Table 18-5 lists the thread management functions that are described in this section.
Table 18-5 Thread Management Functions
| Function | Purpose |
|---|---|
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Close a thread handle |
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Create a new thread |
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Retrieve the OCIThreadHandle of the thread in which it is called |
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Destroy and deallocate the thread handle |
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Allocate and initialize the thread handle |
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Destroy and deallocate a thread ID |
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Retrieve the |
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Allocate and initialize the thread ID |
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Determine whether a given |
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Determine whether two |
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Set one |
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Set the |
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Initialize OCIThread context |
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Tell the caller whether the application is running in a multithreaded environment or a single-threaded environment |
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Allow the calling thread to join with another thread |
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Destroy and deallocate the key pointed to by |
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Get the calling thread's current value for a key |
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Create a key |
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Set the calling thread's value for a key |
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Acquire a mutex for the thread in which it is called |
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Destroy and deallocate a mutex |
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Allocate and initialize a mutex |
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Release a mutex |
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Perform OCIThread process initialization |
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Release the OCIThread context |
Purpose
Closes a thread handle.
Syntax
sword OCIThreadClose ( void *hndl,
OCIError *err,
OCIThreadHandle *tHnd );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().
The OCIThread thread handle to close.
Comments
The tHnd parameter should be initialized by OCIThreadHndInit(). Both the thread handle and the thread ID that was returned by the same call to OCIThreadCreate() are invalid after the call to OCIThreadClose().
Related Functions
Purpose
Creates a new thread.
Syntax
sword OCIThreadCreate ( void *hndl,
OCIError *err,
void (*start) (void *),
void *arg,
OCIThreadId *tid,
OCIThreadHandle *tHnd );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().
The function in which the new thread should begin execution.
The argument to give the function pointed to by start.
If not NULL, gets the ID for the new thread.
If not NULL, gets the handle for the new thread.
Comments
The new thread starts by executing a call to the function pointed to by start with the argument given by arg. When that function returns, the new thread terminates. The function should not return a value and should accept one parameter, a void. The call to OCIThreadCreate() must be matched by a call to OCIThreadClose() if and only if tHnd is non-NULL.
If tHnd is NULL, a thread ID placed in *tid is not valid in the calling thread because the timing of the spawned threads termination is unknown.
The tid parameter should be initialized by OCIThreadIdInit() and tHnd should be initialized by OCIThreadHndInit().
Related Functions
Purpose
Retrieves the OCIThreadHandle of the thread in which it is called.
Syntax
sword OCIThreadHandleGet ( void *hndl,
OCIError *err,
OCIThreadHandle *tHnd );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().
If not NULL, the location to place the thread handle for the thread.
Comments
The tHnd parameter should be initialized by OCIThreadHndInit().
The thread handle tHnd retrieved by this function must be closed with OCIThreadClose() and destroyed by OCIThreadHndDestroy() after it is used.
Related Functions
Purpose
Destroys and deallocates the thread handle.
Syntax
sword OCIThreadHndDestroy ( void *hndl,
OCIError *err,
OCIThreadHandle **thnd );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().
The address of pointer to the thread handle to destroy.
Comments
The thnd parameter should be initialized by OCIThreadHndInit().
Related Functions
Purpose
Allocates and initializes the thread handle.
Syntax
sword OCIThreadHndInit ( void *hndl,
OCIError *err,
OCIThreadHandle **thnd );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().
The address of the pointer to the thread handle to initialize.
Related Functions
Purpose
Destroys and deallocates a thread ID.
Syntax
sword OCIThreadIdDestroy (void *hndl,
OCIError *err,
OCIThreadId **tid );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error and OCI_ERROR is returned, the error is recorded in err and diagnostic information can be obtained by calling OCIErrorGet().
Pointer to the thread ID to destroy.
Comments
The tid parameter should be initialized by OCIThreadHndInit().
