✨ Add file sink reopen and failure counters

bitlogger/BitLogger_wbtest.mbt

@@ -90,6 +90,9 @@ test "native file support flag is queryable" {
 test "file sink availability reflects backend support" {
   let sink = file_sink("bitlogger-test.log")
   inspect(sink.is_available() == native_files_supported(), content="true")
+  inspect(sink.open_failures(), content=if sink.is_available() { "0" } else { "1" })
+  inspect(sink.write_failures(), content="0")
+  inspect(sink.flush_failures(), content="0")
   if sink.is_available() {
     inspect(sink.flush(), content="true")
     inspect(sink.close(), content="true")
@@ -110,9 +113,34 @@ test "file sink tracks rotation failures on unavailable backend" {
   sink.write(record(Level::Info, "a"))
   if sink.is_available() {
     inspect(sink.rotation_failures(), content="0")
+    inspect(sink.write_failures(), content="0")
     ignore(sink.close())
   } else {
     inspect(sink.rotation_failures(), content="0")
+    inspect(sink.write_failures(), content="1")
+  }
+}
+
+test "file sink reopen and failure counters reflect backend state" {
+  let sink = file_sink("bitlogger-reopen.log")
+  if sink.is_available() {
+    inspect(sink.open_failures(), content="0")
+    inspect(sink.close(), content="true")
+    inspect(sink.reopen(), content="true")
+    inspect(sink.is_available(), content="true")
+    inspect(sink.open_failures(), content="0")
+    sink.write(record(Level::Info, "reopened"))
+    inspect(sink.write_failures(), content="0")
+    inspect(sink.flush_failures(), content="0")
+    inspect(sink.close(), content="true")
+    ignore(remove_file_internal("bitlogger-reopen.log"))
+  } else {
+    inspect(sink.open_failures(), content="1")
+    sink.write(record(Level::Info, "dropped"))
+    inspect(sink.write_failures(), content="1")
+    inspect(sink.reopen(), content="false")
+    inspect(sink.open_failures(), content="2")
+    inspect(sink.flush_failures(), content="0")
   }
 }
 

bitlogger/README.mbt.md

@@ -46,8 +46,8 @@ BitLogger 是一个基于 MoonBit 的结构化日志库。
 - 支持 `parse_logger_config_text(...)`、`stringify_logger_config(...)` 进行最小 JSON 配置读写
 - config-driven logger assembly via `build_logger(...)`
 - 支持 `build_logger(...)` 将配置组装为可直接使用的 logger
-- native-only file output via `file_sink(...)`, with basic size rotation and backup retention
-- 支持 `file_sink(...)`、基础 size rotation 与 backup retention，但当前仅保证 `native/llvm` backend 可用
+- native-only file output via `file_sink(...)`, with basic size rotation, backup retention, explicit `reopen()`, and failure counters
+- 支持 `file_sink(...)`、基础 size rotation / backup retention、显式 `reopen()` 与失败计数，但当前仅保证 `native/llvm` backend 可用
 
 ## Example / 示例
 
@@ -220,3 +220,6 @@ test {
 - basic rotation is size-based / 当前基础轮转为按文件大小触发
 - `file_rotation(max_bytes, max_backups=...)` controls threshold and retained backups / `file_rotation(max_bytes, max_backups=...)` 控制触发阈值和保留备份数
 - JSON config uses `sink.rotation.max_bytes` and `sink.rotation.max_backups` / JSON 配置使用 `sink.rotation.max_bytes` 与 `sink.rotation.max_backups`
+- `FileSink::reopen()` can explicitly reopen the current file handle / `FileSink::reopen()` 可显式重开当前文件句柄
+- `open_failures()`、`write_failures()`、`flush_failures()`、`rotation_failures()` expose basic sink health counters / `open_failures()`、`write_failures()`、`flush_failures()`、`rotation_failures()` 可用于观察基础 sink 健康状态
+- current scope is observability-first, not a full self-healing sink runtime / 当前定位仍以可观测性优先，不是完整自愈型 sink runtime

bitlogger/sinks.mbt

@@ -51,6 +51,9 @@ pub struct FileSink {
   formatter : RecordFormatter
   auto_flush : Bool
   rotation : FileRotation?
+  open_failures : Ref[Int]
+  write_failures : Ref[Int]
+  flush_failures : Ref[Int]
   rotation_failures : Ref[Int]
 }
 
@@ -79,13 +82,17 @@ pub fn file_sink(
     format_text(rec)
   },
 ) -> FileSink {
+  let handle = open_file_handle_internal(path, append)
   {
     path,
     append,
-    handle: Ref::new(open_file_handle_internal(path, append)),
+    handle: Ref::new(handle),
     formatter,
     auto_flush,
     rotation,
+    open_failures: Ref::new(if handle is Some(_) { 0 } else { 1 }),
+    write_failures: Ref::new(0),
+    flush_failures: Ref::new(0),
     rotation_failures: Ref::new(0),
   }
 }
@@ -97,7 +104,13 @@ pub fn FileSink::is_available(self : FileSink) -> Bool {
 pub fn FileSink::flush(self : FileSink) -> Bool {
   match self.handle.val {
     None => false
-    Some(handle) => flush_file_handle_internal(handle)
+    Some(handle) => {
+      let ok = flush_file_handle_internal(handle)
+      if !ok {
+        self.flush_failures.val += 1
+      }
+      ok
+    }
   }
 }
 
@@ -116,6 +129,37 @@ pub fn FileSink::rotation_failures(self : FileSink) -> Int {
   self.rotation_failures.val
 }
 
+pub fn FileSink::open_failures(self : FileSink) -> Int {
+  self.open_failures.val
+}
+
+pub fn FileSink::write_failures(self : FileSink) -> Int {
+  self.write_failures.val
+}
+
+pub fn FileSink::flush_failures(self : FileSink) -> Int {
+  self.flush_failures.val
+}
+
+pub fn FileSink::reopen(self : FileSink, append~ : Bool? = None) -> Bool {
+  let append_mode = append.unwrap_or(self.append)
+  match self.handle.val {
+    None => ()
+    Some(handle) => {
+      ignore(close_file_handle_internal(handle))
+      self.handle.val = None
+    }
+  }
+  let reopened = open_file_handle_internal(self.path, append_mode)
+  self.handle.val = reopened
+  if reopened is Some(_) {
+    true
+  } else {
+    self.open_failures.val += 1
+    false
+  }
+}
+
 fn rotated_file_path(path : String, index : Int) -> String {
   "\{path}.\{index}"
 }
@@ -171,20 +215,33 @@ fn rotate_if_needed_internal(sink : FileSink, next_line_bytes : Int) -> Bool {
 
 pub impl Sink for FileSink with write(self, rec) {
   match self.handle.val {
-    None => ()
+    None => {
+      self.write_failures.val += 1
+    }
     Some(_) => {
       let line = "\{(self.formatter)(rec)}\n"
       let can_write = rotate_if_needed_internal(self, string_byte_length_internal(line))
       if can_write {
         match self.handle.val {
-          None => ()
+          None => {
+            self.write_failures.val += 1
+          }
           Some(active) => {
-            ignore(write_file_handle_internal(active, line))
-            if self.auto_flush {
-              ignore(flush_file_handle_internal(active))
+            let wrote = write_file_handle_internal(active, line)
+            if wrote {
+              if self.auto_flush {
+                let flushed = flush_file_handle_internal(active)
+                if !flushed {
+                  self.flush_failures.val += 1
+                }
+              }
+            } else {
+              self.write_failures.val += 1
             }
           }
         }
+      } else {
+        self.write_failures.val += 1
       }
     }
   }