Add TimeMeasurer for Spa

To measure the app list first loaded time.

Bug: 235727273
Test: Manual with App List page
Change-Id: I4edc54edd850e2d7d3026782aa317428b13c27aa

packages/SettingsLib/Spa/spa/src/com/android/settingslib/spa/framework/compose/TimeMeasurer.kt

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2022 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(ExperimentalTime::class)
+
+package com.android.settingslib.spa.framework.compose
+
+import android.util.Log
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import kotlin.time.ExperimentalTime
+import kotlin.time.TimeSource
+
+const val ENABLE_MEASURE_TIME = false
+
+interface TimeMeasurer {
+    fun log(msg: String) {}
+    fun logFirst(msg: String) {}
+
+    companion object {
+        private object EmptyTimeMeasurer : TimeMeasurer
+
+        @Composable
+        fun rememberTimeMeasurer(tag: String): TimeMeasurer = remember {
+            if (ENABLE_MEASURE_TIME) TimeMeasurerImpl(tag) else EmptyTimeMeasurer
+        }
+    }
+}
+
+private class TimeMeasurerImpl(private val tag: String) : TimeMeasurer {
+    private val mark = TimeSource.Monotonic.markNow()
+    private val msgLogged = mutableSetOf<String>()
+
+    override fun log(msg: String) {
+        Log.d(tag, "Timer $msg: ${mark.elapsedNow()}")
+    }
+
+    override fun logFirst(msg: String) {
+        if (msgLogged.add(msg)) {
+            Log.d(tag, "Timer $msg: ${mark.elapsedNow()}")
+        }
+    }
+}

packages/SettingsLib/SpaPrivileged/src/com/android/settingslib/spaprivileged/template/app/AppList.kt

@@ -28,6 +28,7 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.res.stringResource
 import androidx.lifecycle.viewmodel.compose.viewModel
 import com.android.settingslib.spa.framework.compose.LogCompositions
+import com.android.settingslib.spa.framework.compose.TimeMeasurer.Companion.rememberTimeMeasurer
 import com.android.settingslib.spa.framework.compose.toState
 import com.android.settingslib.spa.framework.theme.SettingsDimension
 import com.android.settingslib.spa.widget.ui.PlaceholderTitle
@@ -66,7 +67,9 @@ private fun <T : AppRecord> AppListWidget(
     listModel: AppListModel<T>,
     appItem: @Composable (itemState: AppListItemModel<T>) -> Unit,
 ) {
+    val timeMeasurer = rememberTimeMeasurer(TAG)
     appListData.value?.let { (list, option) ->
+        timeMeasurer.logFirst("app list first loaded")
         if (list.isEmpty()) {
             PlaceholderTitle(stringResource(R.string.no_applications))
             return