Disable buffering of file streams to improve performance

rikyoz · Jul 26, 2024 · b9aec79 · b9aec79
1 parent 94d939e
commit b9aec79
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Showing 4 changed files with 6 additions and 23 deletions.
diff --git a/src/internal/cfileinstream.cpp b/src/internal/cfileinstream.cpp
@@ -21,22 +21,16 @@
 
 namespace bit7z {
 
-CFileInStream::CFileInStream( const fs::path& filePath ) : CStdInStream( mFileStream ), mBuffer{} {
+CFileInStream::CFileInStream( const fs::path& filePath ) : CStdInStream( mFileStream ) {
     /* By default, file stream performance is relatively poor due to the default buffer size used
      * (e.g., GCC uses a small 1024-bytes buffer).
      * This is a known problem (see https://stackoverflow.com/questions/26095160/why-are-stdfstreams-so-slow).
      * We make the underlying file stream use a bigger buffer (1 MiB) for optimizing the reading of big files.
      * Note: when using libstdc++, the buffer must be set before opening the file. */
 
-#ifdef __GLIBCXX__
-    mFileStream.rdbuf()->pubsetbuf( mBuffer.data(), kBufferSize );
-#endif
-
+    mFileStream.rdbuf()->pubsetbuf( nullptr, 0 );
     openFile( filePath );
-
-#ifndef __GLIBCXX__
-    mFileStream.rdbuf()->pubsetbuf( mBuffer.data(), kBufferSize );
-#endif
+    mFileStream.rdbuf()->pubsetbuf( nullptr, 0 );
 }
 
 void CFileInStream::openFile( const fs::path& filePath ) {

diff --git a/src/internal/cfileinstream.hpp b/src/internal/cfileinstream.hpp
@@ -25,8 +25,6 @@ class CFileInStream : public CStdInStream {
 
     private:
         fs::ifstream mFileStream;
-        static constexpr auto kBufferSize = 1024 * 1024; // 1 MiB
-        std::array< char, kBufferSize > mBuffer;
 };
 
 }  // namespace bit7z

diff --git a/src/internal/cfileoutstream.cpp b/src/internal/cfileoutstream.cpp
@@ -23,7 +23,7 @@
 namespace bit7z {
 
 CFileOutStream::CFileOutStream( fs::path filePath, bool createAlways )
-    : CStdOutStream( mFileStream ), mFilePath{ std::move( filePath ) }, mBuffer{} {
+    : CStdOutStream( mFileStream ), mFilePath{ std::move( filePath ) } {
     std::error_code error;
     if ( !createAlways && fs::exists( mFilePath, error ) ) {
         if ( !error ) {
@@ -33,10 +33,7 @@ CFileOutStream::CFileOutStream( fs::path filePath, bool createAlways )
         throw BitException( "Failed to create the output file", error, path_to_tstring( mFilePath ) );
     }
 
-#ifdef __GLIBCXX__
-    mFileStream.rdbuf()->pubsetbuf( mBuffer.data(), kBufferSize );
-#endif
-
+    mFileStream.rdbuf()->pubsetbuf( nullptr, 0 );
     mFileStream.open( mFilePath, std::ios::binary | std::ios::trunc ); // flawfinder: ignore
     if ( mFileStream.fail() ) {
 #if defined( __MINGW32__ ) || defined( __MINGW64__ )
@@ -46,10 +43,7 @@ CFileOutStream::CFileOutStream( fs::path filePath, bool createAlways )
         throw BitException( "Failed to open the output file", last_error_code(), path_to_tstring( mFilePath ) );
 #endif
     }
-
-#ifndef __GLIBCXX__
-    mFileStream.rdbuf()->pubsetbuf( mBuffer.data(), kBufferSize );
-#endif
+    mFileStream.rdbuf()->pubsetbuf( nullptr, 0 );
 }
 
 auto CFileOutStream::fail() const -> bool {

diff --git a/src/internal/cfileoutstream.hpp b/src/internal/cfileoutstream.hpp
@@ -32,9 +32,6 @@ class CFileOutStream : public CStdOutStream {
     private:
         fs::path mFilePath;
         fs::ofstream mFileStream;
-
-        static constexpr auto kBufferSize = 1024 * 1024; // 1 MiB
-        std::array< char, kBufferSize > mBuffer;
 };
 
 }  // namespace bit7z