase, SingleMemberTestCase
 from hazelcast.client import HazelcastClient
 from hazelcast.lifecycle import LifecycleState
 from tests.hzrc.ttypes import Lang
-from tests.util import get_current_timestamp
+from tests.util import get_current_timestamp, compare_client_version, random_string
 
 
 class ClientTest(HazelcastTestCase):
@@ -110,3 +111,35 @@ def get_labels_from_member(self, client_uuid):
             client_uuid
         )
         return self.rc.executeOnController(self.cluster.id, script, Lang.JAVASCRIPT).result
+
+
+@unittest.skipIf(
+    compare_client_version("4.2.2") < 0, "Tests the features added in 4.1 version of the client"
+)
+class ClientTcpMetricsTest(SingleMemberTestCase):
+    @classmethod
+    def configure_client(cls, config):
+        config["cluster_name"] = cls.cluster.id
+        return config
+
+    def test_bytes_received(self):
+        reactor = self.client._reactor
+
+        bytes_received = reactor.bytes_received
+        self.assertGreater(bytes_received, 0)
+
+        m = self.client.get_map(random_string()).blocking()
+        m.get(random_string())
+
+        self.assertGreater(reactor.bytes_received, bytes_received)
+
+    def test_bytes_sent(self):
+        reactor = self.client._reactor
+
+        bytes_sent = reactor.bytes_sent
+        self.assertGreater(bytes_sent, 0)
+
+        m = self.client.get_map(random_string()).blocking()
+        m.set(random_string(), random_string())
+
+        self.assertGreater(reactor.bytes_sent, bytes_sent)