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| author | Jörg Frings-Fürst <debian@jff-webhosting.net> | 2023-01-29 15:45:51 +0100 |
|---|---|---|
| committer | Jörg Frings-Fürst <debian@jff-webhosting.net> | 2023-01-29 15:45:51 +0100 |
| commit | 517ad9d4b6eae320b708d03a9340a22893b0cab7 (patch) | |
| tree | 37cf1907008821b4155cf90718b8d7b00a9d3461 /docs/html/xbc12.htm | |
| parent | 4875a3dd9b183dcd2256e2abfc4ccf7484c233b4 (diff) | |
New upstream version 4.0.3upstream/4.0.3
Diffstat (limited to 'docs/html/xbc12.htm')
| -rwxr-xr-x | docs/html/xbc12.htm | 72 |
1 files changed, 0 insertions, 72 deletions
diff --git a/docs/html/xbc12.htm b/docs/html/xbc12.htm deleted file mode 100755 index f9fe114..0000000 --- a/docs/html/xbc12.htm +++ /dev/null @@ -1,72 +0,0 @@ -<!DOCTYPE HTML PUBLIC> -<HTML> -<TITLE>Xbase DBMS Chapter 8</TITLE> -<BODY BGCOLOR=#FFFFFF> -<H1><p align="center">Record and File Locking</p></H1> -<p align="center">Chapter Updated 11/29/22</p><hr> - -<h3>Locking Overview</h3> - -Xbase64 supports multi-user processing through file and record locks. -Record locking restricts multiple cooperating programs from simultaneously -accessing the same data and corrupting it. Without record and file locking -in a multi-user environment, simultaneous access to the data and index files -can cause the files to become inaccurate and unusable.<br><br> - -Automatic record locking is on by default in the Xbase64 library. To disable it, -use method xbXBase::DisableDefaultAutoLock() and to enable it, use method xbXBase::EnableDefaultAutoLock(). - -Locking can also be enabled / disabled at the table level with with xbDbf::SetAutoLock(). - - -<br><br> -The current Xbase64 record locking logic is modeled after DBase (tm) V7 locking. -<br><br> - -The locking methods return either XB_LOCK_FAILED or XB_NO_ERROR. If they return -XB_LOCK_FAILED the actual reason can be found in the global variable -<em>errno</em> or function <em>perror()</em> can be executed to view the -results. -<br><br> - -The errno field may contain one of the following values if the lock was not -successful.<br><br> -<TABLE BORDER> -<TR VALIGN="BASELINE"> -<TR><TH ALIGN="LEFT">Error Code<TD>Description -<TR><TH ALIGN="LEFT">EBADF<TD>Invalid file descriptor -<TR><TH ALIGN="LEFT">EINVAL<TD>Invalid lock information or file does not support locks -<TR><TH ALIGN="LEFT">EACCESS<BR>EAGAIN<TD>Lock can not be set because it is blocked by an existing lock on the file. -<TR><TH ALIGN="LEFT">ENOLCK<TD>The system is out of lock resources, too many file locks in place. -<TR><TH ALIGN="LEFT">EDEADLK<TD>Deadlock condition -<TR><TH ALIGN="LEFT">EINTR<TD>Process was interrupted by a signal while it was waiting -</TABLE> -<br><br> - -<h3>Linux/Windows File Locking Compatibility Issue</h3> - -There is a compatibility locking issue to be aware of. Windows environments allow for the exclusive -opening of file handles and Linux/Unix platforms do not. If you are writing an application that will be -using a tool like Dbase on a Windows machine, accessing a file on a Linux/Samba configure machine, -be aware that the file could be opened in exclusive mode by DBase on the Windows system, and the same file could -be simultaneously opened with a program on the Unix box. That could cause some issues. - -<br><br> -In Unix, a program can not lock a file so another process can not access it.<br> -In Windows, a program can lock a file so another process can not access it.<br> -DBase(tm) supports routines to open files exclusively, preventing other users from opening a file.<br> - -<br><h3>Samba settings</h3> - -If you will be using Samba on Linux/Unix and sharing files between Linux and Windows machines, -you will need to disable oplocks. In the smb.conf file, set:<br> -<h4>oplocks = no</h4> - - - - -<br> -<hr><br> -<p><img src="xbase.jpg"><br><hr> -</BODY> -</HTML> |