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The new branch should have been previously authorized. Authorization is provided either by a matching call to $JOIN_RM with the DDTM$M_COORDINATOR flag set or by a matching call to $ADD_BRANCH. Two calls, one to $ADD_BRANCH and one to $START_BRANCH or one to $JOIN_RM and one to $START_BRANCH, are said to be matching when the following conditions are true:
$START_BRANCH does not check that there has been a matching call to $ADD_BRANCH or $JOIN_RM unless the tm_name argument passed to $START_BRANCH specifies the local node.
The atomicity of the transaction is not guaranteed if there is a call to $START_BRANCH that does not have a matching call to $ADD_BRANCH or $JOIN_RM. |
Preconditions for the successful completion of $START_BRANCH are:
$START_BRANCH may fail because:
When $START_BRANCH completes successfully:
A branch may:
(The way to invoke a resource manager operation is defined by the interfaces provided by the resource manager; see the resource manager documentation.)
A synchronized branch is removed from the transaction by calling $END_BRANCH, specifying the appropriate BID and TID. An unsynchronized branch is removed from the transaction by DECdtm during commit or abort processing.
The branch is also removed from the transaction (and the transaction aborted):
There is also a wait form of the service, $START_BRANCHW.
None
BYTLM, ASTLM
$ABORT_TRANS, $ABORT_TRANSW, $ACK_EVENT, $ADD_BRANCH, $ADD_BRANCHW, $CREATE_UID, $DECLARE_RM, $DECLARE_RMW, $END_BRANCH, $END_BRANCHW, $END_TRANS, $END_TRANSW, $FORGET_RM, $FORGET_RMW, $GETDTI, $GETDTIW, $GET_DEFAULT_TRANS, $JOIN_RM, $JOIN_RMW, $SETDTI, $SETDTIW, $SET_DEFAULT_TRANS, $SET_DEFAULT_TRANSW, $START_BRANCHW, $START_TRANS, $START_TRANSW, $TRANS_EVENT, $TRANS_EVENTW
SS$_NORMAL If returned in R0, the request was successfully queued. If returned in the I/O status block, the service completed successfully. SS$_SYNCH The service completed successfully and synchronously (returned only if the DDTM$M_SYNC flag is set). SS$_ACCVIO An argument was not accessible to the caller. SS$_ALRCURTID Either:
- An attempt was made to make the transaction specified by the tid argument the default transaction (the DDTM$M_NONDEFAULT flag was clear) when the calling process had an unended default transaction.
- The DDTM$M_NONDEFAULT flag was clear and a call to $SET_DEFAULT_TRANS by the calling process was in progress.
SS$_BADPARAM Either the options flags were invalid or the tid argument was omitted but the bid argument was not zero. SS$_BRANCHSTARTED There has already been a call to $START_BRANCH on the local node specifying that TID and BID (returned only if the node specified by the tm_name argument was the local node). SS$_CONNECFAIL The node specified by the tm_name argument was not the local node, and there was no communications link between the DECdtm transaction managers on the local node and the specified node. SS$_EXASTLM The process AST limit (ASTLM) was exceeded. SS$_EXQUOTA The job buffered I/O byte limit quota (BYTLM) was exceeded. SS$_ILLEFC The event flag number was invalid. SS$_INSFARGS A required argument was missing. SS$_INSFMEM There was insufficient system dynamic memory for the operation. SS$_INVBUFLEN The string passed in the tx_class argument was longer than 31 characters, or the string passed in the tm_name argument was longer than 256 characters. SS$_NOLOG The local node did not have a transaction log. SS$_NOSUCHBID Either:
- The specified BID was not returned by any call to $ADD_BRANCH or $JOIN_RM on the local node (returned only if the node specified by the tm_name argument was the local node).
- An BID of zero was supplied.
SS$_NOSUCHTID The local node did not have any branches in the specified transaction (returned only if the node specified by the tm_name argument was the local node). SS$_TPDISABLED The TP_SERVER process was not running on the local node. SS$_WRONGSTATE The transaction was in the wrong state for the attempted operation because either:
- An abort event has occurred for the transaction.
- A call to $END_TRANS to end the transaction is in progress and it is now too late to add a new branch to the transaction.
Adds a new branch to a transaction.$START_BRANCHW always waits for the request to complete before returning to the caller. Other than this, it is identical to $START_BRANCH.
SYS$START_BRANCHW [efn] ,[flags] ,iosb ,[astadr] ,[astprm] ,tid ,tm_name ,bid [,[timout] ,[acmode], [tx_class]]
int sys$start_branchw (unsigned int efn, unsigned int flags, struct _iosb *iosb, void (*astadr)(__unknown_params), int astprm, unsigned int tid [4], void *tm_name, unsigned int bid [4],...);
Starts a new transaction.
