make MultiplexLogHandler a value (#12)

Author: weissi

Diff for: Sources/Logging/Logging.swift

@@ -474,8 +474,7 @@ extension Logger {
 /// The first `LogHandler` passed to the initialisation function of `MultiplexLogHandler` control the `logLevel` as
 /// well as the `metadata` for this `LogHandler`. Any subsequent `LogHandler`s used to initialise a
 /// `MultiplexLogHandler` are merely to emit the log message to another place.
-public class MultiplexLogHandler: LogHandler {
-    private let lock = Lock()
+public struct MultiplexLogHandler: LogHandler {
     private var handlers: [LogHandler]
 
     public init(_ handlers: [LogHandler]) {
@@ -488,7 +487,9 @@ public class MultiplexLogHandler: LogHandler {
             return self.handlers[0].logLevel
         }
         set {
-            self.mutateHandlers { $0.logLevel = newValue }
+            self.mutatingForEachHandler {
+                $0.logLevel = newValue
+            }
         }
     }
 
@@ -503,7 +504,7 @@ public class MultiplexLogHandler: LogHandler {
             return self.handlers[0].metadata
         }
         set {
-            self.mutateHandlers { $0.metadata = newValue }
+            self.mutatingForEachHandler { $0.metadata = newValue }
         }
     }
 
@@ -512,18 +513,14 @@ public class MultiplexLogHandler: LogHandler {
             return self.handlers[0].metadata[metadataKey]
         }
         set {
-            self.mutateHandlers { $0[metadataKey: metadataKey] = newValue }
+            self.mutatingForEachHandler { $0[metadataKey: metadataKey] = newValue }
         }
     }
 
-    private func mutateHandlers(mutator: (inout LogHandler) -> Void) {
-        var newHandlers = [LogHandler]()
-        self.handlers.forEach {
-            var handler = $0
-            mutator(&handler)
-            newHandlers.append(handler)
+    private mutating func mutatingForEachHandler(_ mutator: (inout LogHandler) -> Void) {
+        for index in self.handlers.indices {
+            mutator(&self.handlers[index])
         }
-        self.lock.withLock { self.handlers = newHandlers }
     }
 }
 

Diff for: Tests/LoggingTests/LoggingTest+XCTest.swift

@@ -38,6 +38,7 @@ extension LoggingTest {
                 ("testAllLogLevelsWork", testAllLogLevelsWork),
                 ("testLogMessageWithStringInterpolation", testLogMessageWithStringInterpolation),
                 ("testLoggingAString", testLoggingAString),
+                ("testMultiplexerIsValue", testMultiplexerIsValue),
            ]
    }
 }

Diff for: Tests/LoggingTests/LoggingTest.swift

@@ -286,4 +286,23 @@ class LoggingTest: XCTestCase {
         logger.debug("\(anActualString)")
         testLogging.history.assertExist(level: .debug, message: "hello world!")
     }
+
+    func testMultiplexerIsValue() {
+        let multi = MultiplexLogHandler([StdoutLogHandler(label: "x"), StdoutLogHandler(label: "y")])
+        LoggingSystem.bootstrapInternal { _ in
+            print("new multi")
+            return multi
+        }
+        var logger1: Logger = {
+            var logger = Logger(label: "foo")
+            logger.logLevel = .debug
+            return logger
+        }()
+        XCTAssertEqual(.debug, logger1.logLevel)
+        var logger2 = logger1
+        logger2.logLevel = .error
+        XCTAssertEqual(.error, logger2.logLevel)
+        XCTAssertEqual(.debug, logger1.logLevel)
+        logger1.error("hey")
+    }
 }