Multithreading--C language

rely on C language , to execute , the most efficient

I. Serial queue

//1. Create a channeling queue

//(1) get the created serial queue to implement thread synchronization in the main Thread

dispatch_queue_t quene1 = dispatch_get_main_queue();

//(2) create a serial queue yourself , tasks are implemented in child threads

dispatch_queue_t quene2 = dispatch_queue_create("Com.lanou3g.oa", Dispatch_queue_ SERIAL); // string -- function of the unique identifier ( anti-domain form ) dispatch_queue_serial-- specified as serial queue

//2. Add a task to the network queue

Dispatch_async(quene2, ^{

NSLog(@ " task 1:%@", [nsthread currentthread]);

});

...

// release

dispatch_release(quene2);

Two. Parallel queue

//1. Create a parallel queue

//(1) get the created parallel queue

dispatch_queue_t quene1 = dispatch_get_global_queue(dispatch_queue_priority_default, 0); // two parameters are priority , reserved parameters

//(2) Create your own concurrency

dispatch_queue_t quene2 = dispatch_queue_create("Com.lanou3g.oa", Dispatch_queue_ CONCURRENT); // parameter 1-- unique indicator

// parameter 2-- specified as concurrent queue

//2 Adding tasks to the queue

Dispatch_async(quene2, ^{

NSLog(@ " task 1:%@", [nsthread currentthread]);

});

...

// request picture

// jump to main thread refresh interface

dispatch_async(dispatch_get_main_queue(), ^{

// update UI display picture

});

// release

dispatch_release(quene2);

Three. Grouping Tasks

//1 Creating a parallel queue

dispatch_queue_t quene = dispatch_get_global_queue(dispatch_queue_priority_default, 0 );

//2 creating groups

dispatch_group_t group = dispatch_group_create();

//3 Just add a task to a group

Dispatch_group_async(Group, Quene, ^{

NSLog(@ " task one request 0-20m data ");

});

...

//4 When all tasks within a group are completed , the stitching operation

dispatch_group_notify(Group, Quene, ^{

NSLog(@ " stitching data !") );

});

// release

dispatch_release(group);

Four. Single-case variables

Static Singleton *single = nil;

Static dispatch_once_t oncetoken;

dispatch_once(&oncetoken, ^{

single = [[Singleton alloc]init];

});

Five. Obstacles

The role of the//obstacle task : You can guarantee that the concurrency task after the barrier must be completed before the execution of the task is executed before the obstacle can begin execution

// Note : to add an obstacle task , you must use the concurrency task you created

// Create concurrent Tasks

dispatch_queue_t queue = dispatch_queue_create("Com.lanoug.oa", Dispatch_queue_ CONCURRENT);

// add tasks to the queue

dispatch_async(queue, ^{

NSLog(@ "A Write file ");

});

...

// add ( set ) Barrier task

dispatch_barrier_async(queue, ^{

NSLog(@ " here is the Roadblock mission ");

});

dispatch_async(queue, ^{

NSLog(@ "E Read file ");

});

// release

dispatch_release(queue);

Six. Delay

dispatch_after(dispatch_time(dispatch_time_now, (int64_t) (5 * nsec_ PER_SEC)), dispatch_get_main_queue(), ^{

NSLog(@ "5 seconds True man ");

});

Dispatch_get_main_queue is executed in the main thread ( default ), if you want to execute in a child thread , This is a child thread here ;

Seven. repeated execution

dispatch_apply( dispatch_get_global_queue(dispatch_queue_priority_default, 0), ^ (size_t index) {

NSLog(@ " haha -%ld", index);

}); ///size_t to add parameter names such as : Index

***********************

dispatch_apply( dispatch_get_main_queue(), ^ (size_t index) {

NSLog(@ " haha -%ld", index);

});

Multithreading--C language