[SPARK-51967] Use discardableResult to prevent unnecessary warnings

Sources/SparkConnect/Catalog.swift

@@ -114,7 +114,7 @@ public actor Catalog: Sendable {
       catalog.catType = .setCurrentCatalog(setCurrentCatalog)
       return catalog
     })
-    _ = try await df.count()
+    try await df.count()
   }
 
   /// Returns a list of catalogs in this session.
@@ -156,7 +156,7 @@ public actor Catalog: Sendable {
       catalog.catType = .setCurrentDatabase(setCurrentDatabase)
       return catalog
     })
-    _ = try await df.count()
+    try await df.count()
   }
 
   /// Returns a list of databases available across all sessions.

Sources/SparkConnect/DataFrame.swift

@@ -136,6 +136,7 @@ public actor DataFrame: Sendable {
 
   /// Return the total number of rows.
   /// - Returns: a `Int64` value.
+  @discardableResult
   public func count() async throws -> Int64 {
     let counter = Atomic(Int64(0))
 
@@ -440,6 +441,7 @@ public actor DataFrame: Sendable {
 
   /// Persist this `DataFrame` with the given storage level.
   /// - Parameter storageLevel: A storage level to apply.
+  @discardableResult
   public func persist(storageLevel: StorageLevel = StorageLevel.MEMORY_AND_DISK) async throws
     -> DataFrame
   {
@@ -456,6 +458,7 @@ public actor DataFrame: Sendable {
   /// This will not un-persist any cached data that is built upon this `DataFrame`.
   /// - Parameter blocking: Whether to block until all blocks are deleted.
   /// - Returns: A `DataFrame`
+  @discardableResult
   public func unpersist(blocking: Bool = false) async throws -> DataFrame {
     try await withGPRC { client in
       let service = Spark_Connect_SparkConnectService.Client(wrapping: client)

Sources/SparkConnect/DataFrameReader.swift

@@ -85,10 +85,11 @@ public actor DataFrameReader: Sendable {
   /// the schema inference step, and thus speed up data loading.
   /// - Parameter schema: A DDL schema string.
   /// - Returns: A `DataFrameReader`.
+  @discardableResult
   public func schema(_ schema: String) async throws -> DataFrameReader {
     // Validate by parsing.
     do {
-      _ = try await sparkSession.client.ddlParse(schema)
+      try await sparkSession.client.ddlParse(schema)
     } catch {
       throw SparkConnectError.InvalidTypeException
     }

Sources/SparkConnect/DataFrameWriter.swift

@@ -177,7 +177,7 @@ public actor DataFrameWriter: Sendable {
     var command = Spark_Connect_Command()
     command.writeOperation = write
 
-    _ = try await df.spark.client.execute(df.spark.sessionID, command)
+    try await df.spark.client.execute(df.spark.sessionID, command)
   }
 
   /// Saves the content of the `DataFrame` in CSV format at the specified path.

Sources/SparkConnect/DataFrameWriterV2.swift

@@ -147,6 +147,6 @@ public actor DataFrameWriterV2: Sendable {
 
     var command = Spark_Connect_Command()
     command.writeOperationV2 = write
-    _ = try await df.spark.client.execute(df.spark.sessionID, command)
+    try await df.spark.client.execute(df.spark.sessionID, command)
   }
 }

Sources/SparkConnect/RuntimeConf.swift

@@ -32,14 +32,14 @@ public actor RuntimeConf {
   ///   - key: A string for the configuration key.
   ///   - value: A string for the configuration value.
   public func set(_ key: String, _ value: String) async throws {
-    _ = try await client.setConf(map: [key: value])
+    try await client.setConf(map: [key: value])
   }
 
   /// Reset a configuration.
   /// - Parameters:
   ///   - key: A string for the configuration key.
   public func unset(_ key: String) async throws {
-    _ = try await client.unsetConf(keys: [key])
+    try await client.unsetConf(keys: [key])
   }
 
   /// Get a configuration.

