Add support for specifying an end log_pos (#357)

Co-authored-by: dongwook-chan <dongwook.chan@gmail.com>

Author: paulvic

pymysqlreplication/binlogstream.py

@@ -130,7 +130,8 @@ class BinLogStreamReader(object):
     def __init__(self, connection_settings, server_id,
                  ctl_connection_settings=None, resume_stream=False,
                  blocking=False, only_events=None, log_file=None,
-                 log_pos=None, filter_non_implemented_events=True,
+                 log_pos=None, end_log_pos=None,
+                 filter_non_implemented_events=True,
                  ignored_events=None, auto_position=None,
                  only_tables=None, ignored_tables=None,
                  only_schemas=None, ignored_schemas=None,
@@ -152,6 +153,7 @@ def __init__(self, connection_settings, server_id,
             log_file: Set replication start log file
             log_pos: Set replication start log pos (resume_stream should be
                      true)
+            end_log_pos: Set replication end log pos
             auto_position: Use master_auto_position gtid to set position
             only_tables: An array with the tables you want to watch (only works
                          in binlog_format ROW)
@@ -205,10 +207,14 @@ def __init__(self, connection_settings, server_id,
         # Store table meta information
         self.table_map = {}
         self.log_pos = log_pos
+        self.end_log_pos = end_log_pos
         self.log_file = log_file
         self.auto_position = auto_position
         self.skip_to_timestamp = skip_to_timestamp
 
+        if end_log_pos:
+            self.is_past_end_log_pos = False
+
         if report_slave:
             self.report_slave = ReportSlave(report_slave)
         self.slave_uuid = slave_uuid
@@ -417,6 +423,9 @@ def __connect_to_stream(self):
 
     def fetchone(self):
         while True:
+            if self.end_log_pos and self.is_past_end_log_pos:
+                return None
+
             if not self.__connected_stream:
                 self.__connect_to_stream()
 
@@ -470,6 +479,10 @@ def fetchone(self):
             elif binlog_event.log_pos:
                 self.log_pos = binlog_event.log_pos
 
+            if self.end_log_pos and self.log_pos >= self.end_log_pos:
+                # We're currently at, or past, the specified end log position.
+                self.is_past_end_log_pos = True
+
             # This check must not occur before clearing the ``table_map`` as a
             # result of a RotateEvent.
             #

pymysqlreplication/event.py

@@ -188,11 +188,6 @@ def _dump(self):
         print("Execution time: %d" % (self.execution_time))
         print("Query: %s" % (self.query))
 
-    
-    # TODO: check if instance attribute with the same name already exists
-    # TODO: put all the instace attribute in separate class? called status_vars
-    # TODO: does length need to be remembered?
-    # TODO: ref(mysql doc. and mysql-server) for each hunk
     def _read_status_vars_value_for_key(self, key):
         """parse status variable VALUE for given KEY
 

pymysqlreplication/tests/test_abnormal.py

@@ -72,3 +72,4 @@ def _remove_trailing_rotate_event_from_first_binlog(self):
         for _ in reader:
             reader.truncatebinlog()
             break
+

pymysqlreplication/tests/test_basic.py

@@ -482,6 +482,43 @@ def test_skip_to_timestamp(self):
         self.assertIsInstance(event, QueryEvent)
         self.assertEqual(event.query, query2)
 
+    def test_end_log_pos(self):
+        """Test end_log_pos parameter for BinLogStreamReader
+
+        MUST BE TESTED IN DEFAULT SYSTEM VARIABLES SETTING
+
+        Raises:
+            AssertionError: if null_bitmask isn't set as specified in 'bit_mask' variable
+        """
+
+        self.execute('CREATE TABLE test (id INT NOT NULL AUTO_INCREMENT, PRIMARY KEY(id))')
+        self.execute('INSERT INTO test values (NULL)')
+        self.execute('INSERT INTO test values (NULL)')
+        self.execute('INSERT INTO test values (NULL)')
+        self.execute('INSERT INTO test values (NULL)')
+        self.execute('INSERT INTO test values (NULL)')
+        self.execute('COMMIT')
+        #import os
+        #os._exit(1)
+
+        binlog = self.execute("SHOW BINARY LOGS").fetchone()[0]
+
+        self.stream.close()
+        self.stream = BinLogStreamReader(
+            self.database,
+            server_id=1024,
+            log_pos=0,
+            log_file=binlog,
+            end_log_pos=888)
+
+        last_log_pos = 0
+        last_event_type = 0
+        for event in self.stream:
+            last_log_pos = self.stream.log_pos
+            last_event_type = event.event_type
+
+        self.assertEqual(last_log_pos, 888)
+        self.assertEqual(last_event_type, TABLE_MAP_EVENT)
 
 class TestMultipleRowBinLogStreamReader(base.PyMySQLReplicationTestCase):
     def ignoredEvents(self):