Sync adapter: improve HttpClient and cancellation (#100)

* Sync adapter: share single HttpClient between all SyncManagers (should fix bitfireAT/davx5#99)
* HttpClient: use producer for CertManager
* Call setAccountVisibility only when necessary
* Fix tests

20 files changed, 114 insertions, 60 deletions

diff --git a/app/src/androidTest/java/at/bitfire/davdroid/settings/AccountSettingsTest.kt b/app/src/androidTest/java/at/bitfire/davdroid/settings/AccountSettingsTest.kt
index 1d7644c8..612f3899 100644
--- a/app/src/androidTest/java/at/bitfire/davdroid/settings/AccountSettingsTest.kt
+++ b/app/src/androidTest/java/at/bitfire/davdroid/settings/AccountSettingsTest.kt
@@ -33,20 +33,16 @@ class AccountSettingsTest {
     @Inject
     lateinit var settingsManager: SettingsManager
 
-    @Before
-    fun inject() {
-        hiltRule.inject()
-    }
-
 
     val context = InstrumentationRegistry.getInstrumentation().targetContext
 
     val account = Account("Test Account", context.getString(R.string.account_type))
     val fakeCredentials = Credentials("test", "test")
 
-
     @Before
-    fun prepareAccount() {
+    fun setUp() {
+        hiltRule.inject()
+
         assertTrue(AccountUtils.createAccount(context, account, AccountSettings.initialUserData(fakeCredentials)))
         ContentResolver.setIsSyncable(account, CalendarContract.AUTHORITY, 1)
         ContentResolver.setIsSyncable(account, ContactsContract.AUTHORITY, 0)
diff --git a/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/AccountUtilsTest.kt b/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/AccountUtilsTest.kt
index 4e48435a..bda06c6d 100644
--- a/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/AccountUtilsTest.kt
+++ b/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/AccountUtilsTest.kt
@@ -9,15 +9,34 @@ import android.accounts.AccountManager
 import android.os.Bundle
 import androidx.test.platform.app.InstrumentationRegistry
 import at.bitfire.davdroid.R
+import at.bitfire.davdroid.settings.SettingsManager
+import dagger.hilt.android.testing.HiltAndroidRule
+import dagger.hilt.android.testing.HiltAndroidTest
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertTrue
+import org.junit.Before
+import org.junit.Rule
 import org.junit.Test
 import java.util.concurrent.TimeUnit
+import javax.inject.Inject
 
+@HiltAndroidTest
 class AccountUtilsTest {
 
-    val context = InstrumentationRegistry.getInstrumentation().targetContext
-    val account = Account("Test Account", context.getString(R.string.account_type))
+    @get:Rule
+    val hiltRule = HiltAndroidRule(this)
+
+    @Inject
+    lateinit var settingsManager: SettingsManager
+
+    @Before
+    fun inject() {
+        hiltRule.inject()
+    }
+
+
+    val context by lazy { InstrumentationRegistry.getInstrumentation().targetContext }
+    val account by lazy { Account("Test Account", context.getString(R.string.account_type)) }
 