SYS$START_TRANS [efn] ,[flags] ,iosb [,[astadr] ,[astprm] ,[tid] ,[timout] ,[acmode] ,[tx_class]]
int sys$start_trans (unsigned int efn, unsigned int flags, struct _iosb *iosb,...);
efn
OpenVMS usage: ef_number type: longword (unsigned) access: read only mechanism: by value
Number of the event flag that is set when the service completes. If this argument is omitted, event flag 0 is used.flags
OpenVMS usage: mask_longword type: longword (unsigned) access: read only mechanism: by value
Flags specifying options for the service. The flags argument is a longword bit mask in which each bit corresponds to an option flag. The $DDTMDEF macro defines symbolic names for these option flags, which are described in Table SYS-57. All undefined bits must be 0. If this argument is omitted, no flags are used.
Table SYS-57 $START_TRANS Option Flags Flag Description DDTM$M_NONDEFAULT Set this flag if you do not want the new transaction to be the default transaction of the calling process. An error is returned if this flag is set and the tid argument is zero or omitted. If this flag is clear, the new transaction becomes the default transaction of the calling process. An error is returned if this flag is clear and the calling process already has a default transaction.
DDTM$M_SYNC Set this flag to specify that successful synchronous completion is to be indicated by returning SS$_SYNCH. When SS$_SYNCH is returned, the AST routine is not called, the event flag is not set, and the I/O status block is not filled in. iosb
OpenVMS usage: io_status_block type: quadword (unsigned) access: write only mechanism: by reference
I/O status block in which the completion status of the service is returned as a condition value. See the Condition Values Returned section.The following diagram shows the structure of the I/O status block:
| OpenVMS usage: | ast_procedure |
| type: | procedure entry mask |
| access: | call without stack unwinding |
| mechanism: | by reference |
| OpenVMS usage: | user_arg |
| type: | longword (unsigned) |
| access: | read only |
| mechanism: | by value |
| OpenVMS usage: | trans_id |
| type: | octaword (unsigned) |
| access: | write only |
| mechanism: | by reference |
No other call to $START_TRANS on any node ever returns the same TID value.
The default value of this argument is zero. An error is returned if the DDTM$M_NONDEFAULT flag is set and this argument is either omitted or zero.
| OpenVMS usage: | date_time |
| type: | quadword (unsigned) |
| access: | read only |
| mechanism: | by reference |
A positive time value specifies an absolute time. The absolute value of a negative time specifies an offset (delta time) from the current time.
The transaction is aborted at the next timer interval if you specify either a zero time value or any time in the past. If this argument is omitted, the new transaction has no timeout.
| OpenVMS usage: | access_mode |
| type: | longword (unsigned) |
| access: | read only |
| mechanism: | by value |
An access mode is maintained for each transaction per process. All branches in a transaction in a process have the same access mode. Subsequent operations do not alter it. The access mode of a branch is the least privileged mode in which a successful call to $END_TRANS may be made.
Note that the transaction may be aborted by a call to $ABORT_TRANS from any access mode.
The access mode of the branch is the least privileged of the following:
If the acmode argument is omitted, the access mode of the new branch is the same as that of the caller.
| OpenVMS usage: | char_string |
| type: | character-coded text string |
| access: | read only |
| mechanism: | by descriptor--fixed-length string descriptor |
This string must be no longer than 31 characters. If this argument is omitted or the string is of length zero, the new transaction has no transaction class on the local node. In this case, the class of the transaction on the local node can be specified by a subsequent call to $START_BRANCH on that node.
The $START_TRANS system service starts a new transaction whose commit or abort processing is to be coordinated by the local DECdtm transaction manager. The service:
- Adds a branch running in the calling process to the new transaction. The identifier (BID) of the new branch is 0.
- Sets the default transaction of the calling process to the new transaction, if the DDTM$M_NONDEFAULT flag is clear and the process does not have a default transaction.
- Delivers an event of type Transaction Started to each RMI in the calling process that requested Transaction Started events and has an access mode that is the same as or more privileged than that specified in this call to $START_TRANS. See the description of the acmode argument.
The event delivered to all such RMIs is either a default transaction-started event or a nondefault transaction-started event, depending on whether the DDTM$M_NONDEFAULT flag is clear or not.
Preconditions for the successful completion of $START_TRANS are:
- The local node must have a DECdtm transaction log.
- The TP_SERVER process must be running on the local node.
- If the DDTM$M_NONDEFAULT flag is clear, the calling process must not have an unended default transaction.
