process writer and csv pooling

main.py

@@ -6,6 +6,7 @@
 from src.daemon import Daemon
 
 import sys
+import multiprocessing as mp
 
 
 if sys.version_info[0] < 3:
@@ -17,6 +18,7 @@ class Main(Daemon):
     config = None
 
     def __init__(self):
+        mp.set_start_method('forkserver')
         self.config = CLIOpts.config()
         super().__init__(pidfile=self.config.pid_file())
 

run.sh

@@ -1,13 +1,22 @@
 #!/bin/bash
 
 python3 main.py \
-	--src-resume --src-wait \
-	--src-host=127.0.0.1 --src-user=reader --src-password=qwerty \
-	--dst-host=192.168.74.251 \
-	--dst-db=db --dst-table=datatypes \
-	--mempool --mempool-max-events-num=3 --mempool-max-flush-interval=30 \
-	--csvpool --csvpool-file-path-prefix=qwe \
-	--csv-column-default-value date_1=2000-01-01 datetime_1=2000-01-01\ 01:02:03 time_1=2001-01-01\ 01:02:03 timestamp_1=2002-01-01\ 01:02:03
+    --src-resume \
+    --src-wait \
+    --src-host=127.0.0.1 \
+    --src-user=reader \
+    --src-password=qwerty \
+    --dst-host=192.168.74.251 \
+    --csvpool \
+    --csvpool-file-path-prefix=qwe_ \
+    --csv-column-default-value date_1=2000-01-01 datetime_1=2000-01-01\ 01:02:03 time_1=2001-01-01\ 01:02:03 timestamp_1=2002-01-01\ 01:02:03 \
+    --mempool-max-flush-interval=600 \
+    --mempool-max-events-num=900000
 
-#	--dst-file=dst.csv 
+#	--mempool
+#   --mempool-max-events-num=3
+#   --mempool-max-flush-interval=30
+#	--dst-file=dst.csv
+#	--dst-schema=db
+#   --dst-table=datatypes
 #	--csvpool-keep-files

src/cliopts.py

@@ -52,7 +52,7 @@ def config():
         argparser.add_argument(
             '--dry',
             action='store_true',
-            help='Dry mode - do not do anything that can harm.'
+            help='Dry mode - do not do anything that can harm. '
             'Useful for debugging.'
         )
         argparser.add_argument(
@@ -74,30 +74,30 @@ def config():
         argparser.add_argument(
             '--mempool-max-events-num',
             type=int,
-            default=1000,
-            help='max events num to pool before batch write'
+            default=100000,
+            help='Max events number to pool - triggering pool flush'
         )
         argparser.add_argument(
             '--mempool-max-flush-interval',
             type=int,
             default=60,
-            help='max seconds num between flushes'
+            help='Max seconds number between pool flushes'
         )
         argparser.add_argument(
             '--csvpool',
             action='store_true',
-            help='Cache data in csv files.'
+            help='Cache data in CSV pool files on disk. Requires memory pooling, thus enables --mempool even if it is not explicitly specified'
         )
         argparser.add_argument(
             '--csvpool-file-path-prefix',
             type=str,
-            default='/tmp/csvpool',
-            help='file path prefix to CSV pool files'
+            default='/tmp/csvpool_',
+            help='File path prefix to CSV pool files'
         )
         argparser.add_argument(
             '--csvpool-keep-files',
             action='store_true',
-            help='Keep pool csv files.'
+            help='Keep CSV pool files. Useful for debugging'
         )
 
         argparser.add_argument(
@@ -156,7 +156,7 @@ def config():
             '--src-file',
             type=str,
             default=None,
-            help='Source file tp read data from'
+            help='Source file to read data from'
         )
 
         argparser.add_argument(
@@ -190,10 +190,10 @@ def config():
             help='Password to be used when writing to dst'
         )
         argparser.add_argument(
-            '--dst-db',
+            '--dst-schema',
             type=str,
             default=None,
-            help='Database to be used when writing to dst'
+            help='Database/schema to be used when writing to dst'
         )
         argparser.add_argument(
             '--dst-table',
@@ -220,7 +220,7 @@ def config():
                 'dry': args.dry,
                 'daemon': args.daemon,
                 'pid_file': args.pid_file,
-                'mempool': args.mempool,
+                'mempool': args.mempool or args.csvpool, # csvpool assumes mempool to be enabled
                 'mempool-max-events-num': args.mempool_max_events_num,
                 'mempool-max-flush-interval': args.mempool_max_flush_interval,
                 'csvpool': args.csvpool,
@@ -262,15 +262,15 @@ def config():
                         'user': args.dst_user,
                         'password': args.dst_password,
                     },
-                    'dst_db': args.dst_db,
+                    'dst_schema': args.dst_schema,
                     'dst_table': args.dst_table,
                 },
                 'file': {
                     'csv_file_path': args.dst_file,
                     'csv_file_path_prefix': args.csvpool_file_path_prefix,
                     'csv_file_path_suffix_parts': [],
                     'csv_keep_file': args.csvpool_keep_files,
-                    'dst_db': args.dst_db,
+                    'dst_schema': args.dst_schema,
                     'dst_table': args.dst_table,
                 },
             },

src/config.py

@@ -8,8 +8,11 @@
 from .writer.csvwriter import CSVWriter
 from .writer.chcsvwriter import CHCSVWriter
 from .writer.poolwriter import PoolWriter
+from .writer.processwriter import ProcessWriter
+from .objectbuilder import ObjectBuilder
 
 from .converter.csvwriteconverter import CSVWriteConverter
+from .converter.chwriteconverter import CHWriteConverter
 
 
 class Config(object):
@@ -40,30 +43,47 @@ def reader(self):
         else:
             return MySQLReader(**self.config['reader-config']['mysql'])
 