     @Test
     fun testCreateAccount() {
diff --git a/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/SyncAdapterTest.kt b/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/SyncAdapterTest.kt
index b7288cc6..a4a7f03b 100644
--- a/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/SyncAdapterTest.kt
+++ b/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/SyncAdapterTest.kt
@@ -10,6 +10,7 @@ import android.content.Context
 import android.content.SyncResult
 import android.os.Bundle
 import androidx.test.platform.app.InstrumentationRegistry
+import at.bitfire.davdroid.HttpClient
 import at.bitfire.davdroid.R
 import at.bitfire.davdroid.db.AppDatabase
 import at.bitfire.davdroid.settings.SettingsManager
@@ -135,6 +136,7 @@ class SyncAdapterTest {
             account: Account,
             extras: Bundle,
             authority: String,
+            httpClient: Lazy<HttpClient>,
             provider: ContentProviderClient,
             syncResult: SyncResult
         ) {
diff --git a/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/SyncManagerTest.kt b/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/SyncManagerTest.kt
index e5821748..b494110c 100644
--- a/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/SyncManagerTest.kt
+++ b/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/SyncManagerTest.kt
@@ -14,6 +14,7 @@ import at.bitfire.dav4jvm.PropStat
 import at.bitfire.dav4jvm.Response
 import at.bitfire.dav4jvm.Response.HrefRelation
 import at.bitfire.dav4jvm.property.GetETag
+import at.bitfire.davdroid.HttpClient
 import at.bitfire.davdroid.R
 import at.bitfire.davdroid.db.Credentials
 import at.bitfire.davdroid.db.SyncState
@@ -74,6 +75,7 @@ class SyncManagerTest {
                     account,
                     Bundle(),
                     "TestAuthority",
+                    HttpClient.Builder().build(),
                     SyncResult(),
                     collection,
                     server
diff --git a/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/TestSyncManager.kt b/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/TestSyncManager.kt
index 5203b1c7..6e664bed 100644
--- a/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/TestSyncManager.kt
+++ b/app/src/androidTestStandard/java/at/bitfire/davdroid/syncadapter/TestSyncManager.kt
@@ -13,6 +13,7 @@ import at.bitfire.dav4jvm.DavResponseCallback
 import at.bitfire.dav4jvm.Response
 import at.bitfire.dav4jvm.property.GetCTag
 import at.bitfire.davdroid.DavUtils
+import at.bitfire.davdroid.HttpClient
 import at.bitfire.davdroid.db.SyncState
 import at.bitfire.davdroid.resource.LocalResource
 import at.bitfire.davdroid.settings.AccountSettings
@@ -27,10 +28,11 @@ class TestSyncManager(
         account: Account,
         extras: Bundle,
         authority: String,
+        httpClient: HttpClient,
         syncResult: SyncResult,
         localCollection: LocalTestCollection,
         val mockWebServer: MockWebServer
-): SyncManager<LocalTestResource, LocalTestCollection, DavCollection>(context, account, AccountSettings(context, account), extras, authority, syncResult, localCollection) {
+): SyncManager<LocalTestResource, LocalTestCollection, DavCollection>(context, account, AccountSettings(context, account), httpClient, extras, authority, syncResult, localCollection) {
 
     override fun prepare(): Boolean {
         collectionURL = mockWebServer.url("/")
diff --git a/app/src/main/java/at/bitfire/davdroid/HttpClient.kt b/app/src/main/java/at/bitfire/davdroid/HttpClient.kt
index a968961d..9e1863bc 100644
--- a/app/src/main/java/at/bitfire/davdroid/HttpClient.kt
+++ b/app/src/main/java/at/bitfire/davdroid/HttpClient.kt
@@ -91,7 +91,13 @@ class HttpClient private constructor(
         val logger: java.util.logging.Logger? = Logger.log,
         val loggerLevel: HttpLoggingInterceptor.Level = HttpLoggingInterceptor.Level.BODY
     ) {
-        private var certManager: CustomCertManager? = null
+
+        fun interface CertManagerProducer {
+            fun certManager(): CustomCertManager
+        }
+
+        private var appInForeground = false
+        private var certManagerProducer: CertManagerProducer? = null
         private var certificateAlias: String? = null
         private var offerCompression: Boolean = false
 
@@ -136,9 +142,11 @@ class HttpClient private constructor(
                     Logger.log.log(Level.SEVERE, "Can't set proxy, ignoring", e)
                 }
 
-                // TODO don't instantiate CustomCertManager in .Builder (causes service leaks)
-                customCertManager(CustomCertManager(context, true /*BuildConfig.customCertsUI*/,
-                        !(settings.getBoolean(Settings.DISTRUST_SYSTEM_CERTIFICATES))))
+                customCertManager() {
+                    // by default, use a CustomCertManager that respects the "distrust system certificates" setting
+                    val trustSystemCerts = !settings.getBoolean(Settings.DISTRUST_SYSTEM_CERTIFICATES)
+                    CustomCertManager(context, true /*BuildConfig.customCertsUI*/, trustSystemCerts)
+                }
             }
 
             // use account settings for authentication and cookies
@@ -178,11 +186,11 @@ class HttpClient private constructor(
             return this
         }
 
-        fun customCertManager(manager: CustomCertManager) {
-            certManager = manager
+        fun customCertManager(producer: CertManagerProducer) {
+            certManagerProducer = producer
         }
         fun setForeground(foreground: Boolean): Builder {
-            certManager?.appInForeground = foreground
+            appInForeground = foreground
             return this
         }
 
@@ -208,15 +216,6 @@ class HttpClient private constructor(
                 // offer Brotli and gzip compression
                 orig.addInterceptor(BrotliInterceptor)
 
