Synchronized DefaultLogHandler writes.

andrewlalis · Apr 3, 2024 · e52d411 · e52d411
1 parent 1d09eb3
commit e52d411
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diff --git a/changelogs/3.0.1.md b/changelogs/3.0.1.md
@@ -0,0 +1,7 @@
+# Version 3.0.1
+
+- Added synchronization to the DefaultLogHandler to avoid interleaving messages
+  between the stdout and stderr streams. Each is individually synchronized by
+  the library/system, but both are not synchronized with respect to each other,
+  so errors and info messages may overwrite each other when printed into a
+  single source.
diff --git a/source/slf4d/default_provider/handler.d b/source/slf4d/default_provider/handler.d
@@ -35,12 +35,14 @@ class DefaultLogHandler : LogHandler {
     public void handle(immutable LogMessage msg) {
         import std.stdio;
         string logStr = formatLogMessage(msg, this.colored);
-        if (msg.level.value >= Levels.ERROR.value) {
-            stderr.writeln(logStr);
-            stderr.flush();
-        } else {
-            stdout.writeln(logStr);
-            stdout.flush();
+        synchronized(this) {
+            if (msg.level.value >= Levels.ERROR.value) {
+                stderr.writeln(logStr);
+                stderr.flush();
+            } else {
+                stdout.writeln(logStr);
+                stdout.flush();
+            }
         }
     }
 }