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Code Activity

Code cleanup, mostly in the smgr:

Browse Source 
- Update comment in IsReservedName() to the present day

     - Improve some variable & function names in commands/vacuum.c. I
       was planning to rewrite this to avoid lappend(), but since I
       still intend to do the list rewrite, there's no need for that.

     - Update some smgr comments which seemed to imply that we still
       forced all dirty pages to disk at commit-time.

     - Replace some #ifdef DIAGNOSTIC code with assertions.

     - Make the distinction between OS-level file descriptors and
       virtual file descriptors a little clearer in a few comments

     - Other minor comment improvements in the smgr code
This commit is contained in:
Neil Conway
2004-01-06 18:07:32 +00:00
parent 030f8e7313
commit dfc7e7b71d
6 changed files with 73 additions and 98 deletions
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93
src/backend/storage/smgr/md.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/smgr/md.c,v 1.99 2003/11/29 19:51:57 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/storage/smgr/md.c,v 1.100 2004/01/06 18:07:31 neilc Exp $
*
*-------------------------------------------------------------------------
*/
@@ -25,18 +25,15 @@
#include "utils/inval.h"
#include "utils/memutils.h"
#undef DIAGNOSTIC
/*
* The magnetic disk storage manager keeps track of open file descriptors
* in its own descriptor pool. This happens for two reasons. First, at
* transaction boundaries, we walk the list of descriptors and flush
* anything that we've dirtied in the current transaction. Second, we want
* to support relations larger than the OS' file size limit (often 2GBytes).
* In order to do that, we break relations up into chunks of < 2GBytes
* and store one chunk in each of several files that represent the relation.
* See the BLCKSZ and RELSEG_SIZE configuration constants in include/pg_config.h.
* The magnetic disk storage manager keeps track of open file
* descriptors in its own descriptor pool. This is done to make it
* easier to support relations that are larger than the operating
* system's file size limit (often 2GBytes). In order to do that, we
* we break relations up into chunks of < 2GBytes and store one chunk
* in each of several files that represent the relation. See the
* BLCKSZ and RELSEG_SIZE configuration constants in
* include/pg_config.h.
*
* The file descriptor stored in the relation cache (see RelationGetFile())
* is actually an index into the Md_fdvec array. -1 indicates not open.
@@ -67,7 +64,7 @@ static MdfdVec *Md_fdvec = (MdfdVec *) NULL;
static int Md_Free = -1; /* head of freelist of unused fdvec
* entries */
static int CurFd = 0; /* first never-used fdvec index */
static MemoryContext MdCxt; /* context for all my allocations */
static MemoryContext MdCxt; /* context for all md.c allocations */
/* routines declared here */
static void mdclose_fd(int fd);
@@ -84,11 +81,8 @@ static BlockNumber _mdnblocks(File file, Size blcksz);
/*
* mdinit() -- Initialize private state for magnetic disk storage manager.
*
* We keep a private table of all file descriptors. Whenever we do
* a write to one, we mark it dirty in our table. Whenever we force
* changes to disk, we mark the file descriptor clean. At transaction
* commit, we force changes to disk for all dirty file descriptors.
* This routine allocates and initializes the table.
* We keep a private table of all file descriptors. This routine
* allocates and initializes the table.
*
* Returns SM_SUCCESS or SM_FAIL with errno set as appropriate.
*/
@@ -247,16 +241,13 @@ mdextend(Relation reln, BlockNumber blocknum, char *buffer)
#ifndef LET_OS_MANAGE_FILESIZE
seekpos = (long) (BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE)));
#ifdef DIAGNOSTIC
if (seekpos >= BLCKSZ * RELSEG_SIZE)
elog(FATAL, "seekpos too big");
#endif
Assert(seekpos < BLCKSZ * RELSEG_SIZE);
