* md.c
* This code manages relations that reside on magnetic disk.
*
- * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
+ * Or at least, that was what the Berkeley folk had in mind when they named
+ * this file. In reality, what this code provides is an interface from
+ * the smgr API to Unix-like filesystem APIs, so it will work with any type
+ * of device for which the operating system provides filesystem support.
+ * It doesn't matter whether the bits are on spinning rust or some other
+ * storage technology.
+ *
+ * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
#include <fcntl.h>
#include <sys/file.h>
-#include "catalog/catalog.h"
#include "miscadmin.h"
+#include "access/xlogutils.h"
+#include "access/xlog.h"
+#include "pgstat.h"
#include "portability/instr_time.h"
#include "postmaster/bgwriter.h"
#include "storage/fd.h"
#include "pg_trace.h"
-/* interval for calling AbsorbFsyncRequests in mdsync */
+/* intervals for calling AbsorbFsyncRequests in mdsync and mdpostckpt */
#define FSYNCS_PER_ABSORB 10
+#define UNLINKS_PER_ABSORB 10
/*
* Special values for the segno arg to RememberFsyncRequest.
*
- * Note that CompactBgwriterRequestQueue assumes that it's OK to remove an
+ * Note that CompactCheckpointerRequestQueue assumes that it's OK to remove an
* fsync request from the queue if an identical, subsequent request is found.
* See comments there before making changes here.
*/
* ENOENT, because if a file is unlinked-but-not-yet-gone on that platform,
* that's what you get. Ugh. This code is designed so that we don't
* actually believe these cases are okay without further evidence (namely,
- * a pending fsync request getting revoked ... see mdsync).
+ * a pending fsync request getting canceled ... see mdsync).
*/
#ifndef WIN32
#define FILE_POSSIBLY_DELETED(err) ((err) == ENOENT)
* Inactive segments are those that once contained data but are currently
* not needed because of an mdtruncate() operation. The reason for leaving
* them present at size zero, rather than unlinking them, is that other
- * backends and/or the bgwriter might be holding open file references to
- * such segments. If the relation expands again after mdtruncate(), such
+ * backends and/or the checkpointer might be holding open file references to
+ * such segments. If the relation expands again after mdtruncate(), such
* that a deactivated segment becomes active again, it is important that
* such file references still be valid --- else data might get written
* out to an unlinked old copy of a segment file that will eventually
* disappear.
*
- * The file descriptor pointer (md_fd field) stored in the SMgrRelation
- * cache is, therefore, just the head of a list of MdfdVec objects, one
- * per segment. But note the md_fd pointer can be NULL, indicating
- * relation not open.
- *
- * Also note that mdfd_chain == NULL does not necessarily mean the relation
- * doesn't have another segment after this one; we may just not have
- * opened the next segment yet. (We could not have "all segments are
- * in the chain" as an invariant anyway, since another backend could
- * extend the relation when we weren't looking.) We do not make chain
+ * File descriptors are stored in the per-fork md_seg_fds arrays inside
+ * SMgrRelation. The length of these arrays is stored in md_num_open_segs.
+ * Note that a fork's md_num_open_segs having a specific value does not
+ * necessarily mean the relation doesn't have additional segments; we may
+ * just not have opened the next segment yet. (We could not have "all
+ * segments are in the array" as an invariant anyway, since another backend
+ * could extend the relation while we aren't looking.) We do not have
* entries for inactive segments, however; as soon as we find a partial
* segment, we assume that any subsequent segments are inactive.
*
- * All MdfdVec objects are palloc'd in the MdCxt memory context.
+ * The entire MdfdVec array is palloc'd in the MdCxt memory context.
*/
typedef struct _MdfdVec
{
File mdfd_vfd; /* fd number in fd.c's pool */
BlockNumber mdfd_segno; /* segment number, from 0 */
- struct _MdfdVec *mdfd_chain; /* next segment, or NULL */
} MdfdVec;
-static MemoryContext MdCxt; /* context for all md.c allocations */
+static MemoryContext MdCxt; /* context for all MdfdVec objects */
/*
- * In some contexts (currently, standalone backends and the bgwriter process)
+ * In some contexts (currently, standalone backends and the checkpointer)
* we keep track of pending fsync operations: we need to remember all relation
* segments that have been written since the last checkpoint, so that we can
* fsync them down to disk before completing the next checkpoint. This hash
- * table remembers the pending operations. We use a hash table mostly as
- * a convenient way of eliminating duplicate requests.
+ * table remembers the pending operations. We use a hash table mostly as
+ * a convenient way of merging duplicate requests.
*
* We use a similar mechanism to remember no-longer-needed files that can
* be deleted after the next checkpoint, but we use a linked list instead of
* a hash table, because we don't expect there to be any duplicate requests.
*
+ * These mechanisms are only used for non-temp relations; we never fsync
+ * temp rels, nor do we need to postpone their deletion (see comments in
+ * mdunlink).
+ *
* (Regular backends do not track pending operations locally, but forward
- * them to the bgwriter.)
+ * them to the checkpointer.)
*/
-typedef struct
-{
- RelFileNodeBackend rnode; /* the targeted relation */
- ForkNumber forknum;
- BlockNumber segno; /* which segment */
-} PendingOperationTag;
-
typedef uint16 CycleCtr; /* can be any convenient integer size */
typedef struct
{
- PendingOperationTag tag; /* hash table key (must be first!) */
- bool canceled; /* T => request canceled, not yet removed */
- CycleCtr cycle_ctr; /* mdsync_cycle_ctr when request was made */
+ RelFileNode rnode; /* hash table key (must be first!) */
+ CycleCtr cycle_ctr; /* mdsync_cycle_ctr of oldest request */
+ /* requests[f] has bit n set if we need to fsync segment n of fork f */
+ Bitmapset *requests[MAX_FORKNUM + 1];
+ /* canceled[f] is true if we canceled fsyncs for fork "recently" */
+ bool canceled[MAX_FORKNUM + 1];
} PendingOperationEntry;
typedef struct
{
- RelFileNodeBackend rnode; /* the dead relation to delete */
+ RelFileNode rnode; /* the dead relation to delete */
CycleCtr cycle_ctr; /* mdckpt_cycle_ctr when request was made */
} PendingUnlinkEntry;
static HTAB *pendingOpsTable = NULL;
static List *pendingUnlinks = NIL;
+static MemoryContext pendingOpsCxt; /* context for the above */
static CycleCtr mdsync_cycle_ctr = 0;
static CycleCtr mdckpt_cycle_ctr = 0;
-typedef enum /* behavior for mdopen & _mdfd_getseg */
-{
- EXTENSION_FAIL, /* ereport if segment not present */
- EXTENSION_RETURN_NULL, /* return NULL if not present */
- EXTENSION_CREATE /* create new segments as needed */
-} ExtensionBehavior;
+/*** behavior for mdopen & _mdfd_getseg ***/
+/* ereport if segment not present */
+#define EXTENSION_FAIL (1 << 0)
+/* return NULL if segment not present */
+#define EXTENSION_RETURN_NULL (1 << 1)
+/* create new segments as needed */
+#define EXTENSION_CREATE (1 << 2)
+/* create new segments if needed during recovery */
+#define EXTENSION_CREATE_RECOVERY (1 << 3)
+/*
+ * Allow opening segments which are preceded by segments smaller than
+ * RELSEG_SIZE, e.g. inactive segments (see above). Note that this is breaks
+ * mdnblocks() and related functionality henceforth - which currently is ok,
+ * because this is only required in the checkpointer which never uses
+ * mdnblocks().
+ */
+#define EXTENSION_DONT_CHECK_SIZE (1 << 4)
+
/* local routines */
-static MdfdVec *mdopen(SMgrRelation reln, ForkNumber forknum,
- ExtensionBehavior behavior);
+static void mdunlinkfork(RelFileNodeBackend rnode, ForkNumber forkNum,
+ bool isRedo);
+static MdfdVec *mdopen(SMgrRelation reln, ForkNumber forknum, int behavior);
static void register_dirty_segment(SMgrRelation reln, ForkNumber forknum,
MdfdVec *seg);
static void register_unlink(RelFileNodeBackend rnode);
-static MdfdVec *_fdvec_alloc(void);
+static void _fdvec_resize(SMgrRelation reln,
+ ForkNumber forknum,
+ int nseg);
static char *_mdfd_segpath(SMgrRelation reln, ForkNumber forknum,
BlockNumber segno);
static MdfdVec *_mdfd_openseg(SMgrRelation reln, ForkNumber forkno,
BlockNumber segno, int oflags);
static MdfdVec *_mdfd_getseg(SMgrRelation reln, ForkNumber forkno,
- BlockNumber blkno, bool skipFsync, ExtensionBehavior behavior);
+ BlockNumber blkno, bool skipFsync, int behavior);
static BlockNumber _mdnblocks(SMgrRelation reln, ForkNumber forknum,
MdfdVec *seg);
{
MdCxt = AllocSetContextCreate(TopMemoryContext,
"MdSmgr",
- ALLOCSET_DEFAULT_MINSIZE,
- ALLOCSET_DEFAULT_INITSIZE,
- ALLOCSET_DEFAULT_MAXSIZE);
+ ALLOCSET_DEFAULT_SIZES);
/*
* Create pending-operations hashtable if we need it. Currently, we need
- * it if we are standalone (not under a postmaster) OR if we are a
- * bootstrap-mode subprocess of a postmaster (that is, a startup or
- * bgwriter process).
