From 8dca8b719f634d06c86628f154b2ff45d1bd6c79 Mon Sep 17 00:00:00 2001
From: Levi Bostian <levi@customer.io>
Date: Wed, 8 Jun 2022 16:28:31 -0500
Subject: [PATCH] feat: delete expired background queue tasks

---
 .../base/extenstions/DateExtensions.kt        |   5 +
 .../base/extensions/DateExtensionsTest.kt     |  13 ++
 .../java/io/customer/common_test/BaseTest.kt  |  17 +-
 .../io/customer/common_test/DateUtilStub.kt   |  10 +-
 .../util/DispatchersProviderStub.kt           |  29 ++++
 .../run Android tests.run.xml                 |   6 +-
 .../main/java/io/customer/sdk/CustomerIO.kt   |  20 ++-
 .../java/io/customer/sdk/CustomerIOConfig.kt  |   5 +
 .../io/customer/sdk/di/CustomerIOComponent.kt |  17 +-
 .../main/java/io/customer/sdk/di/DiGraph.kt   |  31 ++++
 .../main/java/io/customer/sdk/queue/Queue.kt  |  15 +-
 .../io/customer/sdk/queue/QueueStorage.kt     | 147 +++++++++++-------
 .../sdk/repository/CleanupRepository.kt       |  19 +++
 .../customer/sdk/util/DispatchersProvider.kt  |  18 +++
 .../main/java/io/customer/sdk/util/Seconds.kt |   7 +-
 .../java/io/customer/sdk/util/SimpleTimer.kt  |   7 +-
 .../java/io/customer/sdk/util/Singleton.kt    |  28 ----
 .../java/io/customer/sdk/CustomerIOTest.kt    |  20 +++
 .../sdk/queue/QueueIntegrationTests.kt        |   1 +
 .../sdk/queue/QueueStorageIntegrationTest.kt  |  53 ++++++-
 .../java/io/customer/sdk/queue/QueueTest.kt   |   2 +-
 .../java/io/customer/sdk/util/SecondsTest.kt  |  10 ++
 22 files changed, 363 insertions(+), 117 deletions(-)
 create mode 100644 common-test/src/main/java/io/customer/common_test/util/DispatchersProviderStub.kt
 create mode 100644 sdk/src/main/java/io/customer/sdk/repository/CleanupRepository.kt
 create mode 100644 sdk/src/main/java/io/customer/sdk/util/DispatchersProvider.kt
 delete mode 100644 sdk/src/main/java/io/customer/sdk/util/Singleton.kt

diff --git a/base/src/main/java/io/customer/base/extenstions/DateExtensions.kt b/base/src/main/java/io/customer/base/extenstions/DateExtensions.kt
index 6904e4428..8f1aa1d73 100644
--- a/base/src/main/java/io/customer/base/extenstions/DateExtensions.kt
+++ b/base/src/main/java/io/customer/base/extenstions/DateExtensions.kt
@@ -18,6 +18,7 @@ fun Date.add(unit: Long, type: TimeUnit): Date {
     return Date(this.time + type.toMillis(unit))
 }
 
+fun Date.subtract(unit: Double, type: TimeUnit): Date = this.subtract(unit.toLong(), type)
 fun Date.subtract(unit: Int, type: TimeUnit): Date = this.subtract(unit.toLong(), type)
 fun Date.subtract(unit: Long, type: TimeUnit): Date {
     return Date(this.time - type.toMillis(unit))
@@ -26,3 +27,7 @@ fun Date.subtract(unit: Long, type: TimeUnit): Date {
 fun Date.hasPassed(): Boolean {
     return this.time < Date().time
 }
+
+fun Date.isOlderThan(otherDate: Date): Boolean {
+    return this.time < otherDate.time
+}
diff --git a/base/src/test/java/io/customer/base/extensions/DateExtensionsTest.kt b/base/src/test/java/io/customer/base/extensions/DateExtensionsTest.kt
index 142f957b3..3dc653678 100644
--- a/base/src/test/java/io/customer/base/extensions/DateExtensionsTest.kt
+++ b/base/src/test/java/io/customer/base/extensions/DateExtensionsTest.kt
@@ -3,9 +3,12 @@ package io.customer.base.extensions
 import io.customer.base.extenstions.add
 import io.customer.base.extenstions.getUnixTimestamp
 import io.customer.base.extenstions.hasPassed
+import io.customer.base.extenstions.isOlderThan
 import io.customer.base.extenstions.subtract
 import io.customer.base.extenstions.unixTimeToDate
 import org.amshove.kluent.shouldBeEqualTo
+import org.amshove.kluent.shouldBeFalse
+import org.amshove.kluent.shouldBeTrue
 import org.junit.Test
 import java.text.SimpleDateFormat
 import java.util.*
@@ -61,4 +64,14 @@ class DateExtensionsTest {
     fun hasPassed_givenDateInFuture_expectFalse() {
         Date().add(1, TimeUnit.MINUTES).hasPassed() shouldBeEqualTo false
     }
+
+    @Test
+    fun isOlderThan_givenDateThatIsOlder_expectTrue() {
+        Date().subtract(2, TimeUnit.DAYS).isOlderThan(Date().subtract(1, TimeUnit.DAYS)).shouldBeTrue()
+    }
+
+    @Test
+    fun isOlderThan_givenDateThatIsNewer_expectFalse() {
+        Date().subtract(1, TimeUnit.DAYS).isOlderThan(Date().subtract(2, TimeUnit.DAYS)).shouldBeFalse()
+    }
 }
diff --git a/common-test/src/main/java/io/customer/common_test/BaseTest.kt b/common-test/src/main/java/io/customer/common_test/BaseTest.kt
index 6fc85e46a..e372d141e 100644
--- a/common-test/src/main/java/io/customer/common_test/BaseTest.kt
+++ b/common-test/src/main/java/io/customer/common_test/BaseTest.kt
@@ -4,14 +4,16 @@ import android.app.Application
 import android.content.Context
 import androidx.test.core.app.ApplicationProvider
 import androidx.test.platform.app.InstrumentationRegistry
+import io.customer.common_test.util.DispatchersProviderStub
 import io.customer.sdk.CustomerIOConfig
 import io.customer.sdk.data.model.Region
 import io.customer.sdk.data.store.DeviceStore
 import io.customer.sdk.di.CustomerIOComponent
 import io.customer.sdk.util.CioLogLevel
 import io.customer.sdk.util.DateUtil
+import io.customer.sdk.util.DispatchersProvider
 import io.customer.sdk.util.JsonAdapter
-import kotlinx.coroutines.test.TestCoroutineDispatcher
+import io.customer.sdk.util.Seconds
 import okhttp3.ResponseBody.Companion.toResponseBody
 import okhttp3.mockwebserver.MockWebServer
 import org.junit.After
@@ -36,9 +38,7 @@ abstract class BaseTest {
     protected lateinit var cioConfig: CustomerIOConfig
 
