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One 、 Concept

queue (queue) It's a first in, first out (First In First Out) The linear table , abbreviation FIFO. Queues allow insertion at one end , And delete at the other end . The end of the line is allowed to be inserted , Allow to delete the end for the team head . Queues are not allowed to operate in the middle

Two 、 effect

decoupling : Make the program loose coupling directly , Modify a function , There won't be a tandem .

Improve processing efficiency :FIFO = Now in, first out ,LIFO = After the first out .

notes : Queues can send multiple threads concurrently , Processing of arranged threads , And every thread that needs to be processed only needs to put the requested data into the memory of the queue container , Threads don't need to wait , When the data has been processed , The thread can fetch the data on time . The thread requesting data only has a relationship with this queue container , Threads that process data down Dropping does not affect the thread requesting data , The queue will be sent to other threads to process the data , It's decoupled , Increase of efficiency . There will be a sequential container in the queue , The list is different from this container , Although the data in the list is arranged , But the data will be kept after it is taken away , The data of this container in the queue will not be retained after being fetched . When it is necessary to exchange information safely between multiple threads , Queues are especially useful in thread programming .

 class Queue:
def queue(self):
''' The team '''
def dequeue(self):
''' Out of the team '''
if __name__ == '__main__':
xxt = [1, 2, 3, 4]
# It's equivalent to inserting elements at the end of the team
xxt.insert(1, 10)
xxt.insert(0, 20)#0 At the end of the team
print('insert:',xxt) # It's equivalent to deleting elements from the head of the team
xxt.pop()
print('pop:',xxt)
''' result

insert: [20, 1, 10, 2, 3, 4]

pop: [20, 1, 10, 2, 3]

'''

3、 ... and 、 Introduction to queue parameters

Queue.Queue(maxsize=0)   FIFO, If maxsize Less than 1 That means the queue length is infinite

Queue.LifoQueue(maxsize=0)   LIFO, If maxsize Less than 1 That means the queue length is infinite

Queue.qsize()   Returns the size of the queue

Queue.empty()   If the queue is empty , return True, conversely False

Queue.full()   If the queue is full , return True, conversely False

Queue.get([block[, timeout]])   Read the queue , Take out the data , No data will wait timeout Waiting time

Queue.put(item, [block[, timeout]])   Write a queue , Put in the data ,timeout Waiting time

Queue.queue.clear()   Clear queue

class queue.PriorityQueue(maxsize=0) Priority queues can be set when storing data , The lower the number of priority settings, the higher the level

Queue.get(timeout = 1) If 1 Seconds later, I quit without getting the data

Queue.get_nowait() Take the data , If there's no data queue.Empty abnormal

Queue.task_done() Subsequent calls tell the queue , The processing of the task is complete .

 from collections import deque
queue = deque(["Eric", "John", "Michael"])
print('queue:',queue)
queue.append("Terry")
print('queue.append:',queue)
queue.append("Graham")
print('queue.append:',queue)
queue.popleft()
print('queue.popleft:',queue)
queue.popleft()
print('queue.popleft:',queue) ''' result
queue: deque(['Eric', 'John', 'Michael'])
queue.append: deque(['Eric', 'John', 'Michael', 'Terry'])
queue.append: deque(['Eric', 'John', 'Michael', 'Terry', 'Graham'])
queue.popleft: deque(['John', 'Michael', 'Terry', 'Graham'])
queue.popleft: deque(['Michael', 'Terry', 'Graham'])
'''

source : https://www.cnblogs.com/xiangsikai/p/8185031.html

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