+ * it if we are standalone (not under a postmaster) or if we are a startup
+ * or checkpointer auxiliary process.
*/
- if (!IsUnderPostmaster || IsBootstrapProcessingMode())
+ if (!IsUnderPostmaster || AmStartupProcess() || AmCheckpointerProcess())
{
HASHCTL hash_ctl;
+ /*
+ * XXX: The checkpointer needs to add entries to the pending ops table
+ * when absorbing fsync requests. That is done within a critical
+ * section, which isn't usually allowed, but we make an exception. It
+ * means that there's a theoretical possibility that you run out of
+ * memory while absorbing fsync requests, which leads to a PANIC.
+ * Fortunately the hash table is small so that's unlikely to happen in
+ * practice.
+ */
+ pendingOpsCxt = AllocSetContextCreate(MdCxt,
+ "Pending ops context",
+ ALLOCSET_DEFAULT_SIZES);
+ MemoryContextAllowInCriticalSection(pendingOpsCxt, true);
+
MemSet(&hash_ctl, 0, sizeof(hash_ctl));
- hash_ctl.keysize = sizeof(PendingOperationTag);
+ hash_ctl.keysize = sizeof(RelFileNode);
hash_ctl.entrysize = sizeof(PendingOperationEntry);
- hash_ctl.hash = tag_hash;
- hash_ctl.hcxt = MdCxt;
+ hash_ctl.hcxt = pendingOpsCxt;
pendingOpsTable = hash_create("Pending Ops Table",
100L,
&hash_ctl,
- HASH_ELEM | HASH_FUNCTION | HASH_CONTEXT);
+ HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
pendingUnlinks = NIL;
}
}
/*
- * In archive recovery, we rely on bgwriter to do fsyncs, but we will have
+ * In archive recovery, we rely on checkpointer to do fsyncs, but we will have
* already created the pendingOpsTable during initialization of the startup
* process. Calling this function drops the local pendingOpsTable so that
- * subsequent requests will be forwarded to bgwriter.
+ * subsequent requests will be forwarded to checkpointer.
*/
void
SetForwardFsyncRequests(void)
{
- /* Perform any pending ops we may have queued up */
+ /* Perform any pending fsyncs we may have queued up, then drop table */
if (pendingOpsTable)
+ {
mdsync();
+ hash_destroy(pendingOpsTable);
+ }
pendingOpsTable = NULL;
+
+ /*
+ * We should not have any pending unlink requests, since mdunlink doesn't
+ * queue unlink requests when isRedo.
+ */
+ Assert(pendingUnlinks == NIL);
}
/*
void
mdcreate(SMgrRelation reln, ForkNumber forkNum, bool isRedo)
{
+ MdfdVec *mdfd;
char *path;
File fd;
- if (isRedo && reln->md_fd[forkNum] != NULL)
+ if (isRedo && reln->md_num_open_segs[forkNum] > 0)
return; /* created and opened already... */
- Assert(reln->md_fd[forkNum] == NULL);
+ Assert(reln->md_num_open_segs[forkNum] == 0);
path = relpath(reln->smgr_rnode, forkNum);
- fd = PathNameOpenFile(path, O_RDWR | O_CREAT | O_EXCL | PG_BINARY, 0600);
+ fd = PathNameOpenFile(path, O_RDWR | O_CREAT | O_EXCL | PG_BINARY);
if (fd < 0)
{
* During bootstrap, there are cases where a system relation will be
* accessed (by internal backend processes) before the bootstrap
* script nominally creates it. Therefore, allow the file to exist
- * already, even if isRedo is not set. (See also mdopen)
+ * already, even if isRedo is not set. (See also mdopen)
*/
if (isRedo || IsBootstrapProcessingMode())
- fd = PathNameOpenFile(path, O_RDWR | PG_BINARY, 0600);
+ fd = PathNameOpenFile(path, O_RDWR | PG_BINARY);
if (fd < 0)
{
/* be sure to report the error reported by create, not open */
pfree(path);
- reln->md_fd[forkNum] = _fdvec_alloc();
-
- reln->md_fd[forkNum]->mdfd_vfd = fd;
- reln->md_fd[forkNum]->mdfd_segno = 0;
- reln->md_fd[forkNum]->mdfd_chain = NULL;
+ _fdvec_resize(reln, forkNum, 1);
+ mdfd = &reln->md_seg_fds[forkNum][0];
+ mdfd->mdfd_vfd = fd;
+ mdfd->mdfd_segno = 0;
}
/*
* mdunlink() -- Unlink a relation.
*
- * Note that we're passed a RelFileNode --- by the time this is called,
+ * Note that we're passed a RelFileNodeBackend --- by the time this is called,
* there won't be an SMgrRelation hashtable entry anymore.
*
- * Actually, we don't unlink the first segment file of the relation, but
- * just truncate it to zero length, and record a request to unlink it after
+ * forkNum can be a fork number to delete a specific fork, or InvalidForkNumber
+ * to delete all forks.
+ *
+ * For regular relations, we don't unlink the first segment file of the rel,
+ * but just truncate it to zero length, and record a request to unlink it after
* the next checkpoint. Additional segments can be unlinked immediately,
* however. Leaving the empty file in place prevents that relfilenode
* number from being reused. The scenario this protects us from is:
* if the contents of the file were repopulated by subsequent WAL entries.
* But if we didn't WAL-log insertions, but instead relied on fsyncing the
* file after populating it (as for instance CLUSTER and CREATE INDEX do),
- * the contents of the file would be lost forever. By leaving the empty file
+ * the contents of the file would be lost forever. By leaving the empty file
* until after the next checkpoint, we prevent reassignment of the relfilenode
* number until it's safe, because relfilenode assignment skips over any
* existing file.
*
- * If isRedo is true, it's okay for the relation to be already gone.
+ * We do not need to go through this dance for temp relations, though, because
+ * we never make WAL entries for temp rels, and so a temp rel poses no threat
+ * to the health of a regular rel that has taken over its relfilenode number.
+ * The fact that temp rels and regular rels have different file naming
+ * patterns provides additional safety.
+ *
+ * All the above applies only to the relation's main fork; other forks can
+ * just be removed immediately, since they are not needed to prevent the
+ * relfilenode number from being recycled. Also, we do not carefully
+ * track whether other forks have been created or not, but just attempt to
+ * unlink them unconditionally; so we should never complain about ENOENT.
+ *
+ * If isRedo is true, it's unsurprising for the relation to be already gone.
* Also, we should remove the file immediately instead of queuing a request
* for later, since during redo there's no possibility of creating a
* conflicting relation.
void
mdunlink(RelFileNodeBackend rnode, ForkNumber forkNum, bool isRedo)
{
- char *path;
- int ret;
-
/*
* We have to clean out any pending fsync requests for the doomed
- * relation, else the next mdsync() will fail.
+ * relation, else the next mdsync() will fail. There can't be any such
+ * requests for a temp relation, though. We can send just one request
+ * even when deleting multiple forks, since the fsync queuing code accepts
+ * the "InvalidForkNumber = all forks" convention.
*/
- ForgetRelationFsyncRequests(rnode, forkNum);
+ if (!RelFileNodeBackendIsTemp(rnode))
+ ForgetRelationFsyncRequests(rnode.node, forkNum);
+
+ /* Now do the per-fork work */
+ if (forkNum == InvalidForkNumber)
+ {
+ for (forkNum = 0; forkNum <= MAX_FORKNUM; forkNum++)
+ mdunlinkfork(rnode, forkNum, isRedo);
+ }
+ else
+ mdunlinkfork(rnode, forkNum, isRedo);
+}
+
+static void
+mdunlinkfork(RelFileNodeBackend rnode, ForkNumber forkNum, bool isRedo)
+{
+ char *path;
+ int ret;
path = relpath(rnode, forkNum);
/*
* Delete or truncate the first segment.
