Add a file writer that replaces its target only on completion.

The data is written to <fn>.tmp in the same directory as the target
and moved to <fn> on Commit(); a failed or interrupted write leaves
the previous file untouched, with an orphaned .tmp.

server/TracySafeFileWrite.hpp

@@ -0,0 +1,53 @@
+#ifndef __TRACYSAFEFILEWRITE_HPP__
+#define __TRACYSAFEFILEWRITE_HPP__
+
+#include <filesystem>
+#include <memory>
+#include <string>
+#include <system_error>
+#include <utility>
+
+#include "TracyFileWrite.hpp"
+
+namespace tracy
+{
+
+class SafeFileWrite
+{
+public:
+    static SafeFileWrite* Open( const char* fn, FileCompression comp = FileCompression::Fast, int level = 1, int streams = -1 )
+    {
+        std::string final( fn );
+        std::string tmp = final + ".tmp";
+        auto f = FileWrite::Open( tmp.c_str(), comp, level, streams );
+        if( !f ) return nullptr;
+        return new SafeFileWrite( std::unique_ptr<FileWrite>( f ), std::move( final ), std::move( tmp ) );
+    }
+
+    SafeFileWrite( const SafeFileWrite& ) = delete;
+    SafeFileWrite& operator=( const SafeFileWrite& ) = delete;
+
+    FileWrite& File() { return *m_file; }
+    std::pair<size_t, size_t> GetCompressionStatistics() const { return m_file->GetCompressionStatistics(); }
+
+    bool Commit()
+    {
+        std::error_code ec;
+        std::filesystem::rename( m_tmp, m_final, ec );
+        return !ec;
+    }
+
+private:
+    SafeFileWrite( std::unique_ptr<FileWrite> f, std::string final, std::string tmp )
+        : m_file( std::move( f ) )
+        , m_final( std::move( final ) )
+        , m_tmp( std::move( tmp ) )
+    {}
+
+    std::unique_ptr<FileWrite> m_file;
+    std::string m_final, m_tmp;
+};
+
+}
+
+#endif