Page headers shared by all Zero pages. More...
#include <generic_page.h>
Public Member Functions | |
| uint32_t | calculate_checksum () const |
| Calculate the correct value of checksum for this page. More... | |
Public Attributes | |
| uint32_t | checksum |
| Stored checksum of this page. More... | |
| PageID | pid |
| ID of this page. More... | |
| lsn_t | lsn |
| LSN (Log Sequence Number) of the last write to this page. More... | |
| StoreID | store |
| ID of the store to which this page belongs (0 if none) More... | |
| uint16_t | tag |
| Page type (a page_tag_t) More... | |
Static Public Attributes | |
| static const size_t | page_sz = SM_PAGESIZE |
| Size of all Zero pages. More... | |
Protected Attributes | |
| uint16_t | page_flags |
| Page flags (an OR of page_flag_t's) More... | |
| uint64_t | reserved |
| Reserved for subclass usage. More... | |
Friends | |
| class | fixable_page_h |
| std::ostream & | operator<< (std::ostream &, generic_page_header &) |
Detailed Description
Page headers shared by all Zero pages.
All page data types (e.g., generic_page, alloc_page, btree_page, stnode_page) inherit (indirectly) from this class. This is a POD.
The checksum field is placed first to make the region of data
it covers continuous. The order of the other fields has been arranged to maximize packing into the fewest number of words possible.
Because this class contains an 8-byte aligned object (lsn_t),
it must be a multiple of eight bytes. The extra space not needed for all pages (field reserved) is reserved for subclass usage.
Some page types (alloc_page, stnode_page) do not currently
(9/2013) use the lsn, reserved, or page_flags fields.
Member Function Documentation
§ calculate_checksum()
| uint32_t generic_page_header::calculate_checksum | ( | ) | const |
Calculate the correct value of checksum for this page.
Friends And Related Function Documentation
§ fixable_page_h
|
friend |
§ operator<<
|
friend |
Member Data Documentation
§ checksum
|
mutable |
Stored checksum of this page.
Checksum is calculated from various parts of this page and updated just before this page is written out to permanent storage. It is checked each time this page is read in from the permanent storage.
§ lsn
| lsn_t generic_page_header::lsn |
LSN (Log Sequence Number) of the last write to this page.
§ page_flags
|
protected |
Page flags (an OR of page_flag_t's)
§ page_sz
|
static |
Size of all Zero pages.
§ pid
| PageID generic_page_header::pid |
ID of this page.
§ reserved
|
protected |
Reserved for subclass usage.
§ store
| StoreID generic_page_header::store |
ID of the store to which this page belongs (0 if none)
§ tag
| uint16_t generic_page_header::tag |
Page type (a page_tag_t)
The documentation for this class was generated from the following files:
- src/sm/generic_page.h
- src/sm/generic_page.cpp
