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MDEV-39101 Make BACKUP SERVER mutually exclusive with itself and BACKUP STAGE
MTR tests for running concurrent backups. BACKUP SERVER acquires backup lock before starting the backup. This prevents it from running concurrently with another instance of BACKUP SERVER or BACKUP STAGE, blocking when a backup is running concurrently in another connection. If BACKUP SERVER is run on a connection on which BACKUP STAGE has been started, it will fail with an error.
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Lines changed: 205 additions & 31 deletions

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‎mysql-test/main/backup_server_concurrency,debug.rdiff‎

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--- main/backup_server_locking.result
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+++ main/backup_server_locking.reject
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@@ -1,3 +1,31 @@
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+connect blocking,localhost,root,,test;
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+SET DEBUG_SYNC='after_backup_server_lock_acquired SIGNAL blocking WAIT_FOR unblock';
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+SET DEBUG_SYNC='backup_server_finalizing SIGNAL finalizing WAIT_FOR finish';
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+BACKUP SERVER TO '<MYSQLTEST_VARDIR>/some_directory';
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+connect blocked,localhost,root,,test;
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+SET DEBUG_SYNC='now WAIT_FOR blocking';
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+BACKUP SERVER TO '<MYSQLTEST_VARDIR>/other_directory';
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+connection default;
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+SET @blocked_conn_id = $blocked_conn_id;
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+SELECT COMMAND, STATE, INFO FROM INFORMATION_SCHEMA.PROCESSLIST
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+WHERE ID = @blocked_conn_id;
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+COMMAND STATE INFO
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+Query Waiting for backup lock BACKUP SERVER TO '<MYSQLTEST_VARDIR>/other_directory'
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+SET DEBUG_SYNC='now SIGNAL unblock';
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+SET DEBUG_SYNC='now WAIT_FOR finalizing';
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+connection blocked;
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+SELECT COUNT(*) FROM INFORMATION_SCHEMA.PROCESSLIST
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+WHERE Info LIKE 'BACKUP SERVER TO %' AND State = 'Waiting for backup lock';
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+COUNT(*)
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+0
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+BACKUP SERVER TO '$MYSQLTEST_VARDIR/another_directory';
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+disconnect blocked;
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+connection default;
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+SET DEBUG_SYNC='now SIGNAL finish';
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+connection blocking;
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+disconnect blocking;
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+connection default;
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+SET DEBUG_SYNC='RESET';
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BACKUP SERVER TO '$MYSQLTEST_VARDIR/some_directory';
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ERROR HY000: Can't create directory 'MYSQLTEST_VARDIR/some_directory' (Errcode: 17 "File exists")
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BACKUP STAGE START;

mysql-test/main/backup_server_locking.result renamed to mysql-test/main/backup_server_concurrency.result

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@@ -15,3 +15,19 @@ BACKUP SERVER TO '$MYSQLTEST_VARDIR/some_directory';
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ERROR HY000: Can't create directory 'MYSQLTEST_VARDIR/some_directory' (Errcode: 17 "File exists")
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disconnect backup;
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connection default;
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BACKUP STAGE START;
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connect con1,localhost,root,,test;
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BACKUP SERVER TO '<MYSQLTEST_VARDIR>/some_directory';
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connection default;
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SET @con1_id = <con1_id>;
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SELECT COMMAND, STATE, INFO FROM INFORMATION_SCHEMA.PROCESSLIST WHERE ID = @con1_id;
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COMMAND STATE INFO
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Query Waiting for backup lock BACKUP SERVER TO '<MYSQLTEST_VARDIR>/some_directory'
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BACKUP STAGE END;
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connection con1;
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disconnect con1;
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connection default;
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BACKUP STAGE START;
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BACKUP SERVER TO '$MYSQLTEST_VARDIR/some_directory';
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ERROR HY000: Can't execute the command as you have a BACKUP STAGE active
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BACKUP STAGE END;

