• Stars
    star
    385
  • Rank 111,042 (Top 3 %)
  • Language
    Java
  • License
    Apache License 2.0
  • Created over 8 years ago
  • Updated 10 months ago

Reviews

There are no reviews yet. Be the first to send feedback to the community and the maintainers!

Repository Details

Utilities for working with futures in Java 8

completable-futures

Build Status Test Coverage Maven Central License

completable-futures is a set of utility functions to simplify working with asynchronous code in Java8.

Usage

Using completable-futures requires Java 8 but has no additional dependencies. It is meant to be included as a library in other software. To import it with maven, add this to your pom:

<dependency>
    <groupId>com.spotify</groupId>
    <artifactId>completable-futures</artifactId>
    <version>0.3.1</version>
</dependency>

Features

Combining more than two things

The builtin CompletableFuture API includes future.thenCombine(otherFuture, function) but if you want to combine more than two things it gets trickier. The CompletableFutures class contains the following APIs to simplify this use-case:

allAsList

If you want to join a list of futures of uniform type, use allAsList. This returns a future which completes to a list of all values of its inputs:

List<CompletableFuture<String>> futures = asList(completedFuture("a"), completedFuture("b"));
CompletableFuture<List<String>> joined = CompletableFutures.allAsList(futures);

allAsMap

If you want to join a map of key and value-futures, each of uniform type, use allAsMap. This returns a future which completes to a map of all key values of its inputs:

  Map<String, CompletableFuture<String>> futures = new HashMap() {{
    put("key", completedFuture("value"));
  }};
  CompletableFuture<Map<String, String>> joined = CompletableFutures.allAsMap(futures);

successfulAsList

Works like allAsList, but futures that fail will not fail the joined future. Instead, the defaultValueMapper function will be called once for each failed future and value returned will be put in the resulting list on the place corresponding to the failed future. The default value returned by the function may be anything, such as null or Optional.empty().

List<CompletableFuture<String>> input = asList(
    completedFuture("a"),
    exceptionallyCompletedFuture(new RuntimeException("boom")));
CompletableFuture<List<String>> joined = CompletableFutures.successfulAsList(input, t -> "default");

joinList

joinList is a stream collector that combines multiple futures into a list. This is handy if you apply an asynchronous operation to a collection of entities:

collection.stream()
    .map(this::someAsyncFunction)
    .collect(CompletableFutures.joinList())
    .thenApply(this::consumeList)

joinMap

joinMap is a stream collector that applies an asynchronous operation to each element of the stream, and associates the result of that operation to a key derived from the original element. This is useful when you need to keep the association between the entity that triggered the asynchronous operation and the result of that operation:

collection.stream()
    .collect(joinMap(this::toKey, this::someAsyncFunc))
    .thenApply(this::consumeMap)

combine

If you want to combine more than two futures of different types, use the combine method:

CompletableFutures.combine(f1, f2, (a, b) -> a + b);
CompletableFutures.combine(f1, f2, f3, (a, b, c) -> a + b + c);
CompletableFutures.combine(f1, f2, f3, f4, (a, b, c, d) -> a + b + c + d);
CompletableFutures.combine(f1, f2, f3, f4, f5, (a, b, c, d, e) -> a + b + c + d + e);

combineFutures

If you want to combine multiple futures into another future, use combineFutures:

CompletableFutures.combineFutures(f1, f2, (a, b) -> completedFuture(a + b));
CompletableFutures.combineFutures(f1, f2, f3, (a, b, c) -> completedFuture(a + b + c));
CompletableFutures.combineFutures(f1, f2, f3, f4, (a, b, c, d) -> completedFuture(a + b + c + d));
CompletableFutures.combineFutures(f1, f2, f3, f4, f5, (a, b, c, d, e) -> completedFuture(a + b + c + d + e));

Combine an arbitrary number of futures

If you want to combine more than six futures of different types, use the other combine method. Since it supports vararg usage, the function is now the first argument. The CombinedFutures object that is input to the function can be used to extract values from the input functions.

This is effectively the same thing as calling join() on the input future, but it's safer because calling .get(f) on a future that is not part of the combine, you will get an IllegalArgumentException.