-            val trustManager = certManager ?: run {
-                val factory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm())
-                factory.init(null as KeyStore?)
-                factory.trustManagers.first() as X509TrustManager
-            }
-
-            val hostnameVerifier = certManager?.hostnameVerifier(OkHostnameVerifier)
-                    ?: OkHostnameVerifier
-
             var keyManager: KeyManager? = null
             certificateAlias?.let { alias ->
                 val context = requireNotNull(context)
@@ -249,15 +248,30 @@ class HttpClient private constructor(
                 orig.protocols(listOf(Protocol.HTTP_1_1))
             }
 
-            val sslContext = SSLContext.getInstance("TLS")
-            sslContext.init(
+            if (certManagerProducer != null || keyManager != null) {
+                val certManager = certManagerProducer?.certManager()
+                certManager?.appInForeground = appInForeground
+
+                val trustManager = certManager ?: {     // fall back to system default trust manager
+                    val factory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm())
+                    factory.init(null as KeyStore?)
+                    factory.trustManagers.first() as X509TrustManager
+                }()
+
+                val hostnameVerifier = certManager?.hostnameVerifier(OkHostnameVerifier)
+                    ?: OkHostnameVerifier
+
+                val sslContext = SSLContext.getInstance("TLS")
+                sslContext.init(
                     if (keyManager != null) arrayOf(keyManager) else null,
                     arrayOf(trustManager),
                     null)
-            orig.sslSocketFactory(sslContext.socketFactory, trustManager)
-            orig.hostnameVerifier(hostnameVerifier)
+                orig.sslSocketFactory(sslContext.socketFactory, trustManager)
+                orig.hostnameVerifier(hostnameVerifier)
 
-            return HttpClient(orig.build(), certManager)
+                return HttpClient(orig.build(), certManager)
+            } else
+                return HttpClient(orig.build(), null)
         }
 
     }
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/AddressBooksSyncAdapterService.kt b/app/src/main/java/at/bitfire/davdroid/syncadapter/AddressBooksSyncAdapterService.kt
index bc270e07..275ab782 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/AddressBooksSyncAdapterService.kt
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/AddressBooksSyncAdapterService.kt
@@ -13,6 +13,7 @@ import android.content.pm.PackageManager
 import android.os.Bundle
 import android.provider.ContactsContract
 import androidx.core.content.ContextCompat
+import at.bitfire.davdroid.HttpClient
 import at.bitfire.davdroid.closeCompat
 import at.bitfire.davdroid.db.AppDatabase
 import at.bitfire.davdroid.db.Collection
@@ -34,7 +35,7 @@ class AddressBooksSyncAdapterService : SyncAdapterService() {
         appDatabase: AppDatabase
     ) : SyncAdapter(context, appDatabase) {
 
-        override fun sync(account: Account, extras: Bundle, authority: String, provider: ContentProviderClient, syncResult: SyncResult) {
+        override fun sync(account: Account, extras: Bundle, authority: String, httpClient: Lazy<HttpClient>, provider: ContentProviderClient, syncResult: SyncResult) {
             try {
                 val accountSettings = AccountSettings(context, account)
 
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarSyncManager.kt b/app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarSyncManager.kt
index 2e2d2588..c3840055 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarSyncManager.kt
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarSyncManager.kt
@@ -14,6 +14,7 @@ import at.bitfire.dav4jvm.Response
 import at.bitfire.dav4jvm.exception.DavException
 import at.bitfire.dav4jvm.property.*
 import at.bitfire.davdroid.DavUtils
+import at.bitfire.davdroid.HttpClient
 import at.bitfire.davdroid.R
 import at.bitfire.davdroid.db.SyncState
 import at.bitfire.davdroid.log.Logger
@@ -46,10 +47,11 @@ class CalendarSyncManager(
     account: Account,
     accountSettings: AccountSettings,
     extras: Bundle,
+    httpClient: HttpClient,
     authority: String,
     syncResult: SyncResult,
     localCalendar: LocalCalendar
-): SyncManager<LocalEvent, LocalCalendar, DavCalendar>(context, account, accountSettings, extras, authority, syncResult, localCalendar) {
+): SyncManager<LocalEvent, LocalCalendar, DavCalendar>(context, account, accountSettings, httpClient, extras, authority, syncResult, localCalendar) {
 