*/
- if (isRedo || forkNum != MAIN_FORKNUM)
+ if (isRedo || forkNum != MAIN_FORKNUM || RelFileNodeBackendIsTemp(rnode))
{
ret = unlink(path);
- if (ret < 0)
- {
- if (!isRedo || errno != ENOENT)
- ereport(WARNING,
- (errcode_for_file_access(),
- errmsg("could not remove file \"%s\": %m", path)));
- }
+ if (ret < 0 && errno != ENOENT)
+ ereport(WARNING,
+ (errcode_for_file_access(),
+ errmsg("could not remove file \"%s\": %m", path)));
}
else
{
/* truncate(2) would be easier here, but Windows hasn't got it */
int fd;
- fd = BasicOpenFile(path, O_RDWR | PG_BINARY, 0);
+ fd = OpenTransientFile(path, O_RDWR | PG_BINARY);
if (fd >= 0)
{
int save_errno;
ret = ftruncate(fd, 0);
save_errno = errno;
- close(fd);
+ CloseTransientFile(fd);
errno = save_errno;
}
else
ereport(WARNING,
(errcode_for_file_access(),
errmsg("could not truncate file \"%s\": %m", path)));
+
+ /* Register request to unlink first segment later */
+ register_unlink(rnode);
}
/*
if (errno != ENOENT)
ereport(WARNING,
(errcode_for_file_access(),
- errmsg("could not remove file \"%s\": %m", segpath)));
+ errmsg("could not remove file \"%s\": %m", segpath)));
break;
}
}
}
pfree(path);
-
- /* Register request to unlink first segment later */
- if (!isRedo && forkNum == MAIN_FORKNUM)
- register_unlink(rnode);
}
/*
v = _mdfd_getseg(reln, forknum, blocknum, skipFsync, EXTENSION_CREATE);
- seekpos = (off_t) BLCKSZ *(blocknum % ((BlockNumber) RELSEG_SIZE));
+ seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
- /*
- * Note: because caller usually 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)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not seek to block %u in file \"%s\": %m",
- blocknum, FilePathName(v->mdfd_vfd))));
-
- if ((nbytes = FileWrite(v->mdfd_vfd, buffer, BLCKSZ)) != BLCKSZ)
+ if ((nbytes = FileWrite(v->mdfd_vfd, buffer, BLCKSZ, seekpos, WAIT_EVENT_DATA_FILE_EXTEND)) != BLCKSZ)
{
if (nbytes < 0)
ereport(ERROR,
* invent one out of whole cloth.
*/
static MdfdVec *
-mdopen(SMgrRelation reln, ForkNumber forknum, ExtensionBehavior behavior)
+mdopen(SMgrRelation reln, ForkNumber forknum, int behavior)
{
MdfdVec *mdfd;
char *path;
File fd;
/* No work if already open */
- if (reln->md_fd[forknum])
- return reln->md_fd[forknum];
+ if (reln->md_num_open_segs[forknum] > 0)
+ return &reln->md_seg_fds[forknum][0];
path = relpath(reln->smgr_rnode, forknum);
- fd = PathNameOpenFile(path, O_RDWR | PG_BINARY, 0600);
+ fd = PathNameOpenFile(path, O_RDWR | PG_BINARY);
if (fd < 0)
{
* substitute for mdcreate() in bootstrap mode only. (See mdcreate)
*/
if (IsBootstrapProcessingMode())
- fd = PathNameOpenFile(path, O_RDWR | O_CREAT | O_EXCL | PG_BINARY, 0600);
+ fd = PathNameOpenFile(path, O_RDWR | O_CREAT | O_EXCL | PG_BINARY);
if (fd < 0)
{
- if (behavior == EXTENSION_RETURN_NULL &&
+ if ((behavior & EXTENSION_RETURN_NULL) &&
FILE_POSSIBLY_DELETED(errno))
{
pfree(path);
pfree(path);
- reln->md_fd[forknum] = mdfd = _fdvec_alloc();
-
+ _fdvec_resize(reln, forknum, 1);
+ mdfd = &reln->md_seg_fds[forknum][0];
mdfd->mdfd_vfd = fd;
mdfd->mdfd_segno = 0;
- mdfd->mdfd_chain = NULL;
+
Assert(_mdnblocks(reln, forknum, mdfd) <= ((BlockNumber) RELSEG_SIZE));
return mdfd;
void
mdclose(SMgrRelation reln, ForkNumber forknum)
{
- MdfdVec *v = reln->md_fd[forknum];
+ int nopensegs = reln->md_num_open_segs[forknum];
/* No work if already closed */
- if (v == NULL)
+ if (nopensegs == 0)
return;
- reln->md_fd[forknum] = NULL; /* prevent dangling pointer after error */
-
- while (v != NULL)
+ /* close segments starting from the end */
+ while (nopensegs > 0)
{
- MdfdVec *ov = v;
+ MdfdVec *v = &reln->md_seg_fds[forknum][nopensegs - 1];
/* if not closed already */
if (v->mdfd_vfd >= 0)
+ {
FileClose(v->mdfd_vfd);
- /* Now free vector */
- v = v->mdfd_chain;
- pfree(ov);
+ v->mdfd_vfd = -1;
+ }
+
+ nopensegs--;
}
+
+ /* resize just once, avoids pointless reallocations */
+ _fdvec_resize(reln, forknum, 0);
}
/*
v = _mdfd_getseg(reln, forknum, blocknum, false, EXTENSION_FAIL);
- seekpos = (off_t) BLCKSZ *(blocknum % ((BlockNumber) RELSEG_SIZE));
+ seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
- (void) FilePrefetch(v->mdfd_vfd, seekpos, BLCKSZ);
-#endif /* USE_PREFETCH */
+ (void) FilePrefetch(v->mdfd_vfd, seekpos, BLCKSZ, WAIT_EVENT_DATA_FILE_PREFETCH);
+#endif /* USE_PREFETCH */
}
+/*
+ * mdwriteback() -- Tell the kernel to write pages back to storage.
+ *
+ * This accepts a range of blocks because flushing several pages at once is
+ * considerably more efficient than doing so individually.
+ */
+void
+mdwriteback(SMgrRelation reln, ForkNumber forknum,
+ BlockNumber blocknum, BlockNumber nblocks)
+{
+ /*
+ * Issue flush requests in as few requests as possible; have to split at
+ * segment boundaries though, since those are actually separate files.
+ */
+ while (nblocks > 0)
+ {
+ BlockNumber nflush = nblocks;
+ off_t seekpos;
+ MdfdVec *v;
+ int segnum_start,
+ segnum_end;
+
+ v = _mdfd_getseg(reln, forknum, blocknum, true /* not used */ ,
+ EXTENSION_RETURN_NULL);
+
+ /*
+ * We might be flushing buffers of already removed relations, that's
+ * ok, just ignore that case.
+ */
+ if (!v)
+ return;
+
+ /* compute offset inside the current segment */
+ segnum_start = blocknum / RELSEG_SIZE;
+
+ /* compute number of desired writes within the current segment */
+ segnum_end = (blocknum + nblocks - 1) / RELSEG_SIZE;
+ if (segnum_start != segnum_end)
+ nflush = RELSEG_SIZE - (blocknum % ((BlockNumber) RELSEG_SIZE));
+
+ Assert(nflush >= 1);
+ Assert(nflush <= nblocks);
+
+ seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
+
+ FileWriteback(v->mdfd_vfd, seekpos, (off_t) BLCKSZ * nflush, WAIT_EVENT_DATA_FILE_FLUSH);
+
+ nblocks -= nflush;
+ blocknum += nflush;
+ }
+}
/*
* mdread() -- Read the specified block from a relation.
reln->smgr_rnode.node.relNode,
reln->smgr_rnode.backend);
- v = _mdfd_getseg(reln, forknum, blocknum, false, EXTENSION_FAIL);
+ v = _mdfd_getseg(reln, forknum, blocknum, false,
+ EXTENSION_FAIL | EXTENSION_CREATE_RECOVERY);
- seekpos = (off_t) BLCKSZ *(blocknum % ((BlockNumber) RELSEG_SIZE));
+ seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
- if (FileSeek(v->mdfd_vfd, seekpos, SEEK_SET) != seekpos)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not seek to block %u in file \"%s\": %m",
- blocknum, FilePathName(v->mdfd_vfd))));
-
- nbytes = FileRead(v->mdfd_vfd, buffer, BLCKSZ);
+ nbytes = FileRead(v->mdfd_vfd, buffer, BLCKSZ, seekpos, WAIT_EVENT_DATA_FILE_READ);
TRACE_POSTGRESQL_SMGR_MD_READ_DONE(forknum, blocknum,
reln->smgr_rnode.node.spcNode,
reln->smgr_rnode.node.relNode,
reln->smgr_rnode.backend);
- v = _mdfd_getseg(reln, forknum, blocknum, skipFsync, EXTENSION_FAIL);
+ v = _mdfd_getseg(reln, forknum, blocknum, skipFsync,
+ EXTENSION_FAIL | EXTENSION_CREATE_RECOVERY);
- seekpos = (off_t) BLCKSZ *(blocknum % ((BlockNumber) RELSEG_SIZE));
+ seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
- if (FileSeek(v->mdfd_vfd, seekpos, SEEK_SET) != seekpos)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not seek to block %u in file \"%s\": %m",
- blocknum, FilePathName(v->mdfd_vfd))));
-
- nbytes = FileWrite(v->mdfd_vfd, buffer, BLCKSZ);
+ nbytes = FileWrite(v->mdfd_vfd, buffer, BLCKSZ, seekpos, WAIT_EVENT_DATA_FILE_WRITE);
TRACE_POSTGRESQL_SMGR_MD_WRITE_DONE(forknum, blocknum,
reln->smgr_rnode.node.spcNode,
* mdnblocks() -- Get the number of blocks stored in a relation.
