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Add explicit buffering in backend libpq, to compensate for

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buffering lost by not going through stdio anymore for client I/O.
This commit is contained in:
Tom Lane
1999-01-23 22:27:29 +00:00
parent 13c7c183f7
commit e6725d1574
5 changed files with 193 additions and 98 deletions
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178
src/backend/libpq/pqcomm.c
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@@ -5,39 +5,40 @@
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: pqcomm.c,v 1.63 1999/01/17 06:18:26 momjian Exp $
* $Id: pqcomm.c,v 1.64 1999/01/23 22:27:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
/*
* INTERFACE ROUTINES
* pq_init - initialize libpq
* pq_init - initialize libpq
* pq_getport - return the PGPORT setting
* pq_close - close input / output connections
* pq_flush - flush pending output
* pq_recvbuf - load some bytes into the input buffer
* pq_getstr - get a null terminated string from connection
* pq_getchar - get 1 character from connection
* pq_peekchar - peek at first character in connection
* pq_getchar - get 1 character from connection
* pq_peekchar - peek at next character from connection
* pq_getnchar - get n characters from connection, and null-terminate
* pq_getint - get an integer from connection
* pq_putchar - send 1 character to connection
* pq_putchar - send 1 character to connection
* pq_putstr - send a null terminated string to connection
* pq_putnchar - send n characters to connection
* pq_putint - send an integer to connection
* pq_putncharlen - send n characters to connection
* pq_putncharlen - send n characters to connection
* (also send an int header indicating
* the length)
* pq_getinaddr - initialize address from host and port number
* pq_getinserv - initialize address from host and service name
*
* StreamDoUnlink - Shutdown UNIX socket connectioin
* StreamServerPort - Open sock stream
* StreamConnection - Create new connection with client
* StreamClose - Close a client/backend connection
* StreamDoUnlink - Shutdown UNIX socket connection
* StreamServerPort - Open socket stream
* StreamConnection - Create new connection with client
* StreamClose - Close a client/backend connection
*
* NOTES
* Frontend is now completey in interfaces/libpq, and no
* functions from this file is used.
* Frontend is now completely in interfaces/libpq, and no
* functions from this file are used there.
*
*/
#include "postgres.h"
@@ -79,6 +80,14 @@
extern FILE * debug_port; /* in util.c */
/*
* Buffers
*/
char PqSendBuffer[PQ_BUFFER_SIZE];
char PqRecvBuffer[PQ_BUFFER_SIZE];
int PqSendPointer,PqRecvPointer,PqRecvLength;
/* --------------------------------
* pq_init - open portal file descriptors
* --------------------------------
@@ -86,6 +95,7 @@ extern FILE * debug_port; /* in util.c */
void
pq_init(int fd)
{
PqSendPointer = PqRecvPointer = PqRecvLength = 0;
PQnotifies_init();
if (getenv("LIBPQ_DEBUG"))
debug_port = stderr;
@@ -94,40 +104,40 @@ pq_init(int fd)
/* -------------------------
* pq_getchar()
*
* get a character from the input file,
*
* get a character from the input file, or EOF if trouble
* --------------------------------
*/
int
pq_getchar(void)
{
char c;
while (recv(MyProcPort->sock, &c, 1, 0) != 1) {
if (errno != EINTR)
return EOF; /* Not interrupted, so something went wrong */
while (PqRecvPointer >= PqRecvLength)
{
if (pq_recvbuf()) /* If nothing in buffer, then recv some */
return EOF; /* Failed to recv data */
}
return c;
return PqRecvBuffer[PqRecvPointer++];
