57 lines
1.7 KiB
Plaintext
57 lines
1.7 KiB
Plaintext
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#!/bin/sh
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# Flush MySQL tables to the disk before the filesystem is frozen.
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# At the same time, this keeps a read lock in order to avoid write accesses
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# from the other clients until the filesystem is thawed.
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MYSQL="/usr/bin/mysql"
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MYSQL_OPTS="-uroot" #"-prootpassword"
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FIFO=/var/run/mysql-flush.fifo
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# Check mysql is installed and the server running
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[ -x "$MYSQL" ] && "$MYSQL" $MYSQL_OPTS < /dev/null || exit 0
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flush_and_wait() {
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printf "FLUSH TABLES WITH READ LOCK \\G\n"
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trap 'printf "$(date): $0 is killed\n">&2' HUP INT QUIT ALRM TERM
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read < $FIFO
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printf "UNLOCK TABLES \\G\n"
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rm -f $FIFO
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}
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case "$1" in
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freeze)
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mkfifo $FIFO || exit 1
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flush_and_wait | "$MYSQL" $MYSQL_OPTS &
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# wait until every block is flushed
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while [ "$(echo 'SHOW STATUS LIKE "Key_blocks_not_flushed"' |\
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"$MYSQL" $MYSQL_OPTS | tail -1 | cut -f 2)" -gt 0 ]; do
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sleep 1
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done
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# for InnoDB, wait until every log is flushed
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INNODB_STATUS=$(mktemp /tmp/mysql-flush.XXXXXX)
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[ $? -ne 0 ] && exit 2
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trap "rm -f $INNODB_STATUS; exit 1" HUP INT QUIT ALRM TERM
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while :; do
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printf "SHOW ENGINE INNODB STATUS \\G" |\
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"$MYSQL" $MYSQL_OPTS > $INNODB_STATUS
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LOG_CURRENT=$(grep 'Log sequence number' $INNODB_STATUS |\
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tr -s ' ' | cut -d' ' -f4)
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LOG_FLUSHED=$(grep 'Log flushed up to' $INNODB_STATUS |\
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tr -s ' ' | cut -d' ' -f5)
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[ "$LOG_CURRENT" = "$LOG_FLUSHED" ] && break
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sleep 1
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done
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rm -f $INNODB_STATUS
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;;
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thaw)
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[ ! -p $FIFO ] && exit 1
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echo > $FIFO
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;;
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*)
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exit 1
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;;
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esac
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