     override fun prepare(): Boolean {
         collectionURL = (localCollection.name ?: return false).toHttpUrlOrNull() ?: return false
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarsSyncAdapterService.kt b/app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarsSyncAdapterService.kt
index 0570c10b..83633b5b 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarsSyncAdapterService.kt
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarsSyncAdapterService.kt
@@ -10,6 +10,7 @@ import android.content.Context
 import android.content.SyncResult
 import android.os.Bundle
 import android.provider.CalendarContract
+import at.bitfire.davdroid.HttpClient
 import at.bitfire.davdroid.db.AppDatabase
 import at.bitfire.davdroid.db.Collection
 import at.bitfire.davdroid.db.Service
@@ -34,7 +35,7 @@ class CalendarsSyncAdapterService: SyncAdapterService() {
         appDatabase: AppDatabase
     ) : SyncAdapter(context, appDatabase) {
 
-        override fun sync(account: Account, extras: Bundle, authority: String, provider: ContentProviderClient, syncResult: SyncResult) {
+        override fun sync(account: Account, extras: Bundle, authority: String, httpClient: Lazy<HttpClient>, provider: ContentProviderClient, syncResult: SyncResult) {
             try {
                 val accountSettings = AccountSettings(context, account)
 
@@ -58,7 +59,7 @@ class CalendarsSyncAdapterService: SyncAdapterService() {
                         .sortedByDescending { priorityCalendars.contains(it.id) }
                 for (calendar in calendars) {
                     Logger.log.info("Synchronizing calendar #${calendar.id}, URL: ${calendar.name}")
-                    CalendarSyncManager(context, account, accountSettings, extras, authority, syncResult, calendar).use {
+                    CalendarSyncManager(context, account, accountSettings, extras, httpClient.value, authority, syncResult, calendar).let {
                         it.performSync()
                     }
                 }
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncAdapterService.kt b/app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncAdapterService.kt
index e41f6dbc..83aa7496 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncAdapterService.kt
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncAdapterService.kt
@@ -11,6 +11,7 @@ import android.content.Context
 import android.content.SyncResult
 import android.os.Bundle
 import android.provider.ContactsContract
+import at.bitfire.davdroid.HttpClient
 import at.bitfire.davdroid.db.AppDatabase
 import at.bitfire.davdroid.log.Logger
 import at.bitfire.davdroid.resource.LocalAddressBook
@@ -31,7 +32,7 @@ class ContactsSyncAdapterService: SyncAdapterService() {
         appDatabase: AppDatabase
     ) : SyncAdapter(context, appDatabase) {
 
-        override fun sync(account: Account, extras: Bundle, authority: String, provider: ContentProviderClient, syncResult: SyncResult) {
+        override fun sync(account: Account, extras: Bundle, authority: String, httpClient: Lazy<HttpClient>, provider: ContentProviderClient, syncResult: SyncResult) {
             try {
                 val addressBook = LocalAddressBook(context, account, provider)
                 val accountSettings = AccountSettings(context, addressBook.mainAccount)
@@ -62,7 +63,7 @@ class ContactsSyncAdapterService: SyncAdapterService() {
                 Logger.log.info("Synchronizing address book: ${addressBook.url}")
                 Logger.log.info("Taking settings from: ${addressBook.mainAccount}")
 
-                ContactsSyncManager(context, account, accountSettings, extras, authority, syncResult, provider, addressBook).use {
+                ContactsSyncManager(context, account, accountSettings, httpClient.value, extras, authority, syncResult, provider, addressBook).let {
                     it.performSync()
                 }
             } catch(e: Exception) {
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncManager.kt b/app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncManager.kt
index 3f6e940a..2401a0a0 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncManager.kt
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncManager.kt
@@ -82,12 +82,13 @@ class ContactsSyncManager(
     context: Context,
     account: Account,
     accountSettings: AccountSettings,
+    httpClient: HttpClient,
     extras: Bundle,
     authority: String,
     syncResult: SyncResult,
     val provider: ContentProviderClient,
     localAddressBook: LocalAddressBook
-): SyncManager<LocalAddress, LocalAddressBook, DavAddressBook>(context, account, accountSettings, extras, authority, syncResult, localAddressBook) {
+): SyncManager<LocalAddress, LocalAddressBook, DavAddressBook>(context, account, accountSettings, httpClient, extras, authority, syncResult, localAddressBook) {
 