‎mysql-test/main/backup_server_concurrency.test‎

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# BACKUP SERVER acquires Bacup Lock, disallowing concurrent backup either
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# by another instance of BACKUP SERVER or using BACKUP STAGE.
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# Using DEBUG_SYNC facility in debug configuration we directly test
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# that while one instance of BACKUP SERVER has already acquired the
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# backup lock, a second instance running on another connection will
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# block waiting on that lock. BACKUP SERVER releases the lock before
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# it returns, when it reaches its finalization stage, as actions
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# taken in that stage affect only the backup directory and may be
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# performed concurrently with other backup processes.
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--source include/not_embedded.inc
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--source include/maybe_debug.inc
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if ($have_debug) {
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--source include/have_debug_sync.inc
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--connect (blocking,localhost,root,,test)
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# Simulate long-running backup by blocking it on a debug sync point
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SET DEBUG_SYNC='after_backup_server_lock_acquired SIGNAL blocking WAIT_FOR unblock';
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SET DEBUG_SYNC='backup_server_finalizing SIGNAL finalizing WAIT_FOR finish';
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--replace_result $MYSQLTEST_VARDIR <MYSQLTEST_VARDIR>
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--send_eval BACKUP SERVER TO '$MYSQLTEST_VARDIR/some_directory'
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--connect (blocked,localhost,root,,test)
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# Wait for the "long-running" backup to lock the system
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SET DEBUG_SYNC='now WAIT_FOR blocking';
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let $blocked_conn_id= `SELECT CONNECTION_ID()`;
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# Attempt a backup while the other backup is running
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--replace_result $MYSQLTEST_VARDIR <MYSQLTEST_VARDIR>
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--send_eval BACKUP SERVER TO '$MYSQLTEST_VARDIR/other_directory'
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--connection default
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# Check that the backup on "blocked" connection is waiting for the blocking
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# backup to finish
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evalp SET @blocked_conn_id = $blocked_conn_id;
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let $wait_condition=
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SELECT COUNT(*) = 1 FROM INFORMATION_SCHEMA.PROCESSLIST
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WHERE ID = @blocked_conn_id AND State = 'Waiting for backup lock';
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--source include/wait_condition.inc
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--replace_result $MYSQLTEST_VARDIR <MYSQLTEST_VARDIR>
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SELECT COMMAND, STATE, INFO FROM INFORMATION_SCHEMA.PROCESSLIST
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WHERE ID = @blocked_conn_id;
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SET DEBUG_SYNC='now SIGNAL unblock';
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SET DEBUG_SYNC='now WAIT_FOR finalizing';
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# The blocking backup is still running, but no longer blocking
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--connection blocked
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# Original blocked backup can complete now
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--reap
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# No blocked backup process at this point
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SELECT COUNT(*) FROM INFORMATION_SCHEMA.PROCESSLIST
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WHERE Info LIKE 'BACKUP SERVER TO %' AND State = 'Waiting for backup lock';
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# Run new BACKUP SERVER while the old one is finalizing
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--evalp BACKUP SERVER TO '$MYSQLTEST_VARDIR/another_directory'
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--disconnect blocked
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--connection default
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SET DEBUG_SYNC='now SIGNAL finish';
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--connection blocking
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--reap
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--disconnect blocking
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--connection default
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SET DEBUG_SYNC='RESET';
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--rmdir $MYSQLTEST_VARDIR/some_directory
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--rmdir $MYSQLTEST_VARDIR/other_directory
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--rmdir $MYSQLTEST_VARDIR/another_directory
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}
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# To test that BACKUP SERVER blocks itself on a release server we rely
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# on timing: a BACKUP SERVER set up to fail because the target directory
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# exists will fail with error code 21 if it is not blocked, but if
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# blocked will time out if max_statement_time is sufficiently short.
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#
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# This is a heuristic test that might fail depending on how long it takes
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# the initial backup to fail; it may give false positives or false
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# negatives, and does not test that the lcok is released in the
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# finalization phase, but it may uncover bugs that the DEBUG_SYNC test
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# would miss.
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--mkdir $MYSQLTEST_VARDIR/some_directory
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--replace_result $MYSQLTEST_VARDIR MYSQLTEST_VARDIR
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--error 21
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evalp BACKUP SERVER TO '$MYSQLTEST_VARDIR/some_directory';
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BACKUP STAGE START;
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--connect (backup,localhost,root)
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--error ER_STATEMENT_TIMEOUT
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evalp SET STATEMENT max_statement_time=0.1 FOR
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BACKUP SERVER TO '$MYSQLTEST_VARDIR/some_directory';
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--connection default
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--error ER_BACKUP_LOCK_IS_ACTIVE
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evalp BACKUP SERVER TO '$MYSQLTEST_VARDIR/some_directory';
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BACKUP STAGE END;
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--connection backup
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--replace_result $MYSQLTEST_VARDIR MYSQLTEST_VARDIR
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--error 21
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evalp SET STATEMENT max_statement_time=0.1 FOR
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BACKUP SERVER TO '$MYSQLTEST_VARDIR/some_directory';
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--disconnect backup
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--connection default
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--rmdir $MYSQLTEST_VARDIR/some_directory
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# Test that BACKUP SERVER blocks when a BACKUP STAGE process is in progress
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BACKUP STAGE START;
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--connect (con1,localhost,root,,test)
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let $con1_id= `SELECT CONNECTION_ID()`;
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--replace_result $MYSQLTEST_VARDIR <MYSQLTEST_VARDIR>
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--send_eval BACKUP SERVER TO '$MYSQLTEST_VARDIR/some_directory'
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--connection default
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--replace_result $con1_id <con1_id>
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eval SET @con1_id = $con1_id;
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let $wait_condition=
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SELECT COUNT(*) = 1 FROM INFORMATION_SCHEMA.PROCESSLIST
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WHERE ID = @con1_id AND State = 'Waiting for backup lock';
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--source include/wait_condition.inc
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--replace_result $MYSQLTEST_VARDIR <MYSQLTEST_VARDIR>
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SELECT COMMAND, STATE, INFO FROM INFORMATION_SCHEMA.PROCESSLIST WHERE ID = @con1_id;
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BACKUP STAGE END;
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# BACKUP SERVER is no longer blocked
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--connection con1
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--reap
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--disconnect con1
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--connection default
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--rmdir $MYSQLTEST_VARDIR/some_directory
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# Test that BACKUP SERVER will fail when ran on a connection which is
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# between BACKUP STAGE START and BACKUP STAGE END
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BACKUP STAGE START;
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--error ER_BACKUP_LOCK_IS_ACTIVE
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--evalp BACKUP SERVER TO '$MYSQLTEST_VARDIR/some_directory'
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BACKUP STAGE END;

‎mysql-test/main/backup_server_locking.test‎

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This file was deleted.

‎sql/sql_backup.cc‎

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thd->variables.lock_wait_timeout))
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return true;
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DEBUG_SYNC(thd, "after_backup_server_lock_acquired");
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if (my_mkdir(target.str, 0755, MYF(MY_WME)))
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{
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#ifndef _WIN32
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/* The final part will not interfere with the use of the server datadir.
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Release the locks. */
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thd->mdl_context.release_lock(mdl_request.ticket);
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DEBUG_SYNC(thd, "backup_server_finalizing");
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plugin_foreach_with_mask(thd, backup_finalize, MYSQL_STORAGE_ENGINE_PLUGIN,
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PLUGIN_IS_DELETED|PLUGIN_IS_READY, nullptr);
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#ifndef _WIN32

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