*
* Important side effect: all active segments of the relation are opened
- * and added to the mdfd_chain list. If this routine has not been
+ * and added to the mdfd_seg_fds array. If this routine has not been
* called, then only segments up to the last one actually touched
- * are present in the chain.
+ * are present in the array.
*/
BlockNumber
mdnblocks(SMgrRelation reln, ForkNumber forknum)
BlockNumber nblocks;
BlockNumber segno = 0;
+ /* mdopen has opened the first segment */
+ Assert(reln->md_num_open_segs[forknum] > 0);
+
/*
- * Skip through any segments that aren't the last one, to avoid redundant
- * seeks on them. We have previously verified that these segments are
- * exactly RELSEG_SIZE long, and it's useless to recheck that each time.
+ * Start from the last open segments, to avoid redundant seeks. We have
+ * previously verified that these segments are exactly RELSEG_SIZE long,
+ * and it's useless to recheck that each time.
*
* NOTE: this assumption could only be wrong if another backend has
- * truncated the relation. We rely on higher code levels to handle that
+ * truncated the relation. We rely on higher code levels to handle that
* scenario by closing and re-opening the md fd, which is handled via
- * relcache flush. (Since the bgwriter doesn't participate in relcache
- * flush, it could have segment chain entries for inactive segments;
- * that's OK because the bgwriter never needs to compute relation size.)
+ * relcache flush. (Since the checkpointer doesn't participate in
+ * relcache flush, it could have segment entries for inactive segments;
+ * that's OK because the checkpointer never needs to compute relation
+ * size.)
*/
- while (v->mdfd_chain != NULL)
- {
- segno++;
- v = v->mdfd_chain;
- }
+ segno = reln->md_num_open_segs[forknum] - 1;
+ v = &reln->md_seg_fds[forknum][segno];
for (;;)
{
*/
segno++;
- if (v->mdfd_chain == NULL)
- {
- /*
- * Because we pass O_CREAT, we will create the next segment (with
- * zero length) immediately, if the last segment is of length
- * RELSEG_SIZE. While perhaps not strictly necessary, this keeps
- * the logic simple.
- */
- v->mdfd_chain = _mdfd_openseg(reln, forknum, segno, O_CREAT);
- if (v->mdfd_chain == NULL)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not open file \"%s\": %m",
- _mdfd_segpath(reln, forknum, segno))));
- }
-
- v = v->mdfd_chain;
+ /*
+ * We used to pass O_CREAT here, but that's has the disadvantage that
+ * it might create a segment which has vanished through some operating
+ * system misadventure. In such a case, creating the segment here
+ * undermines _mdfd_getseg's attempts to notice and report an error
+ * upon access to a missing segment.
+ */
+ v = _mdfd_openseg(reln, forknum, segno, 0);
+ if (v == NULL)
+ return segno * ((BlockNumber) RELSEG_SIZE);
}
}
void
mdtruncate(SMgrRelation reln, ForkNumber forknum, BlockNumber nblocks)
{
- MdfdVec *v;
BlockNumber curnblk;
BlockNumber priorblocks;
+ int curopensegs;
/*
* NOTE: mdnblocks makes sure we have opened all active segments, so that
if (nblocks == curnblk)
return; /* no work */
- v = mdopen(reln, forknum, EXTENSION_FAIL);
-
- priorblocks = 0;
- while (v != NULL)
+ /*
+ * Truncate segments, starting at the last one. Starting at the end makes
+ * managing the memory for the fd array easier, should there be errors.
+ */
+ curopensegs = reln->md_num_open_segs[forknum];
+ while (curopensegs > 0)
{
- MdfdVec *ov = v;
+ MdfdVec *v;
+
+ priorblocks = (curopensegs - 1) * RELSEG_SIZE;
+
+ v = &reln->md_seg_fds[forknum][curopensegs - 1];
if (priorblocks > nblocks)
{
/*
- * This segment is no longer active (and has already been unlinked
- * from the mdfd_chain). We truncate the file, but do not delete
- * it, for reasons explained in the header comments.
+ * This segment is no longer active. We truncate the file, but do
+ * not delete it, for reasons explained in the header comments.
*/
- if (FileTruncate(v->mdfd_vfd, 0) < 0)
+ if (FileTruncate(v->mdfd_vfd, 0, WAIT_EVENT_DATA_FILE_TRUNCATE) < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not truncate file \"%s\": %m",
if (!SmgrIsTemp(reln))
register_dirty_segment(reln, forknum, v);
- v = v->mdfd_chain;
- Assert(ov != reln->md_fd[forknum]); /* we never drop the 1st
- * segment */
- pfree(ov);
+
+ /* we never drop the 1st segment */
+ Assert(v != &reln->md_seg_fds[forknum][0]);
+
+ FileClose(v->mdfd_vfd);
+ _fdvec_resize(reln, forknum, curopensegs - 1);
}
else if (priorblocks + ((BlockNumber) RELSEG_SIZE) > nblocks)
{
/*
* This is the last segment we want to keep. Truncate the file to
- * the right length, and clear chain link that points to any
- * remaining segments (which we shall zap). NOTE: if nblocks is
- * exactly a multiple K of RELSEG_SIZE, we will truncate the K+1st
- * segment to 0 length but keep it. This adheres to the invariant
- * given in the header comments.
+ * the right length. NOTE: if nblocks is exactly a multiple K of
+ * RELSEG_SIZE, we will truncate the K+1st segment to 0 length but
+ * keep it. This adheres to the invariant given in the header
+ * comments.
*/
BlockNumber lastsegblocks = nblocks - priorblocks;
- if (FileTruncate(v->mdfd_vfd, (off_t) lastsegblocks * BLCKSZ) < 0)
+ if (FileTruncate(v->mdfd_vfd, (off_t) lastsegblocks * BLCKSZ, WAIT_EVENT_DATA_FILE_TRUNCATE) < 0)
ereport(ERROR,
(errcode_for_file_access(),
- errmsg("could not truncate file \"%s\" to %u blocks: %m",
- FilePathName(v->mdfd_vfd),
- nblocks)));
+ errmsg("could not truncate file \"%s\" to %u blocks: %m",
+ FilePathName(v->mdfd_vfd),
+ nblocks)));
if (!SmgrIsTemp(reln))
register_dirty_segment(reln, forknum, v);
- v = v->mdfd_chain;
- ov->mdfd_chain = NULL;
}
else
{
/*
- * We still need this segment and 0 or more blocks beyond it, so
- * nothing to do here.
+ * We still need this segment, so nothing to do for this and any
+ * earlier segment.
*/
- v = v->mdfd_chain;
+ break;
}
- priorblocks += RELSEG_SIZE;
+ curopensegs--;
}
}
void
mdimmedsync(SMgrRelation reln, ForkNumber forknum)
{
- MdfdVec *v;
- BlockNumber curnblk;
+ int segno;
/*
* NOTE: mdnblocks makes sure we have opened all active segments, so that
* fsync loop will get them all!
*/
- curnblk = mdnblocks(reln, forknum);
+ mdnblocks(reln, forknum);
- v = mdopen(reln, forknum, EXTENSION_FAIL);
+ segno = reln->md_num_open_segs[forknum];
- while (v != NULL)
+ while (segno > 0)
{
- if (FileSync(v->mdfd_vfd) < 0)
- ereport(ERROR,
+ MdfdVec *v = &reln->md_seg_fds[forknum][segno - 1];
+
+ if (FileSync(v->mdfd_vfd, WAIT_EVENT_DATA_FILE_IMMEDIATE_SYNC) < 0)
+ ereport(data_sync_elevel(ERROR),
(errcode_for_file_access(),
errmsg("could not fsync file \"%s\": %m",
FilePathName(v->mdfd_vfd))));
- v = v->mdfd_chain;
+ segno--;
}
}
elog(ERROR, "cannot sync without a pendingOpsTable");
/*
- * If we are in the bgwriter, the sync had better include all fsync
- * requests that were queued by backends up to this point. The tightest
+ * If we are in the checkpointer, the sync had better include all fsync
+ * requests that were queued by backends up to this point. The tightest
* race condition that could occur is that a buffer that must be written
* and fsync'd for the checkpoint could have been dumped by a backend just
* before it was visited by BufferSync(). We know the backend will have
hash_seq_init(&hstat, pendingOpsTable);
while ((entry = (PendingOperationEntry *) hash_seq_search(&hstat)) != NULL)
{
+ ForkNumber forknum;
+
/*
- * If the entry is new then don't process it this time. Note that
+ * If the entry is new then don't process it this time; it might
+ * contain multiple fsync-request bits, but they are all new. Note
* "continue" bypasses the hash-remove call at the bottom of the loop.