Related Functions
OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSet(), OCIThreadIdSetNull()
Purpose
Retrieves the OCIThreadId of the thread in which it is called.
Syntax
sword OCIThreadIdGet ( void *hndl,
OCIError *err,
OCIThreadId *tid );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().
This should point to the location in which to place the ID of the calling thread.
Comments
The tid parameter should be initialized by OCIThreadHndInit(). When OCIThread is used in a single-threaded environment, OCIThreadIdGet() always places the same value in the location pointed to by tid. The exact value itself is not important. The important thing is that it is different from the NULL thread ID and that it is always the same value.
Related Functions
OCIThreadIdDestroy(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSet(), OCIThreadIdSetNull()
Purpose
Allocate and initialize the thread ID tid.
Syntax
sword OCIThreadIdInit ( void *hndl,
OCIError *err,
OCIThreadId **tid );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error and OCI_ERROR is returned, the error is recorded in err and diagnostic information can be obtained by calling OCIErrorGet().
Pointer to the thread ID to initialize.
Related Functions
OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSet(), OCIThreadIdSetNull()
Purpose
Determines whether a given OCIThreadId is the NULL thread ID.
Syntax
sword OCIThreadIdNull ( void *hndl,
OCIError *err,
OCIThreadId *tid,
boolean *result );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().
Pointer to the OCIThreadId to check.
Pointer to the result.
Comments
If tid is the NULL thread ID, result is set to TRUE. Otherwise, result is set to FALSE. The tid parameter should be initialized by OCIThreadIdInit().
Related Functions
OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdSame(), OCIThreadIdSet(), OCIThreadIdSetNull()
Purpose
Determines whether two OCIThreadIds represent the same thread.
Syntax
sword OCIThreadIdSame ( void *hndl,
OCIError *err,
OCIThreadId *tid1,
OCIThreadId *tid2,
boolean *result );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().
Pointer to the first OCIThreadId.
Pointer to the second OCIThreadId.
Pointer to the result.
Comments
If tid1 and tid2 represent the same thread, result is set to TRUE. Otherwise, result is set to FALSE. The result parameter is set to TRUE if both tid1 and tid2 are the NULL thread ID. The parameters tid1 and tid2 should be initialized by OCIThreadIdInit().
Related Functions
OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSet(), OCIThreadIdSetNull()
Purpose
Sets one OCIThreadId to another.
Syntax
sword OCIThreadIdSet ( void *hndl,
OCIError *err,
OCIThreadId *tidDest,
OCIThreadId *tidSrc );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error and OCI_ERROR is returned, the error is recorded in err and diagnostic information can be obtained by calling OCIErrorGet().
This should point to the location of the OCIThreadId to set to.
This should point to the OCIThreadId to set from.
Comments
The tid parameter should be initialized by OCIThreadIdInit().
Related Functions
OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSetNull()
Purpose
Sets the NULL thread ID to a given OCIThreadId.
Syntax
sword OCIThreadIdSetNull ( void *hndl,
OCIError *err,
OCIThreadId *tid );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().
This should point to the OCIThreadId in which to put the NULL thread ID.
Comments
The tid parameter should be initialized by OCIThreadIdInit().
Related Functions
OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSet()
Purpose
Initializes the OCIThread context.
Syntax
sword OCIThreadInit ( void *hndl,
OCIError *err );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error and OCI_ERROR is returned, the error is recorded in err and diagnostic information can be obtained by calling OCIErrorGet().
Comments
It is illegal for OCIThread clients to try to examine the memory pointed to by the returned pointer. It is safe to make concurrent calls to OCIThreadInit(). Unlike OCIThreadProcessInit(), there is no need to have a first call that occurs before all the others.
The first time OCIThreadInit() is called, it initializes the OCIThread context. It also saves a pointer to the context in some system-dependent manner. Subsequent calls to OCIThreadInit() return the same context.
Each call to OCIThreadInit() must eventually be matched by a call to OCIThreadTerm().
