Beispiel #1
0
/*
 * __ckpt_process --
 *	Process the list of checkpoints.
 */
static int
__ckpt_process(WT_SESSION_IMPL *session, WT_BLOCK *block, WT_CKPT *ckptbase)
{
	WT_BLOCK_CKPT *a, *b, *ci;
	WT_CKPT *ckpt, *next_ckpt;
	WT_DECL_ITEM(tmp);
	WT_DECL_RET;
	uint64_t ckpt_size;
	bool deleting, locked;

	ci = &block->live;
	locked = false;

#ifdef HAVE_DIAGNOSTIC
	WT_RET(__ckpt_verify(session, ckptbase));
#endif

	/*
	 * Checkpoints are a two-step process: first, write a new checkpoint to
	 * disk (including all the new extent lists for modified checkpoints
	 * and the live system).  As part of this, create a list of file blocks
	 * newly available for reallocation, based on checkpoints being deleted.
	 * We then return the locations of the new checkpoint information to our
	 * caller.  Our caller has to write that information into some kind of
	 * stable storage, and once that's done, we can actually allocate from
	 * that list of newly available file blocks.  (We can't allocate from
	 * that list immediately because the allocation might happen before our
	 * caller saves the new checkpoint information, and if we crashed before
	 * the new checkpoint location was saved, we'd have overwritten blocks
	 * still referenced by checkpoints in the system.)  In summary, there is
	 * a second step: after our caller saves the checkpoint information, we
	 * are called to add the newly available blocks into the live system's
	 * available list.
	 *
	 * This function is the first step, the second step is in the resolve
	 * function.
	 *
	 * If we're called to checkpoint the same file twice, without the second
	 * resolution step, it's an error at an upper level and our choices are
	 * all bad: either leak blocks or risk crashing with our caller not
	 * having saved the checkpoint information to stable storage.  Leaked
	 * blocks are a safer choice, but that means file verify will fail for
	 * the rest of "forever", and the chance of us allocating a block and
	 * then crashing such that it matters is reasonably low: don't leak the
	 * blocks.
	 */
	if (block->ckpt_inprogress) {
		__wt_errx(session,
		    "%s: checkpointed without first resolving the previous "
		    "checkpoint",
		    block->name);

		WT_RET(__wt_block_checkpoint_resolve(session, block));
	}

	/*
	 * Extents newly available as a result of deleting previous checkpoints
	 * are added to a list of extents.  The list should be empty, but as
	 * described above, there is no "free the checkpoint information" call
	 * into the block manager; if there was an error in an upper level that
	 * resulted in some previous checkpoint never being resolved, the list
	 * may not be empty.  We should have caught that with the "checkpoint
	 * in progress" test, but it doesn't cost us anything to be cautious.
	 *
	 * We free the checkpoint's allocation and discard extent lists as part
	 * of the resolution step, not because they're needed at that time, but
	 * because it's potentially a lot of work, and waiting allows the btree
	 * layer to continue eviction sooner.  As for the checkpoint-available
	 * list, make sure they get cleaned out.
	 */
	__wt_block_extlist_free(session, &ci->ckpt_avail);
	WT_RET(__wt_block_extlist_init(
	    session, &ci->ckpt_avail, "live", "ckpt_avail", true));
	__wt_block_extlist_free(session, &ci->ckpt_alloc);
	__wt_block_extlist_free(session, &ci->ckpt_discard);

	/*
	 * To delete a checkpoint, we'll need checkpoint information for it and
	 * the subsequent checkpoint into which it gets rolled; read them from
	 * disk before we lock things down.
	 */
	deleting = false;
	WT_CKPT_FOREACH(ckptbase, ckpt) {
		if (F_ISSET(ckpt, WT_CKPT_FAKE) ||
		    !F_ISSET(ckpt, WT_CKPT_DELETE))
			continue;
		deleting = true;

		/*
		 * Read the checkpoint and next checkpoint extent lists if we
		 * haven't already read them (we may have already read these
		 * extent blocks if there is more than one deleted checkpoint).
		 */
		if (ckpt->bpriv == NULL)
			WT_ERR(__ckpt_extlist_read(session, block, ckpt));

		for (next_ckpt = ckpt + 1;; ++next_ckpt)
			if (!F_ISSET(next_ckpt, WT_CKPT_FAKE))
				break;

		/*
		 * The "next" checkpoint may be the live tree which has no
		 * extent blocks to read.
		 */
		if (next_ckpt->bpriv == NULL &&
		    !F_ISSET(next_ckpt, WT_CKPT_ADD))
			WT_ERR(__ckpt_extlist_read(session, block, next_ckpt));
	}