This prevents accidental misuse where you would join on a future that is either not complete, or might never complete at all.

CompletionStage<String> f1;
CompletionStage<String> f2;
CompletionStage<String> result = combine(combined -> combined.get(f1) + combined.get(f2), f1, f2);

If you want to do this in a combineFutures form, you can do that like this:

CompletionStage<String> f1;
CompletionStage<String> f2;
CompletionStage<String> result = dereference(combine(combined -> completedFuture(combined.get(f1) + combined.get(f2)), f1, f2));

Scheduling

Polling an external resource

If you are dealing with a long-running external task that only exposes a polling API, you can transform that into a future like so:

Supplier<Optional<T>> pollingTask = () -> Optional.ofNullable(resource.result());
Duration frequency = Duration.ofSeconds(2);
CompletableFuture<T> result = CompletableFutures.poll(pollingTask, frequency, executor);

Missing parts of the CompletableFuture API

The CompletableFutures class includes utility functions for operating on futures that is missing from the builtin API.

handleCompose

Like CompletableFuture.handle but lets you return a new CompletionStage instead of a direct value.

CompletionStage<String> composed = handleCompose(future, (value, throwable) -> completedFuture("hello"));

exceptionallyCompose

Like CompletableFuture.exceptionally but lets you return a new CompletionStage instead of a direct value.

CompletionStage<String> composed = CompletableFutures.exceptionallyCompose(future, throwable -> completedFuture("fallback"));

dereference

Unwrap a CompletionStage<CompletionStage<T>> to a plain CompletionStage<T>.

CompletionStage<CompletionStage<String>> wrapped = completedFuture(completedFuture("hello"));
CompletionStage<String> unwrapped = CompletableFutures.dereference(wrapped);

exceptionallyCompletedFuture

Creates a new future that is already exceptionally completed with the given exception.

return CompletableFutures.exceptionallyCompletedFuture(new RuntimeException("boom"));

License

Copyright 2016 Spotify AB. Licensed under the Apache License, Version 2.0.

Code of Conduct

This project adheres to the Open Code of Conduct. By participating, you are expected to honor this code.

Releases

See the instructions in spotify/foss-root

Ownership

The Weaver squad is currently owning this project internally. We are currently in the evaluating process of the ownership of this and other OSS Java libraries. The ownership takes into account ONLY security maintenance.

This repo is also co-owned by other people:

More Repositories

1

luigi

Luigi is a Python module that helps you build complex pipelines of batch jobs. It handles dependency resolution, workflow management, visualization etc. It also comes with Hadoop support built in.
Python
17,581
star
2

annoy

Approximate Nearest Neighbors in C++/Python optimized for memory usage and loading/saving to disk
C++
12,982
star
3

pedalboard

๐ŸŽ› ๐Ÿ”Š A Python library for audio.
C++
5,147
star
4

docker-gc

INACTIVE: Docker garbage collection of containers and images
Shell
5,068
star
5

chartify

Python library that makes it easy for data scientists to create charts.
Python
3,510
star
6

basic-pitch

A lightweight yet powerful audio-to-MIDI converter with pitch bend detection
Python
3,184
star
7

dockerfile-maven

MATURE: A set of Maven tools for dealing with Dockerfiles
Java
2,748
star
8

docker-maven-plugin

INACTIVE: A maven plugin for Docker
Java
2,652
star
9

scio

A Scala API for Apache Beam and Google Cloud Dataflow.
Scala
2,485
star
10

helios

Docker container orchestration platform
Java
2,097
star
11

web-api-examples

Basic examples to authenticate and fetch data using the Spotify Web API
HTML
1,889
star
12

