Sloth

Sloth is the fastest hot code reload library for FTC.

Hot reloading involves sending only your teamcode to the robot when you make a change, to get very fast Write -> Run -> Test development cycles. Say goodbye to waiting 40+ seconds for your teamcode to be uploaded, Sloth gets code on your robot in under a second.

Sloth is also a Sinister runtime that enables the use of Sinister's classpath scanning and dynamic loading capabilities on the android FTC platform. This allows Sloth to support a wide range of libraries that need to know about and react to hot reloading your code.

Sloth has some major improvements over its predecessor, fastload:

1. Sloth is much faster than fastload. fastload advertises ~7 seconds upload time; Sloth has a upper ceiling of 2 seconds, but often is less than 1.
2. Sloth will keep changes across restarts and power cycles of the robot.
3. Sloth only processes the change in code when your OpMode ends, which means it is safe to deploy with Sloth while running other code.
4. @Pinned can be put on classes to prevent dynamically changing it, or any subclasses of it.
5. Sloth is a more capable runtime, that does more than just swap over your code:
   • Sloth sets up Dairy.
   • Sloth updates parts of the SDK properly when you upload code changes, including your hardwaremap if you're uploading drivers with your teamcode (e.g. the goBILDA Pinpoint driver before it was part of the SDK).
   • Libraries that rely on looking at your code, like FTC Dashboard, can be easily tweaked to be compatible with Sloth, and thus load faster, and support hotreloading. (Please open an issue if you have a favourite library that is currently incompatible with Sloth; I don't mind maintaining a fork, or doing the setup work to make it easy for others to maintain.)
   • Sloth supports custom user classpath scanning, so you can write your own systems that listen and react to hot reloads.
6. Sloth includes a drop-in replacement of FTC Dashboard that replaces some internal mechanisms of FTC Dashboard to use the Sloth and Sinister equivalents. This fork fully supports hot reloading for Configuration (@Config) and OpModes.

There are some precautions to take when using Sloth:

1. Sloth will only dynamically hot reload classes in the org.firsinspires.ftc.teamcode package (and subpackages).
2. It is possible to upload code that compiles, but does not work when hot reloaded due to:
   • Installing or changing libraries.
   • Changing files that are not hot reloaded.
   • Changing @Pinned on files. Be careful to ensure that you make changes that will be changed, and if make changes that will not, that you perform a full install in order to propagate them.

Warning

If you used an older version of the Pedro Pathing quickstart, you will need to move your files to the org.firstinspires.ftc.teamcode package.

Installation

Important

If you are already using Dairy, skip straight to the Dairy Core section.

Note

If you are using FTC Dashboard, check out the FTC Dashboard section.

Sloth Library

Add the dairy releases repository to your TeamCode build.gradle, above the dependencies block:

repositories {
    maven {
        url = "https://repo.dairy.foundation/releases"
    }
}

Then add sloth to the dependencies block:

dependencies {
    implementation("dev.frozenmilk.sinister:Sloth:0.2.4")
}

Now install the Load plugin.

Dairy Core

To use this release of Sloth with Dairy you need to install a snapshot version of Dairy's Core.

Add the Dairy releases and snapshots repository to your TeamCode build.gradle, above the dependencies block:

repositories {
    maven {
        url = "https://repo.dairy.foundation/releases"
    }
    maven {
        url = "https://repo.dairy.foundation/snapshots"
    }
}

Then add core to the dependencies block:

dependencies {
    implementation("dev.frozenmilk.dairy:Core:2.2.4")
}

Warning

You do not need to install Sloth as well, and if you currently have any installations of either "dev.frozenmilk.dairy:Util" or "dev.frozenmilk:Sinister" then you need to remove those, as this Core version will provide the correct versions of these libraries.

Now install the Load plugin.

Load Plugin

Add this to the top of your TeamCode build.gradle:

buildscript {
    repositories {
        mavenCentral()
        maven {
            url "https://repo.dairy.foundation/releases"
        }
    }
    dependencies {
        classpath "dev.frozenmilk:Load:0.2.4"
    }
}

Add this after the apply plugin: lines in the same file:

// there should be 2 or 3 more lines that start with 'apply plugin:' here
apply plugin: 'dev.frozenmilk.sinister.sloth.load'

Sync and download the code onto your robot via standard install.

Now add the Gradle tasks.

NOTE: If you use FTC Dashboard, install that now, then setup the gradle tasks:

FTC Dashboard

Add the dairy releases repository to your TeamCode build.gradle, above the dependencies block (if you already have it, no need to do so again)

repositories {
    maven {
        url = "https://repo.dairy.foundation/releases"
    }
}

Then add dashboard to the dependencies block:

dependencies {
    implementation("com.acmerobotics.slothboard:dashboard:0.2.4+0.4.17")
}

Note

If you use a library that imports dashboard via a implementation or api dependency, ask the library maintainers to consider changing it to compileOnly. This will allow it to work with the modified version of FTC Dashboard that Sloth uses.

Change the implementation like so:

implementation("com.pedropathing:pedro:1.0.8") {
   exclude group: "com.acmerobotics.dashboard"
}

implementation("com.acmerobotics.roadrunner:ftc:0.1.21") {
   exclude group: "com.acmerobotics.dashboard"
}
implementation ("com.acmerobotics.roadrunner:actions:1.0.1"){
   exclude group: "com.acmerobotics.dashboard"
}

Note that both Pedro Pathing and Road Runner require this.

Pedro Pathing and Road Runner version numbers may not be up to date; they are provided only as an example.

Gradle Tasks

Edit configurations:

Add new configuration:

Select gradle:

Add deploySloth and save it:

NOTE: android studio will not auto complete the names of these tasks, just write it and it will work.

Edit TeamCode configuration:

Add new gradle task:

Add removeSlothRemote:

Note: Type :TeamCode into the Gradle Project box to get the right contents, do not copy mine.

Put removeSlothRemote first and save:

Run the deploySloth task you just added to deploy the code.

Congratulations! You are now set up with lightning-fast software deployment using Sloth.