Automatic ios memory management

CHANGELOG.md

@@ -66,6 +66,7 @@ GRDB adheres to [Semantic Versioning](https://semver.org/), with one exception:
 ### New
 
 - [#706](https://github.com/groue/GRDB.swift/pull/706): Enhance SQLLiteral and SQL interpolation again
+- [#712](https://github.com/groue/GRDB.swift/pull/712) by [@pakko972](https://github.com/pakko972): Automatic iOS memory management
 
 ### Breaking Change
 

Documentation/DemoApps/GRDBDemoiOS/GRDBDemoiOS/AppDelegate.swift

@@ -18,9 +18,5 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
             .url(for: .applicationSupportDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
             .appendingPathComponent("db.sqlite")
         dbQueue = try AppDatabase.openDatabase(atPath: databaseURL.path)
-
-        // Be a nice iOS citizen, and don't consume too much memory
-        // See https://github.com/groue/GRDB.swift/blob/master/README.md#memory-management
-        dbQueue.setupMemoryManagement(in: application)
     }
 }

GRDB/Core/DatabasePool.swift

@@ -24,10 +24,6 @@ public final class DatabasePool: DatabaseWriter {
 
     var databaseSnapshotCount = LockedBox(value: 0)
 
-    #if os(iOS)
-    private weak var application: UIApplication?
-    #endif
-
     // MARK: - Database Information
 
     /// The path to the database.
@@ -138,10 +134,16 @@ public final class DatabasePool: DatabaseWriter {
         }
 
         setupSuspension()
+
+        // Be a nice iOS citizen, and don't consume too much memory
+        // See https://github.com/groue/GRDB.swift/#memory-management
+        #if os(iOS)
+        setupAutomaticMemoryManagement()
+        #endif
     }
 
     deinit {
-        // Undo job done in setupMemoryManagement()
+        // Undo job done in setupAutomaticMemoryManagement()
         //
         // https://developer.apple.com/library/mac/releasenotes/Foundation/RN-Foundation/index.html#10_11Error
         // Explicit unregistration is required before iOS 9 and OS X 10.11.
@@ -194,8 +196,6 @@ extension DatabasePool {
     ///
     /// This method blocks the current thread until all database accesses
     /// are completed.
-    ///
-    /// See also setupMemoryManagement(application:)
     public func releaseMemory() {
         // Release writer memory
         writer.sync { $0.releaseMemory() }
@@ -207,15 +207,20 @@ extension DatabasePool {
 
 
     #if os(iOS)
+    // swiftlint:disable:next line_length
+    @available(*, deprecated, message: "Memory management is now enabled by default. This deprecated method does nothing.")
+    public func setupMemoryManagement(in application: UIApplication) {
+        // No op.
+    }
+
     /// Listens to UIApplicationDidEnterBackgroundNotification and
     /// UIApplicationDidReceiveMemoryWarningNotification in order to release
     /// as much memory as possible.
     ///
     /// - param application: The UIApplication that will start a background
     ///   task to let the database pool release its memory when the application
     ///   enters background.
-    public func setupMemoryManagement(in application: UIApplication) {
-        self.application = application
+    private func setupAutomaticMemoryManagement() {
         let center = NotificationCenter.default
         center.addObserver(
             self,
@@ -231,7 +236,7 @@ extension DatabasePool {
 
     @objc
     private func applicationDidEnterBackground(_ notification: NSNotification) {
-        guard let application = application else {
+        guard let application = notification.object as? UIApplication else {
             return
         }
 

GRDB/Core/DatabaseQueue.swift

@@ -7,9 +7,6 @@ import UIKit
 /// A DatabaseQueue serializes access to an SQLite database.
 public final class DatabaseQueue: DatabaseWriter {
     private var writer: SerializedDatabase
-    #if os(iOS)
-    private weak var application: UIApplication?
-    #endif
 