Sources/SparkConnect/SparkConnectClient.swift

@@ -87,6 +87,7 @@ public actor SparkConnectClient {
   /// As a test connection, this sends the server `SparkVersion` request.
   /// - Parameter sessionID: A string for the session ID.
   /// - Returns: An `AnalyzePlanResponse` instance for `SparkVersion`
+  @discardableResult
   func connect(_ sessionID: String) async throws -> AnalyzePlanResponse {
     try await withGPRC { client in
       // To prevent server-side `INVALID_HANDLE.FORMAT (SQLSTATE: HY000)` exception.
@@ -137,14 +138,15 @@ public actor SparkConnectClient {
   /// Request the server to set a map of configurations for this session.
   /// - Parameter map: A map of key-value pairs to set.
   /// - Returns: Always return true.
+  @discardableResult
   func setConf(map: [String: String]) async throws -> Bool {
     try await withGPRC { client in
       let service = SparkConnectService.Client(wrapping: client)
       var request = getConfigRequestSet(map: map)
       request.clientType = clientType
       request.userContext = userContext
       request.sessionID = self.sessionID!
-      let _ = try await service.config(request)
+      _ = try await service.config(request)
       return true
     }
   }
@@ -160,7 +162,11 @@ public actor SparkConnectClient {
     request.operation.opType = .unset(unset)
     return request
   }
-
+
+  /// Request the server to unset keys
+  /// - Parameter keys: An array of keys
+  /// - Returns: Always return true
+  @discardableResult
   func unsetConf(keys: [String]) async throws -> Bool {
     try await withGPRC { client in
       let service = SparkConnectService.Client(wrapping: client)
@@ -509,6 +515,7 @@ public actor SparkConnectClient {
     self.result.append(response)
   }
 
+  @discardableResult
   func execute(_ sessionID: String, _ command: Command) async throws -> [ExecutePlanResponse] {
     self.result.removeAll()
     try await withGPRC { client in
@@ -555,6 +562,7 @@ public actor SparkConnectClient {
   /// Parse a DDL string to ``Spark_Connect_DataType`` instance.
   /// - Parameter ddlString: A string to parse.
   /// - Returns: A ``Spark_Connect_DataType`` instance.
+  @discardableResult
   func ddlParse(_ ddlString: String) async throws -> Spark_Connect_DataType {
     try await withGPRC { client in
       let service = SparkConnectService.Client(wrapping: client)

Sources/SparkConnect/SparkFileUtils.swift

@@ -85,7 +85,7 @@ public enum SparkFileUtils {
   static func createDirectory(root: String, namePrefix: String = "spark") -> URL {
     let tempDir = URL(fileURLWithPath: root).appendingPathComponent(
       "\(namePrefix)-\(UUID().uuidString)")
-    _ = createDirectory(at: tempDir)
+    createDirectory(at: tempDir)
     return tempDir
   }
 

Sources/SparkConnect/SparkSession.swift

@@ -201,6 +201,7 @@ public actor SparkSession {
 
     /// Remove all stored configurations.
     /// - Returns: self
+    @discardableResult
     func clear() -> Builder {
       sparkConf.removeAll()
       return self

Tests/SparkConnectTests/BuilderTests.swift

@@ -42,7 +42,7 @@ struct BuilderTests {
     // Don't try to connect
     let builder = await SparkSession.builder.remote("sc://spark:1234")
     #expect(await builder.sparkConf["spark.remote"] == "sc://spark:1234")
-    _ = await builder.clear()
+    await builder.clear()
   }
 
   @Test

Tests/SparkConnectTests/CatalogTests.swift

@@ -104,7 +104,7 @@ struct CatalogTests {
     let dbName = "DB_" + UUID().uuidString.replacingOccurrences(of: "-", with: "")
     #expect(try await spark.catalog.databaseExists(dbName) == false)
     try await SQLHelper.withDatabase(spark, dbName) ({
-      _ = try await spark.sql("CREATE DATABASE \(dbName)").count()
+      try await spark.sql("CREATE DATABASE \(dbName)").count()
       #expect(try await spark.catalog.databaseExists(dbName))
     })
     #expect(try await spark.catalog.databaseExists(dbName) == false)

