This commit makes psycopg2 responsible for sending the status update
(feedback) messages to the server regardless of whether a synchronous or
asynchronous connection is used.
Feedback is sent every *status_update* (default value is 10) seconds,
which could be configured by passing a corresponding parameter to the
`start_replication()` or `start_replication_expert()` methods.
The actual feedback message is sent by the
`pq_read_replication_message()` when the *status_update* timeout is
reached.
The default behavior of the `send_feedback()` method is changed.
It doesn't send a feedback message on every call anymore but just
updates internal structures. There is still a way to *force* sending
a message if *force* or *reply* parameters are set.
The new approach has certain advantages:
1. The client can simply call the `send_feedback()` for every
processed message and the library will take care of not overwhelming
the server. Actually, in the synchronous mode it is even mandatory
to confirm every processed message.
2. The library tracks internally the pointer of the last received
message which is not keepalive. If the client confirmed the last
message and after that server sends only keepalives with increasing
*wal_end*, the library can safely move forward *flush* position to
the *wal_end* and later automatically report it to the server.
Reporting of the *wal_end* received from keepalive messages is very
important. Not doing so casing:
1. Excessive disk usage, because the replication slot prevents from
WAL being cleaned up.
2. The smart and fast shutdown of the server could last indefinitely
because walsender waits until the client report *flush* position
equal to the *wal_end*.
This implementation is only extending the existing API and therefore
should not break any of the existing code.
Now its state is unmodified, so apart from special-casing creation
and initial population can work unmodified, and all the desired
properties just work (modifiability, picklability...)
Close#886.
Previous one didn't refresh by last use. Use the stdlib version for py3
and one of our own for py2.
Max size set to 512, which should be fine for everyone (tweaking is
still possible by monkeypatching, as the tests do, but I don't want to
make an interface of it).
They can be valid chars in Python 3. Or maybe not? In which case Python
will throw an exception, but that's fine.
Fix regression introduced fixing #211
Make all library code compatible with both Python 2 and Python 3. Helps
move to modern Python idioms. Can now write for Python 3 (with
workarounds for Python 2) instead of the other way around.
In the future, when it is eventually time to drop Python 2, the library
will be in a better position to remove workarounds
Added a very small comparability module compat.py where required. It
includes definitions for:
- text_type -- A type. str on Python 3. unicode on Python 2.
- string_types -- A tuple. Contains only str on Python 3. Contains str &
unicode on Python 2.
Deprecated in commit b263fbf274 on
2010-01-13. The deprecation warning was first released in version 2.2.2.
The function used to register an alternate type caster for TIMESTAMP
WITH TIME ZONE to deal with historical time zones with seconds in the
UTC offset. These are now correctly handled by the default type caster,
so currently the function doesn't do anything.
namedtuple is available on all Python versions supported by psycopg2. It
was first introduced in Python 2.6. Can remove all workarounds and
special documentation.
The syntax "except Exception, exc:" is deprecated. All Python versions
supported by psycopg2 support the newer, modern syntax. Forward
compatible with future Python versions.