     protected val deviceStore: DeviceStore = DeviceStoreStub().deviceStore
-
-    // when you need a CoroutineDispatcher in a test function, use this as it runs your tests synchronous.
-    protected val testDispatcher = TestCoroutineDispatcher()
+    protected lateinit var dispatchersProviderStub: DispatchersProviderStub
 
     protected lateinit var di: CustomerIOComponent
     protected val jsonAdapter: JsonAdapter
@@ -53,13 +53,16 @@ abstract class BaseTest {
 
     @Before
     open fun setup() {
-        cioConfig = CustomerIOConfig(siteId, "xyz", Region.EU, 100, null, true, true, 10, 30.0, CioLogLevel.DEBUG, null)
+        cioConfig = CustomerIOConfig(siteId, "xyz", Region.EU, 100, null, true, true, 10, 30.0, Seconds.fromDays(3).value, CioLogLevel.DEBUG, null)
 
         // Initialize the mock web server before constructing DI graph as dependencies may require information such as hostname.
         mockWebServer = MockWebServer().apply {
             start()
         }
         cioConfig.trackingApiUrl = mockWebServer.url("/").toString()
+        if (!cioConfig.trackingApiUrl!!.contains("localhost")) {
+            throw RuntimeException("server didnt' start ${cioConfig.trackingApiUrl}")
+        }
 
         di = CustomerIOComponent(
             sdkConfig = cioConfig,
@@ -71,10 +74,14 @@ abstract class BaseTest {
         dateUtilStub = DateUtilStub().also {
             di.overrideDependency(DateUtil::class.java, it)
         }
+        dispatchersProviderStub = DispatchersProviderStub().also {
+            di.overrideDependency(DispatchersProvider::class.java, it)
+        }
     }
 
     @After
     open fun teardown() {
         mockWebServer.shutdown()
+        di.reset()
     }
 }
diff --git a/common-test/src/main/java/io/customer/common_test/DateUtilStub.kt b/common-test/src/main/java/io/customer/common_test/DateUtilStub.kt
index 63d098339..4fc2d0adc 100644
--- a/common-test/src/main/java/io/customer/common_test/DateUtilStub.kt
+++ b/common-test/src/main/java/io/customer/common_test/DateUtilStub.kt
@@ -1,6 +1,6 @@
 package io.customer.common_test
 
-import io.customer.base.extenstions.unixTimeToDate
+import io.customer.base.extenstions.getUnixTimestamp
 import io.customer.sdk.util.DateUtil
 import java.util.*
 
@@ -8,15 +8,13 @@ import java.util.*
  * Convenient alternative to mocking [DateUtil] in your test since the code is boilerplate.
  */
 class DateUtilStub : DateUtil {
-    // modify this value in your test class if you need to.
-    var givenDateMillis = 1646238885L
 
-    val givenDate: Date
-        get() = givenDateMillis.unixTimeToDate()
+    // modify this value in your test class if you need to.
+    var givenDate: Date = Date(1646238885L)
 
     override val now: Date
         get() = givenDate
 
     override val nowUnixTimestamp: Long
-        get() = givenDateMillis
+        get() = now.getUnixTimestamp()
 }
diff --git a/common-test/src/main/java/io/customer/common_test/util/DispatchersProviderStub.kt b/common-test/src/main/java/io/customer/common_test/util/DispatchersProviderStub.kt
new file mode 100644
index 000000000..e1c36bbd8
--- /dev/null
+++ b/common-test/src/main/java/io/customer/common_test/util/DispatchersProviderStub.kt
@@ -0,0 +1,29 @@
+package io.customer.common_test.util
+
+import io.customer.sdk.util.DispatchersProvider
+import io.customer.sdk.util.SdkDispatchers
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.TestCoroutineDispatcher
+
+class DispatchersProviderStub : DispatchersProvider {
+    private var overrideBackground: CoroutineDispatcher? = null
+    private var overrideMain: CoroutineDispatcher? = null
+
+    // If your test function requires real dispatchers to be used, call this function.
+    // the default behavior is test dispatchers because they are fast and synchronous for more predictable test execution.
+    fun setRealDispatchers() {
+        SdkDispatchers().also {
+            overrideBackground = it.background
+            overrideMain = it.main
+        }
+    }
+
+    @OptIn(ExperimentalCoroutinesApi::class)
+    override val background: CoroutineDispatcher
+        get() = overrideBackground ?: TestCoroutineDispatcher()
+
+    @OptIn(ExperimentalCoroutinesApi::class)
+    override val main: CoroutineDispatcher
+        get() = overrideMain ?: TestCoroutineDispatcher()
+}
diff --git a/scripts/androidStudioRunConfigurations/run Android tests.run.xml b/scripts/androidStudioRunConfigurations/run Android tests.run.xml
index 7b25fe0c7..0afa837bf 100644
--- a/scripts/androidStudioRunConfigurations/run Android tests.run.xml	
+++ b/scripts/androidStudioRunConfigurations/run Android tests.run.xml	
@@ -1,5 +1,5 @@
 <component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="run Android tests" type="AndroidTestRunConfigurationType" factoryName="Android Instrumented Tests">
+  <configuration default="false" name="run Android tests" type="AndroidTestRunConfigurationType" factoryName="Android Instrumented Tests" singleton="true">
     <module name="Customer.io_SDK.sdk" />
     <option name="TESTING_TYPE" value="1" />
     <option name="METHOD_NAME" value="" />
@@ -11,9 +11,9 @@
     <option name="RETENTION_ENABLED" value="No" />
     <option name="RETENTION_MAX_SNAPSHOTS" value="2" />
     <option name="RETENTION_COMPRESS_SNAPSHOTS" value="false" />
-    <option name="CLEAR_LOGCAT" value="false" />
+    <option name="CLEAR_LOGCAT" value="true" />
     <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
-    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
+    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="false" />
     <option name="FORCE_STOP_RUNNING_APP" value="true" />
     <option name="INSPECTION_WITHOUT_ACTIVITY_RESTART" value="false" />
     <option name="TARGET_SELECTION_MODE" value="DEVICE_AND_SNAPSHOT_COMBO_BOX" />
diff --git a/sdk/src/main/java/io/customer/sdk/CustomerIO.kt b/sdk/src/main/java/io/customer/sdk/CustomerIO.kt
index e9c7f3824..df5a869c0 100644
--- a/sdk/src/main/java/io/customer/sdk/CustomerIO.kt
+++ b/sdk/src/main/java/io/customer/sdk/CustomerIO.kt
@@ -8,11 +8,15 @@ import io.customer.sdk.data.communication.CustomerIOUrlHandler
 import io.customer.sdk.data.model.Region
 import io.customer.sdk.data.request.MetricEvent
 import io.customer.sdk.di.CustomerIOComponent
+import io.customer.sdk.repository.CleanupRepository
 import io.customer.sdk.extensions.getScreenNameFromActivity
 import io.customer.sdk.repository.DeviceRepository
 import io.customer.sdk.repository.ProfileRepository
 import io.customer.sdk.repository.TrackRepository
 import io.customer.sdk.util.CioLogLevel
+import io.customer.sdk.util.Seconds
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.launch
 