     companion object {
         infix fun <T> Set<T>.disjunct(other: Set<T>) = (this - other) union (other - this)
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/JtxSyncAdapterService.kt b/app/src/main/java/at/bitfire/davdroid/syncadapter/JtxSyncAdapterService.kt
index 9d8e6526..2653a184 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/JtxSyncAdapterService.kt
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/JtxSyncAdapterService.kt
@@ -12,6 +12,7 @@ import android.content.Context
 import android.content.SyncResult
 import android.os.Build
 import android.os.Bundle
+import at.bitfire.davdroid.HttpClient
 import at.bitfire.davdroid.db.AppDatabase
 import at.bitfire.davdroid.db.Collection
 import at.bitfire.davdroid.db.Service
@@ -37,7 +38,7 @@ class JtxSyncAdapterService: SyncAdapterService() {
         appDatabase: AppDatabase
     ) : SyncAdapter(context, appDatabase) {
 
-        override fun sync(account: Account, extras: Bundle, authority: String, provider: ContentProviderClient, syncResult: SyncResult) {
+        override fun sync(account: Account, extras: Bundle, authority: String, httpClient: Lazy<HttpClient>, provider: ContentProviderClient, syncResult: SyncResult) {
 
             try {
                 // check whether jtx Board is new enough
@@ -62,7 +63,7 @@ class JtxSyncAdapterService: SyncAdapterService() {
                 val collections = JtxCollection.find(account, provider, context, LocalJtxCollection.Factory, null, null)
                 for (collection in collections) {
                     Logger.log.info("Synchronizing $collection")
-                    JtxSyncManager(context, account, accountSettings, extras, authority, syncResult, collection).use {
+                    JtxSyncManager(context, account, accountSettings, extras, httpClient.value, authority, syncResult, collection).let {
                         it.performSync()
                     }
                 }
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/JtxSyncManager.kt b/app/src/main/java/at/bitfire/davdroid/syncadapter/JtxSyncManager.kt
index 638c36f5..c003e659 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/JtxSyncManager.kt
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/JtxSyncManager.kt
@@ -14,6 +14,7 @@ import at.bitfire.dav4jvm.Response
 import at.bitfire.dav4jvm.exception.DavException
 import at.bitfire.dav4jvm.property.*
 import at.bitfire.davdroid.DavUtils
+import at.bitfire.davdroid.HttpClient
 import at.bitfire.davdroid.R
 import at.bitfire.davdroid.db.SyncState
 import at.bitfire.davdroid.log.Logger
@@ -38,10 +39,11 @@ class JtxSyncManager(
     account: Account,
     accountSettings: AccountSettings,
     extras: Bundle,
+    httpClient: HttpClient,
     authority: String,
     syncResult: SyncResult,
     localCollection: LocalJtxCollection
-):  SyncManager<LocalJtxICalObject, LocalJtxCollection, DavCalendar>(context, account, accountSettings, extras, authority, syncResult, localCollection) {
+):  SyncManager<LocalJtxICalObject, LocalJtxCollection, DavCalendar>(context, account, accountSettings, httpClient, extras, authority, syncResult, localCollection) {
 
     override fun prepare(): Boolean {
         collectionURL = (localCollection.url ?: return false).toHttpUrlOrNull() ?: return false
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/SyncAdapterService.kt b/app/src/main/java/at/bitfire/davdroid/syncadapter/SyncAdapterService.kt
index 7fbb2a3a..969cbd25 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/SyncAdapterService.kt
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/SyncAdapterService.kt
@@ -13,6 +13,7 @@ import android.net.wifi.WifiManager
 import android.os.Bundle
 import androidx.core.content.getSystemService
 import at.bitfire.davdroid.ConcurrentUtils
+import at.bitfire.davdroid.HttpClient
 import at.bitfire.davdroid.InvalidAccountException
 import at.bitfire.davdroid.PermissionUtils
 import at.bitfire.davdroid.db.AppDatabase
@@ -103,7 +104,7 @@ abstract class SyncAdapterService: Service() {
         }
 
 
-        abstract fun sync(account: Account, extras: Bundle, authority: String, provider: ContentProviderClient, syncResult: SyncResult)
+        abstract fun sync(account: Account, extras: Bundle, authority: String, httpClient: Lazy<HttpClient>, provider: ContentProviderClient, syncResult: SyncResult)
 
         override fun onPerformSync(account: Account, extras: Bundle, authority: String, provider: ContentProviderClient, syncResult: SyncResult) {
             Logger.log.log(Level.INFO, "$authority sync of $account has been initiated", extras.keySet().joinToString(", "))
@@ -114,11 +115,14 @@ abstract class SyncAdapterService: Service() {
                 // required for ServiceLoader -> ical4j -> ical4android
                 Thread.currentThread().contextClassLoader = context.classLoader
 
