Run a "hook" lambda after a block of code regardless of whether the block succeeds, fails, or the application is killed.

changeSomething()
withFinalizationHook(
  hook = { resetSomething() },
  block = {
    doWork()
  },
)

This function should only be used when the changes being made are outside the application itself. An example would be writing a lock file to the file system, and then deleting it when an operation completes. If you are only changing state within the application, a regular try/finally will suffice.

Build the :test-app project to see this in action. Run the app and then hit Ctrl+C:

$ ./test-app/build/bin/macosArm64/releaseExecutable/test-app.kexe
START
BLOCK
^CHOOK

Or run the app and kill the PID:

$ ./test-app/build/bin/macosArm64/releaseExecutable/test-app.kexe
START
BLOCK
HOOK
Terminated: 15

(In another terminal pane)

$ ps | grep test-app
32769 ttys004    0:00.02 ./test-app/build/bin/macosArm64/releaseExecutable/test-app.kexe
32943 ttys005    0:00.00 grep test-app

$ kill 32769

A JVM version is also available at test-app/build/install/test-app/bin/test-app.

dependencies {
  implementation("com.jakewharton.finalization:finalization-hook:0.1.0")
}

Documentation is available at jakewharton.github.io/finalization-hook/docs/0.x/.

repository {
  mavenCentral()
  maven {
    url 'https://central.sonatype.com/repository/maven-snapshots/'
  }
}
dependencies {
  implementation("com.jakewharton.finalization:finalization-hook:0.2.0-SNAPSHOT")
}

Copyright 2024 Jake Wharton

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.