Thread Management Functions

This section describes the thread management functions.

Table 17-9 Thread Management functions

Function	Purpose
OCIThreadClose()	Closes a thread handle
OCIThreadCreate()	Creates a new thread
OCIThreadHandleGet()	Retrieves the OCIThreadHandle of the thread in which it is called
OCIThreadHndDestroy()	Destroys and deallocates the thread handle
OCIThreadHndInit()	Allocates and initializes the thread handle
OCIThreadIdDestroy()	Destroys and deallocates a thread id
OCIThreadIdGet()	Retrieves the `OCIThreadId` of the thread in which it is called
OCIThreadIdInit()	Allocates and initializes the thread id
OCIThreadIdNull()	Determines whether or not a given `OCIThreadId` is the `NULL` thread ID
OCIThreadIdSame()	Determines whether or not two `OCIThreadId`s represent the same thread
OCIThreadIdSet()	Sets one `OCIThreadId` to another
OCIThreadIdSetNull()	Sets the `NULL` thread ID to a given `OCIThreadId`
OCIThreadInit()	Initializes OCIThread context
OCIThreadIsMulti()	Tells the caller whether the application is running in a multithreaded environment or a single-threaded environment
OCIThreadJoin()	Allows the calling thread to join with another thread
OCIThreadKeyDestroy()	Destroy and deallocate the key pointed to by `key`
OCIThreadKeyGet()	Gets the calling threads current value for a key
OCIThreadKeyInit()	Creates a key
OCIThreadKeySet()	Sets the calling threads value for a key
OCIThreadMutexAcquire()	Acquires a mutex for the thread in which it is called
OCIThreadMutexDestroy()	Destroys and deallocate a mutex
OCIThreadMutexInit()	Allocates and initializes a mutex
OCIThreadMutexRelease()	Releases a mutex
OCIThreadProcessInit()	Performs OCIThread process initialization
OCIThreadTerm()	Releases the OCIThread context

OCIThreadClose()

Purpose

Closes a thread handle.

Syntax

sword OCIThreadClose ( void             *hndl, 
                       OCIError         *err, 
                       OCIThreadHandle  *tHnd );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
tHnd (IN/OUT): The OCIThread thread handle to close.

Comments

tHnd should be initialized by OCIThreadHndInit(). Both thread handle and the thread ID that was returned by the same call to OCIThreadCreate() are invalid after the call to OCIThreadClose().

Related Functions

OCIThreadCreate()

Purpose

Creates a new thread.

Syntax

sword OCIThreadCreate ( void             *hndl, 
                        OCIError         *err, 
                        void (*start)    (void 
                        void             *arg, 
                        OCIThreadId      *tid, 
                        OCIThreadHandle  *tHnd );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
start (IN): The function in which the new thread should begin execution.
arg (IN): The argument to give the function pointed to by start.
tid (IN/OUT): If not NULL, gets the ID for the new thread.
tHnd (IN/OUT): 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 will terminate. 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 will not be valid in the calling thread because the timing of the spawned threads termination is unknown.

tid should be initialized by OCIThreadIdInit() and tHnd should be initialized by OCIThreadHndInit().

Related Functions

OCIThreadClose(), OCIThreadIdInit(), OCIThreadHndInit()

OCIThreadHandleGet()

Purpose

Retrieves the OCIThreadHandle of the thread in which it is called.

Syntax

sword OCIThreadHandleGet ( void             *hndl,
                           OCIError         *err,
                           OCIThreadHandle  *tHnd );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
tHnd (IN/OUT): If not NULL, the location to place the thread handle for the thread.

Comments

tHnd 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

OCIThreadHndDestroy(), OCIThreadHndInit()

OCIThreadHndDestroy()

Purpose

Destroys and deallocates the thread handle.

Syntax

sword OCIThreadHndDestroy ( void             *hndl, 
                            OCIError         *err, 
                            OCIThreadHandle  **thnd );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
thnd (IN/OUT): The address of pointer to the thread handle to destroy.

Comments

thnd should be initialized by OCIThreadHndInit().

Related Functions

OCIThreadHandleGet(), OCIThreadHndInit()

OCIThreadHndInit()

Purpose

Allocates and initializes the thread handle.

Syntax

sword OCIThreadHndInit ( void            *hndl, 
                         OCIError        *err,
                         OCIThreadHandle **thnd );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
thnd (OUT): The address of pointer to the thread handle to initialize.

Related Functions

OCIThreadHandleGet(), OCIThreadHndDestroy()

OCIThreadIdDestroy()

Purpose

Destroys and deallocates a thread Id.

