How do you implement an lru cache

Network responses can be cached in RAM to avoid too many network calls. If the element exists in hashmap move the accessed element to the tail of the linked list Otherwise, if eviction is needed i.

Learn in-demand tech skills in half the time. Early Access Courses. Assessments New. Free Trial New. For Business. For Educators. Become an Affiliate. Terms of Service. Business Terms of Service. Careers Hiring. For Bootcamps. It is quite simple to find that the most recently used pages are present near the front end, and on the other hand, we can find the least recently used pages near the rear end of the doubly linked list.

Hash: A key here represents a hash with page number, and a value represents the address of the corresponding queue node. Whenever a user references a page, there may be two cases. Either the page may exist within the memory, and if so, just detach the node of the list and bring that page to the front of the queue. Or, if the page is not available does not exist in the memory, then it is initially moved in the memory.

For it, the user inserts a new node to the front of the queue and, after that, update the address of the corresponding node in the hash. In case if the user determines that the queue is already full all frames are full , just remove a node from the rear end and, after that, add the new node to the front end of the queue. Thus using the LRU page replacement algorithm, one can find the number of page faults where page frames are 3.

In the below-shown diagram, you can see how we have performed the LRU algorithm to find the number of page faults:. To implement the LRU cache via a queue, we need to make use of the Doubly linked list. Although the code is lengthy enough, it is the basic implementation version for the LRU Cache. If we implement using HashMap, we will get a different sequence of the elements, and thus, we may further code to arrange those elements but using LinkedHashMap, we do not need to increase more code lines.

It is clear from the output that we got the appropriate result with fewer lines of code in comparison to the above one. JavaTpoint offers too many high quality services. Mail us on [email protected] , to get more information about given services. Please mail your requirement at [email protected] Duration: 1 week to 2 week. Java Training Java Tutorial. Abstract class Interface Abstract vs Interface.

Package Access Modifiers Encapsulation. Deque; import java. HashMap; import java. LinkedList; import java. Next Topic Goldbach Number in Java. Reinforcement Learning. R Programming. React Native. Python Design Patterns. Related Articles. Table of Contents. Save Article. Improve Article. Like Article. Difficulty Level : Hard. But to fetch the address of the key. LRUCache int ;. LRUCache ca 4 ;. The queue Node. There are two cases:. Frame is not there in memory, we bring it in memory and add to the front.

Frame is there in memory, we move the frame to front of queue. Enqueue queue, hash, pageNumber ;. ReferencePage q, hash, 1 ;. ReferencePage q, hash, 2 ;. ReferencePage q, hash, 3 ;. ReferencePage q, hash, 4 ;. ReferencePage q, hash, 5 ;. But remove a key from the Deque using.