=multiplex #139 more properly handle logLevel in multiplex handler

apple · Jun 29, 2020 · e26592e · e26592e
1 parent afc50b2
commit e26592e
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Showing 2 changed files with 78 additions and 2 deletions.
diff --git a/Sources/Logging/Logging.swift b/Sources/Logging/Logging.swift
@@ -462,6 +462,8 @@ extension Logger {
 /// 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 struct MultiplexLogHandler: LogHandler {
+
+    private var effectiveLogLevel: Logger.Level
     private var handlers: [LogHandler]
 
     /// Create a `MultiplexLogHandler`.
@@ -472,24 +474,30 @@ public struct MultiplexLogHandler: LogHandler {
     public init(_ handlers: [LogHandler]) {
         assert(!handlers.isEmpty)
         self.handlers = handlers
+        self.effectiveLogLevel = MultiplexLogHandler.effectiveLogLevel(handlers.map { $0.logLevel })
     }
 
     public var logLevel: Logger.Level {
         get {
-            return self.handlers[0].logLevel
+            return self.effectiveLogLevel
         }
         set {
             self.mutatingForEachHandler {
                 $0.logLevel = newValue
             }
+            self.effectiveLogLevel = MultiplexLogHandler.effectiveLogLevel(self.handlers.map { $0.logLevel })
         }
     }
+
+    static func effectiveLogLevel(_ levels: [Logger.Level]) -> Logger.Level {
+        levels.min() ?? .trace
+    }
 
     public func log(level: Logger.Level,
                     message: Logger.Message,
                     metadata: Logger.Metadata?,
                     file: String, function: String, line: UInt) {
-        self.handlers.forEach { handler in
+        for handler in self.handlers where handler.logLevel <= level {
             handler.log(level: level, message: message, metadata: metadata, file: file, function: function, line: line)
         }
     }

diff --git a/Tests/LoggingTests/LoggingTest.swift b/Tests/LoggingTests/LoggingTest.swift
@@ -74,6 +74,74 @@ class LoggingTest: XCTestCase {
         logging2.history.assertExist(level: .warning, message: "hello world!", metadata: ["foo": "bar"])
     }
 
+    func testMultiplexLogHandlerWithVariousLogLevels() throws {
+        let logging1 = TestLogging()
+        let logging2 = TestLogging()
+
+        var logger1 = logging1.make(label: "1")
+        logger1.logLevel = .info
+
+        var logger2 = logging2.make(label: "2")
+        logger2.logLevel = .debug
+
+        LoggingSystem.bootstrapInternal { _ in
+            return MultiplexLogHandler([logger1, logger2])
+        }
+
+        let multiplexLogger = Logger(label: "test")
+        multiplexLogger.trace("trace")
+        multiplexLogger.debug("debug")
+        multiplexLogger.info("info")
+        multiplexLogger.warning("warning")
+
+        logging1.history.assertNotExist(level: .trace, message: "trace")
+        logging1.history.assertNotExist(level: .debug, message: "debug")
+        logging1.history.assertExist(level: .info, message: "info")
+        logging1.history.assertExist(level: .warning, message: "warning")
+
+        logging2.history.assertNotExist(level: .trace, message: "trace")
+        logging2.history.assertExist(level: .debug, message: "debug")
+        logging2.history.assertExist(level: .info, message: "info")
+        logging2.history.assertExist(level: .warning, message: "warning")
+    }
+
+    func testMultiplexLogHandlerNeedNotMaterializeValuesMultipleTimes() throws {
+        let logging1 = TestLogging()
+        let logging2 = TestLogging()
+
+        var logger1 = logging1.make(label: "1")
+        logger1.logLevel = .info
+
+        var logger2 = logging2.make(label: "2")
+        logger2.logLevel = .info
+
+        LoggingSystem.bootstrapInternal { _ in
+            return MultiplexLogHandler([logger1, logger2])
+        }
+
+        var messageMaterializations: Int = 0
+        var metadataMaterializations: Int = 0
+
+        let multiplexLogger = Logger(label: "test")
+        multiplexLogger.info(
+            { () -> Logger.Message in
+                messageMaterializations += 1
+                return "info"
+            }(),
+            metadata: { () ->
+                Logger.Metadata in metadataMaterializations += 1
+                return [:]
+            }()
+        )
+
+        logging1.history.assertExist(level: .info, message: "info")
+        logging2.history.assertExist(level: .info, message: "info")
+
+        XCTAssertEqual(messageMaterializations, 1)
+        XCTAssertEqual(metadataMaterializations, 1)
+    }
+
+
     enum TestError: Error {
         case boom
     }