wip: grdb connection pool

Author: stevensJourney

Package.resolved

@@ -7,7 +7,7 @@ let packageName = "PowerSync"
 
 // Set this to the absolute path of your Kotlin SDK checkout if you want to use a local Kotlin
 // build. Also see docs/LocalBuild.md for details
-let localKotlinSdkOverride: String? = nil
+let localKotlinSdkOverride: String? = "/Users/stevenontong/Documents/platform_code/powersync/powersync-kotlin"
 
 // Set this to the absolute path of your powersync-sqlite-core checkout if you want to use a
 // local build of the core extension.
@@ -71,9 +71,15 @@ let package = Package(
             // Dynamic linking is particularly important for XCode previews.
             type: .dynamic,
             targets: ["PowerSync"]
+        ),
+        .library(
+            name: "PowerSyncGRDB",
+            targets: ["PowerSyncGRDB"]
         )
     ],
-    dependencies: conditionalDependencies,
+    dependencies: conditionalDependencies + [
+        .package(url: "https://github.com/groue/GRDB.swift.git", from: "6.0.0")
+    ],
     targets: [
         // Targets are the basic building blocks of a package, defining a module or a test suite.
         // Targets can depend on other targets in this package and products from dependencies.
@@ -84,9 +90,20 @@ let package = Package(
                 .product(name: "PowerSyncSQLiteCore", package: corePackageName)
             ]
         ),
+        .target(
+            name: "PowerSyncGRDB",
+            dependencies: [
+                .target(name: "PowerSync"),
+                .product(name: "GRDB", package: "GRDB.swift")
+            ]
+        ),
         .testTarget(
             name: "PowerSyncTests",
             dependencies: ["PowerSync"]
+        ),
+        .testTarget(
+            name: "PowerSyncGRDBTests",
+            dependencies: ["PowerSync", "PowerSyncGRDB"]
         )
     ] + conditionalTargets
 )

Package.swift

@@ -11,18 +11,11 @@ final class KotlinPowerSyncDatabaseImpl: PowerSyncDatabaseProtocol,
     let currentStatus: SyncStatus
 
     init(
-        schema: Schema,
-        dbFilename: String,
+        kotlinDatabase: PowerSyncKotlin.PowerSyncDatabase,
         logger: DatabaseLogger
     ) {
-        let factory = PowerSyncKotlin.DatabaseDriverFactory()
-        kotlinDatabase = PowerSyncDatabase(
-            factory: factory,
-            schema: KotlinAdapter.Schema.toKotlin(schema),
-            dbFilename: dbFilename,
-            logger: logger.kLogger
-        )
         self.logger = logger
+        self.kotlinDatabase = kotlinDatabase
         currentStatus = KotlinSyncStatus(
             baseStatus: kotlinDatabase.currentStatus
         )
@@ -401,6 +394,39 @@ final class KotlinPowerSyncDatabaseImpl: PowerSyncDatabaseProtocol,
     }
 }
 
+func openKotlinDBWithFactory(
+    schema: Schema,
+    dbFilename: String,
+    logger: DatabaseLogger
+) -> PowerSyncDatabaseProtocol {
+    return KotlinPowerSyncDatabaseImpl(
+        kotlinDatabase: PowerSyncDatabase(
+            factory: PowerSyncKotlin.DatabaseDriverFactory(),
+            schema: KotlinAdapter.Schema.toKotlin(schema),
+            dbFilename: dbFilename,
+            logger: logger.kLogger
+        ),
+        logger: logger
+    )
+}
+
+func openKotlinDBWithPool(
+    schema: Schema,
+    pool: SQLiteConnectionPoolProtocol,
+    identifier: String,
+    logger: DatabaseLogger
+) -> PowerSyncDatabaseProtocol {
+    return KotlinPowerSyncDatabaseImpl(
+        kotlinDatabase: openPowerSyncWithPool(
+            pool: pool.toKotlin(),
+            identifier: identifier,
+            schema: KotlinAdapter.Schema.toKotlin(schema),
+            logger: logger.kLogger
+        ),
+        logger: logger
+    )
+}
+
 private struct ExplainQueryResult {
     let addr: String
     let opcode: String

