For #12802: add StorageStats glean metrics.

app/metrics.yaml

@@ -3236,3 +3236,82 @@ autoplay:
     notification_emails:
       - fenix-core@mozilla.com
     expires: "2021-02-01"
+
+storage.stats:
+  query_stats_duration:
+    send_in_pings:
+      - metrics
+    type: timing_distribution
+    description: >
+      How long it took to query the device for the StorageStats that contain the
+      file size information. The docs say it may be expensive so we want to
+      ensure it's not too expensive.  This value is only available on Android
+      8+.
+    bugs:
+      - https://github.com/mozilla-mobile/fenix/issues/12802
+    data_reviews:
+      - todo
+    notification_emails:
+      - fenix-core@mozilla.com
+      - perf-android-fe@mozilla.com
+      - mcomella@mozilla.com
+    expires: "2020-12-21"
+  app_bytes:
+    send_in_pings:
+      - metrics
+    type: memory_distribution
+    description: >
+      The size of the app's APK and related files as installed: this is expected
+      to be larger than download size. This is the output of
+      [StorageStats.getAppBytes](https://developer.android.com/reference/android/app/usage/StorageStats#getAppBytes())
+      so see that for details. This value is only available on Android 8+. A
+      similar value may be available on the Google Play dashboard: we can use
+      this value to see if that value is reliable enough.
+    memory_unit: byte
+    bugs:
+      - https://github.com/mozilla-mobile/fenix/issues/12802
+    data_reviews:
+      - todo
+    notification_emails:
+      - fenix-core@mozilla.com
+      - perf-android-fe@mozilla.com
+      - mcomella@mozilla.com
+    expires: "2020-12-21"
+  cache_bytes:
+    send_in_pings:
+      - metrics
+    type: memory_distribution
+    description: >
+      The size of all cached data in the app. This is the output of
+      [StorageStats.getCacheBytes](https://developer.android.com/reference/android/app/usage/StorageStats#getCacheBytes())
+      so see that for details. This value is only available on Android 8+.
+    memory_unit: byte
+    bugs:
+      - https://github.com/mozilla-mobile/fenix/issues/12802
+    data_reviews:
+      - todo
+    notification_emails:
+      - fenix-core@mozilla.com
+      - perf-android-fe@mozilla.com
+      - mcomella@mozilla.com
+    expires: "2020-12-21"
+  data_dir_bytes:
+    send_in_pings:
+      - metrics
+    type: memory_distribution
+    description: >
+      The size of all data minus `cache_bytes`. This is the output of
+      [StorageStats.getDataBytes](https://developer.android.com/reference/android/app/usage/StorageStats#getDataBytes())
+      except we subtract the value of `cache_bytes` so the cache is not measured
+      redundantly; see that method for details. This value is only available on
+      Android 8+.
+    memory_unit: byte
+    bugs:
+      - https://github.com/mozilla-mobile/fenix/issues/12802
+    data_reviews:
+      - todo
+    notification_emails:
+      - fenix-core@mozilla.com
+      - perf-android-fe@mozilla.com
+      - mcomella@mozilla.com
+    expires: "2020-12-21"

app/src/main/java/org/mozilla/fenix/FenixApplication.kt

@@ -44,6 +44,7 @@ import org.mozilla.fenix.components.Components
 import org.mozilla.fenix.components.metrics.MetricServiceType
 import org.mozilla.fenix.ext.resetPoliciesAfter
 import org.mozilla.fenix.ext.settings
+import org.mozilla.fenix.perf.StorageStatsMetrics
 import org.mozilla.fenix.perf.StartupTimeline
 import org.mozilla.fenix.push.PushFxaIntegration
 import org.mozilla.fenix.push.WebPushEngineIntegration
@@ -205,12 +206,24 @@ open class FenixApplication : LocaleAwareApplication(), Provider {
             }
         }
 
+        fun queueMetrics() {
+            if (SDK_INT >= Build.VERSION_CODES.O) { // required by StorageStatsMetrics.
+                taskQueue.runIfReadyOrQueue {
+                    // Because it may be slow to capture the storage stats, it might be preferred to
+                    // create a WorkManager task for this metric, however, I ran out of
+                    // implementation time and WorkManager is harder to test.
+                    StorageStatsMetrics.report(this.applicationContext)
+                }
+            }
+        }
+
         initQueue()
 
