ASSA::Socketbuf Class Reference

#include <Socketbuf.h>

Inheritance diagram for ASSA::Socketbuf:

Public Member Functions
	Socketbuf (Socket *s_)
virtual	~Socketbuf ()
Public Member Functions inherited from ASSA::Streambuf
virtual	~Streambuf ()
Streambuf *	pubsetbuf (char *s_, int n_)
	Set buffer.
int	pubsync ()
int	in_avail ()
	This function returns the number of characters immediately available in the get area.
int	snextc ()
	This function moves the get pointer forward one position, then returns the character after the get pointer's new position.
int	sgetc ()
	This function should probably have been called ``sgetc''.
int	sgetn (char *b_, int len_)
	This function gets the next len_ characters following the get pointer, copying them to the char array pointed to by b_; it advances the get pointer past the last character fetched.
int	sputc (char c_)
	This function stores c just after the put pointer, and advances the pointer one position, possibly extending the sequence.
int	sputn (char *b_, int len_)
	From the location pointed to by ptr, stores exactly len characters after the put pointer, advancing the put pointer just past the last character.
void	unbuffered (int i_)
	If i_ is non-zero, then all IO operations are buffered.
int	unbuffered ()
Public Member Functions inherited from ASSA::io_ptrs
	io_ptrs ()
void	dump () const

Protected Member Functions
virtual int	sync ()
	This function synchronizes the streambuf with its actual stream of characters.
virtual int	underflow ()
	This function is called to supply characters for input (from some source) when the get area is empty, although it may be called at other times.
virtual int	overflow (int c_=EOF)
	This function is called to consume characters (flush them to output), typically when the put area is full and an attempt is made to store another character.
virtual int	showmanyc ()
virtual int	doallocate ()
	This function is called by allocate when unbuffered() is zero and base() is zero.
Protected Member Functions inherited from ASSA::Streambuf
	Streambuf ()
	The default constructor is protected for class Streambuf to asssure that only objects for classes derived from this class may be constructed.
	Streambuf (const Streambuf &)
Streambuf &	operator= (const Streambuf &)
char *	base () const
	Returns the lowest possible value for gptr() - the beginning of the get area.
char *	gptr () const
	Returns a pointer to the beginning of the get area, and thus to the next character to be fetched (if there are any).
char *	egptr () const
	Returns a pointer just past the end of the get area, the maximum possible value for gptr().
void	setg (char *gbeg_, char *gnext_, char *gend_)
	Set get area pointers.
char *	pbase () const
	Returns a pointer to the beginning fo the space available for the put area, the lowest possible value for pptr().
char *	pptr () const
	Returns a pointer to the beginning of the put area, and thus to the location of the next character that is stored (if possible).
char *	epptr () const
	Returns a pointer just past the end of the put area, the maximum possible value for pptr().
void	setp (char *pbeg_, char *pend_)
	Set put area pointers.
void	pbump (int n_)
	Advances the next pointer for the output sequence by n_.
void	setb (char *b_, char *eb_, int del_)
	Establish the reserve area (buffer).
void	init ()
virtual Streambuf *	setbuf (char *p_, int len_)
	Performs an operation that is defined separately for each class derived from Streambuf.
virtual int	xsgetn (char *b_, int len_)
	The morphemes of showmanyc are "es-how-many-see", not "show-man-ic".
virtual int	uflow ()
	Reads the characters from the input sequence, if possible, and moves the stream position past it, as follows:
virtual int	xsputn (const char *b_, int len_)
	Writes up to len_ characters to the output sequence as if by repeated calls to sputc (c).

Private Member Functions
int	flush_output ()
int	sys_read (char *b_, int len_)
int	sys_write (char *b_, int len_)
void	xput_char (char c_)

Private Attributes
Socket *	m_s
	Reference to the Socket stream.

Additional Inherited Members
Public Types inherited from ASSA::io_ptrs
enum	{ USER_BUF = 1 , UNBUFFERED = 2 , EOF_SEEN = 4 , ERR_SEEN = 8 }
Public Attributes inherited from ASSA::io_ptrs
char *	m_read_base
char *	m_read_ptr
char *	m_read_end
char *	m_write_base
char *	m_write_ptr
char *	m_write_end
char *	m_buf_base
char *	m_buf_end
int	m_flags
char	m_shortbuf [1]
Static Public Attributes inherited from ASSA::Streambuf
static const int	MAXTCPFRAMESZ = 65536
	Size of the internal input/output buffer.