Tests/SparkConnectTests/DataFrameReaderTests.swift

@@ -82,7 +82,7 @@ struct DataFrameReaderTests {
     let tableName = "TABLE_" + UUID().uuidString.replacingOccurrences(of: "-", with: "")
     let spark = try await SparkSession.builder.getOrCreate()
     try await SQLHelper.withTable(spark, tableName)({
-      _ = try await spark.sql("CREATE TABLE \(tableName) USING ORC AS VALUES (1), (2)").count()
+      try await spark.sql("CREATE TABLE \(tableName) USING ORC AS VALUES (1), (2)").count()
       #expect(try await spark.read.table(tableName).count() == 2)
     })
     await spark.stop()
@@ -103,10 +103,10 @@ struct DataFrameReaderTests {
   func invalidSchema() async throws {
     let spark = try await SparkSession.builder.getOrCreate()
     await #expect(throws: SparkConnectError.InvalidTypeException) {
-      _ = try await spark.read.schema("invalid-name SHORT")
+      try await spark.read.schema("invalid-name SHORT")
     }
     await #expect(throws: SparkConnectError.InvalidTypeException) {
-      _ = try await spark.read.schema("age UNKNOWN_TYPE")
+      try await spark.read.schema("age UNKNOWN_TYPE")
     }
     await spark.stop()
   }

Tests/SparkConnectTests/DataFrameTests.swift

@@ -206,10 +206,10 @@ struct DataFrameTests {
   func selectInvalidColumn() async throws {
     let spark = try await SparkSession.builder.getOrCreate()
     try await #require(throws: Error.self) {
-      let _ = try await spark.range(1).select("invalid").schema
+      try await spark.range(1).select("invalid").schema
     }
     try await #require(throws: Error.self) {
-      let _ = try await spark.range(1).select("id + 1").schema
+      try await spark.range(1).select("id + 1").schema
     }
     await spark.stop()
   }
@@ -447,7 +447,7 @@ struct DataFrameTests {
     try await #require(throws: Error.self) {
       var invalidLevel = StorageLevel.DISK_ONLY
       invalidLevel.replication = 0
-      let _ = try await spark.range(9999).persist(storageLevel: invalidLevel).count()
+      try await spark.range(9999).persist(storageLevel: invalidLevel).count()
     }
     await spark.stop()
   }
@@ -707,14 +707,14 @@ struct DataFrameTests {
     let spark = try await SparkSession.builder.getOrCreate()
     let df = try await spark.range(1)
 
-    _ = try await df.unpersist()
+    try await df.unpersist()
     #expect(try await df.storageLevel == StorageLevel.NONE)
-    _ = try await df.persist()
+    try await df.persist()
     #expect(try await df.storageLevel == StorageLevel.MEMORY_AND_DISK)
 
-    _ = try await df.unpersist()
+    try await df.unpersist()
     #expect(try await df.storageLevel == StorageLevel.NONE)
-    _ = try await df.persist(storageLevel: StorageLevel.MEMORY_ONLY)
+    try await df.persist(storageLevel: StorageLevel.MEMORY_ONLY)
     #expect(try await df.storageLevel == StorageLevel.MEMORY_ONLY)
 
     await spark.stop()

Tests/SparkConnectTests/RuntimeConfTests.swift

@@ -30,7 +30,7 @@ struct RuntimeConfTests {
   @Test
   func get() async throws {
     let client = SparkConnectClient(remote: TEST_REMOTE)
-    _ = try await client.connect(UUID().uuidString)
+    try await client.connect(UUID().uuidString)
     let conf = RuntimeConf(client)
 
     #expect(try await !conf.get("spark.app.name").isEmpty)
@@ -45,7 +45,7 @@ struct RuntimeConfTests {
   @Test
   func set() async throws {
     let client = SparkConnectClient(remote: TEST_REMOTE)
-    _ = try await client.connect(UUID().uuidString)
+    try await client.connect(UUID().uuidString)
     let conf = RuntimeConf(client)
     try await conf.set("spark.test.key1", "value1")
     #expect(try await conf.get("spark.test.key1") == "value1")
@@ -55,7 +55,7 @@ struct RuntimeConfTests {
   @Test
   func reset() async throws {
     let client = SparkConnectClient(remote: TEST_REMOTE)
-    _ = try await client.connect(UUID().uuidString)
+    try await client.connect(UUID().uuidString)
     let conf = RuntimeConf(client)
 
