* hio.c
* POSTGRES heap access method input/output code.
*
- * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
#include "access/heapam.h"
#include "access/hio.h"
+#include "access/htup_details.h"
+#include "access/visibilitymap.h"
#include "storage/bufmgr.h"
#include "storage/freespace.h"
#include "storage/lmgr.h"
void
RelationPutHeapTuple(Relation relation,
Buffer buffer,
- HeapTuple tuple)
+ HeapTuple tuple,
+ bool token)
{
Page pageHeader;
OffsetNumber offnum;
- ItemId itemId;
- Item item;
+
+ /*
+ * A tuple that's being inserted speculatively should already have its
+ * token set.
+ */
+ Assert(!token || HeapTupleHeaderIsSpeculative(tuple->t_data));
/* Add the tuple to the page */
- pageHeader = BufferGetPage(buffer);
+ pageHeader = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
offnum = PageAddItem(pageHeader, (Item) tuple->t_data,
tuple->t_len, InvalidOffsetNumber, false, true);
/* Update tuple->t_self to the actual position where it was stored */
ItemPointerSet(&(tuple->t_self), BufferGetBlockNumber(buffer), offnum);
- /* Insert the correct position into CTID of the stored tuple, too */
- itemId = PageGetItemId(pageHeader, offnum);
- item = PageGetItem(pageHeader, itemId);
- ((HeapTupleHeader) item)->t_ctid = tuple->t_self;
+ /*
+ * Insert the correct position into CTID of the stored tuple, too (unless
+ * this is a speculative insertion, in which case the token is held in
+ * CTID field instead)
+ */
+ if (!token)
+ {
+ ItemId itemId = PageGetItemId(pageHeader, offnum);
+ Item item = PageGetItem(pageHeader, itemId);
+
+ ((HeapTupleHeader) item)->t_ctid = tuple->t_self;
+ }
}
/*
return buffer;
}
+/*
+ * For each heap page which is all-visible, acquire a pin on the appropriate
+ * visibility map page, if we haven't already got one.
+ *
+ * buffer2 may be InvalidBuffer, if only one buffer is involved. buffer1
+ * must not be InvalidBuffer. If both buffers are specified, buffer1 must
+ * be less than buffer2.
+ */
+static void
+GetVisibilityMapPins(Relation relation, Buffer buffer1, Buffer buffer2,
+ BlockNumber block1, BlockNumber block2,
+ Buffer *vmbuffer1, Buffer *vmbuffer2)
+{
+ bool need_to_pin_buffer1;
+ bool need_to_pin_buffer2;
+
+ Assert(BufferIsValid(buffer1));
+ Assert(buffer2 == InvalidBuffer || buffer1 <= buffer2);
+
+ while (1)
+ {
+ /* Figure out which pins we need but don't have. */
+ need_to_pin_buffer1 =
+ PageIsAllVisible(BufferGetPage(buffer1, NULL, NULL,
+ BGP_NO_SNAPSHOT_TEST))
+ && !visibilitymap_pin_ok(block1, *vmbuffer1);
+ need_to_pin_buffer2 = buffer2 != InvalidBuffer
+ && PageIsAllVisible(BufferGetPage(buffer2, NULL, NULL,
+ BGP_NO_SNAPSHOT_TEST))
+ && !visibilitymap_pin_ok(block2, *vmbuffer2);
+ if (!need_to_pin_buffer1 && !need_to_pin_buffer2)
+ return;
+
+ /* We must unlock both buffers before doing any I/O. */
+ LockBuffer(buffer1, BUFFER_LOCK_UNLOCK);
+ if (buffer2 != InvalidBuffer && buffer2 != buffer1)
+ LockBuffer(buffer2, BUFFER_LOCK_UNLOCK);
+
+ /* Get pins. */
+ if (need_to_pin_buffer1)
+ visibilitymap_pin(relation, block1, vmbuffer1);
+ if (need_to_pin_buffer2)
+ visibilitymap_pin(relation, block2, vmbuffer2);
+
+ /* Relock buffers. */
+ LockBuffer(buffer1, BUFFER_LOCK_EXCLUSIVE);
+ if (buffer2 != InvalidBuffer && buffer2 != buffer1)
+ LockBuffer(buffer2, BUFFER_LOCK_EXCLUSIVE);
+
+ /*
+ * If there are two buffers involved and we pinned just one of them,
+ * it's possible that the second one became all-visible while we were
+ * busy pinning the first one. If it looks like that's a possible
+ * scenario, we'll need to make a second pass through this loop.