Syntax

sword OCIThreadIdDestroy (void         *hndl,
                          OCIError     *err,
                          OCIThreadId  **tid );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
tid (IN/OUT): Pointer to the thread ID to destroy.

Comments

tid should be initialized by OCIThreadIdInit().

Related Functions

OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSet(), OCIThreadIdSetNull()

OCIThreadIdGet()

Purpose

Retrieves the OCIThreadId of the thread in which it is called.

Syntax

sword OCIThreadIdGet ( void         *hndl,
                       OCIError     *err, 
                       OCIThreadId  *tid );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
tid (OUT): This should point to the location in which to place the ID of the calling thread.

Comments

tid should be initialized by OCIThreadIdInit(). When OCIThread is used in a single-threaded environment, OCIThreadIdGet() will always place the same value in the location pointed to by tid. The exact value itself is not important. The important thing is that it is not the same as the NULL thread ID and that it is always the same value.

Related Functions

OCIThreadIdDestroy(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSet(), OCIThreadIdSetNull()

OCIThreadIdInit()

Purpose

Allocate and initialize the thread Id tid.

Syntax

sword OCIThreadIdInit ( void         *hndl,
                        OCIError     *err, 
                        OCIThreadId  **tid );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
tid (OUT): Pointer to the thread ID to initialize.

Related Functions

OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSet(), OCIThreadIdSetNull()

OCIThreadIdNull()

Purpose

Determines whether or not a given OCIThreadId is the NULL thread Id.

Syntax

sword OCIThreadIdNull ( void         *hndl, 
                        OCIError     *err, 
                        OCIThreadId  *tid, 
                        boolean      *result );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
tid (IN): Pointer to the OCIThreadId to check.
result (IN/OUT): Pointer to the result.

Comments

If tid is the NULL thread ID, result is set to TRUE. Otherwise, result is set to FALSE. tid should be initialized by OCIThreadIdInit().

Related Functions

OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdSame(), OCIThreadIdSet(), OCIThreadIdSetNull()

OCIThreadIdSame()

Purpose

Determines whether or not two OCIThreadIds represent the same thread.

Syntax

sword OCIThreadIdSame ( void          *hndl, 
                        OCIError      *err,
                        OCIThreadId   *tid1, 
                        OCIThreadId   *tid2, 
                        boolean       *result );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
tid1 (IN): Pointer to the first OCIThreadId.
tid2 (IN): Pointer to the second OCIThreadId.
result (IN/OUT): Pointer to the result.

Comments

If tid1 and tid2 represent the same thread, result is set to TRUE. Otherwise, result is set to FALSE. result is set to TRUE if both tid1 and tid2 are the NULL thread ID. ti1d and tid2 should be initialized by OCIThreadIdInit().

Related Functions

OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSet(), OCIThreadIdSetNull()

OCIThreadIdSet()

Purpose

Sets one OCIThreadId to another.

Syntax

sword OCIThreadIdSet ( void         *hndl,
                       OCIError     *err,
                       OCIThreadId  *tidDest, 
                       OCIThreadId  *tidSrc );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
tidDest (OUT): This should point to the location of the OCIThreadId to be set to.
tidSrc (IN): This should point to the OCIThreadId to set from.

Comments

tid should be initialized by OCIThreadIdInit().

Related Functions

OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSetNull()

OCIThreadIdSetNull()

Purpose

Sets the NULL thread ID to a given OCIThreadId.

Syntax

sword OCIThreadIdSetNull ( void         *hndl,
                           OCIError     *err, 
                           OCIThreadId  *tid );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
tid (OUT): This should point to the OCIThreadId in which to put the NULL thread Id.

Comments

tid should be initialized by OCIThreadIdInit().

Related Functions

OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSet()

OCIThreadInit()

Purpose

Initializes the OCIThread context.

Syntax

sword OCIThreadInit ( void      *hndl,
                      OCIError  *err );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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 an 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 OCI Thread context. It also saves a pointer to the context in some system dependent manner. Subsequent calls to OCIThreadInit() will return the same context.

Each call to OCIThreadInit() must eventually be matched by a call to OCIThreadTerm().

Related Functions

OCIThreadTerm()

OCIThreadIsMulti()

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()

OCIThreadJoin()

Purpose

Allows the calling thread to join with another thread.

Syntax

sword OCIThreadJoin ( void             *hndl,
                      OCIError         *err, 
                      OCIThreadHandle  *tHnd );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
tHnd (IN): The OCIThreadHandle of the thread to join with.

