/*将buffer的数据写入到block对应的文件中*/
int __wt_block_write(WT_SESSION_IMPL *session, WT_BLOCK *block, WT_ITEM *buf, uint8_t *addr, size_t *addr_sizep, int data_cksum)
{
wt_off_t offset;
uint32_t size, cksum;
uint8_t *endp;
WT_RET(__wt_block_write_off(session, block, buf, &offset, &size, &cksum, data_cksum, 0));
endp = addr;
/*将block的checksum/长度对齐个数/偏移位置写入addr中*/
WT_RET(__wt_block_addr_to_buffer(block, &endp, offset, size, cksum));
*addr_sizep = WT_PTRDIFF(endp, addr);
return 0;
}
/*
* __wt_block_checkpoint --
* Create a new checkpoint.
*/
int
__wt_block_checkpoint(WT_SESSION_IMPL *session,
WT_BLOCK *block, WT_ITEM *buf, WT_CKPT *ckptbase, bool data_checksum)
{
WT_BLOCK_CKPT *ci;
WT_DECL_RET;
ci = &block->live;
/* Switch to first-fit allocation. */
__wt_block_configure_first_fit(block, true);
/*
* Write the root page: it's possible for there to be a checkpoint of
* an empty tree, in which case, we store an illegal root offset.
*
* !!!
* We happen to know that checkpoints are single-threaded above us in
* the btree engine. That's probably something we want to guarantee
* for any WiredTiger block manager.
*/
if (buf == NULL) {
ci->root_offset = WT_BLOCK_INVALID_OFFSET;
ci->root_size = ci->root_checksum = 0;
} else
WT_ERR(__wt_block_write_off(session, block, buf,
&ci->root_offset, &ci->root_size, &ci->root_checksum,
data_checksum, true, false));
/*
* Checkpoints are potentially reading/writing/merging lots of blocks,
* pre-allocate structures for this thread's use.
*/
WT_ERR(__wt_block_ext_prealloc(session, 250));
/* Process the checkpoint list, deleting and updating as required. */
ret = __ckpt_process(session, block, ckptbase);
/* Discard any excessive memory we've allocated. */
WT_TRET(__wt_block_ext_discard(session, 250));
/* Restore the original allocation plan. */
err: __wt_block_configure_first_fit(block, false);
return (ret);
}
/*
* __wt_block_write --
* Write a buffer into a block, returning the block's address cookie.
*/
int
__wt_block_write(WT_SESSION_IMPL *session, WT_BLOCK *block,
WT_ITEM *buf, uint8_t *addr, size_t *addr_sizep, bool data_cksum)
{
wt_off_t offset;
uint32_t size, cksum;
uint8_t *endp;
WT_RET(__wt_block_write_off(
session, block, buf, &offset, &size, &cksum, data_cksum, false));
endp = addr;
WT_RET(__wt_block_addr_to_buffer(block, &endp, offset, size, cksum));
*addr_sizep = WT_PTRDIFF(endp, addr);
return (0);
}
/*
* __wt_block_write --
* Write a buffer into a block, returning the block's address cookie.
*/
int
__wt_block_write(WT_SESSION_IMPL *session, WT_BLOCK *block,
WT_ITEM *buf, uint8_t *addr, uint32_t *addr_size, int data_cksum)
{
off_t offset;
uint32_t size, cksum;
uint8_t *endp;
WT_UNUSED(addr_size);
WT_RET(__wt_block_write_off(
session, block, buf, &offset, &size, &cksum, data_cksum, 0));
endp = addr;
WT_RET(__wt_block_addr_to_buffer(block, &endp, offset, size, cksum));
*addr_size = WT_PTRDIFF32(endp, addr);
return (0);
}
/*
* __wt_block_checkpoint --
* Create a new checkpoint.
*/
int
__wt_block_checkpoint(WT_SESSION_IMPL *session,
WT_BLOCK *block, WT_ITEM *buf, WT_CKPT *ckptbase)
{
WT_BLOCK_CKPT *ci;
ci = &block->live;
ci->version = WT_BM_CHECKPOINT_VERSION;
/*
* Write the root page: it's possible for there to be a checkpoint of
* an empty tree, in which case, we store an illegal root offset.
*
* XXX
* We happen to know that checkpoints are single-threaded above us in
* the btree engine. That's probably something we want to guarantee
* for any WiredTiger block manager.
*/
if (buf == NULL) {
ci->root_offset = WT_BLOCK_INVALID_OFFSET;
ci->root_size = ci->root_cksum = 0;
} else
WT_RET(__wt_block_write_off(session, block, buf,
&ci->root_offset, &ci->root_size, &ci->root_cksum, 0));
/* Process the checkpoint list, deleting and updating as required. */
WT_RET(__ckpt_process(session, block, ckptbase));
/*
* Checkpoints have to hit disk (it would be reasonable to configure for
* lazy checkpoints, but we don't support them yet). Regardless, we're
* not holding any locks, other writers can proceed while we wait.
*/
if (F_ISSET(S2C(session), WT_CONN_SYNC))
WT_RET(__wt_fsync(session, block->fh));
return (0);
}