HubFramework

DEPRECATED โ€“ Spotifyโ€™s component-driven UI framework for iOS
Objective-C
1,861
star
13

apollo

Java libraries for writing composable microservices
Java
1,648
star
14

dh-virtualenv

Python virtualenvs in Debian packages
Python
1,608
star
15

docker-client

INACTIVE: A simple docker client for the JVM
Java
1,429
star
16

docker-kafka

Kafka (and Zookeeper) in Docker
Shell
1,399
star
17

SPTPersistentCache

Everyone tries to implement a cache at some point in their iOS appโ€™s lifecycle, and this is ours.
Objective-C
1,243
star
18

voyager

๐Ÿ›ฐ๏ธ An approximate nearest-neighbor search library for Python and Java with a focus on ease of use, simplicity, and deployability.
C++
1,242
star
19

mobius

A functional reactive framework for managing state evolution and side-effects.
Java
1,223
star
20

sparkey

Simple constant key/value storage library, for read-heavy systems with infrequent large bulk inserts.
C
1,153
star
21

ruler

Gradle plugin which helps you analyze the size of your Android apps.
Kotlin
1,130
star
22

XCMetrics

XCMetrics is the easiest way to collect Xcode build metrics and improve developer productivity.
Swift
1,102
star
23

web-api

This issue tracker is no longer used. Join us in the Spotify for Developers forum for support with the Spotify Web API โžก๏ธ https://community.spotify.com/t5/Spotify-for-Developers/bd-p/Spotify_Developer
RAML
981
star
24

echoprint-codegen

Codegen for Echoprint
C++
948
star
25

snakebite

A pure python HDFS client
Python
858
star
26

heroic

The Heroic Time Series Database
Java
843
star
27

klio

Smarter data pipelines for audio.
Python
836
star
28

XCRemoteCache

Swift
830
star
29

ios-sdk

Spotify SDK for iOS
Objective-C
643
star
30

SPTDataLoader

The HTTP library used by the Spotify iOS client
Objective-C
629
star
31

apps-tutorial

A Spotify App that contains working examples of the use of Spotify Apps API
628
star
32

JniHelpers

Tools for writing great JNI code
C++
590
star
33

postgresql-metrics

Tool that extracts and provides metrics on your PostgreSQL database
Python
588
star
34

Mobius.swift

A functional reactive framework for managing state evolution and side-effects [Swift implementation]
Swift
557
star
35

reactochart

๐Ÿ“ˆ React chart component library ๐Ÿ“‰
JavaScript
552
star
36

dockerfile-mode

An emacs mode for handling Dockerfiles
Emacs Lisp
537
star
37

threaddump-analyzer

A JVM threaddump analyzer
JavaScript
488
star
38

featran

A Scala feature transformation library for data science and machine learning
Scala
467
star
39

android-sdk

Spotify SDK for Android
HTML
457
star
40

echoprint-server

Server for the Echoprint audio fingerprint system
Java
395
star
41

web-scripts

DEPRECATED: A collection of base configs and CLI wrappers used to speed up development @ Spotify.
TypeScript
383
star
42

spotify-web-api-ts-sdk

A Typescript SDK for the Spotify Web API with types for returned data.
TypeScript
356
star
43

SpotifyLogin

Swift framework for authenticating with the Spotify API
Swift
347
star
44

ratatool

A tool for data sampling, data generation, and data diffing
Scala
338
star
45

fmt-maven-plugin

Opinionated Maven Plugin that formats your Java code.
Java
324
star
46

big-data-rosetta-code

Code snippets for solving common big data problems in various platforms. Inspired by Rosetta Code
Scala
287
star
47

trickle

A small library for composing asynchronous code
Java
285
star
48

coordinator

A visual interface for turning an SVG into XY coรถrdinates.
HTML
284
star
49

pythonflow

๐Ÿ Dataflow programming for python.
Python
283
star
50

styx

"The path to execution", Styx is a service that schedules batch data processing jobs in Docker containers on Kubernetes.
Java
266
star
51

cstar

Apache Cassandra cluster orchestration tool for the command line
Python
254
star
52

confidence

Python
254
star
53

netty-zmtp

A Netty implementation of ZMTP, the ZeroMQ Message Transport Protocol.
Java
242
star
54

ios-style

Guidelines for iOS development in use at Spotify
241
star
55

cassandra-reaper

Software to run automated repairs of cassandra
235
star
56

docker-cassandra

Cassandra in Docker with fast startup
Shell
220
star
57

basic-pitch-ts

A lightweight yet powerful audio-to-MIDI converter with pitch bend detection.
TypeScript
216
star
58