Sources/PowerSync/Kotlin/KotlinPowerSyncDatabaseImpl.swift

@@ -0,0 +1,62 @@
+import PowerSyncKotlin
+
+final class SwiftSQLiteConnectionPoolAdapter: PowerSyncKotlin.SwiftPoolAdapter {
+    let pool: SQLiteConnectionPoolProtocol
+
+    init(
+        pool: SQLiteConnectionPoolProtocol
+    ) {
+        self.pool = pool
+    }
+
+    func __closePool() async throws {
+        do {
+            try pool.close()
+        } catch {
+            try? PowerSyncKotlin.throwPowerSyncException(
+                exception: PowerSyncException(
+                    message: error.localizedDescription,
+                    cause: nil
+                )
+            )
+        }
+    }
+
+    func __leaseRead(callback: @escaping (Any) -> Void) async throws {
+        do {
+            try await pool.read { pointer in
+                callback(pointer)
+            }
+        } catch {
+            try? PowerSyncKotlin.throwPowerSyncException(
+                exception: PowerSyncException(
+                    message: error.localizedDescription,
+                    cause: nil
+                )
+            )
+        }
+    }
+
+    func __leaseWrite(callback: @escaping (Any) -> Void) async throws {
+        do {
+            try await pool.write { pointer in
+                callback(pointer)
+            }
+        } catch {
+            try? PowerSyncKotlin.throwPowerSyncException(
+                exception: PowerSyncException(
+                    message: error.localizedDescription,
+                    cause: nil
+                )
+            )
+        }
+    }
+}
+
+extension SQLiteConnectionPoolProtocol {
+    func toKotlin() -> PowerSyncKotlin.SwiftSQLiteConnectionPool {
+        return PowerSyncKotlin.SwiftSQLiteConnectionPool(
+            adapter: SwiftSQLiteConnectionPoolAdapter(pool: self)
+        )
+    }
+}

Sources/PowerSync/Kotlin/KotlinSQLiteConnectionPool.swift

@@ -14,10 +14,23 @@ public func PowerSyncDatabase(
     dbFilename: String = DEFAULT_DB_FILENAME,
     logger: (any LoggerProtocol) = DefaultLogger()
 ) -> PowerSyncDatabaseProtocol {
-    
-    return KotlinPowerSyncDatabaseImpl(
+    return openKotlinDBWithFactory(
         schema: schema,
         dbFilename: dbFilename,
         logger: DatabaseLogger(logger)
     )
 }
+
+public func OpenedPowerSyncDatabase(
+    schema: Schema,
+    pool: any SQLiteConnectionPoolProtocol,
+    identifier: String,
+    logger: (any LoggerProtocol) = DefaultLogger()
+) -> PowerSyncDatabaseProtocol {
+    return openKotlinDBWithPool(
+        schema: schema,
+        pool: pool,
+        identifier: identifier,
+        logger: DatabaseLogger(logger)
+    )
+}

Sources/PowerSync/PowerSyncDatabase.swift

@@ -0,0 +1,26 @@
+import Foundation
+
+/// An implementation of a connection pool providing asynchronous access to a single writer and multiple readers.
+/// This is the underlying pool implementation on which the higher-level PowerSync Swift SDK is built on.
+public protocol SQLiteConnectionPoolProtocol {
+    /// Calls the callback with a read-only connection temporarily leased from the pool.
+    func read(
+        onConnection: @Sendable @escaping (OpaquePointer) -> Void,
+    ) async throws
+
+    /// Calls the callback with a read-write connection temporarily leased from the pool.
+    func write(
+        onConnection: @Sendable @escaping (OpaquePointer) -> Void,
+    ) async throws
+
+    /// Invokes the callback with all connections leased from the pool.
+    func withAllConnections(
+        onConnection: @escaping (
+            _ writer: OpaquePointer,
+            _ readers: [OpaquePointer]
+        ) -> Void,
+    ) async throws
+
+    /// Closes the connection pool and associated resources.
+    func close() throws
+}

