Where:

In order to avoid this problem, PxPlus provides for the automatic rollover to new journal files whenever a journal file exceeds 2,000,000,000 bytes in size. This option is enabled by specifying a directory name as the journal$ field when opening a system journal. If a directory is specified the system will automatically will create sub-ordinate files within the directory called journal.1, journal.2, ...

As each file fills up the system will automatically create and start logging to the next highest file.

Automatic journal sequencing is a +PxPlus Exclusive - version 9

SYSTEM_JRNL OPEN journal$

This format opens the journal (serial file); e.g.,

SERIAL "MYJRNL"
SYSTEM_JRNL OPEN "MYJRNL"

Journal Contents

The physical journal file is a binary file that has a special format designed for quick write access and efficient retrieval. Each of the journal file's records has a 16-byte header consisting of:

The rest of the record is the before/after image of the data. The file itself has a four-byte header with the address of the last record on the file.

SYSTEM_JRNL CLOSE

This format closes the open system journal.

SYSTEM_JRNL ENABLE filename$

Use this format to enable journalization for the specified data file (Keyed or Indexed files only). Enabling journalization sets a bit in the file header for the specified file

Specifying a file name of * initiates the journalization of all keyed/indexed file updates..

SYSTEM_JRNL DISABLE filename$

Use this format to disable journalization for the specified data file.

SYSTEM_JRNL WRITE var$

This format adds the contents of var$ to the currently open journal (serial file).

SYSTEM_JRNL BEGIN

This directive is used to mark the start of a transaction. All updates to file systems (EFF, ODB, DB2, Oracle, and MYSQL) will be deferred until the transaction completes and it is committed using the SYSTEM_JRNL SAVE directive.

SYSTEM_JRNL AUTO {ON | OFF}

This format is used to control auto-commit mode of an EFF, ODBC, DB2, Oracle or MySql database connection. Auto-commit means that all updates to the database are made immediately and cannot be rolled back in case of an error.

SYSTEM_JRNL AUTO OFF will disable the auto-commit mode of operation. All updates to the database are deferred until the application successfully ends or a SYSTEM_JRNL SAVE directive is issued. SYSTEM_JRNL AUTO ON re-enables Auto-commit mode.

SYSTEM_JRNL SAVE

This format will commit all pending/deferred updates to a database transaction, if auto-commit mode is disabled; Error #15 is reported, if a database error occurs.

SYSTEM_JRNL BEGIN AUTO

PxPlus provides enhanced auto-commit logic that automatically uses transaction processing logic to defer all updates to a database until the application enters an idle state such as waiting for input or issuance of a WAIT directive. This Dynamic Auto-commit improves both system performance and the reliability of updates since all changes to the database occur at the same time. This helps assure synchronization of all updates between files and/or databases.

Dynamic Auto-commits are a +PxPlus Exclusive

SYSTEM_JRNL RESTORE

This format will roll back and discard all pending/deferred updates within database transaction, if auto-commit mode is disabled; Error #15 is reported, if a database error occurs.

SYSTEM_JRNL DIRECTORY directory$

This format is used to track potential file corruption (dirty files) by maintaining a list of all the files that have been opened and modified during a ProvideX session. ProvideX creates a single tracking file per active process in directory$.

When a session terminates normally, it deletes its tracking file; therefore, the existence of a tracking file means there is either a ProvideX task currently active, or that a ProvideX task has terminated abnormally (due to software fault or operating system failure).

Specifying a null directory name will disable this feature. If the directory name specified does not already exist, an Error #12: File does not exist (or already exists) will be generated. An Error #13: File access mode invalid is reported, if a file of the same name exists, but not as a directory.

Tracking Files

Each tracking file (log) is created with a unique name using the following format:

username.MMDDHHMMSS.log	Windows
username.MMDD.PPPPP.NNN.log	Unix/Linux

Where:

The use of the Process ID on Unix is a +PxPlus Exclusive

The tracking file contains a list of all the data files that have been physically updated and not yet closed by the ProvideX process. Every time a file has an update issued against it, the system will add the pathname to the tracking file. Each line will be separated by a standard (OS dependant) end-of-line sequence.

Multiple occurrences of the same file may exist in the tracking file, as entries are maintained based on open channels.

The tracking file is updated to indicate when a file is being updated prior to the execution of the WRITE or REMOVE directives. When a file that was logged is closed, its entry from the log file will be removed. To help ensure that the contents of the tracking file are accurate, ProvideX will close the file after each write.

SYSTEM_JRNL SWAP

This directive can be used in conjunction with the auto-sequencing of log files which is a +PxPlus Exclusive (version 9)

When issued the current journal file is marked full and a new journal file is started.

00010 ! DumpJrnl - Sample routine to parse a System_Jrnl file
00020 ! Note: Time is in GMT
00030 OPEN (1,ISZ=1)"jrnl.dat"
00040 READ RECORD (1,IND=0,SIZ=4,ERR=0500)filesize$
00050 LET filesize=DEC($00$+filesize$)
00060 PRINT "Size of Journal file is: ",filesize
00070 LET nextindex=4
00080 !
00100 ! !^100
00110 IF nextindex=0 OR nextindex>filesize \
                    THEN GOTO 0500
00120 READ RECORD (1,IND=nextindex,SIZ=16,ERR=0500)header$
00130 LET type$=header$(1,1)
00140 LET recsize=DEC($00$+header$(2,3))
00150 LET time=DEC($00$+header$(5,4))
00160 LET priorrec=DEC($00$+header$(9,4))
00170 LET relatedrec=DEC($00$+header$(13,4))
00180 LET datarec$="";
          IF recsize \
                    THEN READ RECORD (1,IND=nextindex+16,SIZ=recsize-16,ERR=0500)datarec$
00190 LET nextindex+=recsize
00200 !
00300 ! !^100 - Format & display
00310 LET disprec$=SUB(SUB(datarec$,SEP,"~"),ESC,"~")
00320 LET days=INT(time/86400);
          IF (days*86400)>time \
                    THEN days--
00330 LET time=time-days*86400
00340 LET sv_by=PRM('BY'); SET_PARAM 'BY'=1970
00350 LET t$=DTE(days,time/3600:"%Ms%Dz/%Ys-%hz:%mz:%sz%p")
00360 SET_PARAM 'BY'=sv_by
00370 !
00380 PRINT t$," Type: ",type$," Prior Rec:",priorrec:"####,##0"," RelatedRec:",relatedrec:"####,##0"," RecSize",recsize:"###,##0"," Record:",disprec$
00390 GOTO 0100
00400 !
00500 ! ^100

Dir$="/SysJrnl.Dir/"; DIRECTORY Dir$,ERR=*NEXT
WorkFile$="WorkFile.Dat"; KEYED WorkFile$,10,0,-256,ERR=*NEXT
!
! Generate a log file
SYSTEM_JRNL DIRECTORY Dir$
OPEN (UNT)WorkFile$; WorkFile=LFO
WRITE (WorkFile,KEY="Test")"Test","Record"
! List$=""
SELECT Log$ FROM Dir$ WHERE POS(".log"=Log$)
SELECT File$ FROM Dir$+Log$
IF POS(File$+SEP=List$) \
THEN CONTINUE \
ELSE List$+=File$+SEP
PRINT "Checking: ",File$," ",
CALL "*ufac",ERR=*NEXT,File$,1; PRINT "Okay"; CONTINUE
PRINT File$,":",MSG(ERR)
NEXT RECORD
NEXT RECORD
!
CLOSE (WorkFile)