+ */
+ if (buffer2 == InvalidBuffer || buffer1 == buffer2
+ || (need_to_pin_buffer1 && need_to_pin_buffer2))
+ break;
+ }
+}
+
+/*
+ * Extend a relation by multiple blocks to avoid future contention on the
+ * relation extension lock. Our goal is to pre-extend the relation by an
+ * amount which ramps up as the degree of contention ramps up, but limiting
+ * the result to some sane overall value.
+ */
+static void
+RelationAddExtraBlocks(Relation relation, BulkInsertState bistate)
+{
+ Page page;
+ BlockNumber blockNum = InvalidBlockNumber,
+ firstBlock = InvalidBlockNumber;
+ int extraBlocks = 0;
+ int lockWaiters = 0;
+ Size freespace = 0;
+ Buffer buffer;
+
+ /* Use the length of the lock wait queue to judge how much to extend. */
+ lockWaiters = RelationExtensionLockWaiterCount(relation);
+ if (lockWaiters <= 0)
+ return;
+
+ /*
+ * It might seem like multiplying the number of lock waiters by as much
+ * as 20 is too aggressive, but benchmarking revealed that smaller numbers
+ * were insufficient. 512 is just an arbitrary cap to prevent pathological
+ * results.
+ */
+ extraBlocks = Min(512, lockWaiters * 20);
+
+ while (extraBlocks-- >= 0)
+ {
+ /* Ouch - an unnecessary lseek() each time through the loop! */
+ buffer = ReadBufferBI(relation, P_NEW, bistate);
+
+ /* Extend by one page. */
+ LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
+ page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+ PageInit(page, BufferGetPageSize(buffer), 0);
+ MarkBufferDirty(buffer);
+ blockNum = BufferGetBlockNumber(buffer);
+ freespace = PageGetHeapFreeSpace(page);
+ UnlockReleaseBuffer(buffer);
+
+ /* Remember first block number thus added. */
+ if (firstBlock == InvalidBlockNumber)
+ firstBlock = blockNum;
+
+ /*
+ * Immediately update the bottom level of the FSM. This has a good
+ * chance of making this page visible to other concurrently inserting
+ * backends, and we want that to happen without delay.
+ */
+ RecordPageWithFreeSpace(relation, blockNum, freespace);
+ }
+
+ /*
+ * Updating the upper levels of the free space map is too expensive
+ * to do for every block, but it's worth doing once at the end to make
+ * sure that subsequent insertion activity sees all of those nifty free
+ * pages we just inserted.
+ *
+ * Note that we're using the freespace value that was reported for the
+ * last block we added as if it were the freespace value for every block
+ * we added. That's actually true, because they're all equally empty.
+ */
+ UpdateFreeSpaceMap(relation, firstBlock, blockNum, freespace);
+}
+
/*
* RelationGetBufferForTuple
*
* NOTE: it is unlikely, but not quite impossible, for otherBuffer to be the
* same buffer we select for insertion of the new tuple (this could only
* happen if space is freed in that page after heap_update finds there's not
- * enough there). In that case, the page will be pinned and locked only once.
+ * enough there). In that case, the page will be pinned and locked only once.
+ *
+ * For the vmbuffer and vmbuffer_other arguments, we avoid deadlock by
+ * locking them only after locking the corresponding heap page, and taking
+ * no further lwlocks while they are locked.
*
* We normally use FSM to help us find free space. However,
* if HEAP_INSERT_SKIP_FSM is specified, we just append a new empty page to
* for additional constraints needed for safe usage of this behavior.)
*
* The caller can also provide a BulkInsertState object to optimize many
- * insertions into the same relation. This keeps a pin on the current
+ * insertions into the same relation. This keeps a pin on the current
* insertion target page (to save pin/unpin cycles) and also passes a
* BULKWRITE buffer selection strategy object to the buffer manager.
* Passing NULL for bistate selects the default behavior.