Comments

This function blocks the caller until the specified thread terminates.

tHnd 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()

OCIThreadKeyDestroy()

Purpose

Destroy and deallocate the key pointed to by key.

Syntax

sword OCIThreadKeyDestroy ( void          *hndl,
                            OCIError      *err, 
                            OCIThreadKey  **key );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
key (IN/OUT): The OCIThreadKey in which to destroy the key.

Comments

This is different from the destructor function callback passed to the key create routine. This new destroy function OCIThreadKeyDestroy() is used to terminate any resources OCI THREAD acquired when it created key. The OCIThreadKeyDestFunc callback of OCIThreadKeyInit() is a key VALUE destructor; it does in no way operate on the key itself.

This must be called once the user has finished using the key. Not calling the key destroy function may result in memory leaks.

Related Functions

OCIThreadKeyGet(), OCIThreadKeyInit(), OCIThreadKeySet()

OCIThreadKeyGet()

Purpose

Gets the calling threads current value for a key.

Syntax

sword OCIThreadKeyGet ( void          *hndl, 
                        OCIError      *err, 
                        OCIThreadKey  *key, 
                        void          **pValue );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
key (IN): The key.
pValue (IN/OUT): 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()

OCIThreadKeyInit()

Purpose

Creates a key.

Syntax

sword OCIThreadKeyInit (void                  *hndl, 
                        OCIError              *err,
                        OCIThreadKey          **key,
                        OCIThreadKeyDestFunc  destFn );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
key (OUT): The OCIThreadKey in which to create the new key.
destFn (IN): The destructor for the key. NULL is permitted.

Comments

Each call to this routine allocate 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 return. That key can be used with OCIThreadKeyGet() and OCIThreadKeySet(). The initial value of the key will be 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 will be called whenever a thread that has a non-NULL value for the key terminates. The routine will be called with one parameter. The parameter will be the keys 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

OCIThreadKeyDestroy(), OCIThreadKeyGet(), OCIThreadKeySet()

OCIThreadKeySet()

Purpose

Sets the calling threads value for a key.

Syntax

sword OCIThreadKeySet ( void           *hndl,
                        OCIError       *err, 
                        OCIThreadKey   *key,
                        void           *value );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
key (IN/OUT): The key.
value (IN): 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()

OCIThreadMutexAcquire()

Purpose

Acquires a mutex for the thread in which it is called.

Syntax

sword OCIThreadMutexAcquire ( void            *hndl,
                              OCIError        *err, 
                              OCIThreadMutex  *mutex );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
mutex (IN/OUT): 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 functions 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()

OCIThreadMutexDestroy()

Purpose

Destroys and deallocate a mutex.

Syntax

sword OCIThreadMutexDestroy ( void           *hndl, 
                              OCIError       *err, 
                              OCIThreadMutex **mutex );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
mutex (IN/OUT): The mutex to destroy.

Comments

Each mutex must be destroyed once 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()

OCIThreadMutexInit()

Purpose

Allocates and initializes a mutex.

Syntax

sword OCIThreadMutexInit ( void            *hndl,
                           OCIError        *err, 
                           OCIThreadMutex  **mutex );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
mutex (OUT): 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()

OCIThreadMutexRelease()

Purpose

Releases a mutex.

Syntax

sword OCIThreadMutexRelease ( void            *hndl,
                              OCIError        *err, 
                              OCIThreadMutex  *mutex );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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().
mutex (IN/OUT): The mutex to release.

Comments

If there are any threads blocked on the mutex, one of them will acquire it and become 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()

OCIThreadProcessInit()

Purpose

Performs OCIThread process initialization.

Syntax

void OCIThreadProcessInit ( );

Comments

Whether or not this function must be called depends on how OCI Thread 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 will 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 will not have any effect.

Related Functions

OCIThreadIdDestroy(), OCIThreadIdGet(), OCIThreadIdInit(), OCIThreadIdNull(), OCIThreadIdSame(), OCIThreadIdSet()

OCIThreadTerm()

Purpose

Releases the OCIThread context.

Syntax

sword OCIThreadTerm ( void      *hndl, 
                      OCIError  *err );

Parameters

hndl (IN/OUT): The OCI environment or user session handle.
err (IN/OUT): 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() will not do anything until it has been called as many times as OCIThreadInit() has been called. When that happens, it terminates the OCIThread layer and frees the memory allocated for the context. Once this happens, the context should not be re-used. It will be necessary to obtain a new one by calling OCIThreadInit().

Related Functions

OCIThreadInit()