updated logger: integrate mutex into WriterState (move-safety), fix lock/unlock logic in deinit

src/logging/log.zig

@@ -55,20 +55,21 @@ pub const Logger = struct {
     level:     Level             = .info,
     on_error:  ErrorCallback     = null,
 
-    io:        std.Io            = undefined,
-    state:     *WriterState      = undefined,
-    mutex:     std.Io.Mutex      = undefined,
-    allocator: std.mem.Allocator = undefined,
+    io:        std.Io,
+    state:     *WriterState,
+    allocator: std.mem.Allocator,
 
 
     const Self = @This();
 
-    /// Heap-allocated home for the write buffer and the `File.Writer`
-    /// built on top of it. `File.Writer` holds a pointer into
-    /// `buffer`, so both must live at a stable address that survives
-    /// the `Logger` value itself being copied or moved.
+    /// Heap-allocated home for the write buffer, the `File.Writer`
+    /// built on top of it, and the mutex guarding both. `File.Writer`
+    /// holds a pointer into `buffer`, so all three must live at a
+    /// stable address that survives the `Logger` value itself being
+    /// copied or moved.
     const WriterState = struct {
         buffer: []u8,
+        mutex:  std.Io.Mutex,
         writer: std.Io.File.Writer,
     };
 
@@ -92,15 +93,16 @@ pub const Logger = struct {
         const state = try allocator.create(WriterState);
         state.* = .{
             .buffer = buffer,
+            .mutex  = .init,
             .writer = options.file.writer(options.io, buffer),
         };
 
         return Self{
             .level     = options.level,
             .on_error  = options.on_error,
+
             .io        = options.io,
             .state     = state,
-            .mutex     = .init,
             .allocator = allocator,
         };
     }
@@ -116,9 +118,12 @@ pub const Logger = struct {
     /// allocations are freed unconditionally.
     pub fn deinit(logger: *Self) void
     {
-        logger.mutex.lock(logger.io) catch {};
+        if (logger.state.mutex.lock(logger.io)) |_|
+        {
             logger.state.writer.interface.flush() catch {};
-        logger.mutex.unlock(logger.io);
+            logger.state.mutex.unlock(logger.io);
+        }
+        else |_| {}
 
         logger.allocator.free(logger.state.buffer);
         logger.allocator.destroy(logger.state);
@@ -143,8 +148,8 @@ pub const Logger = struct {
     {
         if (@intFromEnum(level) < @intFromEnum(logger.level)) return;
 
-        try logger.mutex.lock(logger.io);
-        defer logger.mutex.unlock(logger.io);
+        try logger.state.mutex.lock(logger.io);
+        defer logger.state.mutex.unlock(logger.io);
 
         try logger.state.writer.interface.print(fmt, args);
         try logger.state.writer.interface.writeByte('\n');
@@ -170,8 +175,8 @@ pub const Logger = struct {
     /// Returns an error if the underlying writer fails to flush.
     pub fn flush(logger: *Self) !void
     {
-        try logger.mutex.lock(logger.io);
-        defer logger.mutex.unlock(logger.io);
+        try logger.state.mutex.lock(logger.io);
+        defer logger.state.mutex.unlock(logger.io);
 
         try logger.state.writer.interface.flush();
     }