-    def writer_class(self):
+    def converter_builder(self):
+        if not self.config['converter-config']['csv']['column_default_value']:
+            # no default values for CSV columns provided
+            return None
 
+        return ObjectBuilder(
+            instance=CSVWriteConverter(
+                defaults=self.config['converter-config']['csv']['column_default_value']
+            ))
+
+    def writer_builder(self):
         if self.config['app-config']['csvpool']:
-            return CSVWriter, {
-                **self.config['writer-config']['file'],
-                'next': CHCSVWriter(**self.config['writer-config']['clickhouse']['connection_settings']),
-                'converter': CSVWriteConverter(defaults=self.config['converter-config']['csv']['column_default_value']) if self.config['converter-config']['csv']['column_default_value'] else None,
-            }
+            return ObjectBuilder(class_name=ProcessWriter, constructor_params={
+                'next_writer_builder': ObjectBuilder(class_name=CSVWriter, constructor_params={
+                    **self.config['writer-config']['file'],
+                    'next_writer_builder': ObjectBuilder(
+                        class_name=CHCSVWriter,
+                        constructor_params=self.config['writer-config']['clickhouse']['connection_settings']
+                    ),
+                    'converter_builder': self.converter_builder(),
+                })
+            })
 
         elif self.config['writer-config']['file']['csv_file_path']:
-            return CSVWriter, self.config['writer-config']['file']
+            return ObjectBuilder(class_name=CSVWriter, constructor_params={
+                **self.config['writer-config']['file'],
+                'converter_builder': self.converter_builder(),
+            })
 
         else:
-            return CHWriter, self.config['writer-config']['clickhouse']
+            return ObjectBuilder(class_name=CHWriter, constructor_params={
+                **self.config['writer-config']['clickhouse'],
+                'converter_builder': ObjectBuilder(instance=CHWriteConverter()),
+            })
 
     def writer(self):
-        writer_class, writer_params = self.writer_class()
-
         if self.config['app-config']['mempool']:
             return PoolWriter(
-                writer_class=writer_class,
-                writer_params=writer_params,
+                writer_builder=self.writer_builder(),
                 max_pool_size=self.config['app-config']['mempool-max-events-num'],
                 max_flush_interval=self.config['app-config']['mempool-max-flush-interval'],
             )
         else:
-            return writer_class(**writer_params)
+            return self.writer_builder().get()

src/converter/chwriteconverter.py

@@ -28,26 +28,27 @@ class CHWriteConverter(Converter):
     def convert(self, event):
 
         columns_to_delete = []
-        for column_name in event.row:
-#                print(column_name, row['values'][column_name], type(row['values'][column_name]))
 
-            if self.delete_empty_columns and (event.row[column_name] is None):
-#                print("Skip None value for column", column_name)
-                columns_to_delete.append(column_name)
+        for column in event.row:
+            if (event.row[column] is None) and self.delete_empty_columns:
+                # include empty column to the list of to be deleted columns
+                columns_to_delete.append(column)
+                # move to next column
                 continue
 
             for t in self.types_to_convert:
-                if isinstance(event.row[column_name], t):
-#                    print("Converting column", column_name, "of type", type(event.row[column_name]),
-#                          event.row[column_name])
-                    event.row[column_name] = str(event.row[column_name])
-#                    print("res", event.row[column_name])
+                if isinstance(event.row[column], t):
+#                    print("Converting column", column, "of type", type(event.row[column]),
+#                          event.row[column])
+                    event.row[column] = str(event.row[column])
+#                    print("res", event.row[column])
                     break
             else:
-#                print("Using asis column", column_name, "of type", type(event.row[column_name]))
+#                print("Using asis column", column, "of type", type(event.row[column]))
                 pass
 
-        for column_to_delete in columns_to_delete:
-            event.row.pop(column_to_delete)
+        # delete columns according to the list
+        for column in columns_to_delete:
+            event.row.pop(column)
 
         return event

src/converter/csvwriteconverter.py

@@ -6,17 +6,25 @@
 
 class CSVWriteConverter(Converter):
 
+    # default values for columns - dict
     defaults = None
 
-    def __init__(self, defaults={}):
+    def __init__(self, defaults=None):
         self.defaults = defaults
 
-
     def convert(self, event):
+        # no defaults - nothing to convert
         if not self.defaults:
             return event
 
+        # defaults are empty - nothing to convert
+        if len(self.defaults) < 1:
+            return event
+
+        # have defaults
         for column in event.row:
-            if column in self.defaults and event.row[column] is None:
+            # replace None column with default value
+            if event.row[column] is None and column in self.defaults:
                 event.row[column] = self.defaults[column]
+
         return event

src/objectbuilder.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+
+class ObjectBuilder(object):
+
+    class_name = None
+    constructor_params = None
+    instance = None
+
+    def __init__(self, class_name=None, constructor_params=None, instance=None):
+        self.class_name = class_name
+        self.constructor_params = constructor_params
+        self.instance = instance
+
+    def param(self, name, value):
+        if not self.constructor_params:
+            self.constructor_params = {}
+        self.constructor_params[name] = value
+
+    def get(self):
+        if not self.class_name:
+            # no class name - return instance, it may be None
+            return self.instance
+
+        # have class name
+
+        if self.constructor_params:
+            return self.class_name(**self.constructor_params)
+        else:
+            return self.class_name()