     // Success with a key that doesn't exist
@@ -76,7 +76,7 @@ struct RuntimeConfTests {
   @Test
   func getAll() async throws {
     let client = SparkConnectClient(remote: TEST_REMOTE)
-    _ = try await client.connect(UUID().uuidString)
+    try await client.connect(UUID().uuidString)
     let conf = RuntimeConf(client)
     let map = try await conf.getAll()
     #expect(map.count > 0)

Tests/SparkConnectTests/SQLHelper.swift

@@ -32,7 +32,7 @@ struct SQLHelper {
         f,
         {
           for name in dbNames {
-            _ = try await spark.sql("DROP DATABASE IF EXISTS \(name) CASCADE").count()
+            try await spark.sql("DROP DATABASE IF EXISTS \(name) CASCADE").count()
           }
         })
     }
@@ -47,7 +47,7 @@ struct SQLHelper {
         f,
         {
           for name in tableNames {
-            _ = try await spark.sql("DROP TABLE IF EXISTS \(name)").count()
+            try await spark.sql("DROP TABLE IF EXISTS \(name)").count()
           }
         })
     }

Tests/SparkConnectTests/SparkConnectClientTests.swift

@@ -48,22 +48,22 @@ struct SparkConnectClientTests {
   func connectWithInvalidUUID() async throws {
     let client = SparkConnectClient(remote: TEST_REMOTE)
     try await #require(throws: SparkConnectError.InvalidSessionIDException) {
-      let _ = try await client.connect("not-a-uuid-format")
+      try await client.connect("not-a-uuid-format")
     }
     await client.stop()
   }
 
   @Test
   func connect() async throws {
     let client = SparkConnectClient(remote: TEST_REMOTE)
-    let _ = try await client.connect(UUID().uuidString)
+    try await client.connect(UUID().uuidString)
     await client.stop()
   }
 
   @Test
   func tags() async throws {
     let client = SparkConnectClient(remote: TEST_REMOTE)
-    let _ = try await client.connect(UUID().uuidString)
+    try await client.connect(UUID().uuidString)
     let plan = await client.getPlanRange(0, 1, 1)
 
     #expect(await client.getExecutePlanRequest(plan).tags.isEmpty)
@@ -79,7 +79,7 @@ struct SparkConnectClientTests {
   @Test
   func ddlParse() async throws {
     let client = SparkConnectClient(remote: TEST_REMOTE)
-    let _ = try await client.connect(UUID().uuidString)
+    try await client.connect(UUID().uuidString)
     #expect(try await client.ddlParse("a int").simpleString == "struct<a:int>")
     await client.stop()
   }
@@ -91,7 +91,7 @@ struct SparkConnectClientTests {
     let response = try await client.connect(UUID().uuidString)
     if response.sparkVersion.version.starts(with: "4.") {
       let json =
-      #"{"type":"struct","fields":[{"name":"id","type":"long","nullable":false,"metadata":{}}]}"#
+        #"{"type":"struct","fields":[{"name":"id","type":"long","nullable":false,"metadata":{}}]}"#
       #expect(try await client.jsonToDdl(json) == "id BIGINT NOT NULL")
     }
     await client.stop()

Tests/SparkConnectTests/SparkSessionTests.swift

@@ -81,7 +81,7 @@ struct SparkSessionTests {
     let tableName = "TABLE_" + UUID().uuidString.replacingOccurrences(of: "-", with: "")
     let spark = try await SparkSession.builder.getOrCreate()
     try await SQLHelper.withTable(spark, tableName)({
-      _ = try await spark.sql("CREATE TABLE \(tableName) USING ORC AS VALUES (1), (2)").count()
+      try await spark.sql("CREATE TABLE \(tableName) USING ORC AS VALUES (1), (2)").count()
       #expect(try await spark.table(tableName).count() == 2)
     })
     await spark.stop()