	/*
	 * Hold a lock so the live extent lists and the file size can't change
	 * underneath us.  I suspect we'll tighten this if checkpoints take too
	 * much time away from real work: we read the historic checkpoint
	 * information without a lock, but we could also merge and re-write the
	 * deleted and merged checkpoint information without a lock, except for
	 * the final merge of ranges into the live tree.
	 */
	__wt_spin_lock(session, &block->live_lock);
	locked = true;

	/*
	 * We've allocated our last page, update the checkpoint size.  We need
	 * to calculate the live system's checkpoint size before merging
	 * checkpoint allocation and discard information from the checkpoints
	 * we're deleting, those operations change the underlying byte counts.
	 */
	ckpt_size = ci->ckpt_size;
	ckpt_size += ci->alloc.bytes;
	ckpt_size -= ci->discard.bytes;

	/* Skip the additional processing if we aren't deleting checkpoints. */
	if (!deleting)
		goto live_update;

	/*
	 * Delete any no-longer-needed checkpoints: we do this first as it frees
	 * blocks to the live lists, and the freed blocks will then be included
	 * when writing the live extent lists.
	 */
	WT_CKPT_FOREACH(ckptbase, ckpt) {
		if (F_ISSET(ckpt, WT_CKPT_FAKE) ||
		    !F_ISSET(ckpt, WT_CKPT_DELETE))
			continue;

		if (WT_VERBOSE_ISSET(session, WT_VERB_CHECKPOINT)) {
			if (tmp == NULL)
				WT_ERR(__wt_scr_alloc(session, 0, &tmp));
			WT_ERR(__ckpt_string(
			    session, block, ckpt->raw.data, tmp));
			WT_ERR(__wt_verbose(session, WT_VERB_CHECKPOINT,
			    "%s: delete-checkpoint: %s: %s",
			    block->name, ckpt->name, (const char *)tmp->data));
		}

		/*
		 * Find the checkpoint into which we'll roll this checkpoint's
		 * blocks: it's the next real checkpoint in the list, and it
		 * better have been read in (if it's not the add slot).
		 */
		for (next_ckpt = ckpt + 1;; ++next_ckpt)
			if (!F_ISSET(next_ckpt, WT_CKPT_FAKE))
				break;

		/*
		 * Set the from/to checkpoint structures, where the "to" value
		 * may be the live tree.
		 */
		a = ckpt->bpriv;
		if (F_ISSET(next_ckpt, WT_CKPT_ADD))
			b = &block->live;
		else
			b = next_ckpt->bpriv;

		/*
		 * Free the root page: there's nothing special about this free,
		 * the root page is allocated using normal rules, that is, it
		 * may have been taken from the avail list, and was entered on
		 * the live system's alloc list at that time.  We free it into
		 * the checkpoint's discard list, however, not the live system's
		 * list because it appears on the checkpoint's alloc list and so
		 * must be paired in the checkpoint.
		 */
		if (a->root_offset != WT_BLOCK_INVALID_OFFSET)
			WT_ERR(__wt_block_insert_ext(session, block,
			    &a->discard, a->root_offset, a->root_size));

		/*
		 * Free the blocks used to hold the "from" checkpoint's extent
		 * lists, including the avail list.
		 */
		WT_ERR(__ckpt_extlist_fblocks(session, block, &a->alloc));
		WT_ERR(__ckpt_extlist_fblocks(session, block, &a->avail));
		WT_ERR(__ckpt_extlist_fblocks(session, block, &a->discard));

		/*
		 * Roll the "from" alloc and discard extent lists into the "to"
		 * checkpoint's lists.
		 */
		if (a->alloc.entries != 0)
			WT_ERR(__wt_block_extlist_merge(
			    session, block, &a->alloc, &b->alloc));
		if (a->discard.entries != 0)
			WT_ERR(__wt_block_extlist_merge(
			    session, block, &a->discard, &b->discard));

		/*
		 * If the "to" checkpoint is also being deleted, we're done with
		 * it, it's merged into some other checkpoint in the next loop.
		 * This means the extent lists may aggregate over a number of
		 * checkpoints, but that's OK, they're disjoint sets of ranges.
		 */
		if (F_ISSET(next_ckpt, WT_CKPT_DELETE))
			continue;

		/*
		 * Find blocks for re-use: wherever the "to" checkpoint's
		 * allocate and discard lists overlap, move the range to
		 * the live system's checkpoint available list.
		 */
		WT_ERR(__wt_block_extlist_overlap(session, block, b));

