/* --------------------------------
* pq_recvbuf - load some bytes into the input buffer
*
* returns 0 if OK, EOF if trouble
* --------------------------------
*/
static int
pq_recvbuf(void)
{
if (PqRecvPointer > 0)
{
if (PqRecvLength > PqRecvPointer)
{
/* still some unread data, left-justify it in the buffer */
memmove(PqRecvBuffer, PqRecvBuffer + PqRecvPointer,
PqRecvLength - PqRecvPointer);
PqRecvLength -= PqRecvPointer;
PqRecvPointer = 0;
}
else
PqRecvLength = PqRecvPointer = 0;
}
/* Ensure that we're in blocking mode */
pq_set_nonblocking(false);
/* Can fill buffer from PqRecvLength and upwards */
for (;;)
{
int r;
r = secure_read(MyProcPort, PqRecvBuffer + PqRecvLength,
PQ_RECV_BUFFER_SIZE - PqRecvLength);
if (r < 0)
{
if (errno == EINTR)
continue; /* Ok if interrupted */
/*
* Careful: an ereport() that tries to write to the client would
* cause recursion to here, leading to stack overflow and core
* dump! This message must go *only* to the postmaster log.
*/
ereport(COMMERROR,
(errcode_for_socket_access(),
errmsg("could not receive data from client: %m")));
return EOF;
}
if (r == 0)
{
/*
* EOF detected. We used to write a log message here, but it's
* better to expect the ultimate caller to do that.
*/
return EOF;
}
/* r contains number of bytes read, so just incr length */
PqRecvLength += r;
return 0;
}
}
/* --------------------------------
* pq_flush - flush pending output
*
* returns 0 if OK, EOF if trouble
* --------------------------------
*/
int
pq_flush(void)
{
int res;
/* No-op if reentrant call */
if (PqCommBusy)
return 0;
PqCommBusy = true;
pq_set_nonblocking(false);
res = internal_flush();
PqCommBusy = false;
return res;
}
/* --------------------------------
* pq_getbyte_if_available - get a single byte from connection,
* if available
*
* The received byte is stored in *c. Returns 1 if a byte was read,
* 0 if no data was available, or EOF if trouble.
* --------------------------------
*/
int
pq_getbyte_if_available(unsigned char *c)
{
int r;
if (PqRecvPointer < PqRecvLength)
{
*c = PqRecvBuffer[PqRecvPointer++];
return 1;
}
/* Put the socket into non-blocking mode */
pq_set_nonblocking(true);
r = secure_read(MyProcPort, c, 1);
if (r < 0)
{
/*
* Ok if no data available without blocking or interrupted (though
* EINTR really shouldn't happen with a non-blocking socket).
* Report other errors.
*/
if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
r = 0;
else
{
/*
* Careful: an ereport() that tries to write to the client
* would cause recursion to here, leading to stack overflow
* and core dump! This message must go *only* to the
* postmaster log.
*/
ereport(COMMERROR,
(errcode_for_socket_access(),
errmsg("could not receive data from client: %m")));
r = EOF;
}
}
else if (r == 0)
{
/* EOF detected */
r = EOF;
}
return r;
}
/* --------------------------------
* pq_flush - flush pending output
*
* returns 0 if OK, EOF if trouble
* --------------------------------
*/
int
pq_flush(void)
{
int res;
if ((Gp_role == GP_ROLE_DISPATCH || Gp_role == GP_ROLE_DISPATCHAGENT) && IsUnderPostmaster)
{
if (!pq_send_mutex_lock())
{
return EOF;
}
}
pq_set_nonblocking(false);
res = internal_flush();
if ((Gp_role == GP_ROLE_DISPATCH || Gp_role == GP_ROLE_DISPATCHAGENT) && IsUnderPostmaster)
pthread_mutex_unlock(&send_mutex);
return res;
}
/* --------------------------------
* pq_flush_if_writable - flush pending output if writable without blocking
*
* Returns 0 if OK, or EOF if trouble.
* --------------------------------
*/
int
pq_flush_if_writable(void)
{
int res;
/* Quick exit if nothing to do */
if (PqSendPointer == PqSendStart)
return 0;
/* No-op if reentrant call */
if (PqCommBusy)
return 0;
/* Temporarily put the socket into non-blocking mode */
pq_set_nonblocking(true);
PqCommBusy = true;
res = internal_flush();
PqCommBusy = false;
return res;
}
/* --------------------------------
* pq_flush_if_writable - flush pending output if writable without blocking
*
* Returns 0 if OK, or EOF if trouble.
* --------------------------------
*/
int
pq_flush_if_writable(void)
{
int res;
/* Quick exit if nothing to do */
if (PqSendPointer == PqSendStart)
return 0;
if ((Gp_role == GP_ROLE_DISPATCH || Gp_role == GP_ROLE_DISPATCHAGENT) && IsUnderPostmaster)
{
if (!pq_send_mutex_lock())
{
return EOF;
}
}
/* Temporarily put the socket into non-blocking mode */
pq_set_nonblocking(true);
res = internal_flush();
if ((Gp_role == GP_ROLE_DISPATCH || Gp_role == GP_ROLE_DISPATCHAGENT) && IsUnderPostmaster)
pthread_mutex_unlock(&send_mutex);
return res;
}
static int
internal_putbytes(const char *s, size_t len)
{
size_t amount;
while (len > 0)
{
/* If buffer is full, then flush it out */
if (PqSendPointer >= PqSendBufferSize)
{
pq_set_nonblocking(false);
if (internal_flush())
return EOF;
}
amount = PqSendBufferSize - PqSendPointer;
if (amount > len)
amount = len;
memcpy(PqSendBuffer + PqSendPointer, s, amount);
PqSendPointer += amount;
s += amount;
len -= amount;
}
return 0;
}
