• This repository has been archived on 11/Jan/2023
  • Stars
    star
    590
  • Rank 75,461 (Top 2 %)
  • Language
    C++
  • License
    Apache License 2.0
  • Created over 10 years ago
  • Updated almost 4 years ago

Reviews

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

Repository Details

Tools for writing great JNI code

JniHelpers

JniHelpers is a library designed to facilitate writing JNI code with C++. It provides the following features:

  • Registry for cached class info (ie, jclass, jmethodID and jfieldID) lookups
  • "Automatic" conversion between Java <--> C++ objects. Note the ironic quotes around "automatic", which means:
    • Conversion must be enabled for the given class. This is as a feature, not a limitation, and means that classes may be represented by a Java/C++ counterpart, but you may not necessarily care to copy data from them in every JNI call. JniHelpers can do this for you, but you can also do it manally if performance is a concern.
    • Conversions are not performed automatically in every native callback. However, getting a C++ instance of a Java class or creating a Java instance of a C++ class is trivial.
    • JniHelpers prefers to copy memory, thus avoiding tricky issues that arise when trying to mix the very different memory management models of the Java garbage collector and C++ RAII paradigm.
  • Conversion between Java String objects and stl::string.
  • Conversion between Java byte arrays and C void* arrays.
  • Persisting native objects through Java without copying data. Persisted objects are created on the heap and leaked; their memory address is stored in a corresponding Java instance in a long field. If you want to access the native instance again, a call is provided to fetch the native instance from the field. This is very useful for creating long-lived native objects without having to make them singletons.
  • Easy registration of native methods. Rather than having to memorize the complex rules of creating JNI type signatures, a simple varargs interface is provided to do the grunt work for you.
  • Conveniences for common JNI functions, including:
    • Lookup Java classes with a given classloader
    • Attach/detach native threads to Java
    • Throw Java exceptions from native code, with printf-style string formatting
    • RAII template classes for JNI local/global/weak global references.
  • Android-friendly. JniHelpers was designed to work well on Android, and although it also runs fine on desktop Java, the CMake configuration is meant to be easily adapted for an Android build.
  • Tested! There is a test suite provided which is executed from Java that will run the native tests and prove communication across JNI works as expected.
  • Documented! Extensive class documentation is provided.

Examples

The best examples for JniHelpers is the test suite itself. See the classes within src/test/cpp, they are documented and explain correct usage of the library.

What JniHelpers is NOT

JniHelpers is not SWIG. It does not attempt to automatically create wrappers around native code.

JniHelpers is also not a complete wrapper around JNI. It does not attempt to completely shield the programmer from all JNI calls. Rather, it just makes the trickiest parts of JNI a bit friendlier to work with.

Building

JniHelpers contains both Java and C++ code, and is built with Gradle and CMake, respectively. To build JniHelpers as a static library, just run the following commands:

$ mkdir build
$ cd build
$ cmake ..
$ make

The Java part of JniHelpers can now be built as a JAR file:

$ ./gradlew assemble

To use JniHelpers in your project, it is not necessary to build standalone artifacts. Rather, you can use this project as a submodule in your code and include the CMake/Gradle script from your project. This is the preferred method for using the library.

Building JniHelpers on Windows has not been tested and may not work. The project is known to build for desktop Linux, Mac OS X, and Android.

Testing

JniHelpers has test cases, which are implemented in JUnit. If you wish to submit a pull request to this project, please add tests for any new code or bugfixes, and make sure that the existing tests continue to pass before sending the request. Pull requests with failing tests will not be merged!

Unfortunately, there is not yet integration between the two Gradle and CMake build system, so one must run them independently to execute the tests (we aim to fix this in a future release so that Gradle can execute the CMake build on its own). First, one must build the C++ parts with CMake as detailed above in the "Building" section. After the JniHelpers libraries have been built, one can run the JUnit tests from the top-level project directory like so:

$ ./gradlew test

If all goes well, Gradle should report "BUILD SUCCESSFUL" and no other output. Any test failures will be reported to the command line.

License

JniHelpers is made available under the Apache 2.0 license. For more information, please see the LICENSE.txt file distributed with JniHelpers.

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

πŸŽ› πŸ”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 – Spotify’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 app’s lifecycle, and this is ours.
Objective-C
1,243
star
18

voyager

πŸ›°οΈ 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 ➑️ 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

postgresql-metrics

Tool that extracts and provides metrics on your PostgreSQL database
Python
588
star
33

Mobius.swift

A functional reactive framework for managing state evolution and side-effects [Swift implementation]
Swift
555
star
34

reactochart

πŸ“ˆ React chart component library πŸ“‰
JavaScript
552
star
35

dockerfile-mode

An emacs mode for handling Dockerfiles
Emacs Lisp
537
star
36

threaddump-analyzer

A JVM threaddump analyzer
JavaScript
488
star
37

featran

A Scala feature transformation library for data science and machine learning
Scala
467
star
38

android-sdk

Spotify SDK for Android
HTML
457
star
39

echoprint-server

Server for the Echoprint audio fingerprint system
Java
395
star
40

completable-futures

Utilities for working with futures in Java 8
Java
385
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 coΓΆrdinates.
HTML
284
star
49

pythonflow

🐍 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
255
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 ➑️ 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