Optimize FileReadStream and BasicIStreamWrapper.
On (my) linux, perftest reports: - ~40% gain for FileReadStream (Take() loop), - ~10% gain for ReaderParse_DummyHandler_FileReadStream. With the same logic applied to BasicIStreamWrapper, which thus can now also be created with a user buffer, performances align with those of FileReadStream (same buffer size). The "unbuffered" versions (added for FileReadStream) work solely with the internal peekBuffer (Ch[4]) and are measured in perftest. When performances don't matter much, they can avoid the use of large stack/heap buffers.
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ylavic
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30d92a6399
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2498c5776f
@ -17,6 +17,7 @@
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#include "stream.h"
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#include <cstdio>
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#include <cstring>
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#ifdef __clang__
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RAPIDJSON_DIAG_PUSH
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@ -35,21 +36,42 @@ class FileReadStream {
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public:
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typedef char Ch; //!< Character type (byte).
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//! Constructor.
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/*!
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\param fp File pointer opened for read.
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*/
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FileReadStream(std::FILE* fp) : fp_(fp), buffer_(peekBuffer_), size_(sizeof(peekBuffer_) / sizeof(Ch)), pos_(), len_(), count_()
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{
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RAPIDJSON_ASSERT(fp_ != 0);
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}
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//! Constructor.
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/*!
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\param fp File pointer opened for read.
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\param buffer user-supplied buffer.
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\param bufferSize size of buffer in bytes. Must >=4 bytes.
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*/
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FileReadStream(std::FILE* fp, char* buffer, size_t bufferSize) : fp_(fp), buffer_(buffer), bufferSize_(bufferSize), bufferLast_(0), current_(buffer_), readCount_(0), count_(0), eof_(false) {
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RAPIDJSON_ASSERT(fp_ != 0);
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RAPIDJSON_ASSERT(bufferSize >= 4);
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Read();
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FileReadStream(std::FILE* fp, Ch *buffer, size_t size) : fp_(fp), buffer_(buffer), size_(size), pos_(), len_(), count_() {
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RAPIDJSON_ASSERT(fp_ != 0 && buffer_ != 0 && size_ > 0);
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if (RAPIDJSON_UNLIKELY(size_ < sizeof(peekBuffer_) / sizeof(Ch))) {
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size_ = sizeof(peekBuffer_) / sizeof(Ch);
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buffer_ = peekBuffer_;
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}
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}
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Ch Peek() const { return *current_; }
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Ch Take() { Ch c = *current_; Read(); return c; }
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size_t Tell() const { return count_ + static_cast<size_t>(current_ - buffer_); }
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Ch Peek() const {
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if (RAPIDJSON_UNLIKELY(pos_ == len_) && !Read())
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return static_cast<Ch>('\0');
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return buffer_[pos_];
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}
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Ch Take() {
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if (RAPIDJSON_UNLIKELY(pos_ == len_) && !Read())
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return static_cast<Ch>('\0');
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return buffer_[pos_++];
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}
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size_t Tell() const { return count_ + pos_; }
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// Not implemented
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void Put(Ch) { RAPIDJSON_ASSERT(false); }
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@ -59,35 +81,36 @@ public:
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// For encoding detection only.
