X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/6c7e0599e34d037c0e280b7622969488fb8f8b2e..7924077e3db2898de26c86599d9f311e02d6db46:/sdk/python/arvados/collection.py

diff --git a/sdk/python/arvados/collection.py b/sdk/python/arvados/collection.py
index 3e92964f4c..59dc49fbbc 100644
--- a/sdk/python/arvados/collection.py
+++ b/sdk/python/arvados/collection.py
@@ -1,22 +1,6 @@
-import gflags
-import httplib
-import httplib2
 import logging
 import os
-import pprint
-import sys
-import types
-import subprocess
-import json
-import UserDict
 import re
-import hashlib
-import string
-import bz2
-import zlib
-import fcntl
-import time
-import threading
 
 from collections import deque
 from stat import *
@@ -51,7 +35,7 @@ def normalize_stream(s, stream):
         fout = f.replace(' ', '\\040')
         for segment in stream[f]:
             segmentoffset = blocks[segment[arvados.LOCATOR]] + segment[arvados.OFFSET]
-            if current_span == None:
+            if current_span is None:
                 current_span = [segmentoffset, segmentoffset + segment[arvados.SEGMENTSIZE]]
             else:
                 if segmentoffset == current_span[1]:
@@ -60,7 +44,7 @@ def normalize_stream(s, stream):
                     stream_tokens.append("{0}:{1}:{2}".format(current_span[0], current_span[1] - current_span[0], fout))
                     current_span = [segmentoffset, segmentoffset + segment[arvados.SEGMENTSIZE]]
 
-        if current_span != None:
+        if current_span is not None:
             stream_tokens.append("{0}:{1}:{2}".format(current_span[0], current_span[1] - current_span[0], fout))
 
         if not stream[f]:
@@ -71,9 +55,9 @@ def normalize_stream(s, stream):
 
 class CollectionBase(object):
     def __enter__(self):
-        pass
+        return self
 
-    def __exit__(self):
+    def __exit__(self, exc_type, exc_value, traceback):
         pass
 
     def _my_keep(self):
@@ -177,22 +161,22 @@ class CollectionReader(CollectionBase):
             return
         error_via_api = None
         error_via_keep = None
-        should_try_keep = (not self._manifest_text and
+        should_try_keep = ((self._manifest_text is None) and
                            util.keep_locator_pattern.match(
                 self._manifest_locator))
-        if (not self._manifest_text and
+        if ((self._manifest_text is None) and
             util.signed_locator_pattern.match(self._manifest_locator)):
             error_via_keep = self._populate_from_keep()
-        if not self._manifest_text:
+        if self._manifest_text is None:
             error_via_api = self._populate_from_api_server()
-            if error_via_api != None and not should_try_keep:
+            if error_via_api is not None and not should_try_keep:
                 raise error_via_api
-        if (not self._manifest_text and
+        if ((self._manifest_text is None) and
             not error_via_keep and
             should_try_keep):
             # Looks like a keep locator, and we didn't already try keep above
             error_via_keep = self._populate_from_keep()
-        if not self._manifest_text:
+        if self._manifest_text is None:
             # Nothing worked!
             raise arvados.errors.NotFoundError(
                 ("Failed to retrieve collection '{}' " +
@@ -290,8 +274,9 @@ class CollectionWriter(CollectionBase):
         self._queued_dirents = deque()
         self._queued_trees = deque()
 
-    def __exit__(self):
-        self.finish()
+    def __exit__(self, exc_type, exc_value, traceback):
+        if exc_type is None:
+            self.finish()
 
     def do_queued_work(self):
         # The work queue consists of three pieces:
@@ -417,7 +402,7 @@ class CollectionWriter(CollectionBase):
         return self._current_file_name
 
     def finish_current_file(self):
-        if self._current_file_name == None:
+        if self._current_file_name is None:
             if self._current_file_pos == self._current_stream_length:
                 return
             raise errors.AssertionError(
@@ -488,10 +473,7 @@ class CollectionWriter(CollectionBase):
             manifest += ' ' + ' '.join("%d:%d:%s" % (sfile[0], sfile[1], sfile[2].replace(' ', '\\040')) for sfile in stream[2])
             manifest += "\n"
 
-        if manifest:
-            return manifest
-        else:
-            return ""
+        return manifest
 
     def data_locators(self):
         ret = []