#else
seekpos = (long) (BLCKSZ * (blocknum));
#endif
/*
* Note: because caller obtained blocknum by calling mdnblocks, which
* 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
@@ -282,10 +273,7 @@ mdextend(Relation reln, BlockNumber blocknum, char *buffer)
}
#ifndef LET_OS_MANAGE_FILESIZE
#ifdef DIAGNOSTIC
if (_mdnblocks(v->mdfd_vfd, BLCKSZ) > ((BlockNumber) RELSEG_SIZE))
elog(FATAL, "segment too big");
#endif
Assert(_mdnblocks(v->mdfd_vfd, BLCKSZ) <= ((BlockNumber) RELSEG_SIZE));
#endif
return SM_SUCCESS;
@@ -335,11 +323,7 @@ mdopen(Relation reln)
Md_fdvec[vfd].mdfd_flags = (uint16) 0;
#ifndef LET_OS_MANAGE_FILESIZE
Md_fdvec[vfd].mdfd_chain = (MdfdVec *) NULL;
#ifdef DIAGNOSTIC
if (_mdnblocks(fd, BLCKSZ) > ((BlockNumber) RELSEG_SIZE))
elog(FATAL, "segment too big");
#endif
Assert(_mdnblocks(fd, BLCKSZ) <= ((BlockNumber) RELSEG_SIZE));
#endif
return vfd;
@@ -348,7 +332,7 @@ mdopen(Relation reln)
/*
* mdclose() -- Close the specified relation, if it isn't closed already.
*
* AND FREE fd vector! It may be re-used for other relation!
* AND FREE fd vector! It may be re-used for other relations!
* reln should be flushed from cache after closing !..
*
* Returns SM_SUCCESS or SM_FAIL with errno set as appropriate.
@@ -418,11 +402,7 @@ mdread(Relation reln, BlockNumber blocknum, char *buffer)
#ifndef LET_OS_MANAGE_FILESIZE
seekpos = (long) (BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE)));
#ifdef DIAGNOSTIC
if (seekpos >= BLCKSZ * RELSEG_SIZE)
elog(FATAL, "seekpos too big");
#endif
Assert(seekpos < BLCKSZ * RELSEG_SIZE);
#else
seekpos = (long) (BLCKSZ * (blocknum));
#endif
@@ -466,10 +446,7 @@ mdwrite(Relation reln, BlockNumber blocknum, char *buffer)
#ifndef LET_OS_MANAGE_FILESIZE
seekpos = (long) (BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE)));
#ifdef DIAGNOSTIC
if (seekpos >= BLCKSZ * RELSEG_SIZE)
elog(FATAL, "seekpos too big");
#endif
Assert(seekpos < BLCKSZ * RELSEG_SIZE);
#else
seekpos = (long) (BLCKSZ * (blocknum));
#endif
@@ -505,10 +482,7 @@ mdblindwrt(RelFileNode rnode,
#ifndef LET_OS_MANAGE_FILESIZE
seekpos = (long) (BLCKSZ * (blkno % ((BlockNumber) RELSEG_SIZE)));
#ifdef DIAGNOSTIC
if (seekpos >= BLCKSZ * RELSEG_SIZE)
elog(FATAL, "seekpos too big");
#endif
Assert(seekpos < BLCKSZ * RELSEG_SIZE);
#else
seekpos = (long) (BLCKSZ * (blkno));
#endif
@@ -722,8 +696,6 @@ mdcommit(void)
/*
* mdabort() -- Abort a transaction.
*
* Changes need not be forced to disk at transaction abort.
*/
int
mdabort(void)
@@ -748,7 +720,7 @@ mdsync(void)
}
/*
* _fdvec_alloc () -- grab a free (or new) md file descriptor vector.
* _fdvec_alloc() -- Grab a free (or new) md file descriptor vector.
*/
static int
_fdvec_alloc(void)
@@ -802,7 +774,7 @@ _fdvec_alloc(void)
}
/*
* _fdvec_free () -- free md file descriptor vector.
* _fdvec_free() -- free md file descriptor vector.
*
*/
static
@@ -853,19 +825,18 @@ _mdfd_openseg(Relation reln, BlockNumber segno, int oflags)
v->mdfd_flags = (uint16) 0;
#ifndef LET_OS_MANAGE_FILESIZE
v->mdfd_chain = (MdfdVec *) NULL;
#ifdef DIAGNOSTIC
if (_mdnblocks(fd, BLCKSZ) > ((BlockNumber) RELSEG_SIZE))
elog(FATAL, "segment too big");
#endif
Assert(_mdnblocks(fd, BLCKSZ) <= ((BlockNumber) RELSEG_SIZE));
#endif
/* all done */
return v;
}
/* Get the fd for the relation, opening it if it's not already open */
/*
* _mdfd_getrelnfd() -- Get the (virtual) fd for the relation,
* opening it if it's not already open
*
*/
static int
_mdfd_getrelnfd(Relation reln)
{
@@ -882,8 +853,11 @@ _mdfd_getrelnfd(Relation reln)
return fd;
}
/* Find the segment of the relation holding the specified block */
/*
* _mdfd_getseg() -- Find the segment of the relation holding the
* specified block
*
*/
static MdfdVec *
_mdfd_getseg(Relation reln, BlockNumber blkno)
{
@@ -942,7 +916,6 @@ _mdfd_getseg(Relation reln, BlockNumber blkno)
*
* The return value is the kernel descriptor, or -1 on failure.
*/
static int
_mdfd_blind_getseg(RelFileNode rnode, BlockNumber blkno)
{