CBL-6066: Implement Database Full-Sync Option (#3317)

- Implemented FullSync DatabaseConfiguration property.
- Only Obj-C tests do check for c4db_config2 kC4DB_DiskSyncFull flag

Objective-C/CBLDatabase.mm

@@ -1024,6 +1024,8 @@ static BOOL setupDatabaseDirectory(NSString *dir, NSError **outError)
 static C4DatabaseConfig2 c4DatabaseConfig2 (CBLDatabaseConfiguration *config) {
     C4DatabaseConfig2 c4config = kDBConfig;
 
+    if (config.fullSync)
+        c4config.flags |= kC4DB_DiskSyncFull;
 #ifdef COUCHBASE_ENTERPRISE
     if (config.encryptionKey)
         c4config.encryptionKey = [CBLDatabase c4EncryptionKey: config.encryptionKey];
@@ -1139,4 +1141,10 @@ - (uint64_t) activeStoppableCount {
     }
 }
 
+#pragma mark - Private for test
+
+- (const C4DatabaseConfig2*) getC4DBConfig {
+    return c4db_getConfig2(_c4db);
+}
+
 @end

Objective-C/CBLDatabaseConfiguration.h

@@ -30,6 +30,19 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property (nonatomic, copy) NSString* directory;
 
+/** 
+ As Couchbase Lite normally configures its databases, there is a very
+ small (though non-zero) chance that a power failure at just the wrong
+ time could cause the most recently committed transaction's changes to
+ be lost. This would cause the database to appear as it did immediately
+ before that transaction.
+ 
+ Setting this mode true ensures that an operating system crash or
+ power failure will not cause the loss of any data. FULL synchronous
+ is very safe but it is also dramatically slower.
+ */
+@property (nonatomic) BOOL fullSync;
+
 /**
  Initializes the CBLDatabaseConfiguration object.
  */

Objective-C/CBLDatabaseConfiguration.m

@@ -19,12 +19,13 @@
 
 #import "CBLDatabaseConfiguration.h"
 #import "CBLDatabase+Internal.h"
+#import "CBLDefaults.h"
 
 @implementation CBLDatabaseConfiguration {
     BOOL _readonly;
 }
 
-@synthesize directory=_directory;
+@synthesize directory=_directory, fullSync=_fullSync;
 
 #ifdef COUCHBASE_ENTERPRISE
 @synthesize encryptionKey=_encryptionKey;
@@ -47,11 +48,14 @@ - (instancetype) initWithConfig: (nullable CBLDatabaseConfiguration*)config
 
         if (config) {
             _directory = config.directory;
+            _fullSync = config.fullSync;
 #ifdef COUCHBASE_ENTERPRISE
             _encryptionKey = config.encryptionKey;
 #endif
-        } else
+        } else {
             _directory = [CBLDatabaseConfiguration defaultDirectory];
+            _fullSync = kCBLDefaultDatabaseFullSync;
+        }
     }
     return self;
 }

Objective-C/CBLDefaults.h

@@ -28,6 +28,11 @@
 
 #endif
 
+#pragma mark - CBLDatabaseConfiguration
+
+/** [NO] Full sync is off by default because the performance hit is seldom worth the benefit */
+extern const BOOL kCBLDefaultDatabaseFullSync;
+
 #pragma mark - CBLLogFileConfiguration
 
 /** [NO] Plaintext is not used, and instead binary encoding is used in log files */

Objective-C/CBLDefaults.m

@@ -22,6 +22,10 @@
 
 #import "CBLDefaults.h"
 
+#pragma mark - CBLDatabaseConfiguration
+
+const BOOL kCBLDefaultDatabaseFullSync = NO;
+
 #pragma mark - CBLLogFileConfiguration
 
 const BOOL kCBLDefaultLogFileUsePlaintext = NO;

Objective-C/Exports/CBL.txt

@@ -91,6 +91,7 @@ _kCBLBlobContentTypeProperty
 _kCBLBlobDigestProperty
 _kCBLBlobLengthProperty
 _kCBLBlobType
+_kCBLDefaultDatabaseFullSync
 _kCBLDefaultCollectionName
 _kCBLDefaultFullTextIndexIgnoreAccents
 _kCBLDefaultLogFileMaxRotateCount

Objective-C/Exports/Generated/CBL.exp

@@ -71,6 +71,7 @@ _kCBLBlobDigestProperty
 _kCBLBlobLengthProperty
 _kCBLBlobType
 _kCBLDefaultCollectionName
+_kCBLDefaultDatabaseFullSync
 _kCBLDefaultFullTextIndexIgnoreAccents
 _kCBLDefaultLogFileMaxRotateCount
 _kCBLDefaultLogFileMaxSize