 /**
  * Allows mocking of [CustomerIO] for your automated tests in your project. Mock [CustomerIO] to assert your code is calling functions
@@ -105,6 +109,7 @@ class CustomerIO internal constructor(
         private var autoTrackDeviceAttributes: Boolean = true
         private var modules: MutableMap<String, CustomerIOModule> = mutableMapOf()
         private var logLevel = CioLogLevel.ERROR
+        internal var overrideDiGraph: CustomerIOComponent? = null // set for automated tests
         private var trackingApiUrl: String? = null
 
         private lateinit var activityLifecycleCallback: CustomerIOActivityLifecycleCallbacks
@@ -178,11 +183,12 @@ class CustomerIO internal constructor(
                 autoTrackDeviceAttributes = autoTrackDeviceAttributes,
                 backgroundQueueMinNumberOfTasks = 10,
                 backgroundQueueSecondsDelay = 30.0,
+                backgroundQueueTaskExpiredSeconds = Seconds.fromDays(3).value,
                 logLevel = logLevel,
                 trackingApiUrl = trackingApiUrl
             )
 
-            val diGraph = CustomerIOComponent(sdkConfig = config, context = appContext)
+            val diGraph = overrideDiGraph ?: CustomerIOComponent(sdkConfig = config, context = appContext)
             val client = CustomerIO(diGraph)
             val logger = diGraph.logger
 
@@ -196,6 +202,8 @@ class CustomerIO internal constructor(
                 it.value.initialize()
             }
 
+            client.postInitialize()
+
             return client
         }
     }
@@ -215,6 +223,16 @@ class CustomerIO internal constructor(
     override val sdkVersion: String
         get() = Version.version
 
+    private val cleanupRepository: CleanupRepository
+        get() = diGraph.cleanupRepository
+
+    private fun postInitialize() {
+        // run cleanup asynchronously in background to prevent taking up the main/UI thread
+        CoroutineScope(diGraph.dispatchersProvider.background).launch {
+            cleanupRepository.cleanup()
+        }
+    }
+
     /**
      * Identify a customer (aka: Add or update a profile).
      * [Learn more](https://customer.io/docs/identifying-people/) about identifying a customer in Customer.io
diff --git a/sdk/src/main/java/io/customer/sdk/CustomerIOConfig.kt b/sdk/src/main/java/io/customer/sdk/CustomerIOConfig.kt
index 7270ac03c..762571847 100644
--- a/sdk/src/main/java/io/customer/sdk/CustomerIOConfig.kt
+++ b/sdk/src/main/java/io/customer/sdk/CustomerIOConfig.kt
@@ -24,6 +24,11 @@ data class CustomerIOConfig(
      */
 
     val backgroundQueueSecondsDelay: Double,
+    /**
+     * The number of seconds old a queue task is when it is "expired" and should be deleted.
+     * We do not recommend modifying this value because it risks losing data or taking up too much space on the user's device.
+     */
+    val backgroundQueueTaskExpiredSeconds: Double,
     val logLevel: CioLogLevel,
     var trackingApiUrl: String?,
 ) {
diff --git a/sdk/src/main/java/io/customer/sdk/di/CustomerIOComponent.kt b/sdk/src/main/java/io/customer/sdk/di/CustomerIOComponent.kt
index f2e29b9de..1e0d1835a 100644
--- a/sdk/src/main/java/io/customer/sdk/di/CustomerIOComponent.kt
+++ b/sdk/src/main/java/io/customer/sdk/di/CustomerIOComponent.kt
@@ -30,11 +30,12 @@ import io.customer.sdk.repository.*
 import io.customer.sdk.util.AndroidSimpleTimer
 import io.customer.sdk.util.DateUtil
 import io.customer.sdk.util.DateUtilImpl
+import io.customer.sdk.util.DispatchersProvider
 import io.customer.sdk.util.JsonAdapter
 import io.customer.sdk.util.LogcatLogger
 import io.customer.sdk.util.Logger
+import io.customer.sdk.util.SdkDispatchers
 import io.customer.sdk.util.SimpleTimer
-import kotlinx.coroutines.Dispatchers
 import okhttp3.OkHttpClient
 import okhttp3.logging.HttpLoggingInterceptor
 import retrofit2.Retrofit
@@ -56,16 +57,22 @@ class CustomerIOComponent(
         get() = override() ?: JsonAdapter(moshi)
 
     val queueStorage: QueueStorage
-        get() = override() ?: QueueStorageImpl(sdkConfig, fileStorage, jsonAdapter, logger)
+        get() = override() ?: QueueStorageImpl(sdkConfig, fileStorage, jsonAdapter, dateUtil, logger)
 
     val queueRunner: QueueRunner
         get() = override() ?: QueueRunnerImpl(jsonAdapter, cioHttpClient, logger)
 