Related Functions
Purpose
Tells the caller whether the application is running in a multithreaded environment or a single-threaded environment.
Syntax
boolean OCIThreadIsMulti ( );
Returns
TRUE if the environment is multithreaded.
FALSE if the environment is single-threaded.
Related Functions
OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSet()
Purpose
Allows the calling thread to join with another thread.
Syntax
sword OCIThreadJoin ( void *hndl,
OCIError *err,
OCIThreadHandle *tHnd );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().
The OCIThreadHandle of the thread to join with.
Comments
This function blocks the caller until the specified thread terminates.
The tHnd parameter should be initialized by OCIThreadHndInit(). The result of multiple threads all trying to join with the same thread is undefined.
Related Functions
OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSet()
Purpose
Destroys and deallocates the key pointed to by key.
Syntax
sword OCIThreadKeyDestroy ( void *hndl,
OCIError *err,
OCIThreadKey **key );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error and OCI_ERROR is returned, the error is recorded in err and diagnostic information can be obtained by calling OCIErrorGet().
The OCIThreadKey in which to destroy the key.
Comments
This is different from the destructor function callback passed to the key create routine. The function OCIThreadKeyDestroy() is used to terminate any resources that the OCIThread acquired when it created key. The OCIThreadKeyDestFunc callback of OCIThreadKeyInit() is a key value destructor; it does not operate on the key itself.
This must be called after the user has finished using the key. Not calling the OCIThreadKeyDestroy() function may result in memory leaks.
Related Functions
Purpose
Gets the calling thread's current value for a key.
Syntax
sword OCIThreadKeyGet ( void *hndl,
OCIError *err,
OCIThreadKey *key,
void **pValue );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error and OCI_ERROR is returned, the error is recorded in err and diagnostic information can be obtained by calling OCIErrorGet().
The key.
The location in which to place the thread-specific key value.
Comments
It is illegal to use this function on a key that has not been created using OCIThreadKeyInit().
If the calling thread has not yet assigned a value to the key, NULL is placed in the location pointed to by pValue.
Related Functions
OCIThreadKeyDestroy(), OCIThreadKeyInit(), OCIThreadKeySet()
Purpose
Creates a key.
Syntax
sword OCIThreadKeyInit (void *hndl,
OCIError *err,
OCIThreadKey **key,
OCIThreadKeyDestFunc destFn );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error and OCI_ERROR is returned, the error is recorded in err and diagnostic information can be obtained by calling OCIErrorGet().
The OCIThreadKey in which to create the new key.
The destructor for the key. NULL is permitted.
Comments
Each call to this routine allocates and generates a new key that is distinct from all other keys. After this function executes successfully, a pointer to an allocated and initialized key is returned. That key can be used with OCIThreadKeyGet() and OCIThreadKeySet(). The initial value of the key is NULL for all threads.
It is illegal for this function to be called more than once with the same value for the key parameter.
If the destFn parameter is not NULL, the routine pointed to by destFn is called whenever a thread that has a non-NULL value for the key terminates. The routine is called with one parameter. The parameter is the key's value for the thread at the time at which the thread terminated. If the key does not need a destructor function, pass NULL for destFn.
Related Functions
Purpose
Sets the calling thread's value for a key.
Syntax
sword OCIThreadKeySet ( void *hndl,
OCIError *err,
OCIThreadKey *key,
void *value );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error and OCI_ERROR is returned, the error is recorded in err and diagnostic information can be obtained by calling OCIErrorGet().
The key.
The thread-specific value to set in the key.
Comments
It is illegal to use this function on a key that has not been created using OCIThreadKeyInit().
Related Functions
OCIThreadKeyDestroy(), OCIThreadKeyGet(), OCIThreadKeyInit()
Purpose
Acquires a mutex for the thread in which it is called.