Detailed Description

Definition at line 29 of file Socketbuf.h.

Constructor & Destructor Documentation

Socketbuf()

Socketbuf::Socketbuf

(

Socket *

s_

)

Definition at line 24 of file Socketbuf.cpp.

    : m_s (s_) 
{
    trace_with_mask("Socketbuf::Socketbuf",STRMBUFTRACE);
    // By default, I am doing buffering IO
    unbuffered (0);
}

References m_s, ASSA::STRMBUFTRACE, trace_with_mask, and ASSA::Streambuf::unbuffered().

~Socketbuf()

Socketbuf::~Socketbuf ( )

virtual

Definition at line 58 of file Socketbuf.cpp.

{
    trace_with_mask("Socketbuf::~Socketbuf",STRMBUFTRACE);
    overflow (EOF);     // flush put area
}

References overflow(), ASSA::STRMBUFTRACE, and trace_with_mask.

Member Function Documentation

doallocate()

int Socketbuf::doallocate ( )

protectedvirtual

This function is called by allocate when unbuffered() is zero and base() is zero.

It attempts to make a buffer of suitable size available. On success it must call setb to establish the reserve area, then return a value greater than zero. On failure it returns EOF. The default behavior is to allocate a buffer using new.

Reimplemented from ASSA::Streambuf.

Definition at line 226 of file Socketbuf.cpp.

{
    trace_with_mask("Socketbuf::doallocate",STRMBUFTRACE);
 
    // Get area comes first and matches entier buffer area.
    // Put area comes right after it. They are two equally-sized
    // separate buffers.
    //
    // ------------ -
    // |          | ^
    // | get area | | buffer area
    // |          | v
    // ------------ -
    // | put area |
    // |          |
    // ------------
    //
    // Return 1 on allocation and 0 if there is no need
 
    if (m_buf_base)
        return 0;
 
    if ( ! (m_flags & UNBUFFERED) ) {
        DL((STRMBUF,"Buffered IO - allocating %d bytes\n",
            2 * MAXTCPFRAMESZ));
        char* buf = new char [2 * MAXTCPFRAMESZ];
 
        setg (buf, buf + MAXTCPFRAMESZ, buf + MAXTCPFRAMESZ);
        setb (buf, buf + MAXTCPFRAMESZ, 1);
   
        buf += MAXTCPFRAMESZ;
        setp (buf, buf+MAXTCPFRAMESZ);
    }
    else {
        DL((STRMBUF,"Unbuffered IO - same 1 byte array\n"));
        setb (m_shortbuf, m_shortbuf+1, 0);
 
        // read_base is pointing to the begining,  and
        // read_end to one past end of the buffer.
        // Because buffer is empty, read_ptr should point
        // to the end (same as read_end). This way, calling
        // routines will detect that get area needs data from sync.
        //
        // +- read_base   +- read_ptr 
        // |              |- read_end 
        // |              |+----- one past end-of-block
        // v              vv
        // +--------------+-+
        // | get area     | |
        // +--------------+-+
        setg (m_shortbuf, m_shortbuf+1, m_shortbuf+1);
 
        // write_base  & write_ptr are pointing to the begining, 
        // and write_end to one past end of the buffer.
        // Because buffer is empty, read_ptr should point
        // to the beginning (same as write_base). This way, calling
        // routines will detect that put area needs data from sync.
        //
        // +- write_base   +- write_end points one past 
        // |- write_ptr    |    end-of-block
        // v               v
        // +--------------+-+
        // | put area     | |
        // +--------------+-+
 
        setp (m_shortbuf, m_shortbuf+1);
    }
    dump ();
    return 1;
}

References DL, ASSA::io_ptrs::dump(), ASSA::io_ptrs::m_buf_base, ASSA::io_ptrs::m_flags, ASSA::io_ptrs::m_shortbuf, ASSA::Streambuf::MAXTCPFRAMESZ, ASSA::Streambuf::setb(), ASSA::Streambuf::setg(), ASSA::Streambuf::setp(), ASSA::STRMBUF, ASSA::STRMBUFTRACE, trace_with_mask, and ASSA::io_ptrs::UNBUFFERED.

Referenced by overflow(), and underflow().

flush_output()

int Socketbuf::flush_output ( )

private

Definition at line 191 of file Socketbuf.cpp.