+    val dispatchersProvider: DispatchersProvider
+        get() = override() ?: SdkDispatchers()
+
     val queue: Queue
-        get() = override() ?: QueueImpl.getInstanceOrCreate {
-            QueueImpl(dispatcher = Dispatchers.IO, queueStorage, queueRunRequest, jsonAdapter, sdkConfig, timer, logger, dateUtil)
+        get() = override() ?: getSingletonInstanceCreate {
+            QueueImpl(dispatchersProvider, queueStorage, queueRunRequest, jsonAdapter, sdkConfig, timer, logger, dateUtil)
         }
 
+    internal val cleanupRepository: CleanupRepository
+        get() = override() ?: CleanupRepositoryImpl(queue)
+
     val queueQueryRunner: QueueQueryRunner
         get() = override() ?: QueueQueryRunnerImpl(logger)
 
@@ -88,7 +95,7 @@ class CustomerIOComponent(
         get() = override() ?: DateUtilImpl()
 
     val timer: SimpleTimer
-        get() = override() ?: AndroidSimpleTimer(logger, uiDispatcher = Dispatchers.Main)
+        get() = override() ?: AndroidSimpleTimer(logger, dispatchersProvider)
 
     val trackRepository: TrackRepository
         get() = override() ?: TrackRepositoryImpl(sharedPreferenceRepository, queue, logger)
diff --git a/sdk/src/main/java/io/customer/sdk/di/DiGraph.kt b/sdk/src/main/java/io/customer/sdk/di/DiGraph.kt
index 5a17008a3..d2948510b 100644
--- a/sdk/src/main/java/io/customer/sdk/di/DiGraph.kt
+++ b/sdk/src/main/java/io/customer/sdk/di/DiGraph.kt
@@ -27,4 +27,35 @@ abstract class DiGraph {
      * Or you may not be able to successfully mock in test functions.
      */
     inline fun <reified DEP> override(): DEP? = overrides[DEP::class.java.simpleName] as? DEP
+
+    /**
+     * We prefer to have all of the SDK's singleton instances held in the dependency injection graph. This makes it easier for automated tests to be able to delete all
+     * singletons between each test function and prevent test flakiness.
+     */
+    val singletons: MutableMap<String, Any> = mutableMapOf()
+
+    /**
+     * In the graph, if you have any dependency that should be a singleton:
+     * ```
+     * val queue: Queue
+     *   get() = override() ?: getSingletonInstanceCreate {
+     *     QueueImpl(...)
+     *   }
+     * ```
+     */
+    inline fun <reified INST : Any> getSingletonInstanceCreate(newInstanceCreator: () -> INST): INST {
+        val singletonKey = INST::class.java.simpleName
+
+        return singletons[singletonKey] as? INST ?: newInstanceCreator().also {
+            singletons[singletonKey] = it
+        }
+    }
+
+    /**
+     * Call to delete instances held by the graph. This is meant to be called in between automated tests but can also be called to reset that state of the SDK at runtime.
+     */
+    fun reset() {
+        overrides.clear()
+        singletons.clear()
+    }
 }
diff --git a/sdk/src/main/java/io/customer/sdk/queue/Queue.kt b/sdk/src/main/java/io/customer/sdk/queue/Queue.kt
index 1cc9e9a44..15d07569c 100644
--- a/sdk/src/main/java/io/customer/sdk/queue/Queue.kt
+++ b/sdk/src/main/java/io/customer/sdk/queue/Queue.kt
@@ -16,12 +16,11 @@ import io.customer.sdk.queue.type.QueueStatus
 import io.customer.sdk.queue.type.QueueTaskGroup
 import io.customer.sdk.queue.type.QueueTaskType
 import io.customer.sdk.util.DateUtil
+import io.customer.sdk.util.DispatchersProvider
 import io.customer.sdk.util.JsonAdapter
 import io.customer.sdk.util.Logger
 import io.customer.sdk.util.Seconds
 import io.customer.sdk.util.SimpleTimer
-import io.customer.sdk.util.Singleton
-import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.launch
 
@@ -40,10 +39,12 @@ interface Queue {
     ): QueueModifyResult
 
     suspend fun run()
+
+    fun deleteExpiredTasks()
 }
 
 class QueueImpl internal constructor(
-    private val dispatcher: CoroutineDispatcher,
+    private val dispatchersProvider: DispatchersProvider,
     private val storage: QueueStorage,
     private val runRequest: QueueRunRequest,
     private val jsonAdapter: JsonAdapter,
@@ -53,8 +54,6 @@ class QueueImpl internal constructor(
     private val dateUtil: DateUtil
 ) : Queue {
 
-    companion object SingletonHolder : Singleton<Queue>()
-
     private val numberSecondsToScheduleTimer: Seconds
         get() = Seconds(sdkConfig.backgroundQueueSecondsDelay)
 
@@ -106,7 +105,7 @@ class QueueImpl internal constructor(
     }
 
     internal fun runAsync() {
-        CoroutineScope(dispatcher).launch {
+        CoroutineScope(dispatchersProvider.background).launch {
             run()
         }
     }
@@ -211,4 +210,8 @@ class QueueImpl internal constructor(
             blockingGroups = blockingGroups
         )
     }
+
+    override fun deleteExpiredTasks() {
+        storage.deleteExpired()
+    }
 }
diff --git a/sdk/src/main/java/io/customer/sdk/queue/QueueStorage.kt b/sdk/src/main/java/io/customer/sdk/queue/QueueStorage.kt
index daf1e402c..8dfdf108c 100644
--- a/sdk/src/main/java/io/customer/sdk/queue/QueueStorage.kt
+++ b/sdk/src/main/java/io/customer/sdk/queue/QueueStorage.kt
@@ -1,5 +1,7 @@
 package io.customer.sdk.queue
 
