Gabime/fwrite unlocked (#3276)

* Use locking fwrite_unlocked if possible

* Added compile definitions to header_only

include/spdlog/details/file_helper-inl.h

@@ -101,7 +101,8 @@ SPDLOG_INLINE void file_helper::write(const memory_buf_t &buf) {
     if (fd_ == nullptr) return;
     size_t msg_size = buf.size();
     auto data = buf.data();
-    if (std::fwrite(data, 1, msg_size, fd_) != msg_size) {
+
+    if (!details::os::fwrite_bytes(data, msg_size, fd_)) {
         throw_spdlog_ex("Failed writing to file " + os::filename_to_str(filename_), errno);
     }
 }

include/spdlog/details/os-inl.h

@@ -589,6 +589,18 @@ SPDLOG_INLINE bool fsync(FILE *fp) {
 #endif
 }
 
+// Do non-locking fwrite if possible by the os or use the regular locking fwrite
+// Return true on success.
+SPDLOG_INLINE bool fwrite_bytes(const void *ptr, const size_t n_bytes, FILE *fp) {
+    #if defined(_WIN32) && defined(SPDLOG_FWRITE_UNLOCKED)
+    return _fwrite_nolock(ptr, 1, n_bytes, fp) == n_bytes;
+    #elif defined(SPDLOG_FWRITE_UNLOCKED)
+    return ::fwrite_unlocked(ptr, 1, n_bytes, fp) == n_bytes;
+    #else
+    return std::fwrite(ptr, 1, n_bytes, fp) == n_bytes;
+    #endif
+}
+
 }  // namespace os
 }  // namespace details
 }  // namespace spdlog

include/spdlog/details/os.h

@@ -114,6 +114,10 @@ SPDLOG_API std::string getenv(const char *field);
 // Return true on success.
 SPDLOG_API bool fsync(FILE *fp);
 
+// Do non-locking fwrite if possible by the os or use the regular locking fwrite
+// Return true on success.
+SPDLOG_API bool fwrite_bytes(const void *ptr, const size_t n_bytes, FILE *fp);
+
 }  // namespace os
 }  // namespace details
 }  // namespace spdlog

include/spdlog/sinks/ansicolor_sink-inl.h

@@ -106,14 +106,14 @@ SPDLOG_INLINE void ansicolor_sink<ConsoleMutex>::set_color_mode(color_mode mode)
 
 template <typename ConsoleMutex>
 SPDLOG_INLINE void ansicolor_sink<ConsoleMutex>::print_ccode_(const string_view_t &color_code) {
-    fwrite(color_code.data(), sizeof(char), color_code.size(), target_file_);
+    details::os::fwrite_bytes(color_code.data(), color_code.size(), target_file_);
 }
 
 template <typename ConsoleMutex>
 SPDLOG_INLINE void ansicolor_sink<ConsoleMutex>::print_range_(const memory_buf_t &formatted,
                                                               size_t start,
                                                               size_t end) {
-    fwrite(formatted.data() + start, sizeof(char), end - start, target_file_);
+    details::os::fwrite_bytes(formatted.data() + start, end - start, target_file_);
 }
 
 template <typename ConsoleMutex>

include/spdlog/sinks/stdout_sinks-inl.h

@@ -10,6 +10,7 @@
 #include <memory>
 #include <spdlog/details/console_globals.h>
 #include <spdlog/pattern_formatter.h>
+#include <spdlog/details/os.h>
 
 #ifdef _WIN32
     // under windows using fwrite to non-binary stream results in \r\r\n (see issue #1675)
@@ -22,7 +23,7 @@
 
     #include <io.h>     // _get_osfhandle(..)
     #include <stdio.h>  // _fileno(..)
-#endif                  // WIN32
+#endif                  // _WIN32
 
 namespace spdlog {
 
@@ -44,7 +45,7 @@ SPDLOG_INLINE stdout_sink_base<ConsoleMutex>::stdout_sink_base(FILE *file)
     if (handle_ == INVALID_HANDLE_VALUE && file != stdout && file != stderr) {
         throw_spdlog_ex("spdlog::stdout_sink_base: _get_osfhandle() failed", errno);
     }
-#endif  // WIN32
+#endif  // _WIN32
 }
 
 template <typename ConsoleMutex>
@@ -67,8 +68,8 @@ SPDLOG_INLINE void stdout_sink_base<ConsoleMutex>::log(const details::log_msg &m
     std::lock_guard<mutex_t> lock(mutex_);
     memory_buf_t formatted;
     formatter_->format(msg, formatted);
-    ::fwrite(formatted.data(), sizeof(char), formatted.size(), file_);
-#endif                // WIN32
+    details::os::fwrite_bytes(formatted.data(), formatted.size(), file_);
+#endif                // _WIN32
     ::fflush(file_);  // flush every line to terminal
 }