DependencyTask

This lib is the framework for dependency tasks, specially for the asynchronous tasks.

Backgroud

Image that there is a progress with some steps, and the order of the dependencies for those steps maybe not fixed. Most often ,like in the android app, we need to do the initilaize progress, such as require permissions , check the account or do some asynchronous initialized progress before letting the user use the app, and there may be some dependency between the steps， for some requirements , the order of the dependencies would be changed， this lib is just for that scenario.

Installation

For gradle

Add it in your root build.gradle at the end of repositories:

allprojects {
  repositories {
    ...
    maven { url 'https://jitpack.io' }
  }
}

Add the dependency:

dependencies {
  implementation 'com.github.Arrowyi:DependencyTask:TheVersion'
}

For maven

Add the JitPack repository to your build file

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

Add the dependency

<dependency>
  <groupId>com.github.Arrowyi</groupId>
  <artifactId>DependencyTask</artifactId>
  <version>TheVersion</version>
</dependency>

How to use

Step 1 : inherite from the Task class

• First, you need to divide your progress into serval tasks
• each task need to inherite from the Task class
• call addDependency function with the task instance to build the releationship of the tasks
• implement the action suspend function for your job
• if the task done its job, call the actionResult function with true(job done successfully) or false(job done failed) to notify the framework the result of the task

Step 2 : start with the TaskProcessor

• create the TaskProcessor class initance with a InitTask (which is your first order task)
• call the start funcation to get a 'flow'
• call collet function of the flow to get the ProgressStatus class( which is represent for the progress status ) sequentially

Example

import kotlinx.coroutines.delay
import kotlinx.coroutines.runBlocking

class SuspendTask : Task() {
  override suspend fun doAction() {
      //do suspend job
      delay(100)
      actionResult(true)
  }
}

class BlockTask : Task() {
  override suspend fun doAction() {
      //some block job
      Thread.sleep(100)
      actionResult(true)
  }
}

class SomeTask(private val name: String) : Task() {
  override suspend fun doAction() {
      actionResult(true)
  }

  override fun getTaskDescription(): String {
      return name
  }
}

fun main() = runBlocking {
  val task1 = SuspendTask()
  val task2 = BlockTask()
  val task3 = SomeTask("task 3")
  val task4 = SomeTask("task 4")

  task2.addDependency(task1)
  task3.addDependency(task1)
  task3.addDependency(task2)
  task4.addDependency(task3)

  TaskProcessor(task1).start().collect() {
      when (it) {
          is Check -> println("check result is : ${it.result}")
          is Progress -> println("task : ${it.task.getDescription()} is done")
          is Complete -> println("all the task is done successfully,and the flow is ended")
          is Failed -> println("task : ${it.failedTask.getDescription()} is failed , and the flow is ended ")
      }
  }

}

The progress status is :

//check if there is circular dependency , true is for check ok (no circular dependency), false will end the processor, and the tasks is all
//the tasks this processor will do.
class Check(val result: Boolean, val tasks: List<Task>?) : ProgressStatus()
//called if the task is done
class Progress(val task: Task) : ProgressStatus()
//called if all the tasks is done successfully, and the processor will be ended
class Complete : ProgressStatus()
//called if any of the task failed, and the processor will be ended immediately
class Failed(val failedTask: Task) : ProgressStatus()
//The Processor is already running, and this flow will be ended
class AlreadyRunning() : ProgressStatus()

Features

• The processor will check the circular dependency
• The task's action will run concurrently if their dependency tasks are done (you could specify the dispatcher the action running on by the parameter of TaskProcessor)
• If you use the same processor instance to start many times, the successful tasks will not do action again, the processor will call the action function from the last failed one.
• If you use the same processor instance to start more than one Flow simultaneously, only one Flow will run and the others will receive the AlreadyRunning status and be ended.
• For the detail of the features you could ref to the unit test

Attention

• there should be only one init task node as the root node of the dependence tree
• you must pass the root node to initlaze the TaskProcessor
• if there is a circular dependency, the Check status will pass a result value false.
• you must call actionResult function of the task after your job is done, whatever it is failed or has an exception，or the Flow will not end.

Progress example

• As the above dependency task tree, when you begin to call the function collect of the Flow(which is got from start function), it will pass the check status with true to indicate that the circular dependency check is OK.
• And then ，it will pass the Progress status to indicate which task is done. the TaskProcessor will call task's action function concurrently if their dependency tasks are done.
• As the above tree, the task7's action function will be called after task2 and task5 are done, and task7 and task8 maybe called concurrently.
• For example, after task2 is done, the onDependencyDone function of task7 will be called, you could override this function to get some info from the dependency task, you must call the super function if you override this function
• And the Complete status will be received if all the tasks are done successfully, otherwise 'Failed` status will be received immediately if there is a failed task. any of those two status will end the Flow.
• If the Check status is with a result false, the Flow will also be ended.

Release Version

The last release version please ref to the Release page