Bug 1768101 - Add process priority test for Android. r=calu

Adding some smoke tests so that we don't regress this feature, additional tests
for fission and for a currently broken case will be addressed later.

Differential Revision: https://phabricator.services.mozilla.com/D145476

mobile/android/geckoview/src/androidTest/java/org/mozilla/geckoview/test/GeckoViewTest.kt

@@ -5,27 +5,26 @@ import androidx.test.ext.junit.runners.AndroidJUnit4
 import androidx.core.view.ViewCompat
 import androidx.test.ext.junit.rules.ActivityScenarioRule
 
-import org.hamcrest.MatcherAssert.assertThat
 import org.hamcrest.Matchers.equalTo
+import org.junit.*
+import org.junit.Assume.assumeThat
 
-import org.junit.After
-import org.junit.Before
-import org.junit.Rule
-import org.junit.Test
 import org.junit.rules.RuleChain
 import org.junit.runner.RunWith
+import org.mozilla.geckoview.Autofill
 
 import org.mozilla.geckoview.GeckoSession
-import org.mozilla.geckoview.test.rule.GeckoSessionTestRule
+import org.mozilla.geckoview.test.rule.GeckoSessionTestRule.NullDelegate
+import org.mozilla.geckoview.test.util.UiThreadUtils
+import java.io.File
 
 @RunWith(AndroidJUnit4::class)
 @LargeTest
-class GeckoViewTest {
+class GeckoViewTest : BaseSessionTest() {
     val activityRule = ActivityScenarioRule(GeckoViewTestActivity::class.java)
-    var sessionRule = GeckoSessionTestRule()
 
     @get:Rule
-    val rules = RuleChain.outerRule(activityRule).around(sessionRule)
+    override val rules = RuleChain.outerRule(activityRule).around(sessionRule)
 
     @Before
     fun setup() {
@@ -78,4 +77,132 @@ class GeckoViewTest {
             it.view.session!!.releaseDisplay(it.view.session!!.acquireDisplay())
         }
     }
+
+    private fun waitUntilContentProcessPriority(high: List<GeckoSession>, low: List<GeckoSession>) {
+        val highPids = high.map { sessionRule.getSessionPid(it) }.toSet()
+        val lowPids = low.map { sessionRule.getSessionPid(it) }.toSet()
+
+        UiThreadUtils.waitForCondition({
+            getContentProcessesPriority(highPids).count { it > 100 } == 0
+                    && getContentProcessesPriority(lowPids).count { it < 300 } == 0
+        }, env.defaultTimeoutMillis)
+    }
+
+    fun getContentProcessesPriority(pids: Collection<Int>) : List<Int> {
+        return pids.map { pid ->
+            File("/proc/$pid/oom_score").readText(Charsets.UTF_8).trim().toInt()
+        }
+    }
+
+    fun setupPriorityTest(): GeckoSession {
+        // This makes the test a little bit faster
+        sessionRule.setPrefsUntilTestEnd(mapOf(
+            "dom.ipc.processPriorityManager.backgroundGracePeriodMS" to 0,
+            "dom.ipc.processPriorityManager.backgroundPerceivableGracePeriodMS" to 0,
+        ))
+
+        val otherSession = sessionRule.createOpenSession()
+        // The process manager sets newly created processes to FOREGROUND priority until they
+        // are de-prioritized, so we need to activate and deactivate the session to trigger
+        // a setPriority call.
+        otherSession.setActive(true)
+        otherSession.setActive(false)
+
+        // Need a dummy page to be able to get the PID from the session
+        otherSession.loadUri("https://example.com")
+        otherSession.waitForPageStop()
+
+        mainSession.loadTestPath(HELLO_HTML_PATH)
+        mainSession.waitForPageStop()
+
+        waitUntilContentProcessPriority(
+            high = listOf(mainSession), low = listOf(otherSession)
+        )
+
+        return otherSession
+    }
+
+    @Test
+    @NullDelegate(Autofill.Delegate::class)
+    fun setTabActiveKeepsTabAtHighPriority() {
+        // Bug 1768102 - Doesn't seem to work on Fission
+        assumeThat(env.isFission || env.isIsolatedProcess, equalTo(false))
+        activityRule.scenario.onActivity {
+            val otherSession = setupPriorityTest()
+
+            // A tab with priority hint does not get de-prioritized even when
+            // the surface is destroyed
+            sessionRule.runtime.webExtensionController.setTabActive(mainSession, true)
+
+            // This will destroy mainSession's surface and create a surface for otherSession
+            it.view.setSession(otherSession)
+
+            waitUntilContentProcessPriority(high = listOf(mainSession, otherSession), low = listOf())
+
+            // Destroying otherSession's surface should leave mainSession as the sole high priority
+            // tab
+            it.view.releaseSession()
+
+            waitUntilContentProcessPriority(high = listOf(mainSession), low = listOf())
+
+            // Cleanup
+            sessionRule.runtime.webExtensionController.setTabActive(mainSession, false)
+        }
+    }
+
+    @Test
+    @NullDelegate(Autofill.Delegate::class)
+    fun extensionCurrentTabRaisesPriority() {
+        // Bug 1767346
+        assumeThat(false, equalTo(true))
+
+        val otherSession = setupPriorityTest()
+
+        // Setting tab active raises priority
+        sessionRule.runtime.webExtensionController.setTabActive(otherSession, true)
+
+        waitUntilContentProcessPriority(
+            high = listOf(mainSession, otherSession), low = listOf()
+        )
+
+        // Unsetting the tab as active should lower priority
+        sessionRule.runtime.webExtensionController.setTabActive(otherSession, false)
+
+        waitUntilContentProcessPriority(
+            high = listOf(mainSession), low = listOf(otherSession)
+        )
+    }
+
+    @Test
+    @NullDelegate(Autofill.Delegate::class)
+    fun processPriorityTest() {
+        // Doesn't seem to work on Fission
+        assumeThat(env.isFission || env.isIsolatedProcess, equalTo(false))
+        activityRule.scenario.onActivity {
+            val otherSession = setupPriorityTest()
+
+            // After setting otherSession to the view, otherSession should be high priority
+            // and mainSession should be de-prioritized
+            it.view.setSession(otherSession)
+
+            waitUntilContentProcessPriority(
+                high = listOf(otherSession), low = listOf(mainSession))
+
+            // After releasing otherSession, both sessions should be low priority
+            it.view.releaseSession()
+
+            waitUntilContentProcessPriority(
+                high = listOf(), low = listOf(mainSession, otherSession))
+
+            // Test that re-setting mainSession in the view raises the priority again
+            it.view.setSession(mainSession)
+            waitUntilContentProcessPriority(
+                high = listOf(mainSession), low = listOf(otherSession))
+
+            // Setting the session to active should also raise priority
+            otherSession.setActive(true)
+            waitUntilContentProcessPriority(
+                high = listOf(mainSession, otherSession), low = listOf())
+        }
+    }
 }