@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $ Header : / cvsroot / pgsql / src / backend / storage / smgr / md . c , v 1.83 2001 / 04 / 02 23 : 20 : 24 tgl Exp $
* $ Header : / cvsroot / pgsql / src / backend / storage / smgr / md . c , v 1.84 2001 / 05 / 10 20 : 38 : 49 tgl Exp $
*
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/
@ -54,10 +54,9 @@ typedef struct _MdfdVec
int mdfd_flags ; /* fd status flags */
/* these are the assigned bits in mdfd_flags: */
# define MDFD_FREE (1 << 0) /* unused entry */
# define MDFD_FREE (1 << 0) /* unused entry */
int mdfd_lstbcnt ; /* most recent block count */
int mdfd_nextFree ; /* next free vector */
int mdfd_nextFree ; /* link to next freelist member, if free */
# ifndef LET_OS_MANAGE_FILESIZE
struct _MdfdVec * mdfd_chain ; /* for large relations */
# endif
@ -164,7 +163,6 @@ mdcreate(Relation reln)
Md_fdvec [ vfd ] . mdfd_vfd = fd ;
Md_fdvec [ vfd ] . mdfd_flags = ( uint16 ) 0 ;
Md_fdvec [ vfd ] . mdfd_lstbcnt = 0 ;
# ifndef LET_OS_MANAGE_FILESIZE
Md_fdvec [ vfd ] . mdfd_chain = ( MdfdVec * ) NULL ;
# endif
@ -225,52 +223,69 @@ mdunlink(RelFileNode rnode)
/*
* mdextend ( ) - - Add a block to the specified relation .
*
* The semantics are basically the same as mdwrite ( ) : write at the
* specified position . However , we are expecting to extend the
* relation ( ie , blocknum is the current EOF ) , and so in case of
* failure we clean up by truncating .
*
* This routine returns SM_FAIL or SM_SUCCESS , with errno set as
* appropriate .
*
* Note : this routine used to call mdnblocks ( ) to get the block position
* to write at , but that ' s pretty silly since the caller needs to know where
* the block will be written , and accordingly must have done mdnblocks ( )
* already . Might as well pass in the position and save a seek .
*/
int
mdextend ( Relation reln , char * buffer )
mdextend ( Relation reln , BlockNumber blocknum , char * buffer )
{
long pos ,
nbytes ;
int nblocks ;
long seekpos ;
int nbytes ;
MdfdVec * v ;
nblocks = mdnblocks ( reln ) ;
v = _mdfd_getseg ( reln , nblocks ) ;
v = _mdfd_getseg ( reln , blocknum ) ;
if ( ( pos = FileSeek ( v - > mdfd_vfd , 0L , SEEK_END ) ) < 0 )
return SM_FAIL ;
# ifndef LET_OS_MANAGE_FILESIZE
seekpos = ( long ) ( BLCKSZ * ( blocknum % RELSEG_SIZE ) ) ;
# ifdef DIAGNOSTIC
if ( seekpos > = BLCKSZ * RELSEG_SIZE )
elog ( FATAL , " seekpos too big! " ) ;
# endif
# else
seekpos = ( long ) ( BLCKSZ * ( blocknum ) ) ;
# endif
if ( pos % BLCKSZ ! = 0 ) /* the last block is incomplete */
{
pos - = pos % BLCKSZ ;
if ( FileSeek ( v - > mdfd_vfd , pos , SEEK_SET ) < 0 )
return SM_FAIL ;
}
/*
* Note : because caller obtained blocknum by calling mdnblocks , which
* did a seek ( SEEK_END ) , this seek is often redundant and will be
* optimized away by fd . c . It ' s not redundant , however , if there is a
* partial page at the end of the file . In that case we want to try to
* overwrite the partial page with a full page . It ' s also not redundant
* if bufmgr . c had to dump another buffer of the same file to make room
* for the new page ' s buffer .
*/
if ( FileSeek ( v - > mdfd_vfd , seekpos , SEEK_SET ) ! = seekpos )
return SM_FAIL ;
if ( ( nbytes = FileWrite ( v - > mdfd_vfd , buffer , BLCKSZ ) ) ! = BLCKSZ )
{
if ( nbytes > 0 )
{
FileTruncate ( v - > mdfd_vfd , pos ) ;
FileSeek ( v - > mdfd_vfd , pos , SEEK_SET ) ;
int save_errno = errno ;
/* Remove the partially-written page */
FileTruncate ( v - > mdfd_vfd , seekpos ) ;
FileSeek ( v - > mdfd_vfd , seekpos , SEEK_SET ) ;
errno = save_errno ;
}
return SM_FAIL ;
}
/* try to keep the last block count current, though it's just a hint */
# ifndef LET_OS_MANAGE_FILESIZE
if ( ( v - > mdfd_lstbcnt = ( + + nblocks % RELSEG_SIZE ) ) = = 0 )
v - > mdfd_lstbcnt = RELSEG_SIZE ;
# ifdef DIAGNOSTIC
if ( _mdnblocks ( v - > mdfd_vfd , BLCKSZ ) > RELSEG_SIZE
| | v - > mdfd_lstbcnt > RELSEG_SIZE )
if ( _mdnblocks ( v - > mdfd_vfd , BLCKSZ ) > RELSEG_SIZE )
elog ( FATAL , " segment too big! " ) ;
# endif
# else
v - > mdfd_lstbcnt = + + nblocks ;
# endif
return SM_SUCCESS ;
@ -319,12 +334,11 @@ mdopen(Relation reln)
Md_fdvec [ vfd ] . mdfd_vfd = fd ;
Md_fdvec [ vfd ] . mdfd_flags = ( uint16 ) 0 ;
Md_fdvec [ vfd ] . mdfd_lstbcnt = _mdnblocks ( fd , BLCKSZ ) ;
# ifndef LET_OS_MANAGE_FILESIZE
Md_fdvec [ vfd ] . mdfd_chain = ( MdfdVec * ) NULL ;
# ifdef DIAGNOSTIC
if ( Md_fdvec [ vfd ] . mdfd_lstbcnt > RELSEG_SIZE )
if ( _mdnblocks ( fd , BLCKSZ ) > RELSEG_SIZE )
elog ( FATAL , " segment too big on relopen! " ) ;
# endif
# endif
@ -440,9 +454,12 @@ mdread(Relation reln, BlockNumber blocknum, char *buffer)
status = SM_SUCCESS ;
if ( ( nbytes = FileRead ( v - > mdfd_vfd , buffer , BLCKSZ ) ) ! = BLCKSZ )
{
if ( nbytes = = 0 )
MemSet ( buffer , 0 , BLCKSZ ) ;
else if ( blocknum = = 0 & & nbytes > 0 & & mdnblocks ( reln ) = = 0 )
/*
* If we are at EOF , return zeroes without complaining .
