#include <CBufferedOutput.h>
class io::CBufferedOutput
{
public:
CBufferedOutput(int fd, size_t nBytes);
virtual void put(const void* pData, size_t nBytes);
virtual void flush();
void sync();
unsigned setTimeout(unsigned timeout);
int getFd() const;
};
template <class T>
CBufferedOutput& operator<<(CBufferedOutput& b, T& data);
The io::CBufferedOutput
class provides buffered output along with a streaming primitive
for simple objects (that don't require deep copies to the
output stream). The class also features the capability of
providing a timeout that ensures that slow writes will
not necessarily require a full buffer to flush.
io::CBufferedOutput(int fd, size_t nBytes);
Wraps a buffered output object around a file descriptor
fd.
The file descriptor must have been opened by
e.g. open(2).
nBytes is the size of the output
buffer. The output buffer is actualy written to the
file descriptor when a
put operation would overflow
the buffer.
Additionally the buffer can be flushed if a timeout has been set and the time between consecutive puts is longer than the timeout. Finally the buffer can be manually flushed as well.
virtual void put(const void* pData, size_t nBytes);
"Writes" nBytes of data from
the data pointed to by pData.
In actual fact, the data are copied into the internal
buffer. See the description of the constructor
for information about when the buffered data
are flushed to disk.
virtual void flush();
Any buffered data are flushed to disk. This is called automatically at destruction time and as described in the documentation for the constructor.
void sync();
Writing data to file via flush does not actually ensure the data get written to disk. The operating system itself may also buffer the data. This method ensures that buffered data are not only written to the file descriptor but that any operating system buffers maintained for the file are also written to disk.
unsigned setTimeout(unsigned timeout);
Sets the flush timeout in seconds. If the time between
a put call and the last flush is greater than the
number of seconds in timeout,
the data will be flushed to disk regardless of the
fullness of the buffer.
The method returns the previous timeout value.
const int getFd()();
Returns the file descriptor used by the
object. Note that prior to writing to that
file descriptor, it's a really good idea to
flush it.
For the most part this is used for
testing and ordinary clients should not need to
call it.