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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.
48 lines
1.6 KiB
C
48 lines
1.6 KiB
C
/* solaris_support.h - definitions for solaris_support.c
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*
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* Copyright (C) 2017 My Karlsson <mk@acc.umu.se>
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* Copyright (c) 2018-2019, Joyent, Inc.
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*
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* This file is part of psycopg.
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*
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* psycopg2 is free software: you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published
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* by the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* In addition, as a special exception, the copyright holders give
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* permission to link this program with the OpenSSL library (or with
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* modified versions of OpenSSL that use the same license as OpenSSL),
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* and distribute linked combinations including the two.
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*
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* You must obey the GNU Lesser General Public License in all respects for
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* all of the code used other than OpenSSL.
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*
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* psycopg2 is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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* License for more details.
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*/
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#ifndef PSYCOPG_SOLARIS_SUPPORT_H
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#define PSYCOPG_SOLARIS_SUPPORT_H
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#include "psycopg/config.h"
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#if defined(__sun) && defined(__SVR4)
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#include <sys/time.h>
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#ifndef timeradd
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extern HIDDEN void timeradd(struct timeval *a, struct timeval *b, struct timeval *c);
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extern HIDDEN void timersub(struct timeval *a, struct timeval *b, struct timeval *c);
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#endif
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#ifndef timercmp
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#define timercmp(a, b, cmp) \
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(((a)->tv_sec == (b)->tv_sec) ? \
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((a)->tv_usec cmp (b)->tv_usec) : \
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((a)->tv_sec cmp (b)->tv_sec))
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#endif
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#endif
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#endif /* !defined(PSYCOPG_SOLARIS_SUPPORT_H) */
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