Add explicit buffering in backend libpq, to compensate for

buffering lost by not going through stdio anymore for client I/O.

src/backend/commands/copy.c

@@ -6,7 +6,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/copy.c,v 1.67 1999/01/17 06:18:15 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/copy.c,v 1.68 1999/01/23 22:27:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -303,9 +303,7 @@ DoCopy(char *relname, bool binary, bool oids, bool from, bool pipe,
 		}
 		else if (!from && !binary)
 		{
-		        CopySendData("\\.\n",3,fp);
-			if (IsUnderPostmaster)
-			        pq_flush();
+			CopySendData("\\.\n",3,fp);
 		}
 	}
 }

src/backend/libpq/pqcomm.c

@@ -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 */
+int
+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;
 }
-
-
-

src/backend/libpq/pqcomprim.c

@@ -98,7 +98,7 @@ pqPutLong(int integer)
 	n = ((PG_PROTOCOL_MAJOR(FrontendProtocol) == 0) ? hton_l(integer) : htonl((uint32) integer));
 #endif
 
-        return pqPutNBytes((char *)&n,4);
+	return pqPutNBytes((char *)&n, 4);
 }
 
 /* --------------------------------------------------------------------- */
@@ -107,7 +107,7 @@ pqGetShort(int *result)
 {
 	uint16		n;
 
-	if (pqGetNBytes((char *)&n,2) != 0)
+	if (pqGetNBytes((char *)&n, 2) != 0)
 	  return EOF;
 
 #ifdef FRONTEND
@@ -138,28 +138,29 @@ pqGetLong(int *result)
 }
 
 /* --------------------------------------------------------------------- */
-/* pqGetNBytes: Read a chunk of exactly len bytes in buffer s (which must be 1
-		byte longer) and terminate it with a '\0'.
-		Return 0 if ok.
-*/
+/* pqGetNBytes: Read a chunk of exactly len bytes into buffer s.
+ *	Return 0 if ok, EOF if trouble.
+ */
 int
 pqGetNBytes(char *s, size_t len)
 {
-	int bytesDone = 0;
-
-	do {
-	  int r = recv(MyProcPort->sock, s+bytesDone, len-bytesDone, 0);
-	  if (r == 0 || r == -1) {
-	    if (errno != EINTR)
-	      return EOF; /* All other than signal-interrupted is error */
-	    continue; /* Otherwise, try again */
-	  }
-	  
-	  /* r contains number of bytes received */
-	  bytesDone += r;
-
-	} while (bytesDone < len);
-	/* Zero-termination now in pq_getnchar() instead */
+	size_t amount;
+
+	while (len > 0)
+	{
+		while (PqRecvPointer >= PqRecvLength)
+		{
+			if (pq_recvbuf())	/* If nothing in buffer, then recv some */
+				return EOF;		/* Failed to recv data */
+		}
+		amount = PqRecvLength - PqRecvPointer;
+		if (amount > len)
+			amount = len;
+		memcpy(s, PqRecvBuffer + PqRecvPointer, amount);
+		PqRecvPointer += amount;
+		s += amount;
+		len -= amount;
+	}
 	return 0;
 }
 
@@ -167,20 +168,21 @@ pqGetNBytes(char *s, size_t len)
 int
 pqPutNBytes(const char *s, size_t len)
 {
-        int bytesDone = 0;
-
-	do {
-	  int r = send(MyProcPort->sock, s+bytesDone, len-bytesDone, 0);
-	  if (r == 0 || r == -1) {
-	    if (errno != EINTR)
-	      return EOF; /* Only signal interruption allowed */
-	    continue; /* If interruped and read nothing, just try again */
-	  }
-	  
-	  /* r contains number of bytes sent so far */
-	  bytesDone += r;
-	} while (bytesDone < len);
-
+	size_t amount;
+
+	while (len > 0)
+	{
+		if (PqSendPointer >= PQ_BUFFER_SIZE)
+			if (pq_flush())		/* If buffer is full, then flush it out */
+				return EOF;
+		amount = PQ_BUFFER_SIZE - PqSendPointer;
+		if (amount > len)
+			amount = len;
+		memcpy(PqSendBuffer + PqSendPointer, s, amount);
+		PqSendPointer += amount;
+		s += amount;
+		len -= amount;
+	}
 	return 0;
 }
 
@@ -191,8 +193,8 @@ pqGetString(char *s, size_t len)
 	int			c;
 
 	/*
-	 * Keep on reading until we get the terminating '\0' and discard those
-	 * bytes we don't have room for.
+	 * Keep on reading until we get the terminating '\0',
+	 * discarding any bytes we don't have room for.
 	 */
 
 	while ((c = pq_getchar()) != EOF && c != '\0')
@@ -216,4 +218,3 @@ pqPutString(const char *s)
 {
   return pqPutNBytes(s,strlen(s)+1);
 }
-

src/backend/utils/error/elog.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/error/elog.c,v 1.37 1999/01/11 03:56:07 scrappy Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/error/elog.c,v 1.38 1999/01/23 22:27:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -192,8 +192,15 @@ elog(int lev, const char *fmt,...)
 			pq_putnchar("N", 1);
 		else
 			pq_putnchar("E", 1);
-		/* pq_putint(-101, 4); *//* should be query id */
 		pq_putstr(line + TIMESTAMP_SIZE);		/* don't show timestamps */
+		/*
+		 * This flush is normally not necessary, since postgres.c will
+		 * flush out waiting data when control returns to the main loop.
+		 * But it seems best to leave it here, so that the client has some
+		 * clue what happened if the backend dies before getting back to the
+		 * main loop ... error/notice messages should not be a performance-
+		 * critical path anyway, so an extra flush won't hurt much ...
+		 */
 		pq_flush();
 	}
 	if (!IsUnderPostmaster)

src/include/libpq/libpq.h

@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: libpq.h,v 1.23 1999/01/12 12:49:52 scrappy Exp $
+ * $Id: libpq.h,v 1.24 1999/01/23 22:27:25 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -254,12 +254,13 @@ extern void pq_init(int fd);
 extern void pq_gettty(char *tp);
 extern int	pq_getport(void);
 extern void pq_close(void);
-extern void pq_flush(void);
+extern int	pq_flush(void);
+extern int	pq_recvbuf(void);
 extern int	pq_getstr(char *s, int maxlen);
 extern int	PQgetline(char *s, int maxlen);
 extern int	PQputline(char *s);
-extern int      pq_getchar(void);
-extern int      pq_peekchar(void);
+extern int	pq_getchar(void);
+extern int	pq_peekchar(void);
 extern int	pq_getnchar(char *s, int off, int maxlen);
 extern int	pq_getint(int b);
 extern int  pq_putchar(char c);
@@ -282,4 +283,18 @@ extern int	StreamServerPort(char *hostName, short portName, int *fdP);
 extern int	StreamConnection(int server_fd, Port *port);
 extern void StreamClose(int sock);
 
+/*
+ * Internal send/receive buffers in libpq.
+ * These probably shouldn't be global at all, but unless we merge
+ * pqcomm.c and pqcomprim.c they have to be...
+ */
+
+#define PQ_BUFFER_SIZE 8192
+
+extern char PqSendBuffer[PQ_BUFFER_SIZE];
+extern int PqSendPointer;	/* Next index to store a byte in PqSendBuffer */
+extern char PqRecvBuffer[PQ_BUFFER_SIZE];
+extern int PqRecvPointer;	/* Next index to read a byte from PqRecvBuffer */
+extern int PqRecvLength;	/* End of data available in PqRecvBuffer */
+
 #endif	 /* LIBPQ_H */