+import io.customer.base.extenstions.isOlderThan
+import io.customer.base.extenstions.subtract
 import io.customer.sdk.CustomerIOConfig
 import io.customer.sdk.data.store.FileStorage
 import io.customer.sdk.data.store.FileType
@@ -10,9 +12,12 @@ import io.customer.sdk.queue.type.QueueTask
 import io.customer.sdk.queue.type.QueueTaskGroup
 import io.customer.sdk.queue.type.QueueTaskMetadata
 import io.customer.sdk.queue.type.QueueTaskRunResults
+import io.customer.sdk.util.DateUtil
 import io.customer.sdk.util.JsonAdapter
+import io.customer.sdk.util.toSeconds
 import io.customer.sdk.util.Logger
 import java.util.*
+import java.util.concurrent.TimeUnit
 
 interface QueueStorage {
     fun getInventory(): QueueInventory
@@ -21,102 +26,134 @@ interface QueueStorage {
     fun update(taskStorageId: String, runResults: QueueTaskRunResults): Boolean
     fun get(taskStorageId: String): QueueTask?
     fun delete(taskStorageId: String): QueueModifyResult
+    fun deleteExpired(): List<QueueTaskMetadata>
 }
 
 class QueueStorageImpl internal constructor(
     private val sdkConfig: CustomerIOConfig,
     private val fileStorage: FileStorage,
     private val jsonAdapter: JsonAdapter,
+    private val dateUtil: DateUtil,
     private val logger: Logger
 ) : QueueStorage {
 
+    @Synchronized
     override fun getInventory(): QueueInventory {
-        synchronized(this) {
-            val dataFromFile = fileStorage.get(FileType.QueueInventory()) ?: return emptyList()
-            return jsonAdapter.fromJsonList(dataFromFile)
-        }
+        val dataFromFile = fileStorage.get(FileType.QueueInventory()) ?: return emptyList()
+        return jsonAdapter.fromJsonList(dataFromFile)
     }
 
+    @Synchronized
     override fun saveInventory(inventory: QueueInventory): Boolean {
-        synchronized(this) {
-            val fileContents = jsonAdapter.toJson(inventory)
-            return fileStorage.save(FileType.QueueInventory(), fileContents)
-        }
+        val fileContents = jsonAdapter.toJson(inventory)
+        return fileStorage.save(FileType.QueueInventory(), fileContents)
     }
 
+    @Synchronized
     override fun create(
         type: String,
         data: String,
         groupStart: QueueTaskGroup?,
         blockingGroups: List<QueueTaskGroup>?
     ): QueueModifyResult {
-        synchronized(this) {
-            val existingInventory = getInventory().toMutableList()
-            val beforeCreateQueueStatus = QueueStatus(sdkConfig.siteId, existingInventory.count())
+        val existingInventory = getInventory().toMutableList()
+        val beforeCreateQueueStatus = QueueStatus(sdkConfig.siteId, existingInventory.count())
 
-            val newTaskStorageId = UUID.randomUUID().toString()
-            val newQueueTask = QueueTask(newTaskStorageId, type, data, QueueTaskRunResults(0))
-
-            if (!update(newQueueTask)) {
-                logger.error("error trying to add new queue task to queue. $newQueueTask")
-                return QueueModifyResult(false, beforeCreateQueueStatus)
-            }
+        val newTaskStorageId = UUID.randomUUID().toString()
+        val newQueueTask = QueueTask(newTaskStorageId, type, data, QueueTaskRunResults(0))
 
-            // Update the inventory *after* a successful insert of the new task into storage. When a task is added to the inventory, it's assumed the task is available in device storage for use.
-            val newInventoryItem = QueueTaskMetadata(
-                newTaskStorageId,
-                type,
-                // Usually, we do not convert data types to a string before converting to a JSON string. We left the JSON parser to take care of the conversion for us. For groups, a String data type works good for use in the background queue.
-                groupStart?.toString(),
-                blockingGroups?.map { it.toString() },
-                Date()
-            )
-            existingInventory.add(newInventoryItem)
-
-            val updatedInventoryCount = existingInventory.count()
-            val afterCreateQueueStatus = QueueStatus(sdkConfig.siteId, updatedInventoryCount)
-
-            if (!saveInventory(existingInventory)) {
-                logger.error("error trying to add new queue task to inventory. task: $newQueueTask, inventory item: $newInventoryItem")
-                return QueueModifyResult(false, beforeCreateQueueStatus)
-            }
+        if (!update(newQueueTask)) {
+            logger.error("error trying to add new queue task to queue. $newQueueTask")
+            return QueueModifyResult(false, beforeCreateQueueStatus)
+        }
 
-            return QueueModifyResult(true, afterCreateQueueStatus)
+        // Update the inventory *after* a successful insert of the new task into storage. When a task is added to the inventory, it's assumed the task is available in device storage for use.
+        val newInventoryItem = QueueTaskMetadata(
+            newTaskStorageId,
+            type,
+            // Usually, we do not convert data types to a string before converting to a JSON string. We left the JSON parser to take care of the conversion for us. For groups, a String data type works good for use in the background queue.
+            groupStart?.toString(),
+            blockingGroups?.map { it.toString() },
+            dateUtil.now
+        )
+        existingInventory.add(newInventoryItem)
+
+        val updatedInventoryCount = existingInventory.count()
+        val afterCreateQueueStatus = QueueStatus(sdkConfig.siteId, updatedInventoryCount)
+
+        if (!saveInventory(existingInventory)) {
+            logger.error("error trying to add new queue task to inventory. task: $newQueueTask, inventory item: $newInventoryItem")
+            return QueueModifyResult(false, beforeCreateQueueStatus)
         }
+
+        return QueueModifyResult(true, afterCreateQueueStatus)
     }
 
+    @Synchronized
     override fun update(taskStorageId: String, runResults: QueueTaskRunResults): Boolean {
-        synchronized(this) {
-            var existingQueueTask = get(taskStorageId) ?: return false
+        var existingQueueTask = get(taskStorageId) ?: return false
 
-            existingQueueTask = existingQueueTask.copy(runResults = runResults)
+        existingQueueTask = existingQueueTask.copy(runResults = runResults)
 
-            return update(existingQueueTask)
-        }
+        return update(existingQueueTask)
     }
 
+    @Synchronized
     override fun get(taskStorageId: String): QueueTask? {
-        synchronized(this) {
-            val fileContents = fileStorage.get(FileType.QueueTask(taskStorageId)) ?: return null
-            return jsonAdapter.fromJson(fileContents)
-        }
+        val fileContents = fileStorage.get(FileType.QueueTask(taskStorageId)) ?: return null
+        return jsonAdapter.fromJson(fileContents)
     }
 
