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Centralize PostgreSQL page header data structures.

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These data structures were copied a few places (but only once in the core code) so put them in a place where everyone can use them.

To do this create a new file, static.auto.h, to contain data types and macros that have stayed the same through all the versions of PostgreSQL that we support.  This allows us to have single, non-versioned set of headers and code for stable data structures like page headers.

Migrate a few types from version.auto.h that are required for page header structures and pull the remaining types from PostgreSQL directly.

We had previously renamed xlog to wal so update those where required since we won't be modifying the PostgreSQL names anymore.
This commit is contained in:
David Steele
2020-03-04 13:31:27 -05:00
parent a88d709962
commit 9d48882268
7 changed files with 218 additions and 133 deletions
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42
src/postgres/pageChecksum.c
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@ -70,45 +70,9 @@ minimize register spilling. For less sophisticated compilers it might be benefic
#include "common/error.h"
#include "common/log.h"
#include "postgres/interface.h"
#include "postgres/interface/static.auto.h"
#include "postgres/pageChecksum.h"
/***********************************************************************************************************************************
For historical reasons, the 64-bit LSN value is stored as two 32-bit values.
***********************************************************************************************************************************/
typedef struct
{
uint32_t walid; // high bits
uint32_t xrecoff; // low bits
} PageWalRecPtr;
/***********************************************************************************************************************************
Space management information generic to any page. Only values required for pgBackRest are represented here.
pd_lsn - identifies wal record for last change to this page.
pd_checksum - page checksum, if set.
The LSN is used by the buffer manager to enforce the basic rule of WAL: "thou shalt write wal before data". A dirty buffer cannot
be dumped to disk until wal has been flushed at least as far as the page's LSN.
pd_checksum stores the page checksum, if it has been set for this page; zero is a valid value for a checksum. If a checksum is not
in use then we leave the field unset. This will typically mean the field is zero though non-zero values may also be present if
databases have been pg_upgraded from releases prior to 9.3, when the same byte offset was used to store the current timelineid when
the page was last updated. Note that there is no indication on a page as to whether the checksum is valid or not, a deliberate
design choice which avoids the problem of relying on the page contents to decide whether to verify it. Hence there are no flag bits
relating to checksums.
***********************************************************************************************************************************/
typedef struct PageHeaderData
{
// LSN is member of *any* block, not only page-organized ones
PageWalRecPtr pd_lsn; // Lsn for last change to this page
uint16_t pd_checksum; // checksum
uint16_t pd_flags; // flag bits, see below
uint16_t pd_lower; // offset to start of free space
uint16_t pd_upper; // offset to end of free space
} PageHeaderData;
typedef PageHeaderData *PageHeader;
/***********************************************************************************************************************************
pageChecksumBlock - block checksum algorithm
@ -214,7 +178,7 @@ pageLsn(const unsigned char *page)
FUNCTION_TEST_PARAM_P(UCHARDATA, page);
FUNCTION_TEST_END();
FUNCTION_TEST_RETURN((uint64_t)((PageHeader)page)->pd_lsn.walid << 32 | ((PageHeader)page)->pd_lsn.xrecoff);
FUNCTION_TEST_RETURN((uint64_t)((PageHeader)page)->pd_lsn.xlogid << 32 | ((PageHeader)page)->pd_lsn.xrecoff);
}
/***********************************************************************************************************************************
@ -238,7 +202,7 @@ pageChecksumTest(
// This is a new page so don't test checksum
((PageHeader)page)->pd_upper == 0 ||
// LSN is after the backup started so checksum is not tested because pages may be torn
(((PageHeader)page)->pd_lsn.walid >= ignoreWalId && ((PageHeader)page)->pd_lsn.xrecoff >= ignoreWalOffset) ||
(((PageHeader)page)->pd_lsn.xlogid >= ignoreWalId && ((PageHeader)page)->pd_lsn.xrecoff >= ignoreWalOffset) ||
// Checksum is valid if a full page
(pageSize == PG_PAGE_SIZE_DEFAULT && ((PageHeader)page)->pd_checksum == pageChecksum(page, blockNo, pageSize)));
}