{
    trace_with_mask("Socketbuf::flush_output",STRMBUFTRACE);
 
    if (pptr () <= pbase ()) {  // Nothing to flush
        return 0;
    }
 
    int requested;
    int xmitted;
 
    requested = pptr () - pbase ();
 
    if ((xmitted = sys_write (pbase (), requested)) < 0) {
        return EOF;
    }
 
    if (unbuffered ()) {
        setp (pbase (), epptr ());
        return 0;
    }
 
    requested -= xmitted;
    setp (pbase (), pbase () + MAXTCPFRAMESZ);
    pbump (requested);
 
    if (requested > 0) {
        ::memmove (pbase (), pbase () + xmitted, requested);
    }
 
    return 0;
}

References ASSA::Streambuf::epptr(), ASSA::Streambuf::MAXTCPFRAMESZ, ASSA::Streambuf::pbase(), ASSA::Streambuf::pbump(), ASSA::Streambuf::pptr(), ASSA::Streambuf::setp(), ASSA::STRMBUFTRACE, sys_write(), trace_with_mask, and ASSA::Streambuf::unbuffered().

Referenced by overflow(), and sync().

overflow()

int Socketbuf::overflow ( int c = EOF )

protectedvirtual

This function is called to consume characters (flush them to output), typically when the put area is full and an attempt is made to store another character.

If c is not EOF, overflow must either store or consume the character, following those already in the put area. It returns EOF on error, any other value on success. The default behavior of the base class version is undefined, so each derived class must define its own overflow. The normal action for a derived class version is to consume the characters in the put area (those between pbase() and pptr()), call setp() to set up a new put area, then store c (using sputc()) if it is not EOF.

Reimplemented from ASSA::Streambuf.

Definition at line 161 of file Socketbuf.cpp.

{
    trace_with_mask("Socketbuf::overflow",STRMBUFTRACE);
 
    // If c == EOF, return flush_output()
    // Otherwise, insert c into the buffer
 
    if (c_ == EOF)
        return flush_output ();
 
    if (pbase () == 0 && doallocate () == EOF)
        return EOF;
 
    if (pptr () >= epptr() && flush_output () == EOF)
        return EOF;
 
    xput_char (c_);
 
    dump ();
 
    if ((unbuffered () || pptr () >= epptr ()) && flush_output () == EOF) 
        return EOF;
 
    dump ();
 
    return c_;
}

References doallocate(), ASSA::io_ptrs::dump(), ASSA::Streambuf::epptr(), flush_output(), ASSA::Streambuf::pbase(), ASSA::Streambuf::pptr(), ASSA::STRMBUFTRACE, trace_with_mask, ASSA::Streambuf::unbuffered(), and xput_char().

Referenced by ~Socketbuf().

showmanyc()

int Socketbuf::showmanyc ( )

protectedvirtual

Definition at line 42 of file Socketbuf.cpp.

{ 
    trace_with_mask("Socketbuf::showmanyc",STRMBUFTRACE);
    return m_s->getBytesAvail (); 
}

References m_s, ASSA::STRMBUFTRACE, and trace_with_mask.

sync()

int Socketbuf::sync ( )

protectedvirtual

This function synchronizes the streambuf with its actual stream of characters.

The derived class version should flush any characters in the put area to their final destination, and if possible give back any characters in the input buffer to their source. It should return EOF on any error, zero on success. The default behavior of the base class version is to return zero if there are no pending input or output characters (in_avail() and out_waiting() are both zero), and return EOF otherwise.

Reimplemented from ASSA::Streambuf.

Definition at line 34 of file Socketbuf.cpp.

{ 
    trace_with_mask("Socketbuf::sync",STRMBUFTRACE);
    return flush_output (); 
}

References flush_output(), ASSA::STRMBUFTRACE, and trace_with_mask.

sys_read()

int Socketbuf::sys_read ( char * b_, int len_ )

private

Definition at line 66 of file Socketbuf.cpp.

{ 
    trace_with_mask("Socketbuf::sys_read",STRMBUFTRACE);
    
    int ret = ::recv (m_s->getHandler (), b_, len_, 0);
 
    DL((STRMBUFTRACE,"Tried to read %d bytes from fd=%d\n", 
        len_, m_s->getHandler ()));
    DL((STRMBUFTRACE,"::recv() returned %d\n", ret));
 
    if (ret == -1) {
        DL((STRMBUFTRACE,"::recv() error: %d (%s)\n",
            errno, strerror (get_errno ())));
    }
    return (ret);
}

References DL, ASSA::get_errno(), m_s, ASSA::STRMBUFTRACE, and trace_with_mask.