Buffer
RelationGetBufferForTuple(Relation relation, Size len,
Buffer otherBuffer, int options,
- struct BulkInsertStateData *bistate)
+ BulkInsertState bistate,
+ Buffer *vmbuffer, Buffer *vmbuffer_other)
{
bool use_fsm = !(options & HEAP_INSERT_SKIP_FSM);
Buffer buffer = InvalidBuffer;
Page page;
- Size pageFreeSpace,
- saveFreeSpace;
+ Size pageFreeSpace = 0,
+ saveFreeSpace = 0;
BlockNumber targetBlock,
otherBlock;
bool needLock;
if (len > MaxHeapTupleSize)
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
- errmsg("row is too big: size %lu, maximum size %lu",
- (unsigned long) len,
- (unsigned long) MaxHeapTupleSize)));
+ errmsg("row is too big: size %zu, maximum size %zu",
+ len, MaxHeapTupleSize)));
/* Compute desired extra freespace due to fillfactor option */
saveFreeSpace = RelationGetTargetPageFreeSpace(relation,
/*
* We first try to put the tuple on the same page we last inserted a tuple
- * on, as cached in the BulkInsertState or relcache entry. If that
+ * on, as cached in the BulkInsertState or relcache entry. If that
* doesn't work, we ask the Free Space Map to locate a suitable page.
* Since the FSM's info might be out of date, we have to be prepared to
* loop around and retry multiple times. (To insure this isn't an infinite
/*
* If the FSM knows nothing of the rel, try the last page before we
- * give up and extend. This avoids one-tuple-per-page syndrome during
+ * give up and extend. This avoids one-tuple-per-page syndrome during
* bootstrapping or in a recently-started system.
*/
if (targetBlock == InvalidBlockNumber)
}
}
+loop:
while (targetBlock != InvalidBlockNumber)
{
/*
* Read and exclusive-lock the target block, as well as the other
* block if one was given, taking suitable care with lock ordering and
* the possibility they are the same block.
+ *
+ * If the page-level all-visible flag is set, caller will need to
+ * clear both that and the corresponding visibility map bit. However,
+ * by the time we return, we'll have x-locked the buffer, and we don't
+ * want to do any I/O while in that state. So we check the bit here
+ * before taking the lock, and pin the page if it appears necessary.
+ * Checking without the lock creates a risk of getting the wrong
+ * answer, so we'll have to recheck after acquiring the lock.
*/
if (otherBuffer == InvalidBuffer)
{
/* easy case */
buffer = ReadBufferBI(relation, targetBlock, bistate);
+ if (PageIsAllVisible(BufferGetPage(buffer, NULL, NULL,
+ BGP_NO_SNAPSHOT_TEST)))
+ visibilitymap_pin(relation, targetBlock, vmbuffer);
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
}
else if (otherBlock == targetBlock)
{
/* also easy case */
buffer = otherBuffer;
+ if (PageIsAllVisible(BufferGetPage(buffer, NULL, NULL,
+ BGP_NO_SNAPSHOT_TEST)))
+ visibilitymap_pin(relation, targetBlock, vmbuffer);
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
}
else if (otherBlock < targetBlock)
{
/* lock other buffer first */
buffer = ReadBuffer(relation, targetBlock);
+ if (PageIsAllVisible(BufferGetPage(buffer, NULL, NULL,
+ BGP_NO_SNAPSHOT_TEST)))
+ visibilitymap_pin(relation, targetBlock, vmbuffer);
LockBuffer(otherBuffer, BUFFER_LOCK_EXCLUSIVE);
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
}
{
/* lock target buffer first */
buffer = ReadBuffer(relation, targetBlock);
+ if (PageIsAllVisible(BufferGetPage(buffer, NULL, NULL,
+ BGP_NO_SNAPSHOT_TEST)))
+ visibilitymap_pin(relation, targetBlock, vmbuffer);
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
LockBuffer(otherBuffer, BUFFER_LOCK_EXCLUSIVE);
}
+ /*
+ * We now have the target page (and the other buffer, if any) pinned
+ * and locked. However, since our initial PageIsAllVisible checks
+ * were performed before acquiring the lock, the results might now be
+ * out of date, either for the selected victim buffer, or for the
+ * other buffer passed by the caller. In that case, we'll need to
+ * give up our locks, go get the pin(s) we failed to get earlier, and
+ * re-lock. That's pretty painful, but hopefully shouldn't happen
+ * often.