+                val accountSettings by lazy { AccountSettings(context, account) }
+                val httpClient = lazy { HttpClient.Builder(context, accountSettings).build() }
+
                 try {
                     val runSync = /* always true in open-source edition */ true
 
                     if (runSync)
-                        sync(account, extras, authority, provider, syncResult)
+                        sync(account, extras, authority, httpClient, provider, syncResult)
 
                 } catch (e: InvalidAccountException) {
                     Logger.log.log(
@@ -126,6 +130,9 @@ abstract class SyncAdapterService: Service() {
                         "Account was removed during synchronization",
                         e
                     )
+                } finally {
+                    if (httpClient.isInitialized())
+                        httpClient.value.close()
                 }
             })
                 Logger.log.log(Level.INFO, "Sync for $currentSyncKey finished", syncResult)
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/SyncManager.kt b/app/src/main/java/at/bitfire/davdroid/syncadapter/SyncManager.kt
index ac143ab6..443f75ba 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/SyncManager.kt
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/SyncManager.kt
@@ -66,11 +66,12 @@ abstract class SyncManager<ResourceType: LocalResource<*>, out CollectionType: L
     val context: Context,
     val account: Account,
     val accountSettings: AccountSettings,
+    val httpClient: HttpClient,
     val extras: Bundle,
     val authority: String,
     val syncResult: SyncResult,
     val localCollection: CollectionType
-): AutoCloseable {
+) {
 
     @EntryPoint
     @InstallIn(SingletonComponent::class)
@@ -122,8 +123,6 @@ abstract class SyncManager<ResourceType: LocalResource<*>, out CollectionType: L
     protected val notificationManager = NotificationManagerCompat.from(context)
     protected val notificationTag = localCollection.tag
 
-    protected val httpClient = HttpClient.Builder(context, accountSettings).build()
-
     protected lateinit var collectionURL: HttpUrl
     protected lateinit var davCollection: RemoteType
 
@@ -132,11 +131,6 @@ abstract class SyncManager<ResourceType: LocalResource<*>, out CollectionType: L
     val workDispatcher = getWorkDispatcher()
 
 
-    override fun close() {
-        httpClient.close()
-    }
-
-
     fun performSync() {
         // dismiss previous error notifications
         notificationManager.cancel(notificationTag, NotificationUtils.NOTIFY_SYNC_ERROR)
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncAdapterService.kt b/app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncAdapterService.kt
index b6e496d5..8b03e803 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncAdapterService.kt
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncAdapterService.kt
@@ -11,6 +11,7 @@ import android.content.Context
 import android.content.SyncResult
 import android.os.Build
 import android.os.Bundle
+import at.bitfire.davdroid.HttpClient
 import at.bitfire.davdroid.db.AppDatabase
 import at.bitfire.davdroid.db.Collection
 import at.bitfire.davdroid.db.Service
@@ -37,14 +38,20 @@ open class TasksSyncAdapterService: SyncAdapterService() {
         appDatabase: AppDatabase,
     ) : SyncAdapter(context, appDatabase) {
 
-        override fun sync(account: Account, extras: Bundle, authority: String, provider: ContentProviderClient, syncResult: SyncResult) {
+        override fun sync(account: Account, extras: Bundle, authority: String, httpClient: Lazy<HttpClient>, provider: ContentProviderClient, syncResult: SyncResult) {
             try {
                 val providerName = TaskProvider.ProviderName.fromAuthority(authority)
                 val taskProvider = TaskProvider.fromProviderClient(context, providerName, provider)
 