+    @Synchronized
     override fun delete(taskStorageId: String): QueueModifyResult {
-        synchronized(this) {
-            // update inventory first so if any deletion operation is unsuccessful, at least the inventory will not contain the task so queue doesn't try running it.
-            val existingInventory = getInventory().toMutableList()
-            val queueStatusBeforeModifyInventory = QueueStatus(sdkConfig.siteId, existingInventory.count())
+        // update inventory first so if any deletion operation is unsuccessful, at least the inventory will not contain the task so queue doesn't try running it.
+        val existingInventory = getInventory().toMutableList()
+        val queueStatusBeforeModifyInventory = QueueStatus(sdkConfig.siteId, existingInventory.count())
+
+        existingInventory.removeAll { it.taskPersistedId == taskStorageId }
+
+        if (!saveInventory(existingInventory) || !fileStorage.delete(FileType.QueueTask(taskStorageId))) {
+            logger.error("error trying to delete task with storage id: $taskStorageId from queue")
+            return QueueModifyResult(false, queueStatusBeforeModifyInventory)
+        }
 
-            existingInventory.removeAll { it.taskPersistedId == taskStorageId }
+        return QueueModifyResult(true, QueueStatus(sdkConfig.siteId, existingInventory.count()))
+    }
 
-            if (!saveInventory(existingInventory) || !fileStorage.delete(FileType.QueueTask(taskStorageId))) {
-                logger.error("error trying to delete task with storage id: $taskStorageId from queue")
-                return QueueModifyResult(false, queueStatusBeforeModifyInventory)
+    @Synchronized
+    override fun deleteExpired(): List<QueueTaskMetadata> {
+        logger.debug("deleting expired tasks from the queue")
+
+        val tasksToDelete: MutableSet<QueueTaskMetadata> = mutableSetOf()
+        val queueTaskExpiredThreshold = Date().subtract(sdkConfig.backgroundQueueTaskExpiredSeconds.toSeconds().value, TimeUnit.SECONDS)
+        logger.debug("deleting tasks older then $queueTaskExpiredThreshold, current time is: ${Date()}")
+
+        getInventory().filter {
+            // Do not delete tasks that are at the start of a group of tasks.
+            // Why? Take for example Identifying a profile. If we identify profile X in an app today, we expire the Identify queue task and delete the
+            // queue task, and then profile X stays logged into an app for 6 months, that means we run the risk of 6 months of data never
+            // successfully being sent to the API.
+            // Also, queue tasks such as Identifying a profile are more rare queue tasks compared to tracking of events (that are not the start of a group). So, it should rarely
+            // be a scenario when there are thousands of "expired" Identifying a profile tasks sitting in a queue. It's the queue tasks such as
+            // tracking that are taking up a large majority of the queue inventory. Those we should be deleting more of.
+            it.groupStart == null
+        }.forEach { taskInventoryItem ->
+            val isItemTooOld = taskInventoryItem.createdAt.isOlderThan(queueTaskExpiredThreshold)
+
+            if (isItemTooOld) {
+                tasksToDelete.add(taskInventoryItem)
             }
+        }
 
-            return QueueModifyResult(true, QueueStatus(sdkConfig.siteId, existingInventory.count()))
+        logger.debug("deleting ${tasksToDelete.count()} tasks. \n Tasks: $tasksToDelete")
+
+        tasksToDelete.forEach {
+            // Because the queue tasks we are deleting are not the start of a group, if deleting a task is not successful, we can ignore that
+            // because it doesn't negatively effect the state of the SDK or the queue.
+            this.delete(it.taskPersistedId)
         }
+
+        return tasksToDelete.toList()
     }
 
     private fun update(queueTask: QueueTask): Boolean {
diff --git a/sdk/src/main/java/io/customer/sdk/repository/CleanupRepository.kt b/sdk/src/main/java/io/customer/sdk/repository/CleanupRepository.kt
new file mode 100644
index 000000000..dd3033120
--- /dev/null
+++ b/sdk/src/main/java/io/customer/sdk/repository/CleanupRepository.kt
@@ -0,0 +1,19 @@
+package io.customer.sdk.repository
+
+import io.customer.sdk.queue.Queue
+
+/**
+ * In charge of cleaning up the SDK. Deleting old data or caches. Keeping the SDK fast and performant.
+ */
+internal interface CleanupRepository {
+    suspend fun cleanup()
+}
+
+class CleanupRepositoryImpl(
+    private val queue: Queue
+) : CleanupRepository {
+
+    override suspend fun cleanup() {
+        queue.deleteExpiredTasks()
+    }
+}
diff --git a/sdk/src/main/java/io/customer/sdk/util/DispatchersProvider.kt b/sdk/src/main/java/io/customer/sdk/util/DispatchersProvider.kt
new file mode 100644
index 000000000..ecd8a00c7
--- /dev/null
+++ b/sdk/src/main/java/io/customer/sdk/util/DispatchersProvider.kt
@@ -0,0 +1,18 @@
+package io.customer.sdk.util
+
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.Dispatchers
+
+// Allows injecting dispatchers in automated tests
+interface DispatchersProvider {
+    val background: CoroutineDispatcher
+    val main: CoroutineDispatcher
+}
+
+class SdkDispatchers : DispatchersProvider {
+    override val background: CoroutineDispatcher
+        get() = Dispatchers.IO
+
+    override val main: CoroutineDispatcher
+        get() = Dispatchers.Main
+}
diff --git a/sdk/src/main/java/io/customer/sdk/util/Seconds.kt b/sdk/src/main/java/io/customer/sdk/util/Seconds.kt
index a0baa54be..64f8a5d47 100644
--- a/sdk/src/main/java/io/customer/sdk/util/Seconds.kt
+++ b/sdk/src/main/java/io/customer/sdk/util/Seconds.kt
@@ -9,8 +9,11 @@ data class Seconds(
     val value: Double
 ) {
     companion object {
-        // used for automated tests. Value that is small to make tests run fast, but long enough to test code's logic.
-        fun testValue(): Seconds = Seconds(0.01)
+        fun fromDays(numDays: Int): Seconds {
+            val secondsIn24Hours = 86400.0
+
+            return Seconds(numDays * secondsIn24Hours)
+        }
     }
 