terraform-gke-kubeflow-cluster

Terraform module for creating GKE clusters to run Kubeflow
HCL
213
star
59

linux

Spotify's Linux kernel for Debian-based systems
C
206
star
60

dns-java

DNS wrapper library that provides SRV lookup functionality
Java
205
star
61

git-test

test your commits
Shell
203
star
62

SPStackedNav

[DEPRECATED] Navigation controller which represents its content in stacks of panes, rather than one at a time
Objective-C
195
star
63

spotify-json

Fast and nice to use C++ JSON library.
C++
194
star
64

quickstart

A CommonJS module resolver, loader and compiler for node.js and browsers.
JavaScript
193
star
65

dbeam

DBeam exports SQL tables into Avro files using JDBC and Apache Beam
Java
189
star
66

flink-on-k8s-operator

Kubernetes operator for managing the lifecycle of Apache Flink and Beam applications.
Go
185
star
67

bazel-tools

Tools for dealing with very large Bazel-managed repositories
Java
165
star
68

magnolify

A collection of Magnolia add-on modules
Scala
163
star
69

dataenum

Algebraic data types in Java.
Java
163
star
70

lingon

A user friendly tool for building single-page JavaScript applications
JavaScript
162
star
71

async-google-pubsub-client

[SUNSET] Async Google Pubsub Client
Java
157
star
72

gcp-audit

A tool for auditing security properties of GCP projects.
Python
157
star
73

spark-bigquery

Google BigQuery support for Spark, SQL, and DataFrames
Scala
155
star
74

should-up

Remove most of the "should" noise from your tests
JavaScript
153
star
75

folsom

An asynchronous memcache client for Java
Java
147
star
76

flo

A lightweight workflow definition library
Java
146
star
77

missinglink

Build time tool for detecting link problems in java projects
Java
144
star
78

android-auth

Spotify authentication and authorization for Android. Part of the Spotify Android SDK.
HTML
143
star
79

proto-registry

An implementation of the Protobuf Registry API
TypeScript
141
star
80

zoltar

Common library for serving TensorFlow, XGBoost and scikit-learn models in production.
Java
138
star
81

annoy-java

Approximate nearest neighbors in Java
Java
137
star
82

futures-extra

Java library for working with Guava futures
Java
136
star
83

spotify-web-playback-sdk-example

React based example app that creates a new player in Spotify Connect to play music from in the browse using Spotify Web Playback SDK.
JavaScript
136
star
84

spydra

Ephemeral Hadoop clusters using Google Compute Platform
Java
134
star
85

docker-stress

Simple docker stress test and monitoring tools
Python
125
star
86

spotify-tensorflow

Provides Spotify-specific TensorFlow helpers
Python
124
star
87

github-java-client

A Java client to Github API
Java
120
star
88

crtauth

a public key backed client/server authentication system
Python
118
star
89

redux-location-state

Utilities for reading & writing Redux store state to & from the URL
JavaScript
118
star
90

sparkey-java

Java implementation of the Sparkey key value store
Java
117
star
91

realbook

Easier audio-based machine learning with TensorFlow.
Python
112
star
92

rspec-dns

Easily test your DNS with RSpec
Ruby
107
star
93

web-playback-sdk

This issue tracker is no longer used. Join us in the Spotify for Developers forum for support with the Spotify Web Playback SDK โžก๏ธ https://community.spotify.com/t5/Spotify-for-Developers/bd-p/Spotify_Developer
107
star
94

ffwd-ruby

An event and metrics fast-forwarding agent.
Ruby
105
star
95

gimme

Creating time bound IAM Conditions with ease and flair
Python
103
star
96

super-smash-brogp

Sends and withdraws BGP prefixes for fun.
Python
98
star
97

spotify.github.io

Showcase site for hand-picked open-source projects by Spotify
HTML
96
star
98

lighthouse-audit-service

TypeScript
95
star
99

python-graphwalker

Python re-implementation of the graphwalker testing tool
Python
93
star
100

noether

Scala Aggregators used for ML Model metrics monitoring
Scala
91
star