Objective-C/Exports/Generated/CBL_EE.exp

@@ -109,6 +109,7 @@ _kCBLCertAttrStateOrProvince
 _kCBLCertAttrSurname
 _kCBLCertAttrURL
 _kCBLDefaultCollectionName
+_kCBLDefaultDatabaseFullSync
 _kCBLDefaultFullTextIndexIgnoreAccents
 _kCBLDefaultListenerDisableTls
 _kCBLDefaultListenerEnableDeltaSync

Objective-C/Internal/CBLDatabase+Internal.h

@@ -46,7 +46,6 @@ NS_ASSUME_NONNULL_BEGIN
 
 /// CBLDatabase:
 
-
 @interface CBLDatabase () <CBLLockable, CBLRemovableListenerToken>
 
 @property (readonly, nonatomic, nullable) C4Database* c4db;
@@ -80,6 +79,10 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (id) mutex;
 
+#pragma mark - Private for test
+
+- (const C4DatabaseConfig2*) getC4DBConfig;
+
 @end
 
 /// CBLDatabaseConfiguration:

Objective-C/Tests/DatabaseTest.m

@@ -2818,6 +2818,79 @@ - (void) testDBEventTrigged {
     [token remove];
 }
 
+#pragma mark - Full Sync Option
+
+/** 
+ Test Spec for Database Full Sync Option https://github.com/couchbaselabs/couchbase-lite-api/blob/master/spec/tests/T0003-SQLite-Options.md
+ */
+
+/**
+ 1. TestSQLiteFullSyncConfig
+ Description
+    Test that the FullSync default is as expected and that it's setter and getter work.
+ Steps
+    1. Create a DatabaseConfiguration object.
+    2. Get and check the value of the FullSync property: it should be false.
+    3. Set the FullSync property true.
+    4. Get the config FullSync property and verify that it is true.
+    5. Set the FullSync property false.
+    6. Get the config FullSync property and verify that it is false.
+ */
+- (void) testSQLiteFullSyncConfig {
+    CBLDatabaseConfiguration* config = [[CBLDatabaseConfiguration alloc] init];
+    AssertFalse(config.fullSync);
+
+    config.fullSync = true;
+    Assert(config.fullSync);
+
+    config.fullSync = false;
+    AssertFalse(config.fullSync);
+}
+
+/**
+ 2. TestDBWithFullSync
+ Description
+    Test that a Database respects the FullSync property.
+ Steps
+    1. Create a DatabaseConfiguration object and set Full Sync false.
+    2. Create a database with the config.
+    3. Get the configuration object from the Database and verify that FullSync is false.
+    4. Use c4db_config2 (perhaps necessary only for this test) to confirm that its config does not contain the kC4DB_DiskSyncFull flag.
+    5. Set the config's FullSync property true.
+    6. Create a database with the config.
+    7. Get the configuration object from the Database and verify that FullSync is true.
+    8. Use c4db_config2 to confirm that its config contains the kC4DB_DiskSyncFull flag.
+ */
+- (void) testDBWithFullSync {
+    NSString* dbName = @"fullsyncdb";
+    [CBLDatabase deleteDatabase: dbName inDirectory: self.directory error: nil];
+    AssertFalse([CBLDatabase databaseExists: dbName inDirectory: self.directory]);
+
+    CBLDatabaseConfiguration* config = [[CBLDatabaseConfiguration alloc] init];
+    config.directory = self.directory;
+    NSError* error;
+    CBLDatabase* db = [[CBLDatabase alloc] initWithName: dbName
+                                                 config: config
+                                                  error: &error];
+    AssertNil(error);
+    AssertNotNil(db, @"Couldn't open db: %@", error);
+    AssertFalse([db config].fullSync);
+    AssertFalse(([db getC4DBConfig]->flags & kC4DB_DiskSyncFull) == kC4DB_DiskSyncFull);
+
+    [self closeDatabase: db];
+
+    config.fullSync = true;
+    db = [[CBLDatabase alloc] initWithName: dbName
+                                    config: config
+                                     error: &error];
+    AssertNil(error);
+    AssertNotNil(db, @"Couldn't open db: %@", error);
+    Assert([db config].fullSync);
+    Assert(([db getC4DBConfig]->flags & kC4DB_DiskSyncFull) == kC4DB_DiskSyncFull);
+
+    [self closeDatabase: db];
+}
+
 #pragma clang diagnostic pop
 
 @end

Swift/DatabaseConfiguration.swift

@@ -2,7 +2,7 @@
 //  DatabaseConfiguration.swift
 //  CouchbaseLite
 //
-//  Copyright (c) 2017 Couchbase, Inc All rights reserved.
+//  Copyright (c) 2024 Couchbase, Inc All rights reserved.
 //
 //  Licensed under the Apache License, Version 2.0 (the "License");
 //  you may not use this file except in compliance with the License.
@@ -27,6 +27,17 @@ public struct DatabaseConfiguration {
     /// Path to the directory to store the database in.
     public var directory: String = CBLDatabaseConfiguration().directory
 