		/*
		 * If we're updating the live system's information, we're done.
		 */
		if (F_ISSET(next_ckpt, WT_CKPT_ADD))
			continue;

		/*
		 * We have to write the "to" checkpoint's extent lists out in
		 * new blocks, and update its cookie.
		 *
		 * Free the blocks used to hold the "to" checkpoint's extent
		 * lists; don't include the avail list, it's not changing.
		 */
		WT_ERR(__ckpt_extlist_fblocks(session, block, &b->alloc));
		WT_ERR(__ckpt_extlist_fblocks(session, block, &b->discard));

		F_SET(next_ckpt, WT_CKPT_UPDATE);
	}

	/* Update checkpoints marked for update. */
	WT_CKPT_FOREACH(ckptbase, ckpt)
		if (F_ISSET(ckpt, WT_CKPT_UPDATE))
			WT_ERR(__ckpt_update(
			    session, block, ckpt, ckpt->bpriv, false));

live_update:
	/* Truncate the file if that's possible. */
	WT_ERR(__wt_block_extlist_truncate(session, block, &ci->avail));

	/* Update the final, added checkpoint based on the live system. */
	WT_CKPT_FOREACH(ckptbase, ckpt)
		if (F_ISSET(ckpt, WT_CKPT_ADD)) {
			/*
			 * Set the checkpoint size for the live system.
			 *
			 * !!!
			 * Our caller wants the final checkpoint size.  Setting
			 * the size here violates layering, but the alternative
			 * is a call for the btree layer to crack the checkpoint
			 * cookie into its components, and that's a fair amount
			 * of work.
			 */
			ckpt->ckpt_size = ci->ckpt_size = ckpt_size;

			WT_ERR(__ckpt_update(session, block, ckpt, ci, true));
		}

	/*
	 * Reset the live system's alloc and discard extent lists, leave the
	 * avail list alone.  This includes freeing a lot of extents, so do it
	 * outside of the system's lock by copying and resetting the original,
	 * then doing the work later.
	 */
	ci->ckpt_alloc = ci->alloc;
	WT_ERR(__wt_block_extlist_init(
	    session, &ci->alloc, "live", "alloc", false));
	ci->ckpt_discard = ci->discard;
	WT_ERR(__wt_block_extlist_init(
	    session, &ci->discard, "live", "discard", false));

#ifdef HAVE_DIAGNOSTIC
	/*
	 * The first checkpoint in the system should always have an empty
	 * discard list.  If we've read that checkpoint and/or created it,
	 * check.
	 */
	WT_CKPT_FOREACH(ckptbase, ckpt)
		if (!F_ISSET(ckpt, WT_CKPT_DELETE))
			break;
	if ((a = ckpt->bpriv) == NULL)
		a = &block->live;
	if (a->discard.entries != 0) {
		__wt_errx(session,
		    "first checkpoint incorrectly has blocks on the discard "
		    "list");
		WT_ERR(WT_ERROR);
	}
#endif

	block->ckpt_inprogress = 1;

err:	if (locked)
		__wt_spin_unlock(session, &block->live_lock);

	/* Discard any checkpoint information we loaded. */
	WT_CKPT_FOREACH(ckptbase, ckpt)
		if ((ci = ckpt->bpriv) != NULL)
			__wt_block_ckpt_destroy(session, ci);

	__wt_scr_free(session, &tmp);
	return (ret);
}
Beispiel #2
0
/*
 * __ckpt_process --
 *	Process the list of checkpoints.
 */
static int
__ckpt_process(
    WT_SESSION_IMPL *session, WT_BLOCK *block, WT_CKPT *ckptbase)
{
	WT_BLOCK_CKPT *a, *b, *ci;
	WT_CKPT *ckpt, *next_ckpt;
	WT_DECL_ITEM(tmp);
	WT_DECL_RET;
	uint64_t ckpt_size;
	int deleting, locked;

	ci = &block->live;
	locked = 0;

	/*
	 * We've allocated our last page, update the checkpoint size.  We need
	 * to calculate the live system's checkpoint size before reading and
	 * merging checkpoint allocation and discard information from the
	 * checkpoints we're deleting, those operations change the underlying
	 * byte counts.
	 */
	ckpt_size = ci->ckpt_size;
	ckpt_size += ci->alloc.bytes;
	ckpt_size -= ci->discard.bytes;