*/
if (entry->cycle_ctr == mdsync_cycle_ctr)
Assert((CycleCtr) (entry->cycle_ctr + 1) == mdsync_cycle_ctr);
/*
- * If fsync is off then we don't have to bother opening the file at
- * all. (We delay checking until this point so that changing fsync on
- * the fly behaves sensibly.) Also, if the entry is marked canceled,
- * fall through to delete it.
+ * Scan over the forks and segments represented by the entry.
+ *
+ * The bitmap manipulations are slightly tricky, because we can call
+ * AbsorbFsyncRequests() inside the loop and that could result in
+ * bms_add_member() modifying and even re-palloc'ing the bitmapsets.
+ * So we detach it, but if we fail we'll merge it with any new
+ * requests that have arrived in the meantime.
*/
- if (enableFsync && !entry->canceled)
+ for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
{
- int failures;
+ Bitmapset *requests = entry->requests[forknum];
+ int segno;
- /*
- * If in bgwriter, we want to absorb pending requests every so
- * often to prevent overflow of the fsync request queue. It is
- * unspecified whether newly-added entries will be visited by
- * hash_seq_search, but we don't care since we don't need to
- * process them anyway.
- */
- if (--absorb_counter <= 0)
- {
- AbsorbFsyncRequests();
- absorb_counter = FSYNCS_PER_ABSORB;
- }
+ entry->requests[forknum] = NULL;
+ entry->canceled[forknum] = false;
- /*
- * The fsync table could contain requests to fsync segments that
- * have been deleted (unlinked) by the time we get to them. Rather
- * than just hoping an ENOENT (or EACCES on Windows) error can be
- * ignored, what we do on error is absorb pending requests and
- * then retry. Since mdunlink() queues a "revoke" message before
- * actually unlinking, the fsync request is guaranteed to be
- * marked canceled after the absorb if it really was this case.
- * DROP DATABASE likewise has to tell us to forget fsync requests
- * before it starts deletions.
- */
- for (failures = 0;; failures++) /* loop exits at "break" */
+ segno = -1;
+ while ((segno = bms_next_member(requests, segno)) >= 0)
{
- SMgrRelation reln;
- MdfdVec *seg;
- char *path;
+ int failures;
+
+ /*
+ * If fsync is off then we don't have to bother opening the
+ * file at all. (We delay checking until this point so that
+ * changing fsync on the fly behaves sensibly.)
+ */
+ if (!enableFsync)
+ continue;
/*
- * Find or create an smgr hash entry for this relation. This
- * may seem a bit unclean -- md calling smgr? But it's really
- * the best solution. It ensures that the open file reference
- * isn't permanently leaked if we get an error here. (You may
- * say "but an unreferenced SMgrRelation is still a leak!" Not
- * really, because the only case in which a checkpoint is done
- * by a process that isn't about to shut down is in the
- * bgwriter, and it will periodically do smgrcloseall(). This
- * fact justifies our not closing the reln in the success path
- * either, which is a good thing since in non-bgwriter cases
- * we couldn't safely do that.) Furthermore, in many cases
- * the relation will have been dirtied through this same smgr
- * relation, and so we can save a file open/close cycle.
+ * If in checkpointer, we want to absorb pending requests
+ * every so often to prevent overflow of the fsync request
+ * queue. It is unspecified whether newly-added entries will
+ * be visited by hash_seq_search, but we don't care since we
+ * don't need to process them anyway.
*/
- reln = smgropen(entry->tag.rnode.node,
- entry->tag.rnode.backend);
+ if (--absorb_counter <= 0)
+ {
+ AbsorbFsyncRequests();
+ absorb_counter = FSYNCS_PER_ABSORB;
+ }
/*
- * It is possible that the relation has been dropped or
- * truncated since the fsync request was entered. Therefore,
- * allow ENOENT, but only if we didn't fail already on this
- * file. This applies both during _mdfd_getseg() and during
- * FileSync, since fd.c might have closed the file behind our
- * back.
+ * The fsync table could contain requests to fsync segments
+ * that have been deleted (unlinked) by the time we get to
+ * them. Rather than just hoping an ENOENT (or EACCES on
+ * Windows) error can be ignored, what we do on error is
+ * absorb pending requests and then retry. Since mdunlink()
+ * queues a "cancel" message before actually unlinking, the
+ * fsync request is guaranteed to be marked canceled after the
+ * absorb if it really was this case. DROP DATABASE likewise
+ * has to tell us to forget fsync requests before it starts
+ * deletions.
*/
- seg = _mdfd_getseg(reln, entry->tag.forknum,
- entry->tag.segno * ((BlockNumber) RELSEG_SIZE),
- false, EXTENSION_RETURN_NULL);
+ for (failures = 0;; failures++) /* loop exits at "break" */
+ {
+ SMgrRelation reln;
+ MdfdVec *seg;
+ char *path;
+ int save_errno;
+
+ /*
+ * Find or create an smgr hash entry for this relation.
+ * This may seem a bit unclean -- md calling smgr? But
+ * it's really the best solution. It ensures that the
+ * open file reference isn't permanently leaked if we get
+ * an error here. (You may say "but an unreferenced
+ * SMgrRelation is still a leak!" Not really, because the
+ * only case in which a checkpoint is done by a process
+ * that isn't about to shut down is in the checkpointer,
+ * and it will periodically do smgrcloseall(). This fact
+ * justifies our not closing the reln in the success path
+ * either, which is a good thing since in non-checkpointer
+ * cases we couldn't safely do that.)
+ */
+ reln = smgropen(entry->rnode, InvalidBackendId);
+
+ /* Attempt to open and fsync the target segment */
+ seg = _mdfd_getseg(reln, forknum,
+ (BlockNumber) segno * (BlockNumber) RELSEG_SIZE,
+ false,
+ EXTENSION_RETURN_NULL
+ | EXTENSION_DONT_CHECK_SIZE);
- if (log_checkpoints)
INSTR_TIME_SET_CURRENT(sync_start);
- else
- INSTR_TIME_SET_ZERO(sync_start);
- if (seg != NULL &&
- FileSync(seg->mdfd_vfd) >= 0)
- {
- if (log_checkpoints && (!INSTR_TIME_IS_ZERO(sync_start)))
+ if (seg != NULL &&
+ FileSync(seg->mdfd_vfd, WAIT_EVENT_DATA_FILE_SYNC) >= 0)
{
+ /* Success; update statistics about sync timing */
INSTR_TIME_SET_CURRENT(sync_end);
sync_diff = sync_end;
INSTR_TIME_SUBTRACT(sync_diff, sync_start);
longest = elapsed;
total_elapsed += elapsed;
processed++;
- elog(DEBUG1, "checkpoint sync: number=%d file=%s time=%.3f msec",
- processed, FilePathName(seg->mdfd_vfd), (double) elapsed / 1000);
+ requests = bms_del_member(requests, segno);
+ if (log_checkpoints)
+ elog(DEBUG1, "checkpoint sync: number=%d file=%s time=%.3f msec",
+ processed,
+ FilePathName(seg->mdfd_vfd),
+ (double) elapsed / 1000);
+
+ break; /* out of retry loop */
}
- break; /* success; break out of retry loop */
- }
-
- /*
- * XXX is there any point in allowing more than one retry?
- * Don't see one at the moment, but easy to change the test
- * here if so.
- */
- path = _mdfd_segpath(reln, entry->tag.forknum,
- entry->tag.segno);
- if (!FILE_POSSIBLY_DELETED(errno) ||
- failures > 0)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not fsync file \"%s\": %m", path)));
- else
- ereport(DEBUG1,
- (errcode_for_file_access(),
- errmsg("could not fsync file \"%s\" but retrying: %m",
- path)));
- pfree(path);
-
- /*
- * Absorb incoming requests and check to see if canceled.
- */
- AbsorbFsyncRequests();
- absorb_counter = FSYNCS_PER_ABSORB; /* might as well... */
-
- if (entry->canceled)
- break;
- } /* end retry loop */
+ /* Compute file name for use in message */
+ save_errno = errno;
+ path = _mdfd_segpath(reln, forknum, (BlockNumber) segno);
+ errno = save_errno;
+
+ /*
+ * It is possible that the relation has been dropped or
+ * truncated since the fsync request was entered.
