schema: support encoding=None connections #172
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Several different problems are fixed here, but all have the same root.
When a connection encoding is None (it is default on Python 2 and may be
set explicitly on Python 3), all mp_str values are decoded into bytes,
not Unicode strings (note that bytes is alias for str in Python 2). But
the database schema parsing code have assumptions that _vspace / _vindex
values are Unicode strings.
The resolved problems are the following:
1. Default encoding in bytes#decode() method is 'ascii', however names
in tarantool can contain symbols beyond ASCII symbol table. Set
'utf-8' for names decoding.
2. Convert all binary values into Unicode strings before parse or store
them. This allows further correct accesses to the local schema
representation.
3. Convert binary parameters like space, index or field name into
Unicode strings, when a schema is accessed to don't trigger redundant
schema refetching.
Those problems are briefly mentioned in [1].
Tested manually with Python 2 and Python 3: my testing tarantool
instance has a space with name '©' and after the changes I'm able to
connect to it when the connection encoding is set to None. Also I
verified that schema is not fetched each time when I do
<connection>.select('©') in Python 2 (where such string literal is str /
bytes, not Unicode string).
Relevant test cases are added in next commits.
[1]: #105 (comment)
On Python 3 load_tests() function that is defined in unit/suites/__init__.py is called to filter unittest.TestCase classes to run. On Python 2 the function is not called and all unittest.TestCase classes are subject to run. I plan to define a hierarchy of test cases in the schema reload test and exclude the base class from the list to run, so this behaviour is not desired. The reason of the difference between unittest behaviour on Python 2 and Python 3 is described in the TestLoader#discover() function documentation (see [1]): | Changed in version 3.5: Found packages are now checked for load_tests | regardless of whether their path matches pattern, because it is | impossible for a package name to match the default pattern. The default pattern is 'test*.py'. [1]: https://docs.python.org/3/library/unittest.html#unittest.TestLoader.discover
In Python 2 a binary string and a Unicode string with the same ASCII characters are considered equal: | >>> 'x' == u'x' | True | >>> u'x' == 'x' | True It works seamlessly with dictionary keys too: | >>> d = dict() | >>> d[u'x'] = 42 | >>> d['x'] | 42 This, however, does not work for non-ASCII characters: | >>> 'ч' == u'ч' | False | >>> u'ч' == 'ч' | False | >>> d = dict() | >>> d[u'ч'] = 42 | >>> d['ч'] | Traceback (most recent call last): | File "<stdin>", line 1, in <module> | KeyError: '\xd1\x87' The implemented test cases verify schema loading for a space or an index with a non-ASCII name, when it is passed just as a literal: say, '∞'. The main purpose of the commit is to add test cases that verify that no extra schema fetch is performed for a space / index name given as non-ASCII string literal (which is binary string on Python 2). If a cache is implemented without taking care to this, an already cached value may be missed.
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assert max_depth > 0@artembo suggested to don't use |
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Several different problems are fixed here, but all have the same root.
When a connection encoding is None (it is default on Python 2 and may be
set explicitly on Python 3), all mp_str values are decoded into bytes,
not Unicode strings (note that bytes is alias for str in Python 2). But
the database schema parsing code have assumptions that _vspace / _vindex
values are Unicode strings.
The resolved problems are the following:
in tarantool can contain symbols beyond ASCII symbol table. Set
'utf-8' for names decoding.
them. This allows further correct accesses to the local schema
representation.
Unicode strings, when a schema is accessed to don't trigger redundant
schema refetching.
Those problems are briefly mentioned in 1.
Tested manually with Python 2 and Python 3: my testing tarantool
instance has a space with name '©' and after the changes I'm able to
connect to it when the connection encoding is set to None. Also I
verified that schema is not fetched each time when I do
<connection>.select('©') in Python 2 (where such string literal is str /
bytes, not Unicode string).
Added relevant test cases as separate commits within the PR.