glib.ThreadPool.ThreadPool Class Reference

List of all members.

Detailed Description

Description Sometimes you wish to asyncronously fork out the execution of work and continue working in your own thread.

If that will happen often, the overhead of starting and destroying a thread each time might be to high. In such cases reusing already started threads seems like a good idea. And it indeed is, but implementing this can be tedious and error-prone. Therefore GLib provides thread pools for your convenience. An added advantage is, that the threads can be shared between the different subsystems of your program, when they are using GLib. To create a new thread pool, you use g_thread_pool_new(). It is destroyed by g_thread_pool_free(). If you want to execute a certain task within a thread pool, you call g_thread_pool_push(). To get the current number of running threads you call g_thread_pool_get_num_threads(). To get the number of still unprocessed tasks you call g_thread_pool_unprocessed(). To control the maximal number of threads for a thread pool, you use g_thread_pool_get_max_threads() and g_thread_pool_set_max_threads(). Finally you can control the number of unused threads, that are kept alive by GLib for future use. The current number can be fetched with g_thread_pool_get_num_unused_threads(). The maximal number can be controlled by g_thread_pool_get_max_unused_threads() and g_thread_pool_set_max_unused_threads(). All currently unused threads can be stopped by calling g_thread_pool_stop_unused_threads().


Public Member Functions

GThreadPoolgetThreadPoolStruct ()
 this (GThreadPool *gThreadPool)
 Sets our main struct and passes it to the parent class.
 this (GFunc func, void *userData, int maxThreads, int exclusive, GError **error)
 This function creates a new thread pool.
void push (void *data, GError **error)
 Inserts data into the list of tasks to be executed by pool.
void setMaxThreads (int maxThreads, GError **error)
 Sets the maximal allowed number of threads for pool.
int getMaxThreads ()
 Returns the maximal number of threads for pool.
uint getNumThreads ()
 Returns the number of threads currently running in pool.
uint unprocessed ()
 Returns the number of tasks still unprocessed in pool.
void free (int immediate, int wait)
 Frees all resources allocated for pool.
void setSortFunction (GCompareDataFunc func, void *userData)
 Sets the function used to sort the list of tasks.

Static Public Member Functions

static void setMaxUnusedThreads (int maxThreads)
 Sets the maximal number of unused threads to max_threads.
static int getMaxUnusedThreads ()
 Returns the maximal allowed number of unused threads.
static uint getNumUnusedThreads ()
 Returns the number of currently unused threads.
static void stopUnusedThreads ()
 Stops all currently unused threads.
static void setMaxIdleTime (uint interval)
 This function will set the maximum interval that a thread waiting in the pool for new tasks can be idle for before being stopped.
static uint getMaxIdleTime ()
 This function will return the maximum interval that a thread will wait in the thread pool for new tasks before being stopped.

Protected Member Functions

void * getStruct ()
 the main Gtk struct as a void*

Protected Attributes

GThreadPoolgThreadPool
 the main Gtk struct


Constructor & Destructor Documentation

glib.ThreadPool.ThreadPool.this ( GThreadPool gThreadPool  ) 

Sets our main struct and passes it to the parent class.

glib.ThreadPool.ThreadPool.this ( GFunc  func,
void *  userData,
int  maxThreads,
int  exclusive,
GError **  error 
)

This function creates a new thread pool.

Whenever you call g_thread_pool_push(), either a new thread is created or an unused one is reused. At most max_threads threads are running concurrently for this thread pool. max_threads = -1 allows unlimited threads to be created for this thread pool. The newly created or reused thread now executes the function func with the two arguments. The first one is the parameter to g_thread_pool_push() and the second one is user_data. The parameter exclusive determines, whether the thread pool owns all threads exclusive or whether the threads are shared globally. If exclusive is TRUE, max_threads threads are started immediately and they will run exclusively for this thread pool until it is destroyed by g_thread_pool_free(). If exclusive is FALSE, threads are created, when needed and shared between all non-exclusive thread pools. This implies that max_threads may not be -1 for exclusive thread pools. error can be NULL to ignore errors, or non-NULL to report errors. An error can only occur when exclusive is set to TRUE and not all max_threads threads could be created. func: a function to execute in the threads of the new thread pool user_data: user data that is handed over to func every time it is called max_threads: the maximal number of threads to execute concurrently in the new thread pool, -1 means no limit exclusive: should this thread pool be exclusive? error: return location for error Returns: the new GThreadPool


Member Function Documentation

void glib.ThreadPool.ThreadPool.free ( int  immediate,
int  wait 
)

Frees all resources allocated for pool.