+ *
+ * Note that there's a small possibility that we didn't pin the page
+ * above but still have the correct page pinned anyway, either because
+ * we've already made a previous pass through this loop, or because
+ * caller passed us the right page anyway.
+ *
+ * Note also that it's possible that by the time we get the pin and
+ * retake the buffer locks, the visibility map bit will have been
+ * cleared by some other backend anyway. In that case, we'll have
+ * done a bit of extra work for no gain, but there's no real harm
+ * done.
+ */
+ if (otherBuffer == InvalidBuffer || buffer <= otherBuffer)
+ GetVisibilityMapPins(relation, buffer, otherBuffer,
+ targetBlock, otherBlock, vmbuffer,
+ vmbuffer_other);
+ else
+ GetVisibilityMapPins(relation, otherBuffer, buffer,
+ otherBlock, targetBlock, vmbuffer_other,
+ vmbuffer);
+
/*
* Now we can check to see if there's enough free space here. If so,
* we're done.
*/
- page = BufferGetPage(buffer);
+ page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
pageFreeSpace = PageGetHeapFreeSpace(page);
if (len + saveFreeSpace <= pageFreeSpace)
{
/*
* Not enough space, so we must give up our page locks and pin (if
- * any) and prepare to look elsewhere. We don't care which order we
+ * any) and prepare to look elsewhere. We don't care which order we
* unlock the two buffers in, so this can be slightly simpler than the
* code above.
*/
*/
needLock = !RELATION_IS_LOCAL(relation);
+ /*
+ * If we need the lock but are not able to acquire it immediately, we'll
+ * consider extending the relation by multiple blocks at a time to manage
+ * contention on the relation extension lock. However, this only makes
+ * sense if we're using the FSM; otherwise, there's no point.
+ */
if (needLock)
- LockRelationForExtension(relation, ExclusiveLock);
+ {
+ if (!use_fsm)
+ LockRelationForExtension(relation, ExclusiveLock);
+ else if (!ConditionalLockRelationForExtension(relation, ExclusiveLock))
+ {
+ /* Couldn't get the lock immediately; wait for it. */
+ LockRelationForExtension(relation, ExclusiveLock);
+
+ /*
+ * Check if some other backend has extended a block for us while
+ * we were waiting on the lock.
+ */
+ targetBlock = GetPageWithFreeSpace(relation, len + saveFreeSpace);
+
+ /*
+ * If some other waiter has already extended the relation, we
+ * don't need to do so; just use the existing freespace.
+ */
+ if (targetBlock != InvalidBlockNumber)
+ {
+ UnlockRelationForExtension(relation, ExclusiveLock);
+ goto loop;
+ }
+
+ /* Time to bulk-extend. */
+ RelationAddExtraBlocks(relation, bistate);
+ }
+ }
/*
+ * In addition to whatever extension we performed above, we always add
+ * at least one block to satisfy our own request.
+ *
* XXX This does an lseek - rather expensive - but at the moment it is the
- * only way to accurately determine how many blocks are in a relation. Is
+ * only way to accurately determine how many blocks are in a relation. Is
* it worth keeping an accurate file length in shared memory someplace,
* rather than relying on the kernel to do it for us?
*/
/*
* Release the file-extension lock; it's now OK for someone else to extend
- * the relation some more. Note that we cannot release this lock before
+ * the relation some more. Note that we cannot release this lock before
* we have buffer lock on the new page, or we risk a race condition
* against vacuumlazy.c --- see comments therein.
*/
* is empty (this should never happen, but if it does we don't want to
* risk wiping out valid data).
*/
- page = BufferGetPage(buffer);
+ page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
if (!PageIsNew(page))
elog(ERROR, "page %u of relation \"%s\" should be empty but is not",
if (len > PageGetHeapFreeSpace(page))
{
/* We should not get here given the test at the top */
- elog(PANIC, "tuple is too big: size %lu", (unsigned long) len);
+ elog(PANIC, "tuple is too big: size %zu", len);
}
/*
projects / postgresql / blobdiff