	/*
	 * Extents newly available as a result of deleting previous checkpoints
	 * are added to a list of extents.  The list should be empty, but there
	 * is no explicit "free the checkpoint information" call into the block
	 * manager; if there was an error in an upper level resulting in some
	 * previous checkpoint never being resolved, the list may not be empty.
	 *
	 * XXX
	 * This isn't sufficient, actually: we're going to leak all the blocks
	 * written as part of the last checkpoint because it was never resolved.
	 */
	__wt_block_extlist_free(session, &ci->ckpt_avail);
	WT_RET(__wt_block_extlist_init(
	    session, &ci->ckpt_avail, "live", "ckpt_avail"));

	/*
	 * To delete a checkpoint, we'll need checkpoint information for it and
	 * the subsequent checkpoint into which it gets rolled; read them from
	 * disk before we lock things down.
	 */
	deleting = 0;
	WT_CKPT_FOREACH(ckptbase, ckpt) {
		if (F_ISSET(ckpt, WT_CKPT_FAKE) ||
		    !F_ISSET(ckpt, WT_CKPT_DELETE))
			continue;
		deleting = 1;

		/*
		 * Read the checkpoint and next checkpoint extent lists if we
		 * haven't already read them (we may have already read these
		 * extent blocks if there is more than one deleted checkpoint).
		 */
		if (ckpt->bpriv == NULL)
			WT_ERR(__ckpt_extlist_read(session, block, ckpt));

		for (next_ckpt = ckpt + 1;; ++next_ckpt)
			if (!F_ISSET(next_ckpt, WT_CKPT_FAKE))
				break;

		/*
		 * The "next" checkpoint may be the live tree which has no
		 * extent blocks to read.
		 */
		if (next_ckpt->bpriv == NULL &&
		    !F_ISSET(next_ckpt, WT_CKPT_ADD))
			WT_ERR(__ckpt_extlist_read(session, block, next_ckpt));
	}

	/*
	 * Hold a lock so the live extent lists and the file size can't change
	 * underneath us.  I suspect we'll tighten this if checkpoints take too
	 * much time away from real work: we read the historic checkpoint
	 * information without a lock, but we could also merge and re-write the
	 * delete checkpoint information without a lock, except for ranges
	 * merged into the live tree.
	 */
	__wt_spin_lock(session, &block->live_lock);
	locked = 1;

	/* Skip the additional processing if we aren't deleting checkpoints. */
	if (!deleting)
		goto live_update;

	/*
	 * Delete any no-longer-needed checkpoints: we do this first as it frees
	 * blocks to the live lists, and the freed blocks will then be included
	 * when writing the live extent lists.
	 */
	WT_CKPT_FOREACH(ckptbase, ckpt) {
		if (F_ISSET(ckpt, WT_CKPT_FAKE) ||
		    !F_ISSET(ckpt, WT_CKPT_DELETE))
			continue;

		if (WT_VERBOSE_ISSET(session, ckpt)) {
			if (tmp == NULL)
				WT_ERR(__wt_scr_alloc(session, 0, &tmp));
			WT_ERR(__ckpt_string(
			    session, block, ckpt->raw.data, tmp));
			WT_VERBOSE_ERR(session, ckpt,
			    "%s: delete-checkpoint: %s: %s",
			    block->name, ckpt->name, (char *)tmp->data);
		}

		/*
		 * Find the checkpoint into which we'll roll this checkpoint's
		 * blocks: it's the next real checkpoint in the list, and it
		 * better have been read in (if it's not the add slot).
		 */
		for (next_ckpt = ckpt + 1;; ++next_ckpt)
			if (!F_ISSET(next_ckpt, WT_CKPT_FAKE))
				break;

		/*
		 * Set the from/to checkpoint structures, where the "to" value
		 * may be the live tree.
		 */
		a = ckpt->bpriv;
		if (F_ISSET(next_ckpt, WT_CKPT_ADD))
			b = &block->live;
		else
			b = next_ckpt->bpriv;

		/*
		 * Free the root page: there's nothing special about this free,
		 * the root page is allocated using normal rules, that is, it
		 * may have been taken from the avail list, and was entered on
		 * the live system's alloc list at that time.  We free it into
		 * the checkpoint's discard list, however, not the live system's
		 * list because it appears on the checkpoint's alloc list and so
		 * must be paired in the checkpoint.
		 */
		if (a->root_offset != WT_BLOCK_INVALID_OFFSET)
			WT_ERR(__wt_block_insert_ext(session,
			    &a->discard, a->root_offset, a->root_size));

