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050c36c7de
Bug#45243: crash on win in sql thread clear_tables_to_lock() -> free() Bug#45242: crash on win in mysql_close() -> free() Bug#45238: rpl_slave_skip, rpl_change_master failed (lost connection) for STOP SLAVE Bug#46030: rpl_truncate_3innodb causes server crash on windows Bug#46014: rpl_stm_reset_slave crashes the server sporadically in pb2 When killing a user session on the server, it's necessary to interrupt (notify) the thread associated with the session that the connection is being killed so that the thread is woken up if waiting for I/O. On a few platforms (Mac, Windows and HP-UX) where the SIGNAL_WITH_VIO_CLOSE flag is defined, this interruption procedure is to asynchronously close the underlying socket of the connection. In order to enable this schema, each connection serving thread registers its VIO (I/O interface) so that other threads can access it and close the connection. But only the owner thread of the VIO might delete it as to guarantee that other threads won't see freed memory (the thread unregisters the VIO before deleting it). A side note: closing the socket introduces a harmless race that might cause a thread attempt to read from a closed socket, but this is deemed acceptable. The problem is that this infrastructure was meant to only be used by server threads, but the slave I/O thread was registering the VIO of a mysql handle (a client API structure that represents a connection to another server instance) as a active connection of the thread. But under some circumstances such as network failures, the client API might destroy the VIO associated with a handle at will, yet the VIO wouldn't be properly unregistered. This could lead to accesses to freed data if a thread attempted to kill a slave I/O thread whose connection was already broken. There was a attempt to work around this by checking whether the socket was being interrupted, but this hack didn't work as intended due to the aforementioned race -- attempting to read from the socket would yield a "bad file descriptor" error. The solution is to add a hook to the client API that is called from the client code before the VIO of a handle is deleted. This hook allows the slave I/O thread to detach the active vio so it does not point to freed memory. server-tools/instance-manager/mysql_connection.cc: Add stub method required for linking. sql-common/client.c: Invoke hook. sql/client_settings.h: Export hook. sql/slave.cc: Introduce hook that clears the active VIO before it is freed by the client API.
43 lines
1.4 KiB
C
43 lines
1.4 KiB
C
/* Copyright (C) 2003 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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#include <thr_alarm.h>
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#define CLIENT_CAPABILITIES (CLIENT_LONG_PASSWORD | CLIENT_LONG_FLAG | \
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CLIENT_SECURE_CONNECTION | CLIENT_TRANSACTIONS | \
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CLIENT_PROTOCOL_41 | CLIENT_SECURE_CONNECTION)
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#define init_sigpipe_variables
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#define set_sigpipe(mysql)
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#define reset_sigpipe(mysql)
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#define read_user_name(A) {}
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#define mysql_rpl_query_type(A,B) MYSQL_RPL_ADMIN
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#define mysql_master_send_query(A, B, C) 1
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#define mysql_slave_send_query(A, B, C) 1
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#define mysql_rpl_probe(mysql) 0
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#undef HAVE_SMEM
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#undef _CUSTOMCONFIG_
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#define mysql_server_init(a,b,c) 0
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#ifdef HAVE_REPLICATION
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C_MODE_START
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void slave_io_thread_detach_vio();
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C_MODE_END
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#else
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#define slave_io_thread_detach_vio()
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#endif
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