* ( XXX Is this still necessary / a good idea ? ? )
*/
if ( nbytes = = 0 | |
( nbytes > 0 & & mdnblocks ( reln ) = = blocknum ) )
MemSet ( buffer , 0 , BLCKSZ ) ;
else
status = SM_FAIL ;
@ -459,7 +476,6 @@ mdread(Relation reln, BlockNumber blocknum, char *buffer)
int
mdwrite ( Relation reln , BlockNumber blocknum , char * buffer )
{
int status ;
long seekpos ;
MdfdVec * v ;
@ -478,11 +494,10 @@ mdwrite(Relation reln, BlockNumber blocknum, char *buffer)
if ( FileSeek ( v - > mdfd_vfd , seekpos , SEEK_SET ) ! = seekpos )
return SM_FAIL ;
status = SM_SUCCESS ;
if ( FileWrite ( v - > mdfd_vfd , buffer , BLCKSZ ) ! = BLCKSZ )
status = SM_FAIL ;
return SM_FAIL ;
return status ;
return SM_SUCCESS ;
}
/*
@ -662,31 +677,29 @@ mdnblocks(Relation reln)
nblocks = _mdnblocks ( v - > mdfd_vfd , BLCKSZ ) ;
if ( nblocks > RELSEG_SIZE )
elog ( FATAL , " segment too big in mdnblocks! " ) ;
v - > mdfd_lstbcnt = nblocks ;
if ( nblocks = = RELSEG_SIZE )
{
segno + + ;
if ( nblocks < RELSEG_SIZE )
return ( segno * RELSEG_SIZE ) + nblocks ;
/*
* If segment is exactly RELSEG_SIZE , advance to next one .
*/
segno + + ;
if ( v - > mdfd_chain = = ( MdfdVec * ) NULL )
{
/*
* Because we pass O_CREAT , we will create the next
* segment ( with zero length ) immediately , if the last
* segment is of length REL_SEGSIZE . This is unnecessary
* but harmless , and testing for the case would take more
* cycles than it seems worth .
*/
v - > mdfd_chain = _mdfd_openseg ( reln , segno , O_CREAT ) ;
if ( v - > mdfd_chain = = ( MdfdVec * ) NULL )
{
/*
* Because we pass O_CREAT , we will create the next
* segment ( with zero length ) immediately , if the last
* segment is of length REL_SEGSIZE . This is unnecessary
* but harmless , and testing for the case would take more
* cycles than it seems worth .
*/
v - > mdfd_chain = _mdfd_openseg ( reln , segno , O_CREAT ) ;
if ( v - > mdfd_chain = = ( MdfdVec * ) NULL )
elog ( ERROR , " cannot count blocks for %s -- open failed: %m " ,
RelationGetRelationName ( reln ) ) ;
}
v = v - > mdfd_chain ;
elog ( ERROR , " cannot count blocks for %s -- open failed: %m " ,
RelationGetRelationName ( reln ) ) ;
}
else
return ( segno * RELSEG_SIZE ) + nblocks ;
v = v - > mdfd_chain ;
}
# else
return _mdnblocks ( v - > mdfd_vfd , BLCKSZ ) ;
@ -761,7 +774,6 @@ mdtruncate(Relation reln, int nblocks)
if ( FileTruncate ( v - > mdfd_vfd , lastsegblocks * BLCKSZ ) < 0 )
return - 1 ;
v - > mdfd_lstbcnt = lastsegblocks ;
v = v - > mdfd_chain ;
ov - > mdfd_chain = ( MdfdVec * ) NULL ;
}
@ -779,7 +791,6 @@ mdtruncate(Relation reln, int nblocks)
# else
if ( FileTruncate ( v - > mdfd_vfd , nblocks * BLCKSZ ) < 0 )
return - 1 ;
v - > mdfd_lstbcnt = nblocks ;
# endif
return nblocks ;
@ -958,13 +969,12 @@ _mdfd_openseg(Relation reln, int segno, int oflags)
/* fill the entry */
v - > mdfd_vfd = fd ;
v - > mdfd_flags = ( uint16 ) 0 ;
v - > mdfd_lstbcnt = _mdnblocks ( fd , BLCKSZ ) ;
# ifndef LET_OS_MANAGE_FILESIZE
v - > mdfd_chain = ( MdfdVec * ) NULL ;
# ifdef DIAGNOSTIC
if ( v - > mdfd_lstbcnt > RELSEG_SIZE )
elog ( FATAL , " segment too big on open! " ) ;
if ( _mdnblocks ( fd , BLCKSZ ) > RELSEG_SIZE )
elog ( FATAL , " segment too big on openseg ! " ) ;
# endif
# endif
Tom Lane
25 years ago