$START_TRANS may fail for various reasons including:
- Preconditions were not met.
- The DDTM$M_NONDEFAULT flag was clear and a call to $SET_DEFAULT_TRANS by the calling process is in progress.
When $START_TRANS completes successfully:
- A new transaction has started, with a unique identifier.
- The transaction has a single branch, with a BID of 0.
- All Transaction Started events reported to RMIs in the calling process have been acknowledged.
- If the DDTM$M_NONDEFAULT flag was clear, the transaction is the default transaction of the calling process.
A branch may:
- Invoke resource manager operations, explicitly passing the TID.
- Invoke resource manager operations without specifying the TID, if the transaction is the default transaction of the calling process, and the resource manager supports default transactions.
- Call $ADD_BRANCH to authorize another branch to be added to the transaction.
(The way to invoke a resource manager operation is defined by the interfaces provided by the resource manager. For additional information, see the resource manager documentation.)
DECdtm cannot commit the transaction until the process calls $END_TRANS.
The transaction is aborted:
- On termination of the current image or process.
- On successful completion of a call to $ABORT_TRANS in the calling process, specifying a BID of 0.
There is also a wait form of the service, $START_TRANSW.
None
ASTLM, BYTLM
$ABORT_TRANS, $ABORT_TRANSW, $ACK_EVENT, $ADD_BRANCH, $ADD_BRANCHW, $CREATE_UID, $DECLARE_RM, $DECLARE_RMW, $END_BRANCH, $END_BRANCHW, $END_TRANS, $END_TRANSW, $FORGET_RM, $FORGET_RMW, $GETDTI, $GETDTIW, $GET_DEFAULT_TRANS, $JOIN_RM, $JOIN_RMW, $SETDTI, $SETDTIW, $SET_DEFAULT_TRANS, $SET_DEFAULT_TRANSW, $START_BRANCH, $START_BRANCHW, $START_TRANSW, $TRANS_EVENT, $TRANS_EVENTW
SS$_NORMAL If returned in R0, the request was successfully queued. If returned in the I/O status block, the service completed successfully. SS$_SYNCH The service completed successfully and synchronously (returned only if the DDTM$M_SYNC flag is set). SS$_ACCVIO An argument was not accessible to the caller. SS$_ALCURTID Either:
- An attempt was made to start a default transaction (the DDTM$M_NONDEFAULT flag was clear) when the calling process had an unended default transaction.
- The DDTM$M_NONDEFAULT flag was clear and a call to $SET_DEFAULT_TRANS by the calling process was in progress.
SS$_BADPARAM Either the DDTM$M_NONDEFAULT flag was set and the tid argument was omitted, or the options flags were invalid. SS$_CURTIDCHANGE The DDTM$M_NONDEFAULT flag was clear and a call to change the default transaction of the calling process was in progress. SS$_EXASTLM The process AST limit (ASTLM) was exceeded. SS$_EXQUOTA The job buffered I/O byte limit quota (BYTLM) was exceeded. SS$_ILLEFC The event flag number was invalid. SS$_INSFARGS A required argument was missing. SS$_INSFMEM There was insufficient system dynamic memory for the operation. SS$_INVBUFLEN The string passed to the tx_class argument was longer than 31 characters. SS$_NOLOG The local node did not have a transaction log. SS$_TPDISABLED The TP_SERVER process was not running on the local node.
Starts a new transaction.$START_TRANSW always waits for the request to complete before returning to the caller. Other than this, it is identical to $START_TRANS.
SYS$START_TRANSW [efn] ,[flags] ,iosb [,[astadr] ,[astprm] ,[tid] ,[timout] ,[acmode]]
int sys$start_transw (unsigned int efn, unsigned int flags, struct _iosb *iosb,...);
On Alpha and Integrity server systems, disables user image alignment fault reporting.
SYS$STOP_ALIGN_FAULT_REPORT
int sys$stop_align_fault_report (void);
None.
The Stop Alignment Fault Reporting service disables user image alignment fault reporting.The service returns SS$_AFR_NOT_ENABLED if user image alignment fault reporting is not enabled; otherwise, it returns success.
None
None
$GET_ALIGN_FAULT_DATA, $GET_SYS_ALIGN_FAULT_DATA, $INIT_SYS_ALIGN_FAULT_REPORT, $PERM_DIS_ALIGN_FAULT_REPORT, $PERM_REPORT_ALIGN_FAULT, $START_ALIGN_FAULT_REPORT, $STOP_SYS_ALIGN_FAULT_REPORT
SS$_NORMAL The service completed successfully. SS$_AFR_NOT_ENABLED The $START_ALIGN_FAULT_REPORT service has not been called.
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