I was trying to rearrange the priority in a queue so that there is no gap in between. # if another customer already has the same priority number, don't increment new_priority # if this customer has a lower priority number, update their priority to the new priority A priority queue is a special instance of a queue where the storage order is based on the priority of the items inside. # if this customer has the current highest priority, keep the same priority number New_priority = current_highest_priority + 1 My data are saved in a list of dictionaries def rearrange_priority(self):Ĭurrent_highest_priority = self.get_highest_priority() Note that methods of asyncio queues don’t have a timeout parameter use asyncio.waitfor () function to do queue operations with a timeout. The vanilla priority queue interface can be. Although asyncio queues are not thread-safe, they are designed to be used specifically in async/await code. A priority queue supports inserting elements with priorities, and removing or peeking at the top priority element. The base makes sure this shouldn't be called if `_qsize` is 0.The result of the following code I wrote is not something I want but I was unsure how to change it. asyncio queues are designed to be similar to classes of the queue module. Here is another implementation follows the official guide: import heapq In case you want to prioritise a task later. I left some print statements uncommented, but commented out the ones I put in while debugging it. I basically started from how they defined PriorityQueue in Queue.py and added a set into it to keep track of unique keys: from Queue import PriorityQueueĬlass UniquePriorityQueue(PriorityQueue):ĭef _put(self, item, heappush=heapq.heappush):īoaz Yaniv beat me to the punch by a few minutes, but I figured I'd post mine too as it supports the full interface of PriorityQueue. Priority: 0.4, Value: value1 (shall not be added again, even though it has different priority).We can also use list, tuple, and dict modules to implement Priority Queue. Similarly, the heapq module in Python also implements Priority Queue. The queue standard library in Python supports Priority Queue. Priority: 0.1, Value: value3 (shall be retrieved first automatically) In Python, there are several options to implement Priority Queue.What is the best way of creating a atomic priority queue (=can be used from multiple threads) with unique values? def listAll (self): print ('PID t Name t Status t Priority') print ('' 42) for, , pcb in self.queue: print (pcb) ADT class PCB. A priority queue is an abstract data type (ADT) which is like a regular queue or stack data structure, but where additionally each element has a priority. the ADT PriorityQueue class ReadyQueue (PriorityQueue). However when I do a for loop, I get the order in which items are added. at the first position of a tuple), so it seems not be great for comparison of already existing values. I extended PriortiyQueue, and got access to the underlying list queue. The docstring for the class doesn't give much of a clue as to how to use it. There are some other implementations on stackoverflow with heapq, but heapq also uses priority within the value (e.g. The Python library documentation has a section 'Priority Queue Implementation Notes' which gives some advice on implementing a priority queue using a heap. The que class on the other hand does offer a function for checking if a value already exists and is even more natural in usage (without locking, but still atomic), but it does not offer a way to sort by priority. The queue.PriorityQueue Class Python provides a built-in implementation of the priority queue data structure. You would use (0.5, myvalue) as value in PriorityQueue and then it would be sorted by the first element of the tuple. Priority queues are used to handle scheduling problems where some tasks are prioritized over others. Instead, you can pass tuples in: arbiter1.put ( (pkt.pri, pkt)) And get tuples out: priority, pkt arbiter1.get () If packets dont have any ordering defined and there may be packets with equal priorities, then youll also want to use a tie-breaker in the tuples. Moreover, PriorityQueue needs the priority to remain within the value, so I could not even search for my value, as I would also have to know the priority. Python has Queue.PriorityQueue, but I cannot see a way to make each value in it unique as there is no method for checking if a value already exists (like find(name) or similar).
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