+ * Therefore, allow ENOENT, but only if we didn't fail
+ * already on this file. This applies both for
+ * _mdfd_getseg() and for FileSync, since fd.c might have
+ * closed the file behind our back.
+ *
+ * XXX is there any point in allowing more than one retry?
+ * Don't see one at the moment, but easy to change the
+ * test here if so.
+ */
+ if (!FILE_POSSIBLY_DELETED(errno) ||
+ failures > 0)
+ {
+ Bitmapset *new_requests;
+
+ /*
+ * We need to merge these unsatisfied requests with
+ * any others that have arrived since we started.
+ */
+ new_requests = entry->requests[forknum];
+ entry->requests[forknum] =
+ bms_join(new_requests, requests);
+
+ errno = save_errno;
+ ereport(data_sync_elevel(ERROR),
+ (errcode_for_file_access(),
+ errmsg("could not fsync file \"%s\": %m",
+ path)));
+ }
+ else
+ ereport(DEBUG1,
+ (errcode_for_file_access(),
+ errmsg("could not fsync file \"%s\" but retrying: %m",
+ path)));
+ pfree(path);
+
+ /*
+ * Absorb incoming requests and check to see if a cancel
+ * arrived for this relation fork.
+ */
+ AbsorbFsyncRequests();
+ absorb_counter = FSYNCS_PER_ABSORB; /* might as well... */
+
+ if (entry->canceled[forknum])
+ break;
+ } /* end retry loop */
+ }
+ bms_free(requests);
}
/*
- * If we get here, either we fsync'd successfully, or we don't have to
- * because enableFsync is off, or the entry is (now) marked canceled.
- * Okay to delete it.
+ * We've finished everything that was requested before we started to
+ * scan the entry. If no new requests have been inserted meanwhile,
+ * remove the entry. Otherwise, update its cycle counter, as all the
+ * requests now in it must have arrived during this cycle.
*/
- if (hash_search(pendingOpsTable, &entry->tag,
- HASH_REMOVE, NULL) == NULL)
- elog(ERROR, "pendingOpsTable corrupted");
+ for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
+ {
+ if (entry->requests[forknum] != NULL)
+ break;
+ }
+ if (forknum <= MAX_FORKNUM)
+ entry->cycle_ctr = mdsync_cycle_ctr;
+ else
+ {
+ /* Okay to remove it */
+ if (hash_search(pendingOpsTable, &entry->rnode,
+ HASH_REMOVE, NULL) == NULL)
+ elog(ERROR, "pendingOpsTable corrupted");
+ }
} /* end loop over hashtable entries */
/* Return sync performance metrics for report at checkpoint end */
void
mdpreckpt(void)
{
- ListCell *cell;
-
- /*
- * In case the prior checkpoint wasn't completed, stamp all entries in the
- * list with the current cycle counter. Anything that's in the list at
- * the start of checkpoint can surely be deleted after the checkpoint is
- * finished, regardless of when the request was made.
- */
- foreach(cell, pendingUnlinks)
- {
- PendingUnlinkEntry *entry = (PendingUnlinkEntry *) lfirst(cell);
-
- entry->cycle_ctr = mdckpt_cycle_ctr;
- }
-
/*
* Any unlink requests arriving after this point will be assigned the next
* cycle counter, and won't be unlinked until next checkpoint.
void
mdpostckpt(void)
{
+ int absorb_counter;
+
+ absorb_counter = UNLINKS_PER_ABSORB;
while (pendingUnlinks != NIL)
{
PendingUnlinkEntry *entry = (PendingUnlinkEntry *) linitial(pendingUnlinks);
/*
* New entries are appended to the end, so if the entry is new we've
* reached the end of old entries.
+ *
+ * Note: if just the right number of consecutive checkpoints fail, we
+ * could be fooled here by cycle_ctr wraparound. However, the only
+ * consequence is that we'd delay unlinking for one more checkpoint,
+ * which is perfectly tolerable.
*/
if (entry->cycle_ctr == mdckpt_cycle_ctr)
break;
- /* Else assert we haven't missed it */
- Assert((CycleCtr) (entry->cycle_ctr + 1) == mdckpt_cycle_ctr);
-
/* Unlink the file */
- path = relpath(entry->rnode, MAIN_FORKNUM);
+ path = relpathperm(entry->rnode, MAIN_FORKNUM);
if (unlink(path) < 0)
{
/*
}
pfree(path);
+ /* And remove the list entry */
pendingUnlinks = list_delete_first(pendingUnlinks);
pfree(entry);
+
+ /*
+ * As in mdsync, we don't want to stop absorbing fsync requests for a
+ * long time when there are many deletions to be done. We can safely
+ * call AbsorbFsyncRequests() at this point in the loop (note it might
+ * try to delete list entries).
+ */
+ if (--absorb_counter <= 0)
+ {
+ AbsorbFsyncRequests();
+ absorb_counter = UNLINKS_PER_ABSORB;
+ }
}
}
*
* If there is a local pending-ops table, just make an entry in it for
* mdsync to process later. Otherwise, try to pass off the fsync request
- * to the background writer process. If that fails, just do the fsync
- * locally before returning (we expect this will not happen often enough
+ * to the checkpointer process. If that fails, just do the fsync
+ * locally before returning (we hope this will not happen often enough
* to be a performance problem).
*/
static void
register_dirty_segment(SMgrRelation reln, ForkNumber forknum, MdfdVec *seg)
{
+ /* Temp relations should never be fsync'd */
+ Assert(!SmgrIsTemp(reln));
+
if (pendingOpsTable)
{
/* push it into local pending-ops table */
- RememberFsyncRequest(reln->smgr_rnode, forknum, seg->mdfd_segno);
+ RememberFsyncRequest(reln->smgr_rnode.node, forknum, seg->mdfd_segno);
}
else
{
- if (ForwardFsyncRequest(reln->smgr_rnode, forknum, seg->mdfd_segno))
+ if (ForwardFsyncRequest(reln->smgr_rnode.node, forknum, seg->mdfd_segno))
return; /* passed it off successfully */
ereport(DEBUG1,
(errmsg("could not forward fsync request because request queue is full")));
- if (FileSync(seg->mdfd_vfd) < 0)
- ereport(ERROR,
+ if (FileSync(seg->mdfd_vfd, WAIT_EVENT_DATA_FILE_SYNC) < 0)
+ ereport(data_sync_elevel(ERROR),
(errcode_for_file_access(),
errmsg("could not fsync file \"%s\": %m",
FilePathName(seg->mdfd_vfd))));
/*
* register_unlink() -- Schedule a file to be deleted after next checkpoint
*
+ * We don't bother passing in the fork number, because this is only used
+ * with main forks.
+ *
* As with register_dirty_segment, this could involve either a local or
* a remote pending-ops table.
*/
static void
register_unlink(RelFileNodeBackend rnode)
{
+ /* Should never be used with temp relations */
+ Assert(!RelFileNodeBackendIsTemp(rnode));
+
if (pendingOpsTable)
{
/* push it into local pending-ops table */
- RememberFsyncRequest(rnode, MAIN_FORKNUM, UNLINK_RELATION_REQUEST);
+ RememberFsyncRequest(rnode.node, MAIN_FORKNUM,
+ UNLINK_RELATION_REQUEST);
}
else
{
/*
- * Notify the bgwriter about it. If we fail to queue the request
+ * Notify the checkpointer about it. If we fail to queue the request
* message, we have to sleep and try again, because we can't simply
* delete the file now. Ugly, but hopefully won't happen often.
*
* XXX should we just leave the file orphaned instead?
*/
Assert(IsUnderPostmaster);
- while (!ForwardFsyncRequest(rnode, MAIN_FORKNUM,
+ while (!ForwardFsyncRequest(rnode.node, MAIN_FORKNUM,
UNLINK_RELATION_REQUEST))
pg_usleep(10000L); /* 10 msec seems a good number */
}
}
/*
- * RememberFsyncRequest() -- callback from bgwriter side of fsync request
+ * RememberFsyncRequest() -- callback from checkpointer side of fsync request
*
- * We stuff most fsync requests into the local hash table for execution
- * during the bgwriter's next checkpoint. UNLINK requests go into a
+ * We stuff fsync requests into the local hash table for execution
+ * during the checkpointer's next checkpoint. UNLINK requests go into a
* separate linked list, however, because they get processed separately.
*
* The range of possible segment numbers is way less than the range of
* BlockNumber, so we can reserve high values of segno for special purposes.
* We define three:
- * - FORGET_RELATION_FSYNC means to cancel pending fsyncs for a relation
+ * - FORGET_RELATION_FSYNC means to cancel pending fsyncs for a relation,
+ * either for one fork, or all forks if forknum is InvalidForkNumber
* - FORGET_DATABASE_FSYNC means to cancel pending fsyncs for a whole database
* - UNLINK_RELATION_REQUEST is a request to delete the file after the next
* checkpoint.