Referenced by underflow().

sys_write()

int Socketbuf::sys_write ( char * b_, int len_ )

private

Definition at line 85 of file Socketbuf.cpp.

{ 
    trace_with_mask("Socketbuf::sys_write",STRMBUFTRACE);
 
    int ret = ::send (m_s->getHandler (), b_, len_, 0);
 
    DL((STRMBUFTRACE,"Tried to write %d bytes to fd=%d\n", 
        len_, m_s->getHandler ()));
    DL((STRMBUFTRACE,"::send() returned %d\n", ret));
 
    if (ret == -1) {
        DL((STRMBUFTRACE,"::send() error: %d\n",errno));
    }
 
    return (ret);
}

References DL, m_s, ASSA::STRMBUFTRACE, and trace_with_mask.

Referenced by flush_output().

underflow()

int Socketbuf::underflow ( )

protectedvirtual

This function is called to supply characters for input (from some source) when the get area is empty, although it may be called at other times.

If the get area is not empty, it should just return the first character (without advancing the get pointer). If the get area is empty, it should establish a new get area, aquire new input, and return the first character, if any. If no input characters are available, it should leave an empty get area and return EOF. The default behavior of the base class version is undefined, so each derived class must define its own underflow.

Reimplemented from ASSA::Streambuf.

Definition at line 104 of file Socketbuf.cpp.

{
    /*
      The important thing to note is that this function
      returns:
        a) pointer to the first character in buffer available.
        b) EOF if sys_read () failed.
        
      In case of peer closing its connection, a) will be true.
      Caller can always find out number of bytes in buffer
      and determine if peer indeed closed connection.
    */
    trace_with_mask("Socketbuf::underflow",STRMBUFTRACE);
 
    if (gptr () < egptr ())                   // The get area is not empty,
    {
        return *(unsigned char*) gptr (); //  return 1st character
    }
 
    if (base () == 0 &&        // If buffer isn't established,
        doallocate () == EOF)  // allocate buffer (both buff & unbuff IO)
    {
        return EOF;
    }
 
    int bufsz = unbuffered () ? 1 : MAXTCPFRAMESZ;
 
    /*
      Read as much as I can up to the allocated buffer size.
      EOF = (-1).
    */
    int rval = sys_read (base (), bufsz); 
 
    DL((STRMBUF,"Socketbuf::sys_read() returned %d bytes\n", rval));
 
    if (rval == EOF) 
    {
        if (get_errno () != EWOULDBLOCK) {
            m_flags |= EOF_SEEN;
        }
        return EOF;
    }
 
    DL((STRMBUF,"Having read %d bytes from socket\n",rval));
    MemDump::dump_to_log (STRMBUF, "Data received:", base (), rval);
 
    // Set get area pointers according to the data just read
 
    setg (base (), base (), base () + rval); 
 
    dump ();
 
    return (*(unsigned char*) gptr ()); // Return front character
}

References ASSA::Streambuf::base(), DL, doallocate(), ASSA::io_ptrs::dump(), ASSA::MemDump::dump_to_log(), ASSA::Streambuf::egptr(), ASSA::io_ptrs::EOF_SEEN, ASSA::get_errno(), ASSA::Streambuf::gptr(), ASSA::io_ptrs::m_flags, ASSA::Streambuf::MAXTCPFRAMESZ, ASSA::Streambuf::setg(), ASSA::STRMBUF, ASSA::STRMBUFTRACE, sys_read(), trace_with_mask, and ASSA::Streambuf::unbuffered().

xput_char()

void Socketbuf::xput_char ( char c_ )

private

Definition at line 50 of file Socketbuf.cpp.

{ 
    trace_with_mask("Socketbuf::xput_char",STRMBUFTRACE);
    *pptr() = c_; 
    pbump (1); 
}

References ASSA::Streambuf::pbump(), ASSA::Streambuf::pptr(), ASSA::STRMBUFTRACE, and trace_with_mask.

Referenced by overflow().

Member Data Documentation

m_s

Socket* ASSA::Socketbuf::m_s

private

Reference to the Socket stream.

Definition at line 51 of file Socketbuf.h.

Referenced by showmanyc(), Socketbuf(), sys_read(), and sys_write().

---

The documentation for this class was generated from the following files:

• Socketbuf.h
• Socketbuf.cpp