}
/*
/* -------------------------
* pq_peekchar()
*
* get a character from the connection, but leave it in the buffer
* to be read again
* --------------------------------
* pq_peekchar - get 1 character from connection, but leave it in the stream
*/
int
pq_peekchar(void) {
char c;
while (recv(MyProcPort->sock, &c, 1, MSG_PEEK) != 1) {
if (errno != EINTR)
return EOF; /* Not interrupted, so something went wrong */
pq_peekchar(void)
{
while (PqRecvPointer >= PqRecvLength)
{
if (pq_recvbuf()) /* If nothing in buffer, then recv some */
return EOF; /* Failed to recv data */
}
return c;
/* Note we don't bump the pointer... */
return PqRecvBuffer[PqRecvPointer];
}
/* --------------------------------
* pq_getport - return the PGPORT setting
@@ -150,18 +160,91 @@ pq_getport()
void
pq_close()
{
close(MyProcPort->sock);
close(MyProcPort->sock);
PQnotifies_init();
}
/* --------------------------------
* pq_flush - flush pending output
*
* returns 0 if OK, EOF if trouble
* --------------------------------
*/
void
int
pq_flush()
{
/* Not supported/required? */
char *bufptr = PqSendBuffer;
char *bufend = PqSendBuffer + PqSendPointer;
while (bufptr < bufend)
{
int r = send(MyProcPort->sock, bufptr, bufend - bufptr, 0);
if (r <= 0)
{
if (errno == EINTR)
continue; /* Ok if we were interrupted */
/* We would like to use elog() here, but cannot because elog
* tries to write to the client, which would cause a recursive
* flush attempt! So just write it out to the postmaster log.
*/
fprintf(stderr, "pq_flush: send() failed, errno %d\n", errno);
/* We drop the buffered data anyway so that processing
* can continue, even though we'll probably quit soon.
*/
PqSendPointer = 0;
return EOF;
}
bufptr += r;
}
PqSendPointer = 0;
return 0;
}
/* --------------------------------
* pq_recvbuf - load some bytes into the input buffer
*
* returns 0 if OK, EOF if trouble
* --------------------------------
*/
int
pq_recvbuf()
{
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;
}
/* Can fill buffer from PqRecvLength and upwards */
for (;;)
{
int r = recv(MyProcPort->sock, PqRecvBuffer + PqRecvLength,
PQ_BUFFER_SIZE - PqRecvLength, 0);
if (r <= 0)
{
if (errno == EINTR)
continue; /* Ok if interrupted */
/* We would like to use elog() here, but dare not because elog
* tries to write to the client, which will cause problems
* if we have a hard communications failure ...
* So just write the message to the postmaster log.
*/
fprintf(stderr, "pq_recvbuf: recv() failed, errno %d\n", errno);
return EOF;
}
/* r contains number of bytes read, so just incr length */
PqRecvLength += r;
return 0;
}
}
/* --------------------------------
@@ -194,7 +277,7 @@ pq_getstr(char *s, int maxlen)
int
pq_getnchar(char *s, int off, int maxlen)
{
int r = pqGetNBytes(s + off, maxlen);
int r = pqGetNBytes(s + off, maxlen);
s[off+maxlen] = '\0';
return r;
}
@@ -602,7 +685,7 @@ StreamConnection(int server_fd, Port *port)
if (setsockopt(port->sock, pe->p_proto, TCP_NODELAY,
&on, sizeof(on)) < 0)
{
elog(ERROR, "postmaster: setsockopt failed");
elog(ERROR, "postmaster: setsockopt failed: %m");
return STATUS_ERROR;
}
}
@@ -644,18 +727,9 @@ pq_putncharlen(char *s, int n)
*/
int pq_putchar(char c)
{
char isDone = 0;
do {
if (send(MyProcPort->sock, &c, 1, 0) != 1) {
if (errno != EINTR)
return EOF; /* Anything other than interrupt is error! */
}
else
isDone = 1; /* Done if we sent one char */
} while (!isDone);
return c;
if (PqSendPointer >= PQ_BUFFER_SIZE)
if (pq_flush()) /* If buffer is full, then flush it out */
return EOF;
PqSendBuffer[PqSendPointer++] = c; /* Put in buffer */
return c;
}