If immediate is TRUE, no new task is processed for pool. Otherwise pool is not freed before the last task is processed. Note however, that no thread of this pool is interrupted, while processing a task. Instead at least all still running threads can finish their tasks before the pool is freed. If wait_ is TRUE, the functions does not return before all tasks to be processed (dependent on immediate, whether all or only the currently running) are ready. Otherwise the function returns immediately. After calling this function pool must not be used anymore. pool: a GThreadPool immediate: should pool shut down immediately? wait_: should the function wait for all tasks to be finished?

static uint glib.ThreadPool.ThreadPool.getMaxIdleTime (  )  [static]

This function will return the maximum interval that a thread will wait in the thread pool for new tasks before being stopped.

If this function returns 0, threads waiting in the thread pool for new work are not stopped. Returns: the maximum interval to wait for new tasks in the thread pool before stopping the thread (1/1000ths of a second). Since 2.10 See Also GThread GLib thread system.

int glib.ThreadPool.ThreadPool.getMaxThreads (  ) 

Returns the maximal number of threads for pool.

pool: a GThreadPool Returns: the maximal number of threads

static int glib.ThreadPool.ThreadPool.getMaxUnusedThreads (  )  [static]

Returns the maximal allowed number of unused threads.

Returns: the maximal number of unused threads

uint glib.ThreadPool.ThreadPool.getNumThreads (  ) 

Returns the number of threads currently running in pool.

pool: a GThreadPool Returns: the number of threads currently running

static uint glib.ThreadPool.ThreadPool.getNumUnusedThreads (  )  [static]

Returns the number of currently unused threads.

Returns: the number of currently unused threads

void* glib.ThreadPool.ThreadPool.getStruct (  )  [protected]

the main Gtk struct as a void*

GThreadPool* glib.ThreadPool.ThreadPool.getThreadPoolStruct (  ) 

void glib.ThreadPool.ThreadPool.push ( void *  data,
GError **  error 
)

Inserts data into the list of tasks to be executed by pool.

When the number of currently running threads is lower than the maximal allowed number of threads, a new thread is started (or reused) with the properties given to g_thread_pool_new(). Otherwise data stays in the queue until a thread in this pool finishes its previous task and processes data. error can be NULL to ignore errors, or non-NULL to report errors. An error can only occur when a new thread couldn't be created. In that case data is simply appended to the queue of work to do. pool: a GThreadPool data: a new task for pool error: return location for error

static void glib.ThreadPool.ThreadPool.setMaxIdleTime ( uint  interval  )  [static]

This function will set the maximum interval that a thread waiting in the pool for new tasks can be idle for before being stopped.

This function is similar to calling g_thread_pool_stop_unused_threads() on a regular timeout, except, this is done on a per thread basis. By setting interval to 0, idle threads will not be stopped. This function makes use of g_async_queue_timed_pop() using interval. interval: the maximum interval (1/1000ths of a second) a thread can be idle. Since 2.10

void glib.ThreadPool.ThreadPool.setMaxThreads ( int  maxThreads,
GError **  error 
)

Sets the maximal allowed number of threads for pool.

A value of -1 means, that the maximal number of threads is unlimited. Setting max_threads to 0 means stopping all work for pool. It is effectively frozen until max_threads is set to a non-zero value again. A thread is never terminated while calling func, as supplied by g_thread_pool_new(). Instead the maximal number of threads only has effect for the allocation of new threads in g_thread_pool_push(). A new thread is allocated, whenever the number of currently running threads in pool is smaller than the maximal number. error can be NULL to ignore errors, or non-NULL to report errors. An error can only occur when a new thread couldn't be created. pool: a GThreadPool max_threads: a new maximal number of threads for pool error: return location for error

static void glib.ThreadPool.ThreadPool.setMaxUnusedThreads ( int  maxThreads  )  [static]

Sets the maximal number of unused threads to max_threads.

If max_threads is -1, no limit is imposed on the number of unused threads. max_threads: maximal number of unused threads

void glib.ThreadPool.ThreadPool.setSortFunction ( GCompareDataFunc  func,
void *  userData 
)

Sets the function used to sort the list of tasks.

This allows the tasks to be processed by a priority determined by func, and not just in the order in which they were added to the pool. Note, if the maximum number of threads is more than 1, the order that threads are executed can not be guranteed 100%. Threads are scheduled by the operating system and are executed at random. It cannot be assumed that threads are executed in the order they are created. pool: a GThreadPool func: the GCompareDataFunc used to sort the list of tasks. This function is passed two tasks. It should return 0 if the order in which they are handled does not matter, a negative value if the first task should be processed before the second or a positive value if the second task should be processed first. user_data: user data passed to func. Since 2.10

static void glib.ThreadPool.ThreadPool.stopUnusedThreads (  )  [static]

Stops all currently unused threads.

This does not change the maximal number of unused threads. This function can be used to regularly stop all unused threads e.g. from g_timeout_add().

uint glib.ThreadPool.ThreadPool.unprocessed (  ) 

Returns the number of tasks still unprocessed in pool.

pool: a GThreadPool Returns: the number of unprocessed tasks


Member Data Documentation

GThreadPool* glib.ThreadPool.ThreadPool.gThreadPool [protected]

the main Gtk struct


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