Merge "Provide @ShellMainThread dispatcher as MainCoroutineDispatcher" into main

package com.android.wm.shell.dagger

import android.os.Handler

import com.android.wm.shell.common.ShellExecutor

import com.android.wm.shell.shared.annotations.ShellBackgroundThread

import com.android.wm.shell.shared.annotations.ShellMainThread

import kotlin.coroutines.CoroutineContext

import kotlinx.coroutines.CoroutineDispatcher

import kotlinx.coroutines.CoroutineScope

import kotlinx.coroutines.MainCoroutineDispatcher

import kotlinx.coroutines.SupervisorJob

import kotlinx.coroutines.android.asCoroutineDispatcher

import kotlinx.coroutines.asCoroutineDispatcher

/** Providers for various WmShell-specific coroutines-related constructs. */

/**

 * Providers for various WmShell-specific coroutines-related constructs.

 *

 * Providers of [MainCoroutineDispatcher] intentionally creates the dispatcher with a [Handler]

 * backing it instead of a [ShellExecutor] because [ShellExecutor.asCoroutineDispatcher] will

 * create a [CoroutineDispatcher] whose [CoroutineDispatcher.isDispatchNeeded] is effectively never

 * dispatching. This is because even if dispatched, the backing [ShellExecutor.execute] always runs

 * the [Runnable] immediately if called from the same thread, whereas

 * [Handler.asCoroutineDispatcher] will create a [MainCoroutineDispatcher] that correctly

 * dispatches (queues) when [CoroutineDispatcher.isDispatchNeeded] is true using [Handler.post].

 * For callers that do need a non-dispatching version, [MainCoroutineDispatcher.immediate] is

 * available.

 */

@Module

class WMShellCoroutinesModule {

  @Provides

  @ShellMainThread

  fun provideMainDispatcher(@ShellMainThread mainExecutor: ShellExecutor): CoroutineDispatcher =

      mainExecutor.asCoroutineDispatcher()

  fun provideMainDispatcher(

    @ShellMainThread mainHandler: Handler

  ): MainCoroutineDispatcher = mainHandler.asCoroutineDispatcher()

  @Provides

  @ShellBackgroundThread

  fun provideBackgroundDispatcher(

      @ShellBackgroundThread backgroundExecutor: ShellExecutor

  ): CoroutineDispatcher = backgroundExecutor.asCoroutineDispatcher()

      @ShellBackgroundThread backgroundHandler: Handler

  ): MainCoroutineDispatcher = backgroundHandler.asCoroutineDispatcher()

  @Provides

  @WMSingleton