Introduce *LatestConflated Flow operators
These are meant to replace the standard *Latest Flow operators, as it
provides more sensible and performant defaults for sysui developers.
Flag: NA
Bug: 334177468
Test: NA
Change-Id: I944a98e96a7f073d9ee5220f7eeab61c5ded3a8e
diff --git a/packages/SystemUI/src/com/android/systemui/common/coroutine/LatestConflated.kt b/packages/SystemUI/src/com/android/systemui/common/coroutine/LatestConflated.kt
new file mode 100644
index 0000000..247fcf7
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/common/coroutine/LatestConflated.kt
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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.
+ */
+
+@file:OptIn(ExperimentalCoroutinesApi::class, ExperimentalTypeInference::class)
+
+package com.android.systemui.common.coroutine
+
+import kotlin.experimental.ExperimentalTypeInference
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.FlowCollector
+import kotlinx.coroutines.flow.conflate
+import kotlinx.coroutines.flow.flatMapLatest
+import kotlinx.coroutines.flow.mapLatest
+import kotlinx.coroutines.flow.transformLatest
+
+/**
+ * Returns a flow that emits elements from the original flow transformed by [transform] function.
+ * When the original flow emits a new value, computation of the [transform] block for previous value
+ * is cancelled.
+ *
+ * For example, the following flow:
+ * ```
+ * flow {
+ * emit("a")
+ * delay(100)
+ * emit("b")
+ * }.mapLatest { value ->
+ * println("Started computing $value")
+ * delay(200)
+ * "Computed $value"
+ * }
+ * ```
+ *
+ * will print "Started computing a" and "Started computing b", but the resulting flow will contain
+ * only "Computed b" value.
+ *
+ * This operator is [conflated][conflate] by default, and as such should be preferred over usage of
+ * [mapLatest], due to the latter's default configuration of using an internal buffer, negatively
+ * impacting system health.
+ *
+ * @see mapLatest
+ */
+fun <T, R> Flow<T>.mapLatestConflated(@BuilderInference transform: suspend (T) -> R): Flow<R> =
+ mapLatest(transform).conflate()
+
+/**
+ * Returns a flow that switches to a new flow produced by [transform] function every time the
+ * original flow emits a value. When the original flow emits a new value, the previous flow produced
+ * by `transform` block is cancelled.
+ *
+ * For example, the following flow:
+ * ```
+ * flow {
+ * emit("a")
+ * delay(100)
+ * emit("b")
+ * }.flatMapLatest { value ->
+ * flow {
+ * emit(value)
+ * delay(200)
+ * emit(value + "_last")
+ * }
+ * }
+ * ```
+ *
+ * produces `a b b_last`
+ *
+ * This operator is [conflated][conflate] by default, and as such should be preferred over usage of
+ * [flatMapLatest], due to the latter's default configuration of using an internal buffer,
+ * negatively impacting system health.
+ *
+ * @see flatMapLatest
+ */
+fun <T, R> Flow<T>.flatMapLatestConflated(
+ @BuilderInference transform: suspend (T) -> Flow<R>,
+): Flow<R> = flatMapLatest(transform).conflate()
+
+/**
+ * Returns a flow that produces element by [transform] function every time the original flow emits a
+ * value. When the original flow emits a new value, the previous `transform` block is cancelled,
+ * thus the name `transformLatest`.
+ *
+ * For example, the following flow:
+ * ```
+ * flow {
+ * emit("a")
+ * delay(100)
+ * emit("b")
+ * }.transformLatest { value ->
+ * emit(value)
+ * delay(200)
+ * emit(value + "_last")
+ * }
+ * ```
+ *
+ * produces `a b b_last`.
+ *
+ * This operator is [conflated][conflate] by default, and as such should be preferred over usage of
+ * [transformLatest], due to the latter's default configuration of using an internal buffer,
+ * negatively impacting system health.
+ *
+ * @see transformLatest
+ */
+fun <T, R> Flow<T>.transformLatestConflated(
+ @BuilderInference transform: suspend FlowCollector<R>.(T) -> Unit,
+): Flow<R> = transformLatest(transform).conflate()