		/*
		 * Free the blocks used to hold the "from" checkpoint's extent
		 * lists, including the avail list.
		 */
		WT_ERR(__ckpt_extlist_fblocks(session, block, &a->alloc));
		WT_ERR(__ckpt_extlist_fblocks(session, block, &a->avail));
		WT_ERR(__ckpt_extlist_fblocks(session, block, &a->discard));

		/*
		 * Roll the "from" alloc and discard extent lists into the "to"
		 * checkpoint's lists.
		 */
		if (a->alloc.entries != 0)
			WT_ERR(__wt_block_extlist_merge(
			    session, &a->alloc, &b->alloc));
		if (a->discard.entries != 0)
			WT_ERR(__wt_block_extlist_merge(
			    session, &a->discard, &b->discard));

		/*
		 * If the "to" checkpoint is also being deleted, we're done with
		 * it, it's merged into some other checkpoint in the next loop.
		 * This means the extent lists may aggregate over a number of
		 * checkpoints, but that's OK, they're disjoint sets of ranges.
		 */
		if (F_ISSET(next_ckpt, WT_CKPT_DELETE))
			continue;

		/*
		 * Find blocks for re-use: wherever the "to" checkpoint's
		 * allocate and discard lists overlap, move the range to
		 * the live system's checkpoint available list.
		 */
		WT_ERR(__wt_block_extlist_overlap(session, block, b));

		/*
		 * If we're updating the live system's information, we're done.
		 */
		if (F_ISSET(next_ckpt, WT_CKPT_ADD))
			continue;

		/*
		 * We have to write the "to" checkpoint's extent lists out in
		 * new blocks, and update its cookie.
		 *
		 * Free the blocks used to hold the "to" checkpoint's extent
		 * lists; don't include the avail list, it's not changing.
		 */
		WT_ERR(__ckpt_extlist_fblocks(session, block, &b->alloc));
		WT_ERR(__ckpt_extlist_fblocks(session, block, &b->discard));

		F_SET(next_ckpt, WT_CKPT_UPDATE);
	}

	/* Update checkpoints marked for update. */
	WT_CKPT_FOREACH(ckptbase, ckpt)
		if (F_ISSET(ckpt, WT_CKPT_UPDATE)) {
			WT_ASSERT(session, !F_ISSET(ckpt, WT_CKPT_ADD));
			WT_ERR(__ckpt_update(
			    session, block, ckpt, ckpt->bpriv, 0, 0));
		}

live_update:
	ci = &block->live;

	/* Truncate the file if that's possible. */
	WT_ERR(__wt_block_extlist_truncate(session, block, &ci->avail));

	/* Update the final, added checkpoint based on the live system. */
	WT_CKPT_FOREACH(ckptbase, ckpt)
		if (F_ISSET(ckpt, WT_CKPT_ADD)) {
			WT_ERR(__ckpt_update(
			    session, block, ckpt, ci, ckpt_size, 1));

			/*
			 * XXX
			 * Our caller wants the final checkpoint size.  Setting
			 * the size here violates layering, but the alternative
			 * is a call for the btree layer to crack the checkpoint
			 * cookie into its components, and that's a fair amount
			 * of work.
			 */
			ckpt->ckpt_size = ci->ckpt_size;
		}

	/*
	 * Reset the live system's alloc and discard extent lists, leave the
	 * avail list alone.
	 */
	__wt_block_extlist_free(session, &ci->alloc);
	WT_ERR(__wt_block_extlist_init(session, &ci->alloc, "live", "alloc"));
	__wt_block_extlist_free(session, &ci->discard);
	WT_ERR(
	    __wt_block_extlist_init(session, &ci->discard, "live", "discard"));

#ifdef HAVE_DIAGNOSTIC
	/*
	 * The first checkpoint in the system should always have an empty
	 * discard list.  If we've read that checkpoint and/or created it,
	 * check.
	 */
	WT_CKPT_FOREACH(ckptbase, ckpt)
		if (!F_ISSET(ckpt, WT_CKPT_DELETE))
			break;
	if ((a = ckpt->bpriv) == NULL)
		a = &block->live;
	if (a->discard.entries != 0) {
		__wt_errx(session,
		    "first checkpoint incorrectly has blocks on the discard "
		    "list");
		WT_ERR(WT_ERROR);
	}
#endif

err:	if (locked)
		__wt_spin_unlock(session, &block->live_lock);

	/* Discard any checkpoint information we loaded. */
	WT_CKPT_FOREACH(ckptbase, ckpt)
		if ((ci = ckpt->bpriv) != NULL)
			__wt_block_ckpt_destroy(session, ci);

	__wt_scr_free(&tmp);
	return (ret);
}