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| 1 | +/* |
| 2 | + * Copyright 2026 Google LLC |
| 3 | + * |
| 4 | + * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | + * you may not use this file except in compliance with the License. |
| 6 | + * You may obtain a copy of the License at |
| 7 | + * |
| 8 | + * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | + * |
| 10 | + * Unless required by applicable law or agreed to in writing, software |
| 11 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | + * See the License for the specific language governing permissions and |
| 14 | + * limitations under the License. |
| 15 | + */ |
| 16 | + |
| 17 | +package com.google.firebase.heartbeatinfo |
| 18 | + |
| 19 | +import androidx.datastore.preferences.core.MutablePreferences |
| 20 | +import androidx.datastore.preferences.core.Preferences |
| 21 | +import androidx.datastore.preferences.core.stringPreferencesKey |
| 22 | +import androidx.test.ext.junit.runners.AndroidJUnit4 |
| 23 | +import com.google.common.truth.Truth.assertThat |
| 24 | +import com.google.firebase.datastorage.JavaDataStorage |
| 25 | +import java.util.Collections |
| 26 | +import java.util.concurrent.CompletableFuture |
| 27 | +import org.junit.Test |
| 28 | +import org.junit.runner.RunWith |
| 29 | +import org.mockito.ArgumentMatchers.any |
| 30 | +import org.mockito.Mockito.doAnswer |
| 31 | +import org.mockito.Mockito.mock |
| 32 | +import org.mockito.Mockito.`when` |
| 33 | + |
| 34 | +@RunWith(AndroidJUnit4::class) |
| 35 | +class HeartBeatInfoStorageKotlinTest { |
| 36 | + |
| 37 | + /** |
| 38 | + * Regression test for https://github.com/firebase/firebase-android-sdk/issues/8016 |
| 39 | + * |
| 40 | + * <p>Root Cause: The synchronized storeHeartBeat() method locks the HeartBeatInfoStorage instance |
| 41 | + * while waiting for JavaDataStorage.editSync(...) to complete. However, editSync schedules its |
| 42 | + * preference updates on a different background thread. If helper methods called inside the |
| 43 | + * editSync transaction block (such as getStoredUserAgentString, updateStoredUserAgent, or |
| 44 | + * cleanUpStoredHeartBeats) are also marked as synchronized, the background thread blocks trying |
| 45 | + * to acquire the HeartBeatInfoStorage lock, which is held by the caller thread waiting for the |
| 46 | + * background thread to complete, causing a permanent deadlock. |
| 47 | + * |
| 48 | + * <p>Fix: Removed the synchronized keyword from helper methods (and isSameDateUtc) since they |
| 49 | + * operate exclusively on thread-local transaction parameters and do not access shared mutable |
| 50 | + * instance state. |
| 51 | + */ |
| 52 | + @Test |
| 53 | + fun storeHeartBeat_whenCalledOnSeparateThread_doesNotDeadlock() { |
| 54 | + val mockDataStore = mock(JavaDataStorage::class.java) |
| 55 | + val heartBeatStorageWithMock = HeartBeatInfoStorage(mockDataStore) |
| 56 | + |
| 57 | + // Mock editSync to run the transform on a background thread and block the caller thread |
| 58 | + doAnswer { invocation -> |
| 59 | + @Suppress("UNCHECKED_CAST") |
| 60 | + val transform = invocation.getArgument<(MutablePreferences) -> Unit>(0) |
| 61 | + |
| 62 | + val future = |
| 63 | + CompletableFuture.runAsync { |
| 64 | + val mockPrefs = mock(MutablePreferences::class.java) |
| 65 | + // Mock get(LAST_STORED_DATE) to return the target date to force entry into the if block |
| 66 | + `when`(mockPrefs.get(stringPreferencesKey("last-used-date"))).thenReturn("1970-01-01") |
| 67 | + // Mock asMap() to avoid NullPointerException |
| 68 | + `when`(mockPrefs.asMap()).thenReturn(Collections.emptyMap()) |
| 69 | + |
| 70 | + transform(mockPrefs) |
| 71 | + } |
| 72 | + |
| 73 | + future.get() // Blocks the caller thread |
| 74 | + mock(Preferences::class.java) |
| 75 | + } |
| 76 | + .`when`(mockDataStore) |
| 77 | + .editSync(anyTransform()) |
| 78 | + |
| 79 | + // Spawn a thread to call storeHeartBeat, which would deadlock under the bug |
| 80 | + val thread = Thread { |
| 81 | + heartBeatStorageWithMock.storeHeartBeat(0L, "test-agent") // 1970-01-01 |
| 82 | + } |
| 83 | + |
| 84 | + thread.start() |
| 85 | + thread.join(3000) // Wait 3 seconds |
| 86 | + |
| 87 | + try { |
| 88 | + // Since the bug is fixed, the thread should not be alive. |
| 89 | + assertThat(thread.isAlive).isFalse() |
| 90 | + } finally { |
| 91 | + thread.interrupt() |
| 92 | + } |
| 93 | + } |
| 94 | + |
| 95 | + private fun anyTransform(): (MutablePreferences) -> Unit { |
| 96 | + any<kotlin.jvm.functions.Function1<MutablePreferences, kotlin.Unit>>() |
| 97 | + return { _: MutablePreferences -> } |
| 98 | + } |
| 99 | +} |
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