From 3a18f01b7aa5f1358156118b58d753c879a60391 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 1 Dec 2002 18:14:22 +0000
Subject: [PATCH] Run COPY OUT in a temporary memory context that's reset once
per row, and eliminate its manual pfree() calls. This solves the
encoding-conversion bug recently reported, and should be faster and more
robust than the original coding anyway. For example, we are no longer at
risk if datatype output routines leak memory or choose to return a constant
string.
---
src/backend/commands/copy.c | 73 +++++++++++++++++++------------------
1 file changed, 37 insertions(+), 36 deletions(-)
diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 242973f20f6..45749ab673a 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -1,13 +1,15 @@
/*-------------------------------------------------------------------------
*
* copy.c
+ * COPY command.
+ *
*
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/commands/copy.c,v 1.183 2002/11/26 03:01:57 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/commands/copy.c,v 1.184 2002/12/01 18:14:22 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -532,6 +534,8 @@ CopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
char *string;
Snapshot mySnapshot;
List *cur;
+ MemoryContext oldcontext;
+ MemoryContext mycontext;
tupDesc = rel->rd_att;
attr = tupDesc->attrs;
@@ -561,6 +565,18 @@ CopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
elog(ERROR, "COPY BINARY: cstring not supported");
}
+ /*
+ * Create a temporary memory context that we can reset once per row
+ * to recover palloc'd memory. This avoids any problems with leaks
+ * inside datatype output routines, and should be faster than retail
+ * pfree's anyway. (We don't need a whole econtext as CopyFrom does.)
+ */
+ mycontext = AllocSetContextCreate(CurrentMemoryContext,
+ "COPY TO",
+ ALLOCSET_DEFAULT_MINSIZE,
+ ALLOCSET_DEFAULT_INITSIZE,
+ ALLOCSET_DEFAULT_MAXSIZE);
+
if (binary)
{
/* Generate header for a binary copy */
@@ -591,6 +607,9 @@ CopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
CHECK_FOR_INTERRUPTS();
+ MemoryContextReset(mycontext);
+ oldcontext = MemoryContextSwitchTo(mycontext);
+
if (binary)
{
/* Binary per-tuple header */
@@ -615,7 +634,6 @@ CopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
string = DatumGetCString(DirectFunctionCall1(oidout,
ObjectIdGetDatum(HeapTupleGetOid(tuple))));
CopySendString(string, fp);
- pfree(string);
need_delim = true;
}
}
@@ -623,11 +641,10 @@ CopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
foreach(cur, attnumlist)
{
int attnum = lfirsti(cur);
- Datum origvalue,
- value;
+ Datum value;
bool isnull;
- origvalue = heap_getattr(tuple, attnum, tupDesc, &isnull);
+ value = heap_getattr(tuple, attnum, tupDesc, &isnull);
if (!binary)
{
@@ -650,17 +667,6 @@ CopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
}
else
{
- /*
- * If we have a toasted datum, forcibly detoast it to
- * avoid memory leakage inside the type's output routine
- * (or for binary case, becase we must output untoasted
- * value).
- */
- if (isvarlena[attnum - 1])
- value = PointerGetDatum(PG_DETOAST_DATUM(origvalue));
- else
- value = origvalue;
-
if (!binary)
{
string = DatumGetCString(FunctionCall3(&out_functions[attnum - 1],
@@ -668,7 +674,6 @@ CopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
ObjectIdGetDatum(elements[attnum - 1]),
Int32GetDatum(attr[attnum - 1]->atttypmod)));
CopyAttributeOut(fp, string, delim);
- pfree(string);
}
else
{
@@ -678,6 +683,10 @@ CopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
{
/* varlena */
Assert(fld_size == -1);
+
+ /* If we have a toasted datum, detoast it */
+ value = PointerGetDatum(PG_DETOAST_DATUM(value));
+
CopySendData(DatumGetPointer(value),
VARSIZE(value),
fp);
@@ -706,15 +715,13 @@ CopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
fp);
}
}
-
- /* Clean up detoasted copy, if any */
- if (value != origvalue)
- pfree(DatumGetPointer(value));
}
}
if (!binary)
CopySendChar('\n', fp);
+
+ MemoryContextSwitchTo(oldcontext);
}
heap_endscan(scandesc);
@@ -727,6 +734,8 @@ CopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
CopySendData(&fld_count, sizeof(int16), fp);
}
+ MemoryContextDelete(mycontext);
+
pfree(out_functions);
pfree(elements);
pfree(isvarlena);
@@ -1235,13 +1244,13 @@ CopyFrom(Relation rel, List *attnumlist, bool binary, bool oids,
*/
copy_lineno = 0;
+ MemoryContextSwitchTo(oldcontext);
+
/*
* Execute AFTER STATEMENT insertion triggers
*/
ExecASInsertTriggers(estate, resultRelInfo);
- MemoryContextSwitchTo(oldcontext);
-
pfree(values);
pfree(nulls);
@@ -1463,7 +1472,6 @@ copy_eof:
attribute_buf.len = 0;
attribute_buf.data[0] = '\0';
appendBinaryStringInfo(&attribute_buf, cvt, strlen(cvt));
- pfree(cvt);
}
}
@@ -1476,24 +1484,16 @@ CopyAttributeOut(FILE *fp, char *server_string, char *delim)
char *string;
char c;
char delimc = delim[0];
-
bool same_encoding;
- char *string_start;
int mblen;
int i;
same_encoding = (server_encoding == client_encoding);
if (!same_encoding)
- {
string = (char *) pg_server_to_client((unsigned char *) server_string,
strlen(server_string));
- string_start = string;
- }
else
- {
string = server_string;
- string_start = NULL;
- }
for (; (c = *string) != '\0'; string += mblen)
{
@@ -1527,7 +1527,11 @@ CopyAttributeOut(FILE *fp, char *server_string, char *delim)
CopySendChar('\\', fp);
CopySendChar(c, fp);
- /* XXX shouldn't this be done even when encoding is same? */
+ /*
+ * We can skip pg_encoding_mblen() overhead when encoding
+ * is same, because in valid backend encodings, extra
+ * bytes of a multibyte character never look like ASCII.
+ */
if (!same_encoding)
{
/* send additional bytes of the char, if any */
@@ -1538,9 +1542,6 @@ CopyAttributeOut(FILE *fp, char *server_string, char *delim)
break;
}
}
-
- if (string_start)
- pfree(string_start); /* pfree pg_server_to_client result */
}
/*
--
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