     // MARK: - Configuration
 
@@ -43,6 +40,12 @@ public final class DatabaseQueue: DatabaseWriter {
             defaultLabel: "GRDB.DatabaseQueue")
 
         setupSuspension()
+
+        // Be a nice iOS citizen, and don't consume too much memory
+        // See https://github.com/groue/GRDB.swift/#memory-management
+        #if os(iOS)
+        setupAutomaticMemoryManagement()
+        #endif
     }
 
     /// Opens an in-memory SQLite database.
@@ -62,7 +65,7 @@ public final class DatabaseQueue: DatabaseWriter {
     }
 
     deinit {
-        // Undo job done in setupMemoryManagement()
+        // Undo job done in setupAutomaticMemoryManagement()
         //
         // https://developer.apple.com/library/mac/releasenotes/Foundation/RN-Foundation/index.html#10_11Error
         // Explicit unregistration is required before iOS 9 and OS X 10.11.
@@ -77,22 +80,25 @@ extension DatabaseQueue {
     /// Free as much memory as possible.
     ///
     /// This method blocks the current thread until all database accesses are completed.
-    ///
-    /// See also setupMemoryManagement(application:)
     public func releaseMemory() {
         writer.sync { $0.releaseMemory() }
     }
 
     #if os(iOS)
+    // swiftlint:disable:next line_length
+    @available(*, deprecated, message: "Memory management is now enabled by default. This deprecated method does nothing.")
+    public func setupMemoryManagement(in application: UIApplication) {
+        // No op.
+    }
+
     /// Listens to UIApplicationDidEnterBackgroundNotification and
     /// UIApplicationDidReceiveMemoryWarningNotification in order to release
     /// as much memory as possible.
     ///
     /// - param application: The UIApplication that will start a background
     ///   task to let the database queue release its memory when the application
     ///   enters background.
-    public func setupMemoryManagement(in application: UIApplication) {
-        self.application = application
+    private func setupAutomaticMemoryManagement() {
         let center = NotificationCenter.default
         center.addObserver(
             self,
@@ -108,7 +114,7 @@ extension DatabaseQueue {
 
     @objc
     private func applicationDidEnterBackground(_ notification: NSNotification) {
-        guard let application = application else {
+        guard let application = notification.object as? UIApplication else {
             return
         }
 

Makefile

@@ -49,7 +49,14 @@ endif
 TEST_ACTIONS = clean build build-for-testing test-without-building
 
 # When adding support for an Xcode version, look for available devices with `instruments -s devices`
-ifeq ($(XCODEVERSION),11.3)
+ifeq ($(XCODEVERSION),11.4)
+  MAX_SWIFT_VERSION = 5.2
+  MIN_SWIFT_VERSION = 4.2
+  MAX_IOS_DESTINATION = "platform=iOS Simulator,name=iPhone 11,OS=13.4"
+  MIN_IOS_DESTINATION = "platform=iOS Simulator,name=iPhone 5,OS=10.3.1"
+  MAX_TVOS_DESTINATION = "platform=tvOS Simulator,name=Apple TV 4K,OS=13.4"
+  MIN_TVOS_DESTINATION = "platform=tvOS Simulator,name=Apple TV,OS=10.2"
+else ifeq ($(XCODEVERSION),11.3)
   MAX_SWIFT_VERSION = 5.1
   MIN_SWIFT_VERSION = 4.2
   MAX_IOS_DESTINATION = "platform=iOS Simulator,name=iPhone 11,OS=13.3"

README.md

@@ -7147,12 +7147,7 @@ This method blocks the current thread until all current database accesses are co
 
 **The iOS operating system likes applications that do not consume much memory.**
 
-[Database queues](#database-queues) and [pools](#database-pools) can call the `releaseMemory` method for you, when application receives memory warnings, and when application enters background: call the `setupMemoryManagement` method after creating the queue or pool instance:
-
-```
-let dbQueue = try DatabaseQueue(...)
-dbQueue.setupMemoryManagement(in: UIApplication.shared)
-```
+[Database queues](#database-queues) and [pools](#database-pools) automatically call the `releaseMemory` method when the application receives a memory warning, and when the application enters background.
 
 
 ## Data Protection