Syntax
sword OCIThreadMutexAcquire ( void *hndl,
OCIError *err,
OCIThreadMutex *mutex );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error, it is recorded in err and this function returns OCI_ERROR. Diagnostic information can be obtained by calling OCIErrorGet().
The mutex to acquire.
Comments
If the mutex is held by another thread, the calling thread is blocked until it can acquire the mutex.
It is illegal to attempt to acquire an uninitialized mutex.
This function's behavior is undefined if it is used by a thread to acquire a mutex that is already held by that thread.
Related Functions
OCIThreadMutexDestroy(), OCIThreadMutexInit(), OCIThreadMutexRelease()
Purpose
Destroys and deallocates a mutex.
Syntax
sword OCIThreadMutexDestroy ( void *hndl,
OCIError *err,
OCIThreadMutex **mutex );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error and OCI_ERROR is returned, the error is recorded in err and diagnostic information can be obtained by calling OCIErrorGet().
The mutex to destroy.
Comments
Each mutex must be destroyed after it is no longer needed.
It is not legal to destroy a mutex that is uninitialized or is currently held by a thread. The destruction of a mutex must not occur concurrently with any other operations on the mutex. A mutex must not be used after it has been destroyed.
Related Functions
OCIThreadMutexAcquire(), OCIThreadMutexInit(), OCIThreadMutexRelease()
Purpose
Allocates and initializes a mutex.
Syntax
sword OCIThreadMutexInit ( void *hndl,
OCIError *err,
OCIThreadMutex **mutex );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error and OCI_ERROR is returned, the error is recorded in err and diagnostic information can be obtained by calling OCIErrorGet().
The mutex to initialize.
Comments
All mutexes must be initialized before use.
Multiple threads must not initialize the same mutex simultaneously. Also, a mutex must not be reinitialized until it has been destroyed (see OCIThreadMutexDestroy()).
Related Functions
OCIThreadMutexDestroy(), OCIThreadMutexAcquire(), OCIThreadMutexRelease()
Purpose
Releases a mutex.
Syntax
sword OCIThreadMutexRelease ( void *hndl,
OCIError *err,
OCIThreadMutex *mutex );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error and OCI_ERROR is returned, the error is recorded in err and diagnostic information can be obtained by calling OCIErrorGet().
The mutex to release.
Comments
If there are any threads blocked on the mutex, one of them acquires it and becomes unblocked.
It is illegal to attempt to release an uninitialized mutex. It is also illegal for a thread to release a mutex that it does not hold.
Related Functions
OCIThreadMutexDestroy(), OCIThreadMutexInit(), OCIThreadMutexAcquire()
Purpose
Performs OCIThread process initialization.
Syntax
void OCIThreadProcessInit ( );
Comments
Whether this function must be called depends on how OCIThread is going to be used.
In a single-threaded application, calling this function is optional. If it is called at all, the first call to it must occur before calls to any other OCIThread functions. Subsequent calls can be made without restriction; they do not have any effect.
In a multithreaded application, this function must be called. The first call to it must occur strictly before any other OCIThread calls; that is, no other calls to OCIThread functions (including other calls to this one) can be concurrent with the first call.
Subsequent calls to this function can be made without restriction; they do not have any effect.
Related Functions
OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSet()
Purpose
Releases the OCIThread context.
Syntax
sword OCIThreadTerm ( void *hndl,
OCIError *err );
Parameters
The OCI environment or user session handle.
The OCI error handle. If there is an error and OCI_ERROR is returned, the error is recorded in err and diagnostic information can be obtained by calling OCIErrorGet().
Comments
This function should be called exactly once for each call made to OCIThreadInit().
It is safe to make concurrent calls to OCIThreadTerm(). OCIThreadTerm() does not do anything until it has been called as many times as OCIThreadInit() has been called. When that happens, OCIThreadTerm() terminates the OCIThread layer and frees the memory allocated for the context. Once this happens, the context should not be reused. It is necessary to obtain a new one by calling OCIThreadInit().
Related Functions