                 // make sure account can be seen by task provider
-                if (Build.VERSION.SDK_INT >= 26)
-                    AccountManager.get(context).setAccountVisibility(account, providerName.packageName, AccountManager.VISIBILITY_VISIBLE)
+                if (Build.VERSION.SDK_INT >= 26) {
+                    /* Warning: If setAccountVisibility is called, Android 12 broadcasts the
+                       AccountManager.LOGIN_ACCOUNTS_CHANGED_ACTION Intent. This cancels running syncs
+                       and starts them again! So make sure setAccountVisibility is only called when necessary. */
+                    val am = AccountManager.get(context)
+                    if (am.getAccountVisibility(account, providerName.packageName) != AccountManager.VISIBILITY_VISIBLE)
+                        am.setAccountVisibility(account, providerName.packageName, AccountManager.VISIBILITY_VISIBLE)
+                }
 
                 val accountSettings = AccountSettings(context, account)
                 /* don't run sync if
@@ -62,7 +69,7 @@ open class TasksSyncAdapterService: SyncAdapterService() {
                         .sortedByDescending { priorityTaskLists.contains(it.id) }
                 for (taskList in taskLists) {
                     Logger.log.info("Synchronizing task list #${taskList.id} [${taskList.syncId}]")
-                    TasksSyncManager(context, account, accountSettings, extras, authority, syncResult, taskList).use {
+                    TasksSyncManager(context, account, accountSettings, httpClient.value, extras, authority, syncResult, taskList).let {
                         it.performSync()
                     }
                 }
@@ -114,4 +121,4 @@ open class TasksSyncAdapterService: SyncAdapterService() {
 
     }
 
-}
+}
\ No newline at end of file
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncManager.kt b/app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncManager.kt
index 3987c498..d1dbc363 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncManager.kt
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncManager.kt
@@ -14,6 +14,7 @@ import at.bitfire.dav4jvm.Response
 import at.bitfire.dav4jvm.exception.DavException
 import at.bitfire.dav4jvm.property.*
 import at.bitfire.davdroid.DavUtils
+import at.bitfire.davdroid.HttpClient
 import at.bitfire.davdroid.R
 import at.bitfire.davdroid.db.SyncState
 import at.bitfire.davdroid.log.Logger
@@ -40,11 +41,12 @@ class TasksSyncManager(
     context: Context,
     account: Account,
     accountSettings: AccountSettings,
+    httpClient: HttpClient,
     extras: Bundle,
     authority: String,
     syncResult: SyncResult,
     localCollection: LocalTaskList
-): SyncManager<LocalTask, LocalTaskList, DavCalendar>(context, account, accountSettings, extras, authority, syncResult, localCollection) {
+): SyncManager<LocalTask, LocalTaskList, DavCalendar>(context, account, accountSettings, httpClient, extras, authority, syncResult, localCollection) {
 
     override fun prepare(): Boolean {
         collectionURL = (localCollection.syncId ?: return false).toHttpUrlOrNull() ?: return false
diff --git a/app/src/main/res/xml/account_authenticator.xml b/app/src/main/res/xml/account_authenticator.xml
index bf6bd348..85eaa203 100644
--- a/app/src/main/res/xml/account_authenticator.xml
+++ b/app/src/main/res/xml/account_authenticator.xml
@@ -3,4 +3,4 @@
     android:icon="@mipmap/ic_launcher"
     android:label="@string/app_name"
     android:smallIcon="@mipmap/ic_launcher"
-    android:accountPreferences="@xml/sync_prefs" />
+    android:accountPreferences="@xml/sync_prefs" />
\ No newline at end of file
diff --git a/app/src/main/res/xml/account_authenticator_address_book.xml b/app/src/main/res/xml/account_authenticator_address_book.xml
index 5ad7d913..6305f31e 100644
--- a/app/src/main/res/xml/account_authenticator_address_book.xml
+++ b/app/src/main/res/xml/account_authenticator_address_book.xml
@@ -3,4 +3,4 @@
     android:icon="@mipmap/ic_launcher"
     android:label="@string/account_title_address_book"
     android:smallIcon="@mipmap/ic_launcher"
-    android:accountPreferences="@xml/sync_prefs" />
+    android:accountPreferences="@xml/sync_prefs" />
\ No newline at end of file
diff --git a/app/src/main/res/xml/sync_address_books.xml b/app/src/main/res/xml/sync_address_books.xml
index f7284820..61bfbaeb 100644
--- a/app/src/main/res/xml/sync_address_books.xml
+++ b/app/src/main/res/xml/sync_address_books.xml
@@ -2,4 +2,4 @@
     android:accountType="@string/account_type"
     android:contentAuthority="@string/address_books_authority"
     android:allowParallelSyncs="true"
-    android:supportsUploading="false" />
+    android:supportsUploading="false" />
\ No newline at end of file