+    /// As Couchbase Lite normally configures its databases, There is a very
+    /// small (though non-zero) chance that a power failure at just the wrong
+    /// time could cause the most recently committed transaction's changes to
+    /// be lost. This would cause the database to appear as it did immediately
+    /// before that transaction.
+    ///
+    /// Setting this mode true ensures that an operating system crash or
+    /// power failure will not cause the loss of any data.  FULL synchronous
+    /// is very safe but it is also dramatically slower.
+    public var fullSync: Bool = defaultFullSync
+
     #if COUCHBASE_ENTERPRISE
     /// The key to encrypt the database with.
     public var encryptionKey: EncryptionKey?
@@ -41,6 +52,7 @@ public struct DatabaseConfiguration {
     public init(config: DatabaseConfiguration?) {
         if let c = config {
             self.directory = c.directory
+            self.fullSync = c.fullSync
             #if COUCHBASE_ENTERPRISE
             self.encryptionKey = c.encryptionKey
             #endif
@@ -52,6 +64,7 @@ public struct DatabaseConfiguration {
     func toImpl() -> CBLDatabaseConfiguration {
         let config = CBLDatabaseConfiguration()
         config.directory = self.directory
+        config.fullSync = self.fullSync
         #if COUCHBASE_ENTERPRISE
         config.encryptionKey = self.encryptionKey?.impl
         #endif

Swift/Tests/DatabaseTest.swift

@@ -2,7 +2,7 @@
 //  DatabaseTest.swift
 //  CouchbaseLite
 //
-//  Copyright (c) 2017 Couchbase, Inc All rights reserved.
+//  Copyright (c) 2024 Couchbase, Inc All rights reserved.
 //
 //  Licensed under the Apache License, Version 2.0 (the "License");
 //  you may not use this file except in compliance with the License.
@@ -1529,4 +1529,57 @@ class DatabaseTest: CBLTestCase {
         XCTAssertNotNil(db.config.encryptionKey)
         #endif
     }
+
+    // MARK: Full Sync Option
+    /// Test Spec for Database Full Sync Option
+    /// https://github.com/couchbaselabs/couchbase-lite-api/blob/master/spec/tests/T0003-SQLite-Options.md
+
+    /// 1. TestSQLiteFullSyncConfig
+    /// Description:
+    ///     Test that the FullSync default is as expected and that it's setter and getter work.
+    /// Steps
+    ///     1. Create a DatabaseConfiguration object.
+    ///     2. Get and check the value of the FullSync property: it should be false.
+    ///     3. Set the FullSync property true.
+    ///     4. Get the config FullSync property and verify that it is true.
+    ///     5. Set the FullSync property false.
+    ///     6. Get the config FullSync property and verify that it is false.
+    func testSQLiteFullSyncConfig() {
+        var config = DatabaseConfiguration()
+        XCTAssertFalse(config.fullSync)
+
+        config.fullSync = true
+        XCTAssert(config.fullSync)
+
+        config.fullSync = false
+        XCTAssertFalse(config.fullSync)
+    }
+
+    /// 2. TestDBWithFullSync
+    /// Description:
+    ///     Test that the FullSync default is as expected and that it's setter and getter work.
+    /// Steps
+    ///     1. Create a DatabaseConfiguration object and set Full Sync false.
+    ///     2. Create a database with the config.
+    ///     3. Get the configuration object from the Database and verify that FullSync is false.
+    ///     4. Use c4db_config2 (perhaps necessary only for this test) to confirm that its config does not contain the kC4DB_DiskSyncFull flag. - done in Obj-C
+    ///     5. Set the config's FullSync property true.
+    ///     6. Create a database with the config.
+    ///     7. Get the configuration object from the Database and verify that FullSync is true.
+    ///     8. Use c4db_config2 to confirm that its config contains the kC4DB_DiskSyncFull flag. - done in Obj-C
+    func testDBWithFullSync() throws {
+        let dbName = "fullsyncdb"
+        try deleteDB(name: dbName)
+        XCTAssertFalse(Database.exists(withName: dbName, inDirectory: self.directory))
+
+        var config = DatabaseConfiguration()
+        config.directory = self.directory
+        db = try Database(name: dbName, config: config)
+        XCTAssertFalse(DatabaseConfiguration(config: config).fullSync)
+
+        db = nil
+        config.fullSync = true
+        db = try Database(name: dbName, config: config)
+        XCTAssert(DatabaseConfiguration(config: config).fullSync)
+    }
 }