patchmap | memory efficient hashmap using sorting to resolve collisions | Hashing library
kandi X-RAY | patchmap Summary
kandi X-RAY | patchmap Summary
A fast and memory efficient hashmap using sorting to resolve collisions. It achieves a very good trade-off between memory efficiency and speed for load factors over ~0.5. It can be an almost drop-in replacement for std::unordered_map, with the caveat however that iterators are possibly invalidated by insertions. This hashmap is inspired by the 1973 publication "Ordered hash tables". The idea presented there is to resolve collisions via an ordering defined by the keys directly. The patchmap however resolves the collisions with an ordering defined by the hash-value of the keys. So long there are no collisions the keys in a hash table are already in hash-order. When there are collisions in the patchmap this order is upheld by inserting the key-value pairs at the appropriate position, displacing keys that compare greater to the right and keys that compare less to the left, essentially performing a single step of insertion sort. This improves the commonly encountered worst-case complexity of O(n) for lookups to O(log(n)) as a binary search can always be employed on a ordered list with random access. In addition, when the hash values are evenly distributed, which is the case for the hash functions supplied with this library, this allowes for an asymptotic complexity of O(log(-log(1-a))) because an interpolation search can be used to retrieve the entries, performing exceptionally well even when the table is almost full. The resulting ordering is very similar to the one resulting from linear bidirectional probing with robin hood hashing (see for example sherwood_map) but allowing interpolation search leads to improved upper bounds while retaining the same average complexity and overall performance, exceeding other implementations at high load factors around 96% at the cost of O((1-a)¯²) reordering operations for insertions and deletions however.
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patchmap Examples and Code Snippets
Lines of Code : 10License : Permissive (MIT)
Copy#include
#include "patchmap.hpp"
int main() {
whash::patchmap hash_table;
hash_table[7] = 77;
for (const auto& elem : hash_table) {
std::cout << elem.first << " " << elem.second << std::endl;
}
}
> g++ -O3 Community Discussions
Trending Discussions on patchmap
QUESTION
Initially, I started the project with IntelliJ Idea Tomcat Local Server configuration (everything worked), but decided to use Spring Boot Application. I added the main class, changed pom.xml (delete spring-context and add spring-boot-starter-parent, spring-boot, spring-boot-starter-tomcat, spring-boot-starter-web, spring-boot-autoconfigure), after that application runs , GET-Method works, but POST - not supported. Help me please!!! Thank you!
Main.class
...ANSWER
Answered 2021-Apr-14 at 08:10To implement the configure method in the main class you could do:
QUESTION
I am using
...ANSWER
Answered 2021-Mar-01 at 20:01Please, make yourself more familiar with what is Messaging Gateway in Spring Integration: https://docs.spring.io/spring-integration/docs/current/reference/html/messaging-endpoints.html#gateway.
In two words: the gateway is an interface to send messages on its method calls.
The Message is like this:
QUESTION
I'd like to do custom exception handling for a REST API.
This is the code I have.
Controller Endpoint
...ANSWER
Answered 2021-Feb-19 at 02:51try to override handleMethodArgumentTypeMismatch
QUESTION
I am learning Spring Boot, and am working with Spring WebFlux, and reactive Mongo DB. My controllers are working fine, but my tests are failing on null pointer exception.
My build.gradle is:
...ANSWER
Answered 2021-Jan-29 at 21:17Your test is annotated with the JUnit4's @Test annotation but you are trying to run it with JUnit5. JUnit5 cannot see it.
Uncomment the org.junit.jupiter.api.Test import and remove import org.junit.Test (CategoryControllerTest).
Remove implementation 'junit:junit:4.12' from the build.gradle as well.
QUESTION
I have a problem, I don't know how to test a method in my controller.
Method:
...ANSWER
Answered 2020-Dec-21 at 20:09This was a problem with a test case.
QUESTION
I have a strange problem. When I test the "edit" method I receive an exception. I know how to fix it: I have to add null checking of "it" in the "let" block in the "edit" method - but this situation shouldn't ever have a place. Let me know what you think about it. What should I change?
Controller:
...ANSWER
Answered 2020-Dec-18 at 10:33I'm an idiot. I mocked another method then I used.
QUESTION
As a newcomer to spring I would like to know the actual difference between:-
...ANSWER
Answered 2020-Dec-08 at 10:50POST is for creating a brand new object.
PUT will replace all of an objects properties in one go.
Leaving a property empty will empty the value in the datastore.
PATCH does a partial update of an object. You can send it just the properties which should be updated. A PATCH request with all object properties included will have the same effect as a POST request. But they are not the same.
The HTTP method is a convention not specific to Spring but is a main pillar of the REST API specification.
They make sure the intent of a request is clear and both the provider and consumer are in agreement of the end result.
Kind of like the pedals or gear shift in our cars. It's a lot easier when they all work the same.
Switching them up could lead to a lot of accidents.
For us as developers, it means we can expect most REST APIs to behave in a similar way, assuming an API is implemented according to or reasonably close to the specification.
POST/PUT/PATCH may look alike but there are subtle differences. As you mention the PUT and PATCH methods require some kind of ID of the object to be updated.
In an example of a combined POST/PUT/PATCH endpoint, sending a request with an object, omitting some of its properties. How does the API react?
- Update only the received properties.
- Update the entire object, emptying the omitted properties.
- Attempt to create a new object.
How is the consumer of the endpoint to know which of the three actions the server took?
This is where the HTTP method and specification/convention help determine the appropriate course of action.
Spring may facilitate the save method which can handle both creation, updates and partial updates. But this is not necessarily the case for other frameworks in Java or other languages.
Also, your application may be simple enough to handle POST/PUT/PATCH in the same controller method right now. But over time as your application grows more complex, the separation of concerns makes your code a lot cleaner, more readable and maintainable.
QUESTION
I have a project using spring boot 2.1.2.RELEASE andangular 6, from the front i send data to the banckend, the sent json is like this { "startDate":"2020-11-10T23:00:00.000Z" }, when i debug my controller i find that the date is less than the sent date by a day Tue Nov 10 00:00:00 WAT 2020
ANSWER
Answered 2020-Nov-11 at 14:11This is the default format
YYYY-MM-DD
So Jackson is formatting the date correctly. If this is not the right behaviour, then pass a format to jackson
You have to fix your JsonFormat annotation
Example
QUESTION
I am trying to design a Spring Boot application that keeps products in database and can perform basic CRUD operations. Methods like Post, Get, Put, Delete work fine, but when I try the Patch method, I can't get the correct result. I tried to follow the path mentioned in the Medium post here.
But different from that, I also want to communicate with Couchbase database. When I try to patch data in the database, the following error message is returned. Thanks to everyone in advance.
...ANSWER
Answered 2020-Oct-15 at 18:31There is a mistake made with the Optional class. When I made the following change in the code block in section 2, the problem was solved.
QUESTION
Is HTTP PATCH not enabled by default in Spring MVC/Boot? I'm getting the ff error:
...ANSWER
Answered 2020-Sep-23 at 21:15The standard HTTP client does not support PATCH requests.
You can just add the apache HTTP client to your project. It should be automatically added by spring boot if it's found on the classpath.
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