include llama.cpp since there were some edits

llama.cpp/common/file-lock.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <functional>
+#include <string>
+
+// Cross-process exclusive lock (flock on POSIX, LockFileEx on Windows).
+// Lazy: acquire() opens the lock file, so a read-only cache works if the lock is never acquired.
+class common_file_lock {
+public:
+    common_file_lock(const std::string & lock_path);
+    ~common_file_lock();
+
+    // take the lock, waiting while another process holds it;
+    // keep_waiting is polled before each retry, false cancels the wait.
+    // Also returns false when locking is unavailable.
+    bool acquire(const std::function<bool()> & keep_waiting = {});
+
+    void close();
+
+    common_file_lock(const common_file_lock &) = delete;
+    common_file_lock & operator=(const common_file_lock &) = delete;
+
+private:
+    enum class status {
+        acquired,
+        busy,  // another process holds the lock
+        error, // file locking is unavailable: no exclusion is possible
+    };
+
+    status try_lock();
+
+    std::string lock_path;
+
+    int  fd     = -1;
+    bool locked = false;
+};