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const Ch* Peek4() const {
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return (current_ + 4 <= bufferLast_) ? current_ : 0;
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if (len_ - pos_ < 4) {
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if (pos_) {
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len_ -= pos_;
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std::memmove(buffer_, buffer_ + pos_, len_);
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count_ += pos_;
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pos_ = 0;
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}
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len_ += std::fread(buffer_ + len_, sizeof(Ch), size_ - len_, fp_);
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if (len_ < 4)
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return 0;
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}
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return &buffer_[pos_];
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}
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private:
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void Read() {
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if (current_ < bufferLast_)
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++current_;
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else if (!eof_) {
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count_ += readCount_;
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readCount_ = std::fread(buffer_, 1, bufferSize_, fp_);
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bufferLast_ = buffer_ + readCount_ - 1;
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current_ = buffer_;
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FileReadStream();
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FileReadStream(const FileReadStream&);
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FileReadStream& operator=(const FileReadStream&);
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if (readCount_ < bufferSize_) {
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buffer_[readCount_] = '\0';
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++bufferLast_;
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eof_ = true;
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}
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}
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size_t Read() const {
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count_ += pos_;
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pos_ = 0;
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len_ = std::fread(buffer_, sizeof(Ch), size_, fp_);
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return len_;
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}
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std::FILE* fp_;
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Ch *buffer_;
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size_t bufferSize_;
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Ch *bufferLast_;
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Ch *current_;
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size_t readCount_;
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size_t count_; //!< Number of characters read
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bool eof_;
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Ch peekBuffer_[4], *buffer_;
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size_t size_;
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mutable size_t pos_, len_, count_;
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};
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RAPIDJSON_NAMESPACE_END
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@ -17,6 +17,7 @@
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#include "stream.h"
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#include <iosfwd>
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#include <cstring>
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#ifdef __clang__
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RAPIDJSON_DIAG_PUSH
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@ -48,26 +49,33 @@ template <typename StreamType>
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class BasicIStreamWrapper {
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public:
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typedef typename StreamType::char_type Ch;
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BasicIStreamWrapper(StreamType& stream) : stream_(stream), count_(), peekBuffer_() {}
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Ch Peek() const {
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typename StreamType::int_type c = stream_.peek();
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return RAPIDJSON_LIKELY(c != StreamType::traits_type::eof()) ? static_cast<Ch>(c) : static_cast<Ch>('\0');
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BasicIStreamWrapper(StreamType& stream) : stream_(stream), buffer_(peekBuffer_), size_(sizeof(peekBuffer_) / sizeof(Ch)), pos_(), len_(), count_() {}
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BasicIStreamWrapper(StreamType& stream, Ch *buffer, size_t size) : stream_(stream), buffer_(buffer), size_(size), pos_(), len_(), count_() {
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RAPIDJSON_ASSERT(buffer_ != 0 && static_cast<std::streamsize>(size_) > 0);
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if (RAPIDJSON_UNLIKELY(size_ < sizeof(peekBuffer_) / sizeof(Ch))) {
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size_ = sizeof(peekBuffer_) / sizeof(Ch);
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buffer_ = peekBuffer_;
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}
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}
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Ch Take() {
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typename StreamType::int_type c = stream_.get();
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if (RAPIDJSON_LIKELY(c != StreamType::traits_type::eof())) {
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count_++;
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return static_cast<Ch>(c);
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}
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else
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return '\0';
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Ch Peek() const {
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if (RAPIDJSON_UNLIKELY(pos_ == len_) && !Read())
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return static_cast<Ch>('\0');
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return buffer_[pos_];
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}
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Ch Take() {
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if (RAPIDJSON_UNLIKELY(pos_ == len_) && !Read())
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return static_cast<Ch>('\0');
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return buffer_[pos_++];
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}
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// tellg() may return -1 when failed. So we count by ourself.
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size_t Tell() const { return count_; }
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size_t Tell() const { return count_ + pos_; }
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// Not implemented
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Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
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void Put(Ch) { RAPIDJSON_ASSERT(false); }
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void Flush() { RAPIDJSON_ASSERT(false); }
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@ -76,29 +84,42 @@ public:
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// For encoding detection only.
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const Ch* Peek4() const {
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RAPIDJSON_ASSERT(sizeof(Ch) == 1); // Only usable for byte stream.
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int i;
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bool hasError = false;
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for (i = 0; i < 4; ++i) {
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typename StreamType::int_type c = stream_.get();
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if (c == StreamType::traits_type::eof()) {
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hasError = true;
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stream_.clear();
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break;
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if (len_ - pos_ < 4) {
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if (pos_) {
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len_ -= pos_;
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std::memmove(buffer_, buffer_ + pos_, len_);
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count_ += pos_;
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pos_ = 0;
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}
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peekBuffer_[i] = static_cast<Ch>(c);
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if (!stream_.read(buffer_ + len_, static_cast<std::streamsize>(size_ - len_))) {
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len_ += static_cast<size_t>(stream_.gcount());
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if (len_ < 4)
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return 0;
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}
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else
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len_ = size_;
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}
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for (--i; i >= 0; --i)