         // We init these items in the visual completeness queue to avoid them initing in the critical
         // startup path, before the UI finishes drawing (i.e. visual completeness).
         queueInitExperiments()
         queueInitStorageAndServices()
+        queueMetrics()
     }
 
     private fun startMetricsIfEnabled() {

app/src/main/java/org/mozilla/fenix/perf/StorageStatsMetrics.kt

@@ -0,0 +1,66 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.perf
+
+import android.app.usage.StorageStats
+import android.app.usage.StorageStatsManager
+import android.content.Context
+import android.os.Build
+import androidx.annotation.RequiresApi
+import androidx.annotation.VisibleForTesting
+import androidx.annotation.VisibleForTesting.PRIVATE
+import androidx.annotation.WorkerThread
+import androidx.core.content.getSystemService
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.launch
+import org.mozilla.fenix.GleanMetrics.StorageStats as Metrics
+
+/**
+ * A collection of functions related to measuring the [StorageStats] of the application such as data
+ * dir size.
+ *
+ * Unfortunately, this API is only available on API 26+ so the data will only be reported for those
+ * platforms.
+ */
+@RequiresApi(Build.VERSION_CODES.O) // StorageStatsManager
+object StorageStatsMetrics {
+
+    fun report(context: Context) {
+        GlobalScope.launch(Dispatchers.IO) {
+            reportSync(context)
+        }
+    }
+
+    // I couldn't get runBlockingTest to work correctly so I moved the functionality under test to
+    // a synchronous function.
+    @VisibleForTesting(otherwise = PRIVATE)
+    @WorkerThread // queryStatsForUid
+    fun reportSync(context: Context) {
+        // I don't expect this to ever be null so we don't report if so.
+        context.getSystemService<StorageStatsManager>()?.let { storageStatsManager ->
+            val appInfo = context.applicationInfo
+            val storageStats = Metrics.queryStatsDuration.measure {
+                // The docs say queryStatsForPackage may be slower if the app uses
+                // android:sharedUserId so we the suggested alternative.
+                //
+                // The docs say this may be slow:
+                // > This method may take several seconds to complete, so it should only be called
+                // > from a worker thread.
+                //
+                // So we call from a worker thread and measure the duration to make sure it's not
+                // too slow.
+                storageStatsManager.queryStatsForUid(appInfo.storageUuid, appInfo.uid)
+            }
+
+            // dataBytes includes the cache so we subtract it.
+            val justDataDirBytes = storageStats.dataBytes - storageStats.cacheBytes
+
+            Metrics.dataDirBytes.accumulate(justDataDirBytes)
+            Metrics.appBytes.accumulate(storageStats.appBytes)
+            Metrics.cacheBytes.accumulate(storageStats.cacheBytes)
+        }
+    }
+}

app/src/test/java/org/mozilla/fenix/perf/StorageStatsMetricsTest.kt

@@ -0,0 +1,61 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.perf
+
+import android.app.usage.StorageStats
+import android.app.usage.StorageStatsManager
+import android.content.Context
+import androidx.core.content.getSystemService
+import io.mockk.MockKAnnotations
+import io.mockk.every
+import io.mockk.impl.annotations.RelaxedMockK
+import mozilla.components.service.glean.testing.GleanTestRule
+import mozilla.components.support.test.robolectric.testContext
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mozilla.fenix.helpers.FenixRobolectricTestRunner
+import org.mozilla.fenix.GleanMetrics.StorageStats as Metrics
+
+@RunWith(FenixRobolectricTestRunner::class) // gleanTestRule
+class StorageStatsMetricsTest {
+
+    @get:Rule
+    val gleanTestRule = GleanTestRule(testContext)
+
+    @RelaxedMockK private lateinit var mockContext: Context
+    @RelaxedMockK private lateinit var storageStats: StorageStats
+
+    @Before
+    fun setUp() {
+        MockKAnnotations.init(this)
+
+        every {
+            mockContext.getSystemService<StorageStatsManager>()?.queryStatsForUid(any(), any())
+        } returns storageStats
+    }
+
+    @Test
+    fun `WHEN reporting THEN the values from the storageStats are accumulated`() {
+        every { storageStats.appBytes } returns 100
+        every { storageStats.cacheBytes } returns 200
+        every { storageStats.dataBytes } returns 1000
+
+        StorageStatsMetrics.reportSync(mockContext)
+
+        assertEquals(100, Metrics.appBytes.testGetValue().sum)
+        assertEquals(200, Metrics.cacheBytes.testGetValue().sum)
+        assertEquals(800, Metrics.dataDirBytes.testGetValue().sum)
+    }
+
+    @Test
+    fun `WHEN reporting THEN the query duration is measured`() {
+        StorageStatsMetrics.reportSync(mockContext)
+        assertTrue(Metrics.queryStatsDuration.testHasValue())
+    }
+}