     val toMilliseconds: Milliseconds
diff --git a/sdk/src/main/java/io/customer/sdk/util/SimpleTimer.kt b/sdk/src/main/java/io/customer/sdk/util/SimpleTimer.kt
index 5e8b2038c..938b43044 100644
--- a/sdk/src/main/java/io/customer/sdk/util/SimpleTimer.kt
+++ b/sdk/src/main/java/io/customer/sdk/util/SimpleTimer.kt
@@ -2,7 +2,6 @@ package io.customer.sdk.util
 
 import android.os.CountDownTimer
 import io.customer.sdk.utils.random
-import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
@@ -20,7 +19,7 @@ interface SimpleTimer {
 
 class AndroidSimpleTimer(
     private val logger: Logger,
-    private val uiDispatcher: CoroutineDispatcher
+    private val dispatchersProvider: DispatchersProvider
 ) : SimpleTimer {
 
     @Volatile private var countdownTimer: CountDownTimer? = null
@@ -29,10 +28,10 @@ class AndroidSimpleTimer(
     private val instanceIdentifier = String.random
 
     override fun scheduleAndCancelPrevious(seconds: Seconds, block: () -> Unit) {
-        // Must start and create timer on the main UI thread or Android will throw an exception saying the current thread doesn't have a Looper.
+        // Must create and start timer on the main UI thread or Android will throw an exception saying the current thread doesn't have a Looper.
         // Because we are starting a new coroutine, there is a chance that there could be a delay in starting the timer. This is OK because
         // this function is designed to be async anyway so the logic from the caller has not changed.
-        startTimerMainThreadJob = CoroutineScope(uiDispatcher).launch {
+        startTimerMainThreadJob = CoroutineScope(dispatchersProvider.main).launch {
             val newTimer: CountDownTimer = synchronized(this) {
                 timerAlreadyScheduled = true
                 unsafeCancel()
diff --git a/sdk/src/main/java/io/customer/sdk/util/Singleton.kt b/sdk/src/main/java/io/customer/sdk/util/Singleton.kt
deleted file mode 100644
index 56d710ed6..000000000
--- a/sdk/src/main/java/io/customer/sdk/util/Singleton.kt
+++ /dev/null
@@ -1,28 +0,0 @@
-package io.customer.sdk.util
-
-/**
- * Quick way to make a class a singleton.
- *
- * ```
- * class Foo(
- *   param1: Param1,
- *   param2: Param2
- * ) {
- *   companion object SingletonHolder: Singleton<QueueRunRequest>()
- * }
- *
- * // to use:
- * Foo.SingletonHolder.getInstanceOrCreate {
- *   Foo(param1, param2)
- * }
- * ```
- */
-abstract class Singleton<INST> {
-    @Volatile var instance: INST? = null
-
-    fun getInstanceOrCreate(newInstanceCreator: () -> INST): INST {
-        return instance ?: newInstanceCreator().also {
-            instance = it
-        }
-    }
-}
diff --git a/sdk/src/sharedTest/java/io/customer/sdk/CustomerIOTest.kt b/sdk/src/sharedTest/java/io/customer/sdk/CustomerIOTest.kt
index e1c326198..fbd777768 100644
--- a/sdk/src/sharedTest/java/io/customer/sdk/CustomerIOTest.kt
+++ b/sdk/src/sharedTest/java/io/customer/sdk/CustomerIOTest.kt
@@ -5,9 +5,11 @@ import androidx.test.ext.junit.runners.AndroidJUnit4
 import io.customer.common_test.BaseTest
 import io.customer.sdk.data.communication.CustomerIOUrlHandler
 import io.customer.sdk.data.model.Region
+import io.customer.sdk.repository.CleanupRepository
 import io.customer.sdk.repository.DeviceRepository
 import io.customer.sdk.repository.ProfileRepository
 import io.customer.sdk.utils.random
+import kotlinx.coroutines.runBlocking
 import org.amshove.kluent.shouldBeEqualTo
 import org.amshove.kluent.shouldNotBeNull
 import org.junit.Before
@@ -21,6 +23,7 @@ import org.mockito.kotlin.whenever
 @RunWith(AndroidJUnit4::class)
 class CustomerIOTest : BaseTest() {
 
+    private val cleanupRepositoryMock: CleanupRepository = mock()
     private val deviceRepositoryMock: DeviceRepository = mock()
     private val profileRepositoryMock: ProfileRepository = mock()
 
@@ -30,6 +33,7 @@ class CustomerIOTest : BaseTest() {
     fun setUp() {
         super.setup()
 
+        di.overrideDependency(CleanupRepository::class.java, cleanupRepositoryMock)
         di.overrideDependency(DeviceRepository::class.java, deviceRepositoryMock)
         di.overrideDependency(ProfileRepository::class.java, profileRepositoryMock)
 
@@ -171,4 +175,20 @@ class CustomerIOTest : BaseTest() {
         verify(givenModule1, never()).initialize()
         verify(givenModule2).initialize()
     }
+
+    @Test
+    fun initializeSdk_expectRunCleanup(): Unit = runBlocking {
+        getRandomCustomerIOBuilder().build()
+
+        verify(cleanupRepositoryMock).cleanup()
+    }
+
+    private fun getRandomCustomerIOBuilder(): CustomerIO.Builder = CustomerIO.Builder(
+        siteId = String.random,
+        apiKey = String.random,
+        region = Region.EU,
+        appContext = application
+    ).apply {
+        this.overrideDiGraph = di
+    }
 }
diff --git a/sdk/src/sharedTest/java/io/customer/sdk/queue/QueueIntegrationTests.kt b/sdk/src/sharedTest/java/io/customer/sdk/queue/QueueIntegrationTests.kt
index 8d1416d29..ea384c0d7 100644
--- a/sdk/src/sharedTest/java/io/customer/sdk/queue/QueueIntegrationTests.kt
+++ b/sdk/src/sharedTest/java/io/customer/sdk/queue/QueueIntegrationTests.kt
@@ -31,6 +31,7 @@ class QueueIntegrationTests : BaseTest() {
         val givenIdentifier = String.random
         queue.queueIdentifyProfile(givenIdentifier, null, emptyMap())
         queue.queueTrack(givenIdentifier, String.random, EventType.event, emptyMap())
+        queueStorage.getInventory().count() shouldBeEqualTo 2
 