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stream_.putback(peekBuffer_[i]);
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return !hasError ? peekBuffer_ : 0;
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return &buffer_[pos_];
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}
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private:
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BasicIStreamWrapper(const BasicIStreamWrapper&);
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BasicIStreamWrapper& operator=(const BasicIStreamWrapper&);
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size_t Read() const {
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count_ += pos_;
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pos_ = 0;
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if (!stream_.read(buffer_, static_cast<std::streamsize>(size_)))
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len_ = static_cast<size_t>(stream_.gcount());
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else
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len_ = size_;
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return len_;
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}
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StreamType& stream_;
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size_t count_; //!< Number of characters read. Note:
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mutable Ch peekBuffer_[4];
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Ch peekBuffer_[4], *buffer_;
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size_t size_;
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mutable size_t pos_, len_, count_;
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};
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typedef BasicIStreamWrapper<std::istream> IStreamWrapper;
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@ -21,9 +21,12 @@
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#include "rapidjson/prettywriter.h"
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#include "rapidjson/stringbuffer.h"
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#include "rapidjson/filereadstream.h"
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#include "rapidjson/istreamwrapper.h"
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#include "rapidjson/encodedstream.h"
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#include "rapidjson/memorystream.h"
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#include <fstream>
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#ifdef RAPIDJSON_SSE2
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#define SIMD_SUFFIX(name) name##_SSE2
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#elif defined(RAPIDJSON_SSE42)
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@ -451,6 +454,16 @@ TEST_F(RapidJson, FileReadStream) {
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}
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}
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TEST_F(RapidJson, FileReadStream_Unbuffered) {
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for (size_t i = 0; i < kTrialCount; i++) {
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FILE *fp = fopen(filename_, "rb");
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FileReadStream s(fp);
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while (s.Take() != '\0')
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;
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fclose(fp);
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}
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}
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TEST_F(RapidJson, SIMD_SUFFIX(ReaderParse_DummyHandler_FileReadStream)) {
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for (size_t i = 0; i < kTrialCount; i++) {
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FILE *fp = fopen(filename_, "rb");
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@ -463,6 +476,88 @@ TEST_F(RapidJson, SIMD_SUFFIX(ReaderParse_DummyHandler_FileReadStream)) {
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}
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}
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TEST_F(RapidJson, SIMD_SUFFIX(ReaderParse_DummyHandler_FileReadStream_Unbuffered)) {
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for (size_t i = 0; i < kTrialCount; i++) {
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FILE *fp = fopen(filename_, "rb");
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FileReadStream s(fp);
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BaseReaderHandler<> h;
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Reader reader;
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reader.Parse(s, h);
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fclose(fp);
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}
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}
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TEST_F(RapidJson, IStreamWrapper) {
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for (size_t i = 0; i < kTrialCount; i++) {
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std::ifstream is(filename_);
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char buffer[65536];
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IStreamWrapper isw(is, buffer, sizeof(buffer));
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while (isw.Take() != '\0')
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;
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is.close();
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}
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}
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TEST_F(RapidJson, IStreamWrapper_Unbuffered) {
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for (size_t i = 0; i < kTrialCount; i++) {
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std::ifstream is(filename_);
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IStreamWrapper isw(is);
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while (isw.Take() != '\0')
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;
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is.close();
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}
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}
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TEST_F(RapidJson, IStreamWrapper_Setbuffered) {
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for (size_t i = 0; i < kTrialCount; i++) {
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std::ifstream is;
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char buffer[65536];
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is.rdbuf()->pubsetbuf(buffer, sizeof(buffer));
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is.open(filename_);
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IStreamWrapper isw(is);
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while (isw.Take() != '\0')
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;
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is.close();
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}
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}
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TEST_F(RapidJson, SIMD_SUFFIX(ReaderParse_DummyHandler_IStreamWrapper)) {
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for (size_t i = 0; i < kTrialCount; i++) {
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std::ifstream is(filename_);
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char buffer[65536];
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IStreamWrapper isw(is, buffer, sizeof(buffer));
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BaseReaderHandler<> h;
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Reader reader;
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reader.Parse(isw, h);
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is.close();
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}
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}
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TEST_F(RapidJson, SIMD_SUFFIX(ReaderParse_DummyHandler_IStreamWrapper_Unbuffered)) {
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for (size_t i = 0; i < kTrialCount; i++) {
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std::ifstream is(filename_);
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IStreamWrapper isw(is);
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BaseReaderHandler<> h;
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Reader reader;
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reader.Parse(isw, h);
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is.close();
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}
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}
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TEST_F(RapidJson, SIMD_SUFFIX(ReaderParse_DummyHandler_IStreamWrapper_Setbuffered)) {
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for (size_t i = 0; i < kTrialCount; i++) {
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std::ifstream is;
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char buffer[65536];
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is.rdbuf()->pubsetbuf(buffer, sizeof(buffer));
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is.open(filename_);
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IStreamWrapper isw(is);
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BaseReaderHandler<> h;
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Reader reader;
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reader.Parse(isw, h);
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is.close();
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}
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}
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TEST_F(RapidJson, StringBuffer) {
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StringBuffer sb;
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for (int i = 0; i < 32 * 1024 * 1024; i++)
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