C++ WT_BM::write_size方法代码示例

/*
 * __cursor_size_chk --
 *	Return if an inserted item is too large.
 */
static inline int
__cursor_size_chk(WT_SESSION_IMPL *session, WT_ITEM *kv)
{
	WT_BM *bm;
	WT_BTREE *btree;
	WT_DECL_RET;
	size_t size;

	btree = S2BT(session);
	bm = btree->bm;

	if (btree->type == BTREE_COL_FIX) {
		/* Fixed-size column-stores take a single byte. */
		if (kv->size != 1)
			WT_RET_MSG(session, EINVAL,
			    "item size of %" WT_SIZET_FMT " does not match "
			    "fixed-length file requirement of 1 byte",
			    kv->size);
		return (0);
	}

	/* Don't waste effort, 1GB is always cool. */
	if (kv->size <= WT_GIGABYTE)
		return (0);

	/*
	 * There are two checks: what we are willing to store in the tree, and
	 * what the block manager can actually write.
	 */
	if (kv->size > WT_BTREE_MAX_OBJECT_SIZE)
		ret = EINVAL;
	else {
		size = kv->size;
		ret = bm->write_size(bm, session, &size);
	}
	if (ret != 0)
		WT_RET_MSG(session, ret,
		    "item size of %" WT_SIZET_FMT " exceeds the maximum "
		    "supported size",
		    kv->size);
	return (0);
}

/*
 * __wt_bt_write --
 *	Write a buffer into a block, returning the block's addr/size and
 * checksum.
 */
int
__wt_bt_write(WT_SESSION_IMPL *session, WT_ITEM *buf,
    uint8_t *addr, size_t *addr_sizep, bool checkpoint, bool compressed)
{
	WT_BM *bm;
	WT_BTREE *btree;
	WT_ITEM *ip;
	WT_DECL_ITEM(tmp);
	WT_DECL_RET;
	WT_PAGE_HEADER *dsk;
	size_t dst_len, len, result_len, size, src_len;
	int compression_failed;		/* Extension API, so not a bool. */
	uint8_t *dst, *src;
	bool data_cksum;

	btree = S2BT(session);
	bm = btree->bm;

	/* Checkpoint calls are different than standard calls. */
	WT_ASSERT(session,
	    (!checkpoint && addr != NULL && addr_sizep != NULL) ||
	    (checkpoint && addr == NULL && addr_sizep == NULL));

#ifdef HAVE_DIAGNOSTIC
	/*
	 * We're passed a table's disk image.  Decompress if necessary and
	 * verify the image.  Always check the in-memory length for accuracy.
	 */
	dsk = buf->mem;
	if (compressed) {
		WT_ERR(__wt_scr_alloc(session, dsk->mem_size, &tmp));

		memcpy(tmp->mem, buf->data, WT_BLOCK_COMPRESS_SKIP);
		WT_ERR(btree->compressor->decompress(
		    btree->compressor, &session->iface,
		    (uint8_t *)buf->data + WT_BLOCK_COMPRESS_SKIP,
		    buf->size - WT_BLOCK_COMPRESS_SKIP,
		    (uint8_t *)tmp->data + WT_BLOCK_COMPRESS_SKIP,
		    tmp->memsize - WT_BLOCK_COMPRESS_SKIP,
		    &result_len));
		WT_ASSERT(session,
		    dsk->mem_size == result_len + WT_BLOCK_COMPRESS_SKIP);
		tmp->size = (uint32_t)result_len + WT_BLOCK_COMPRESS_SKIP;
		ip = tmp;
	} else {
		WT_ASSERT(session, dsk->mem_size == buf->size);
		ip = buf;
	}
	WT_ERR(__wt_verify_dsk(session, "[write-check]", ip));
	__wt_scr_free(session, &tmp);
#endif

	/*
	 * Optionally stream-compress the data, but don't compress blocks that
	 * are already as small as they're going to get.
	 */
	if (btree->compressor == NULL ||
	    btree->compressor->compress == NULL || compressed)
		ip = buf;
	else if (buf->size <= btree->allocsize) {
		ip = buf;
		WT_STAT_FAST_DATA_INCR(session, compress_write_too_small);
	} else {
		/* Skip the header bytes of the source data. */
		src = (uint8_t *)buf->mem + WT_BLOCK_COMPRESS_SKIP;
		src_len = buf->size - WT_BLOCK_COMPRESS_SKIP;

		/*
		 * Compute the size needed for the destination buffer.  We only
		 * allocate enough memory for a copy of the original by default,
		 * if any compressed version is bigger than the original, we
		 * won't use it.  However, some compression engines (snappy is
		 * one example), may need more memory because they don't stop
		 * just because there's no more memory into which to compress.
		 */
		if (btree->compressor->pre_size == NULL)
			len = src_len;
		else
			WT_ERR(btree->compressor->pre_size(btree->compressor,
			    &session->iface, src, src_len, &len));

		size = len + WT_BLOCK_COMPRESS_SKIP;
		WT_ERR(bm->write_size(bm, session, &size));
		WT_ERR(__wt_scr_alloc(session, size, &tmp));

		/* Skip the header bytes of the destination data. */
		dst = (uint8_t *)tmp->mem + WT_BLOCK_COMPRESS_SKIP;
		dst_len = len;

		compression_failed = 0;
		WT_ERR(btree->compressor->compress(btree->compressor,
		    &session->iface,
		    src, src_len,
		    dst, dst_len,
		    &result_len, &compression_failed));
//.........这里部分代码省略.........