std::basic_syncbuf is a wrapper for a std::basic_streambuf (provided at construction time as a pointer). It accumulates output in its own internal buffer, and atomically transmits its entire contents to the wrapped buffer on destruction and when explicitly requested, so that they appear as a contiguous sequence of characters. It guarantees that there are no data races and no interleaving of characters sent to the wrapped buffer as long as all other outputs made to the same buffer are made through, possibly different, instances of std::basic_syncbuf.
Typical implementation of std::basic_syncbuf holds a pointer to the wrapped std::basic_streambuf, a boolean flag indicating whether the buffer will transmit its contents to the wrapped buffer on sync (flush), a boolean flag indicating a pending flush when the policy is to not emit on sync, an internal buffer that uses Allocator (such as std::string), and a pointer to a mutex used to synchronize emit between multiple threads accessing the same wrapped stream buffer (these mutexes may be in a hash map with pointers to std::basic_streambuf objects used as keys).
Like other streambuf classes, std::basic_syncbuf is normally only accessed through the corresponding stream, std::osyncstream, not directly.
Several typedefs for common character types are provided:
repositions the next pointer in the input sequence, output sequence, or both, using relative addressing (virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
repositions the next pointer in the input sequence, output sequence, or both using absolute addressing (virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
obtains the number of characters available for input in the associated input sequence, if known (virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
reads characters from the associated input sequence to the get area and advances the next pointer (virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
puts a character back into the input sequence, possibly modifying the input sequence (virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]