+ * Note also that we're assuming real segment numbers don't exceed INT_MAX.
*
- * (Handling the FORGET_* requests is a tad slow because the hash table has
- * to be searched linearly, but it doesn't seem worth rethinking the table
- * structure for them.)
+ * (Handling FORGET_DATABASE_FSYNC requests is a tad slow because the hash
+ * table has to be searched linearly, but dropping a database is a pretty
+ * heavyweight operation anyhow, so we'll live with it.)
*/
void
-RememberFsyncRequest(RelFileNodeBackend rnode, ForkNumber forknum,
- BlockNumber segno)
+RememberFsyncRequest(RelFileNode rnode, ForkNumber forknum, BlockNumber segno)
{
Assert(pendingOpsTable);
if (segno == FORGET_RELATION_FSYNC)
{
- /* Remove any pending requests for the entire relation */
- HASH_SEQ_STATUS hstat;
+ /* Remove any pending requests for the relation (one or all forks) */
PendingOperationEntry *entry;
- hash_seq_init(&hstat, pendingOpsTable);
- while ((entry = (PendingOperationEntry *) hash_seq_search(&hstat)) != NULL)
+ entry = (PendingOperationEntry *) hash_search(pendingOpsTable,
+ &rnode,
+ HASH_FIND,
+ NULL);
+ if (entry)
{
- if (RelFileNodeBackendEquals(entry->tag.rnode, rnode) &&
- entry->tag.forknum == forknum)
+ /*
+ * We can't just delete the entry since mdsync could have an
+ * active hashtable scan. Instead we delete the bitmapsets; this
+ * is safe because of the way mdsync is coded. We also set the
+ * "canceled" flags so that mdsync can tell that a cancel arrived
+ * for the fork(s).
+ */
+ if (forknum == InvalidForkNumber)
{
- /* Okay, cancel this entry */
- entry->canceled = true;
+ /* remove requests for all forks */
+ for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
+ {
+ bms_free(entry->requests[forknum]);
+ entry->requests[forknum] = NULL;
+ entry->canceled[forknum] = true;
+ }
+ }
+ else
+ {
+ /* remove requests for single fork */
+ bms_free(entry->requests[forknum]);
+ entry->requests[forknum] = NULL;
+ entry->canceled[forknum] = true;
}
}
}
hash_seq_init(&hstat, pendingOpsTable);
while ((entry = (PendingOperationEntry *) hash_seq_search(&hstat)) != NULL)
{
- if (entry->tag.rnode.node.dbNode == rnode.node.dbNode)
+ if (entry->rnode.dbNode == rnode.dbNode)
{
- /* Okay, cancel this entry */
- entry->canceled = true;
+ /* remove requests for all forks */
+ for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
+ {
+ bms_free(entry->requests[forknum]);
+ entry->requests[forknum] = NULL;
+ entry->canceled[forknum] = true;
+ }
}
}
PendingUnlinkEntry *entry = (PendingUnlinkEntry *) lfirst(cell);
next = lnext(cell);
- if (entry->rnode.node.dbNode == rnode.node.dbNode)
+ if (entry->rnode.dbNode == rnode.dbNode)
{
pendingUnlinks = list_delete_cell(pendingUnlinks, cell, prev);
pfree(entry);
else if (segno == UNLINK_RELATION_REQUEST)
{
/* Unlink request: put it in the linked list */
- MemoryContext oldcxt = MemoryContextSwitchTo(MdCxt);
+ MemoryContext oldcxt = MemoryContextSwitchTo(pendingOpsCxt);
PendingUnlinkEntry *entry;
+ /* PendingUnlinkEntry doesn't store forknum, since it's always MAIN */
+ Assert(forknum == MAIN_FORKNUM);
+
entry = palloc(sizeof(PendingUnlinkEntry));
entry->rnode = rnode;
entry->cycle_ctr = mdckpt_cycle_ctr;
else
{
/* Normal case: enter a request to fsync this segment */
- PendingOperationTag key;
+ MemoryContext oldcxt = MemoryContextSwitchTo(pendingOpsCxt);
PendingOperationEntry *entry;
bool found;
- /* ensure any pad bytes in the hash key are zeroed */
- MemSet(&key, 0, sizeof(key));
- key.rnode = rnode;
- key.forknum = forknum;
- key.segno = segno;
-
entry = (PendingOperationEntry *) hash_search(pendingOpsTable,
- &key,
+ &rnode,
HASH_ENTER,
&found);
- /* if new or previously canceled entry, initialize it */
- if (!found || entry->canceled)
+ /* if new entry, initialize it */
+ if (!found)
{
- entry->canceled = false;
entry->cycle_ctr = mdsync_cycle_ctr;
+ MemSet(entry->requests, 0, sizeof(entry->requests));
+ MemSet(entry->canceled, 0, sizeof(entry->canceled));
}
/*
* NB: it's intentional that we don't change cycle_ctr if the entry
- * already exists. The fsync request must be treated as old, even
- * though the new request will be satisfied too by any subsequent
- * fsync.
- *
- * However, if the entry is present but is marked canceled, we should
- * act just as though it wasn't there. The only case where this could
- * happen would be if a file had been deleted, we received but did not
- * yet act on the cancel request, and the same relfilenode was then
- * assigned to a new file. We mustn't lose the new request, but it
- * should be considered new not old.
+ * already exists. The cycle_ctr must represent the oldest fsync
+ * request that could be in the entry.
*/
+
+ entry->requests[forknum] = bms_add_member(entry->requests[forknum],
+ (int) segno);
+
+ MemoryContextSwitchTo(oldcxt);
}
}
/*
- * ForgetRelationFsyncRequests -- forget any fsyncs for a rel
+ * ForgetRelationFsyncRequests -- forget any fsyncs for a relation fork
+ *
+ * forknum == InvalidForkNumber means all forks, although this code doesn't
+ * actually know that, since it's just forwarding the request elsewhere.
*/
void
-ForgetRelationFsyncRequests(RelFileNodeBackend rnode, ForkNumber forknum)
+ForgetRelationFsyncRequests(RelFileNode rnode, ForkNumber forknum)
{
if (pendingOpsTable)
{
else if (IsUnderPostmaster)
{
/*
- * Notify the bgwriter about it. If we fail to queue the revoke
+ * Notify the checkpointer about it. If we fail to queue the cancel
* message, we have to sleep and try again ... ugly, but hopefully
* won't happen often.
*
* XXX should we CHECK_FOR_INTERRUPTS in this loop? Escaping with an
* error would leave the no-longer-used file still present on disk,
- * which would be bad, so I'm inclined to assume that the bgwriter
+ * which would be bad, so I'm inclined to assume that the checkpointer
* will always empty the queue soon.
*/
while (!ForwardFsyncRequest(rnode, forknum, FORGET_RELATION_FSYNC))
pg_usleep(10000L); /* 10 msec seems a good number */
/*
- * Note we don't wait for the bgwriter to actually absorb the revoke
- * message; see mdsync() for the implications.
+ * Note we don't wait for the checkpointer to actually absorb the
+ * cancel message; see mdsync() for the implications.
*/
}
}
void
ForgetDatabaseFsyncRequests(Oid dbid)
{
- RelFileNodeBackend rnode;
+ RelFileNode rnode;
- rnode.node.dbNode = dbid;
- rnode.node.spcNode = 0;
- rnode.node.relNode = 0;
- rnode.backend = InvalidBackendId;
+ rnode.dbNode = dbid;
+ rnode.spcNode = 0;
+ rnode.relNode = 0;
if (pendingOpsTable)
{
}
}
+/*
+ * DropRelationFiles -- drop files of all given relations
+ */
+void
+DropRelationFiles(RelFileNode *delrels, int ndelrels, bool isRedo)
+{
+ SMgrRelation *srels;
+ int i;
+
+ srels = palloc(sizeof(SMgrRelation) * ndelrels);
+ for (i = 0; i < ndelrels; i++)
+ {
+ SMgrRelation srel = smgropen(delrels[i], InvalidBackendId);
+
+ if (isRedo)
+ {
+ ForkNumber fork;
+
+ for (fork = 0; fork <= MAX_FORKNUM; fork++)
+ XLogDropRelation(delrels[i], fork);
+ }
+ srels[i] = srel;
+ }
+
+ smgrdounlinkall(srels, ndelrels, isRedo);
+
+ /*
+ * Call smgrclose() in reverse order as when smgropen() is called.
+ * This trick enables remove_from_unowned_list() in smgrclose()
+ * to search the SMgrRelation from the unowned list,
+ * with O(1) performance.
+ */
+ for (i = ndelrels - 1; i >= 0; i--)
+ smgrclose(srels[i]);
+ pfree(srels);
+}
+
/*
- * _fdvec_alloc() -- Make a MdfdVec object.
