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https://issues.apache.org/jira/browse/BEAM-8143?focusedWorklogId=312373&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-312373
]
ASF GitHub Bot logged work on BEAM-8143:
----------------------------------------
Author: ASF GitHub Bot
Created on: 13/Sep/19 21:52
Start Date: 13/Sep/19 21:52
Worklog Time Spent: 10m
Work Description: robertwb commented on pull request #9366: [BEAM-8143]
Build simple LineSource directly on top of SDF
URL: https://github.com/apache/beam/pull/9366#discussion_r324378492
##########
File path: sdks/python/apache_beam/io/sdf_line_source.py
##########
@@ -0,0 +1,89 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements. See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+from __future__ import absolute_import
+
+import os
+
+from apache_beam import Create
+from apache_beam import pvalue
+from apache_beam.io.restriction_trackers import OffsetRange
+from apache_beam.io.restriction_trackers import OffsetRestrictionTracker
+from apache_beam.transforms import core
+from apache_beam.transforms import ptransform
+
+
+class SdfReadLineRestrictionProvider(core.RestrictionProvider):
+ """ A `core.RestrictionProvider` implementation which provides
+ `OffsetRestrictionTracker`."""
+ def _get_file_size(self, file_name):
+ with open(file_name, 'rb') as f:
+ f.seek(0, os.SEEK_END)
+ return f.tell()
+
+ def initial_restriction(self, element):
+ return OffsetRange(0, self._get_file_size(element['file_pattern']))
+
+ def create_tracker(self, restriction):
+ return OffsetRestrictionTracker(restriction)
+
+ def split(self, element, restriction):
+ return restriction.split(element['desired_chunk_size'])
+
+ def restriction_size(self, element, restriction):
+ return restriction.size()
+
+
+class SdfReadLine(core.DoFn):
+ """ An SplittableDoFn which reads lines from file and as output."""
+ def process(
+ self,
+ element,
+ restriction_tracker=core.DoFn.RestrictionParam(
+ SdfReadLineRestrictionProvider())):
+ with open(element['file_pattern'], 'rb') as f:
+ start = restriction_tracker.start_position()
+ f.seek(start)
+ if start > 0:
+ f.seek(-1, os.SEEK_CUR)
+ start -= 1
+ start += len(f.readline())
+ current = start
+ line = f.readline()
+ while restriction_tracker.try_claim(current):
+ if not line:
+ return
+ yield line.rstrip(b'\n')
+ current += len(line)
Review comment:
Won't this get off by one due to stripping the newline before adding the
value to current? Possibly current = f.tell() would be more consistent.
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Issue Time Tracking
-------------------
Worklog Id: (was: 312373)
Time Spent: 20m (was: 10m)
> Provide a simple LineSource built on top of SDF
> -----------------------------------------------
>
> Key: BEAM-8143
> URL: https://issues.apache.org/jira/browse/BEAM-8143
> Project: Beam
> Issue Type: New Feature
> Components: sdk-py-core
> Reporter: Boyuan Zhang
> Assignee: Boyuan Zhang
> Priority: Major
> Time Spent: 20m
> Remaining Estimate: 0h
>
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