Sources/PowerSync/Protocol/SQLiteConnectionPool.swift

@@ -0,0 +1,89 @@
+import Foundation
+import GRDB
+import PowerSync
+import SQLite3
+
+// The system SQLite does not expose this,
+// linking PowerSync provides them
+// Declare the missing function manually
+@_silgen_name("sqlite3_enable_load_extension")
+func sqlite3_enable_load_extension(_ db: OpaquePointer?, _ onoff: Int32) -> Int32
+
+// Similarly for sqlite3_load_extension if needed:
+@_silgen_name("sqlite3_load_extension")
+func sqlite3_load_extension(_ db: OpaquePointer?, _ fileName: UnsafePointer<Int8>?, _ procName: UnsafePointer<Int8>?, _ errMsg: UnsafeMutablePointer<UnsafeMutablePointer<Int8>?>?) -> Int32
+
+enum PowerSyncGRDBConfigError: Error {
+    case bundleNotFound
+    case extensionLoadFailed(String)
+    case unknownExtensionLoadError
+}
+
+func configurePowerSync(_ config: inout Configuration) {
+    config.prepareDatabase { database in
+        guard let bundle = Bundle(identifier: "co.powersync.sqlitecore") else {
+            throw PowerSyncGRDBConfigError.bundleNotFound
+        }
+
+        // Construct the full path to the shared library inside the bundle
+        let fullPath = bundle.bundlePath + "/powersync-sqlite-core"
+
+        let rc = sqlite3_enable_load_extension(database.sqliteConnection, 1)
+        if rc != SQLITE_OK {
+            throw PowerSyncGRDBConfigError.extensionLoadFailed("Could not enable extension loading")
+        }
+        var errorMsg: UnsafeMutablePointer<Int8>?
+        let loadResult = sqlite3_load_extension(database.sqliteConnection, fullPath, "sqlite3_powersync_init", &errorMsg)
+        if loadResult != SQLITE_OK {
+            if let errorMsg = errorMsg {
+                let message = String(cString: errorMsg)
+                sqlite3_free(errorMsg)
+                throw PowerSyncGRDBConfigError.extensionLoadFailed(message)
+            } else {
+                throw PowerSyncGRDBConfigError.unknownExtensionLoadError
+            }
+        }
+    }
+}
+
+class GRDBConnectionPool: SQLiteConnectionPoolProtocol {
+    let pool: DatabasePool
+
+    init(
+        pool: DatabasePool
+    ) {
+        self.pool = pool
+    }
+
+    func read(
+        onConnection: @Sendable @escaping (OpaquePointer) -> Void
+    ) async throws {
+        try await pool.read { database in
+            guard let connection = database.sqliteConnection else {
+                return
+            }
+            onConnection(connection)
+        }
+    }
+
+    func write(
+        onConnection: @Sendable @escaping (OpaquePointer) -> Void
+    ) async throws {
+        try await pool.write { database in
+            guard let connection = database.sqliteConnection else {
+                return
+            }
+            onConnection(connection)
+        }
+    }
+
+    func withAllConnections(
+        onConnection _: @escaping (OpaquePointer, [OpaquePointer]) -> Void
+    ) async throws {
+        // TODO:
+    }
+
+    func close() throws {
+        try pool.close()
+    }
+}

Sources/PowerSyncGRDB/GRDBPool.swift

@@ -0,0 +1,57 @@
+@testable import GRDB
+@testable import PowerSync
+@testable import PowerSyncGRDB
+
+import XCTest
+
+final class GRDBTests: XCTestCase {
+    private var database: PowerSyncDatabaseProtocol!
+    private var schema: Schema!
+
+    override func setUp() async throws {
+        try await super.setUp()
+        schema = Schema(tables: [
+            Table(name: "users", columns: [
+                .text("count"),
+                .integer("is_active"),
+                .real("weight"),
+                .text("description")
+            ])
+        ])
+
+        var config = Configuration()
+        configurePowerSync(&config)
+
+        let documentsDir = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
+        let dbURL = documentsDir.appendingPathComponent("test.sqlite")
+        let pool = try DatabasePool(
+            path: dbURL.path,
+            configuration: config
+        )
+
+        database = OpenedPowerSyncDatabase(
+            schema: schema,
+            pool: GRDBConnectionPool(
+                pool: pool
+            ),
+            identifier: "test"
+        )
+
+        try await database.disconnectAndClear()
+    }
+
+    override func tearDown() async throws {
+        try await database.disconnectAndClear()
+        database = nil
+        try await super.tearDown()
+    }
+
+    func testValidValues() async throws {
+        let result = try await database.get(
+            "SELECT powersync_rs_version as r"
+        ) { cursor in
+            try cursor.getString(index: 0)
+        }
+        print(result)
+    }
+}

Tests/PowerSyncGRDBTests/BasicTest.swift

@@ -18,7 +18,7 @@ final class ConnectTests: XCTestCase {
             ),
         ])
 
-        database = KotlinPowerSyncDatabaseImpl(
+        database = openKotlinDBWithFactory(
             schema: schema,
             dbFilename: ":memory:",
             logger: DatabaseLogger(DefaultLogger())