+ * _fdvec_resize() -- Resize the fork's open segments array
*/
-static MdfdVec *
-_fdvec_alloc(void)
+static void
+_fdvec_resize(SMgrRelation reln,
+ ForkNumber forknum,
+ int nseg)
{
- return (MdfdVec *) MemoryContextAlloc(MdCxt, sizeof(MdfdVec));
+ if (nseg == 0)
+ {
+ if (reln->md_num_open_segs[forknum] > 0)
+ {
+ pfree(reln->md_seg_fds[forknum]);
+ reln->md_seg_fds[forknum] = NULL;
+ }
+ }
+ else if (reln->md_num_open_segs[forknum] == 0)
+ {
+ reln->md_seg_fds[forknum] =
+ MemoryContextAlloc(MdCxt, sizeof(MdfdVec) * nseg);
+ }
+ else
+ {
+ /*
+ * It doesn't seem worthwhile complicating the code by having a more
+ * aggressive growth strategy here; the number of segments doesn't
+ * grow that fast, and the memory context internally will sometimes
+ * avoid doing an actual reallocation.
+ */
+ reln->md_seg_fds[forknum] =
+ repalloc(reln->md_seg_fds[forknum],
+ sizeof(MdfdVec) * nseg);
+ }
+
+ reln->md_num_open_segs[forknum] = nseg;
}
/*
if (segno > 0)
{
- /* be sure we have enough space for the '.segno' */
- fullpath = (char *) palloc(strlen(path) + 12);
- sprintf(fullpath, "%s.%u", path, segno);
+ fullpath = psprintf("%s.%u", path, segno);
pfree(path);
}
else
fullpath = _mdfd_segpath(reln, forknum, segno);
/* open the file */
- fd = PathNameOpenFile(fullpath, O_RDWR | PG_BINARY | oflags, 0600);
+ fd = PathNameOpenFile(fullpath, O_RDWR | PG_BINARY | oflags);
pfree(fullpath);
if (fd < 0)
return NULL;
- /* allocate an mdfdvec entry for it */
- v = _fdvec_alloc();
+ if (segno <= reln->md_num_open_segs[forknum])
+ _fdvec_resize(reln, forknum, segno + 1);
/* fill the entry */
+ v = &reln->md_seg_fds[forknum][segno];
v->mdfd_vfd = fd;
v->mdfd_segno = segno;
- v->mdfd_chain = NULL;
+
Assert(_mdnblocks(reln, forknum, v) <= ((BlockNumber) RELSEG_SIZE));
/* all done */
*/
static MdfdVec *
_mdfd_getseg(SMgrRelation reln, ForkNumber forknum, BlockNumber blkno,
- bool skipFsync, ExtensionBehavior behavior)
+ bool skipFsync, int behavior)
{
- MdfdVec *v = mdopen(reln, forknum, behavior);
+ MdfdVec *v;
BlockNumber targetseg;
BlockNumber nextsegno;
- if (!v)
- return NULL; /* only possible if EXTENSION_RETURN_NULL */
+ /* some way to handle non-existent segments needs to be specified */
+ Assert(behavior &
+ (EXTENSION_FAIL | EXTENSION_CREATE | EXTENSION_RETURN_NULL));
targetseg = blkno / ((BlockNumber) RELSEG_SIZE);
- for (nextsegno = 1; nextsegno <= targetseg; nextsegno++)
+
+ /* if an existing and opened segment, we're done */
+ if (targetseg < reln->md_num_open_segs[forknum])
+ {
+ v = &reln->md_seg_fds[forknum][targetseg];
+ return v;
+ }
+
+ /*
+ * The target segment is not yet open. Iterate over all the segments
+ * between the last opened and the target segment. This way missing
+ * segments either raise an error, or get created (according to
+ * 'behavior'). Start with either the last opened, or the first segment if
+ * none was opened before.
+ */
+ if (reln->md_num_open_segs[forknum] > 0)
+ v = &reln->md_seg_fds[forknum][reln->md_num_open_segs[forknum] - 1];
+ else
{
+ v = mdopen(reln, forknum, behavior);
+ if (!v)
+ return NULL; /* if behavior & EXTENSION_RETURN_NULL */
+ }
+
+ for (nextsegno = reln->md_num_open_segs[forknum];
+ nextsegno <= targetseg; nextsegno++)
+ {
+ BlockNumber nblocks = _mdnblocks(reln, forknum, v);
+ int flags = 0;
+
Assert(nextsegno == v->mdfd_segno + 1);
- if (v->mdfd_chain == NULL)
+ if (nblocks > ((BlockNumber) RELSEG_SIZE))
+ elog(FATAL, "segment too big");
+
+ if ((behavior & EXTENSION_CREATE) ||
+ (InRecovery && (behavior & EXTENSION_CREATE_RECOVERY)))
{
/*
* Normally we will create new segments only if authorized by the
- * caller (i.e., we are doing mdextend()). But when doing WAL
+ * caller (i.e., we are doing mdextend()). But when doing WAL
* recovery, create segments anyway; this allows cases such as
* replaying WAL data that has a write into a high-numbered
- * segment of a relation that was later deleted. We want to go
+ * segment of a relation that was later deleted. We want to go
* ahead and create the segments so we can finish out the replay.
+ * However if the caller has specified
+ * EXTENSION_REALLY_RETURN_NULL, then extension is not desired
+ * even in recovery; we won't reach this point in that case.
*
* We have to maintain the invariant that segments before the last
- * active segment are of size RELSEG_SIZE; therefore, pad them out
- * with zeroes if needed. (This only matters if caller is
- * extending the relation discontiguously, but that can happen in
- * hash indexes.)
+ * active segment are of size RELSEG_SIZE; therefore, if
+ * extending, pad them out with zeroes if needed. (This only
+ * matters if in recovery, or if the caller is extending the
+ * relation discontiguously, but that can happen in hash indexes.)
*/
- if (behavior == EXTENSION_CREATE || InRecovery)
+ if (nblocks < ((BlockNumber) RELSEG_SIZE))
{
- if (_mdnblocks(reln, forknum, v) < RELSEG_SIZE)
- {
- char *zerobuf = palloc0(BLCKSZ);
+ char *zerobuf = palloc0(BLCKSZ);
- mdextend(reln, forknum,
- nextsegno * ((BlockNumber) RELSEG_SIZE) - 1,
- zerobuf, skipFsync);
- pfree(zerobuf);
- }
- v->mdfd_chain = _mdfd_openseg(reln, forknum, +nextsegno, O_CREAT);
+ mdextend(reln, forknum,
+ nextsegno * ((BlockNumber) RELSEG_SIZE) - 1,
+ zerobuf, skipFsync);
+ pfree(zerobuf);
}
- else
- {
- /* We won't create segment if not existent */
- v->mdfd_chain = _mdfd_openseg(reln, forknum, nextsegno, 0);
- }
- if (v->mdfd_chain == NULL)
+ flags = O_CREAT;
+ }
+ else if (!(behavior & EXTENSION_DONT_CHECK_SIZE) &&
+ nblocks < ((BlockNumber) RELSEG_SIZE))
+ {
+ /*
+ * When not extending (or explicitly including truncated
+ * segments), only open the next segment if the current one is
+ * exactly RELSEG_SIZE. If not (this branch), either return NULL
+ * or fail.
+ */
+ if (behavior & EXTENSION_RETURN_NULL)
{
- if (behavior == EXTENSION_RETURN_NULL &&
- FILE_POSSIBLY_DELETED(errno))
- return NULL;
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not open file \"%s\" (target block %u): %m",
- _mdfd_segpath(reln, forknum, nextsegno),
- blkno)));
+ /*
+ * Some callers discern between reasons for _mdfd_getseg()
+ * returning NULL based on errno. As there's no failing
+ * syscall involved in this case, explicitly set errno to
+ * ENOENT, as that seems the closest interpretation.
+ */
+ errno = ENOENT;
+ return NULL;
}
+
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not open file \"%s\" (target block %u): previous segment is only %u blocks",
+ _mdfd_segpath(reln, forknum, nextsegno),
+ blkno, nblocks)));
+ }
+
+ v = _mdfd_openseg(reln, forknum, nextsegno, flags);
+
+ if (v == NULL)
+ {
+ if ((behavior & EXTENSION_RETURN_NULL) &&
+ FILE_POSSIBLY_DELETED(errno))
+ return NULL;
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not open file \"%s\" (target block %u): %m",
+ _mdfd_segpath(reln, forknum, nextsegno),
+ blkno)));
}
- v = v->mdfd_chain;
}
+
return v;
}
{
off_t len;
- len = FileSeek(seg->mdfd_vfd, 0L, SEEK_END);
+ len = FileSize(seg->mdfd_vfd);
if (len < 0)
ereport(ERROR,
(errcode_for_file_access(),
projects / postgresql / blobdiff