HP OpenVMS Systems Documentation

HP OpenVMS System Services Reference Manual

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.

Format

SYS$START_BRANCHW [efn] ,[flags] ,iosb ,[astadr] ,[astprm] ,tid ,tm_name ,bid [,[timout] ,[acmode], [tx_class]]

C Prototype

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.

Format

SYS$START_TRANS [efn] ,[flags] ,iosb [,[astadr] ,[astprm] ,[tid] ,[timout] ,[acmode] ,[tx_class]]

C Prototype

int sys$start_trans (unsigned int efn, unsigned int flags, struct _iosb *iosb,...);

Arguments

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-58. All undefined bits must be 0. If this argument is omitted, no flags are used.

Table SYS-58 $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:

astadr

astprm

tid

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.

timout

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.

acmode

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:

• The access mode of the caller
• The access mode specified by the acmode argument

If the acmode argument is omitted, the access mode of the new branch is the same as that of the caller.

tx_class

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.

Description

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, explicity 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. Refer to the resource manager documentation for additional information.)

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.

Required Access or Privileges

None

Required Quotas

ASTLM, BYTLM

Related Services

$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

Condition Values Returned

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.

Format

SYS$START_TRANSW [efn] ,[flags] ,iosb [,[astadr] ,[astprm] ,[tid] ,[timout] ,[acmode]]

C Prototype

int sys$start_transw (unsigned int efn, unsigned int flags, struct _iosb *iosb,...);

On Alpha and I64 systems, disables user image alignment fault reporting.

Format

SYS$STOP_ALIGN_FAULT_REPORT

C Prototype

int sys$stop_align_fault_report (void);

Arguments

None.

Description

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.

Required Access or Privileges

None

Required Quota

None

Related Services

$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

Condition Values Returned

SS$_NORMAL	The service completed successfully.
SS$_AFR_NOT_ENABLED	The $START_ALIGN_FAULT_REPORT service has not been called.

On Alpha and I64 systems, disables systemwide alignment fault reporting.

Format

SYS$STOP_SYS_ALIGN_FAULT_REPORT

C Prototype

int sys$stop_sys_align_fault_report (void);

Arguments

None.

Description

The Stop System Alignment Fault Reporting service disables systemwide alignment fault reporting.

The service returns SS$_AFR_NOT_ENABLED if systemwide alignment fault reporting is not enabled; otherwise, it returns success.

Required Access or Privileges

CMKRNL privilege is required.

Required Quota

None

Related Services

$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

Condition Values Returned

SS$_NORMAL	The service completed successfully.
SS$_NOPRIV	The caller lacks sufficient privilege.
SS$_AFR_NOT_ENABLED	The $START_ALIGN_FAULT_REPORT service has not been called.

Saves or restores the process image rights for the current protected subsystem.

Format

SYS$SUBSYSTEM enbflg

C Prototype

int sys$subsystem (unsigned int enbflg);

Argument

enbflg

OpenVMS usage:	boolean
type:	longword (unsigned)
access:	read only
mechanism:	by value

Value specifying whether the protected subsystem identifiers are to be saved or restored. If the enbflg argument is set to 0, the active subsystem is saved. If it is set to 1, the subsystem is restored.

Description

A protected subsystem image is a main image that has in its access control list a special type of ACE that names a set of identifiers and their attributes. Whenever the operating system activates a main image that has protected subsystem identifiers associated with it, these identifiers are automatically granted to the process for the duration of the image.

In essence, a protected subsystem provides the same behavior as if the image had been installed with the identifiers. Subsystem identifiers are sometimes referred to as image rights, in contrast to process rights and system rights.

The Subsystem service provides an easy way for a protected subsystem image to dynamically save and restore its subsystem identifiers. A protected subsystem might choose to turn off its subsystem identifiers at certain times to temporarily revoke the user's access to the objects comprising the protected subsystem. For example, DCL uses the $SUBSYSTEM service to temporarily remove any image identifiers from the process during Ctrl/Y interrupt processing.

The image rights are saved in the process control region and automatically deleted on image rundown ($RMSRUNDWN).

For more information about protected subsystems, refer to the HP OpenVMS Guide to System Security.

Required Access or Privileges

None

Required Quota

None

Related Services

None

Condition Values Returned

SS$_WASCLR	The service completed successfully; protected subsystem had no identifiers associated with it.
SS$_WASSET	The service completed successfully; protected subsystem had identifiers associated with it.

Allows a process to suspend itself or another process.

Format

SYS$SUSPND [pidadr] ,[prcnam] ,[flags]

C Prototype

int sys$suspnd (unsigned int *pidadr, void *prcnam, unsigned int flags);

Arguments

pidadr

OpenVMS usage:	process_id
type:	longword (unsigned)
access:	modify
mechanism:	by reference

Process identification (PID) of the process to be suspended. The pidadr argument is the address of the longword PID.

