TMF Application Programmer's Guide (G06.24+)

File System Procedures

HP NonStop TMF Application Programmer’s Guide—522419-004

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TMF_JOIN_

This procedure allows a process to participate in a transaction initiated by another

process without taking over as the ENDTRANSACTION caller. TMF_JOIN_ can be

called by more than one process in the same Expand node at the same time. The

BEGINTRANSACTION caller need not call TMF_SUSPEND_ before another process

calls TMF_JOIN_ and can participate in the transaction at the same time.

Joining a transaction means:

•

Making the transaction the current transaction.

•

The process calling TMF_JOIN_ is not allowed to call ENDTRANSACTION.

To relinquish control of a joined transaction, the calling process must issue a

TMF_SUSPEND_ call; otherwise, the process that initiated the transaction receives

error 730 when it tries to run ENDTRANSACTION.

TMF_JOIN_ has the same semantics as the implicit transaction propogation provided

by the file system and can provide the same function when file system propogation is

not appropriate to the application.

The transaction identifier passed to this procedure is the one returned by

TMF_GET_TX_ID_.

This procedure cannot be used for transactions that were begun on a different

EXPAND node.

A joined transaction uses one of the entries in the calling process’ TFILE. If the

process has not explicitly opened the TFILE, the joined transaction uses the one TFILE

entry that exists for all processes. If there are no available TFILE entries when the call

to TMF_JOIN_ is issued, the call is rejected with file system error 83 (too many

transactions).

If the calling process is the primary process of a process pair and the TFILE is being

checkpointed, the calling process should checkpoint the TFILE after calling

TMF_JOIN_ to modify the backup process’ TFILE accordingly.