RxMemoization2

RxMemoization2 is a library to allow memoization on RxJava function interfaces.

For the RxJava 1.X version please go to RxMemoization.

Rationale

Memoization stores the results of a function for the same set of parameters, which makes it useful for caching heavy computations that are called often with the same values.

Storage scales linearly inside a ConcurrentHashMap, and it gets garbage collected when the function object goes out of scope. Caching is thread safe but a calculation can very rarely happen twice due to ConcurrentHashMap limitations.

Usage

RxMemoization contains one class with a set of memoize() methods to do memoization for any FunctionN from Callable, Function, BiFunction, and Function3 up to Function9.

Function<String, Integer> parser = 
        RxMemoization.memoize((String s) ->
                                {   System.out.println(s);
                                    return Integer.parseInt(s); });

// All the results for the same parameter correspond to the same object

parser.call("0"); // Integer@65E46F
// Log: "0"
parser.call("0"); // Integer@65E46F
parser.call("0"); // Integer@65E46F
parser.call("1"); // Integer@335A8B
// Log: "1"
parser.call("4"); // Integer@564E21
// Log: "4"
parser.call("1"); // Integer@335A8B
parser.call("4"); // Integer@564E21
parser.call("0"); // Integer@65E46F
parser.call("2"); // Integer@564E21
// Log: "2"

Distribution

Add as a dependency to your build.gradle

repositories {
    ...
    maven { url "https://jitpack.io" }
    ...
}
    
dependencies {
    ...
    compile 'com.github.pakoito:RxMemoization2:1.0.0'
    ...
}

or to your pom.xml

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

<dependency>
    <groupId>com.github.pakoito</groupId>
    <artifactId>RxMemoization2</artifactId>
    <version>1.0.0</version>
</dependency>

License

Copyright (c) pakoito 2017

The Apache Software License, Version 2.0

See LICENSE.md