The pidadr argument can refer to a process running on the local node or a process running on another node in the OpenVMS Cluster system.

You must specify the pidadr argument to suspend a process whose UIC group number is different from that of the calling process.

prcnam

OpenVMS usage:	process_name
type:	character-coded text string
access:	read only
mechanism:	by descriptor--fixed-length string descriptor

Name of the process to be suspended. The prcnam argument is the address of a character string descriptor pointing to the process name. A process running on the local node can be identified with a 1- to 15-character string.

To identify a process on a particular node on a cluster, specify the full process name, which includes the node name as well as the process name. The full process name can contain up to 23 characters.

A process name is implicitly qualified by its UIC group number. Because of this, you can use the prcnam argument only to suspend processes in the same UIC group as the calling process.

To suspend processes in other groups, you must specify the pidadr argument.

flags

OpenVMS usage:	mask_longword
type:	longword (unsigned)
access:	read only
mechanism:	by value

Longword of bit flags specifying options for the suspend operation. Currently, only bit 0 is used for the flags argument. When bit 0 is set, the process is suspended at kernel mode and ASTs are not deliverable to the process.

To request a kernel mode suspend, the caller must be in either kernel mode or executive mode. The default (bit 0 is clear) is to suspend the process at supervisor mode, where executive or kernel mode ASTs can be delivered to the process. If executive or kernel mode ASTs have been delivered to a process suspended at supervisor mode, that process will return to its suspended state after the AST routine executes.

Description

The Suspend Process service allows a process to suspend itself or another process.

A suspended process can receive executive or kernel mode ASTs, unless it is suspended at kernel mode. If a process is suspended at kernel mode, the process cannot receive any ASTs or otherwise be executed until another process resumes or deletes it. If you specify neither the pidadr nor the prcnam argument, the caller process is suspended.

If the longword value at address pidadr is 0, the PID of the target process is returned.

The $SUSPND service requires system dynamic memory.

The $SUSPND service completes successfully if the target process is already suspended.

Unless it has pages locked in the balance set, a suspended process can be removed from the balance set to allow other processes to execute.

Note that a kernel mode suspend request can override a supervisor mode suspend state, but a supervisor suspend request cannot override a kernel mode suspend state.

The Resume Process ($RESUME) service allows a suspended process to continue. If one or more resume requests are issued for a process that is not suspended, a subsequent suspend request completes immediately; that is, the process is not suspended. No count is maintained of outstanding resume requests.

Note When the $SUSPND service is called and the target process is on a different cluster node than that of the process calling the $SUSPND service, the kernel mode suspend flag (bit 0) is ignored. As a result, any suspend is treated as a supervisor-mode suspend.

Required Access or Privileges

Depending on the operation, the calling process might need one of the following privileges to use $SUSPND:

• GROUP privilege to suspend another process in the same group, unless the process to be suspended has the same UIC as the calling process
• WORLD privilege to suspend any other process in the system

Required Quota

None

Related Services

$CANEXH, $CREPRC, $DCLEXH, $DELPRC, $EXIT, $FORCEX, $GETJPI, $GETJPIW, $HIBER, $PROCESS_SCAN, $RESUME, $SETPRI, $SETPRN, $SETPRV, $SETRWM, $WAKE

Condition Values Returned

SS$_NORMAL	The service completed successfully.
SS$_ACCVIO	The process name string or string descriptor cannot be read by the caller, or the process identification cannot be written by the caller.
SS$_INCOMPAT	The remote node is running an incompatible version of the operating system.
SS$_INSFMEM	The system dynamic memory is insufficient for completing the service.
SS$_IVLOGNAM	The specified process name has a length of 0 or has more than 15 characters.
SS$_NONEXPR	The specified process does not exist, or an invalid process identification was specified.
SS$_NOPRIV	The target process was not created by the caller and the calling process does not have GROUP or WORLD privilege, or flag bit 0 was set from outer mode.
SS$_NOSUCHNODE	The process name refers to a node that is not currently recognized as part of the OpenVMS Cluster system.
SS$_NOSUSPEND	The process was previously marked as not suspendable by the PCB$V_NOSUSPEND flag.
SS$_REMRSRC	The remote node has insufficient resources to respond to the request. (Bring this error to the attention of your system manager.)
SS$_UNREACHABLE	The remote node is a member of the cluster but is not accepting requests. (This is normal for a brief period early in the system boot process.)
SS$_WAIT_CALLERS_MODE	Bit 1 was used in the flags argument.