Nested Database Transactions problem

I'm having a problem with nested database transactions. According to the documentation for CAPI.EndTransaction:

Note that CAPI keeps a running tally of the number of times that CAPI.StartTransaction() has been called since the last CAPI.EndTransaction(). In order for a commit to actually take place, the number of StartTransactions for a given operation must be balanced by an equal number of EndTransactions and all EndTransactions must pass CAPI.COMMIT. This structure allows multiple levels of an application to all call StartTransaction and EndTransaction while still allowing the highest level of the code to maintain ultimate controls over the transaction. If, at any level, CAPI.ROLLBACK is passed, the entire transaction will be rolled back at that point.

The last line (in bold) is the part I'm struggling with. Consider the following code snippet. The admin server must be disabled (to prevent memcache in $LLIAPI.CacheUtil from having an influence):

Object prgCtx = $WebProspector.Utils.GetPrgCtx()Assoc resultsecho('-------')// start the outer transaction, which calls CAPI.StartTransaction()if prgCtx.fDbConnect.StartTrans()    // start the inner transaction    if prgCtx.fDbConnect.StartTrans()        results = $LLIAPI.CacheUtil.New(prgCtx, "TEST VALUE")        echo( \            "Inner:   ", \            $LLIAPI.CacheUtil.Load(prgCtx, results.objectid) \            )        // rollback the inner transaction, which calls CAPI.EndTransaction()        prgCtx.fDbConnect.EndTrans( false )        echo( \            "Outer 1: ", \            $LLIAPI.CacheUtil.Load(prgCtx, results.objectid) \            )    end    // commit the outer transaction    prgCtx.fDbConnect.EndTrans( true )endecho( \    "Outer 2: ", \    $LLIAPI.CacheUtil.Load(prgCtx, results.objectid) \    )

The output from this is:

-------Inner:   A<1,?,'apiError'=?,'errMsg'='','expires'=D/2015/3/8:13:36:35,'objectValue'='TEST VALUE','ok'=true>Outer 1: A<1,?,'apiError'=?,'errMsg'='','expires'=D/2015/3/8:13:36:35,'objectValue'='TEST VALUE','ok'=true>Outer 2: A<1,?,'apiError'=?,'errMsg'='','expires'=D/2015/3/8:13:36:35,'objectValue'='TEST VALUE','ok'=true>

I would have expected Outer 1 or at least Outer 2 to return an error since the inner transaction was rolled back and according to the documentation should have caused the entire transaction to be rolled back.

Can anyone confirm if this is a bug in the code, a documentation error, or if I'm doing something wrong? Thanks!

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Comments

John W. Simon, Jr.

I looked at the connect log when I ran that same code. I see some additional start/end transactions which I found to be called by the CacheUtil calls. Any chance those modified the expected behavior?

Cheers....

Chris Meyer

Hi John: I hadn't thought of that, but it shouldn't make a difference since the documentation states that:

If, at any level, CAPI.ROLLBACK is passed, the entire transaction will be rolled back at that point.

I investigated a bit more and found the CAPI.RestartTransaction() or prgCtx.fDbConnect.ResetTransactionsIfNecessary() seems to roll back the entire transaction (but requires care not to cause other problems).

Hans Stoop

My interpretation of this has always been that the inner transactions are ignored and only the outer transaction is actually taking place.

On a side note: There is also a transaction mechanism in dbConnection (StartTrans and EndTrans). I never remember which one should be used. I only remember that they should not be mixed. I hope development will at a comment to both descriptions that indicates which is the preferred one.

Hans

From: eLink Entry: Content Server Development Forum [mailto:development@elinkkc.opentext.com]
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Subject: Nested Database Transactions problem

Nested Database Transactions problem

Posted bychris.meyer@kwe.li (Meyer, Chris) On 03/05/2015 08:42 AM

I'm having a problem with nested database transactions. According to the documentation forCAPI.EndTransaction:

Note that CAPI keeps a running tally of the number of times that CAPI.StartTransaction() has been called since the last CAPI.EndTransaction(). In order for a commit to actually take place, the number of StartTransactions for a given operation must be balanced by an equal number of EndTransactions and all EndTransactions must pass CAPI.COMMIT. This structure allows multiple levels of an application to all call StartTransaction and EndTransaction while still allowing the highest level of the code to maintain ultimate controls over the transaction. If, at any level, CAPI.ROLLBACK is passed, the entire transaction will be rolled back at that point.

The last line (in bold) is the part I'm struggling with. Consider the following code snippet. The admin servermust be disabled (to prevent memcache in $LLIAPI.CacheUtil from having an influence):

Object prgCtx = $WebProspector.Utils.GetPrgCtx()

Assoc results

echo('-------')

// start the outer transaction, which calls CAPI.StartTransaction()

if prgCtx.fDbConnect.StartTrans()

    // start the inner transaction

    if prgCtx.fDbConnect.StartTrans()

        results = $LLIAPI.CacheUtil.New(prgCtx, "TEST VALUE")

        echo( \

            "Inner:   ", \

            $LLIAPI.CacheUtil.Load(prgCtx, results.objectid) \

        // rollback the inner transaction, which calls CAPI.EndTransaction()

        prgCtx.fDbConnect.EndTrans( false )

        echo( \

            "Outer 1: ", \

            $LLIAPI.CacheUtil.Load(prgCtx, results.objectid) \

end

    // commit the outer transaction

    prgCtx.fDbConnect.EndTrans( true )

end

echo( \

    "Outer 2: ", \

    $LLIAPI.CacheUtil.Load(prgCtx, results.objectid) \

The output from this is:

-------

Inner:   A<1,?,'apiError'=?,'errMsg'='','expires'=D/2015/3/8:13:36:35,'objectValue'='TEST VALUE','ok'=true>

Outer 1: A<1,?,'apiError'=?,'errMsg'='','expires'=D/2015/3/8:13:36:35,'objectValue'='TEST VALUE','ok'=true>

Outer 2: A<1,?,'apiError'=?,'errMsg'='','expires'=D/2015/3/8:13:36:35,'objectValue'='TEST VALUE','ok'=true>

I would have expected Outer 1 or at leastOuter 2 to return an error since the inner transaction was rolled back and according to the documetation should have caused theentire transaction to be rolled back.

Can anyone confirm if this is a bug in the code, a documentation error, or if I'm doing something wrong? Thanks!

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