         mockWebServer.enqueueNoInternetConnection()
         queue.run()
diff --git a/sdk/src/sharedTest/java/io/customer/sdk/queue/QueueStorageIntegrationTest.kt b/sdk/src/sharedTest/java/io/customer/sdk/queue/QueueStorageIntegrationTest.kt
index eec91333b..22cb800a0 100644
--- a/sdk/src/sharedTest/java/io/customer/sdk/queue/QueueStorageIntegrationTest.kt
+++ b/sdk/src/sharedTest/java/io/customer/sdk/queue/QueueStorageIntegrationTest.kt
@@ -1,6 +1,7 @@
 package io.customer.sdk.queue
 
 import androidx.test.ext.junit.runners.AndroidJUnit4
+import io.customer.base.extenstions.subtract
 import io.customer.sdk.queue.type.QueueInventory
 import io.customer.sdk.queue.type.QueueModifyResult
 import io.customer.sdk.queue.type.QueueStatus
@@ -13,6 +14,8 @@ import org.amshove.kluent.*
 import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
+import java.util.*
+import java.util.concurrent.TimeUnit
 
 @RunWith(AndroidJUnit4::class)
 class QueueStorageIntegrationTest : BaseTest() {
@@ -24,7 +27,7 @@ class QueueStorageIntegrationTest : BaseTest() {
     override fun setup() {
         super.setup()
 
-        queueStorage = QueueStorageImpl(cioConfig, di.fileStorage, di.jsonAdapter, di.logger)
+        queueStorage = QueueStorageImpl(cioConfig, di.fileStorage, di.jsonAdapter, dateUtilStub, di.logger)
     }
 
     @Test
@@ -136,4 +139,52 @@ class QueueStorageIntegrationTest : BaseTest() {
 
         createdTaskAfterUpdate!!.runResults shouldBeEqualTo givenRunResults
     }
+
+    @Test
+    fun deleteExpired_givenNoTasksInQueue_expectDeleteNoTasks() {
+        val tasksDeleted = queueStorage.deleteExpired()
+
+        tasksDeleted.count() shouldBeEqualTo 0
+    }
+
+    @Test
+    fun deleteExpired_givenTasksNotExpired_expectDeleteNoTasks() {
+        dateUtilStub.givenDate = Date() // make newly created tasks not expired
+        queueStorage.create(String.random, String.random, null, null)
+
+        val tasksDeleted = queueStorage.deleteExpired()
+
+        tasksDeleted.count() shouldBeEqualTo 0
+    }
+
+    @Test
+    fun deleteExpired_givenTasksStartOfGroupAndExpired_expectDeleteNoTasks() {
+        dateUtilStub.givenDate = Date().subtract(10, TimeUnit.DAYS) // make newly created tasks expired
+        queueStorage.create(String.random, String.random, QueueTaskGroup.IdentifyProfile(String.random), null)
+
+        val tasksDeleted = queueStorage.deleteExpired()
+
+        tasksDeleted.count() shouldBeEqualTo 0
+    }
+
+    @Test
+    fun deleteExpired_givenTasksNoStartOfGroupAndExpired_expectDeleteTasksExpired() {
+        val givenGroupOfTasks = QueueTaskGroup.IdentifyProfile(String.random)
+        dateUtilStub.givenDate = Date().subtract(10, TimeUnit.DAYS) // make newly created tasks expired
+        queueStorage.create(String.random, String.random, givenGroupOfTasks, null)
+        val expectedNotDeleted = queueStorage.getInventory()[0]
+        queueStorage.create(String.random, String.random, null, listOf(givenGroupOfTasks))
+        val expectedDeleted = queueStorage.getInventory()[1]
+        expectedNotDeleted.taskPersistedId shouldNotBeEqualTo expectedDeleted.taskPersistedId
+
+        val tasksDeleted = queueStorage.deleteExpired()
+
+        tasksDeleted.count() shouldBeEqualTo 1
+        tasksDeleted[0] shouldBeEqualTo expectedDeleted
+
+        queueStorage.getInventory().apply {
+            count() shouldBeEqualTo 1
+            get(0) shouldBeEqualTo expectedNotDeleted
+        }
+    }
 }
diff --git a/sdk/src/sharedTest/java/io/customer/sdk/queue/QueueTest.kt b/sdk/src/sharedTest/java/io/customer/sdk/queue/QueueTest.kt
index fa25137ee..49db889fb 100644
--- a/sdk/src/sharedTest/java/io/customer/sdk/queue/QueueTest.kt
+++ b/sdk/src/sharedTest/java/io/customer/sdk/queue/QueueTest.kt
@@ -31,7 +31,7 @@ class QueueTest : BaseTest() {
     override fun setup() {
         super.setup()
 
-        queue = QueueImpl(testDispatcher, storageMock, runRequestMock, di.jsonAdapter, di.sdkConfig, queueTimerMock, di.logger, dateUtilStub)
+        queue = QueueImpl(dispatchersProviderStub, storageMock, runRequestMock, di.jsonAdapter, di.sdkConfig, queueTimerMock, di.logger, dateUtilStub)
     }
 
     // our indicator if queue started to run the queue
diff --git a/sdk/src/sharedTest/java/io/customer/sdk/util/SecondsTest.kt b/sdk/src/sharedTest/java/io/customer/sdk/util/SecondsTest.kt
index f6660db5f..55fe425b7 100644
--- a/sdk/src/sharedTest/java/io/customer/sdk/util/SecondsTest.kt
+++ b/sdk/src/sharedTest/java/io/customer/sdk/util/SecondsTest.kt
@@ -24,6 +24,16 @@ class SecondsTest : BaseTest() {
 
         expected shouldBeEqualTo actual
     }
+
+    @Test
+    fun fromDays_given0_expect0Seconds() {
+        Seconds.fromDays(0).value shouldBeEqualTo 0.0
+    }
+
+    @Test
+    fun fromDays_givenNumberOfDays_expectNumberOfSeconds() {
+        Seconds.fromDays(3).value shouldBeEqualTo 259200.0
+    }
 }
 
 @RunWith(AndroidJUnit4::class)