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Convert confusing macros in multixact.c to static inline functions 

The macros were confused about the argument data types. All the
arguments were called 'xid', and some of the macros included casts to
TransactionId, even though the arguments were actually either
MultiXactIds or MultiXactOffsets. It compiles to the same thing,
because TransactionId, MultiXactId and MultiXactOffset are all
typedefs of uint32, but it was highly misleading.

Author: Maxim Orlov <orlovmg@gmail.com>
Discussion: https://www.postgresql.org/message-id/CACG%3DezbLUG-OD1osAW3OchOMxZtdxHh2itYR9Zhh-a13wEBEQw%40mail.gmail.com
Discussion: https://www.postgresql.org/message-id/ff143b24-a093-40da-9833-d36b83726bdf%40iki.fi
This commit is contained in:
Heikki Linnakangas 2024-06-16 20:47:07 +03:00
parent 92aff003d7
commit 0099b9408e
1 changed files with 60 additions and 19 deletions
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79
src/backend/access/transam/multixact.c
View File

@ -108,11 +108,23 @@
/* We need four bytes per offset */
#define MULTIXACT_OFFSETS_PER_PAGE (BLCKSZ / sizeof(MultiXactOffset))
#define MultiXactIdToOffsetPage(xid) \
((xid) / (MultiXactOffset) MULTIXACT_OFFSETS_PER_PAGE)
#define MultiXactIdToOffsetEntry(xid) \
((xid) % (MultiXactOffset) MULTIXACT_OFFSETS_PER_PAGE)
#define MultiXactIdToOffsetSegment(xid) (MultiXactIdToOffsetPage(xid) / SLRU_PAGES_PER_SEGMENT)
static inline int64
MultiXactIdToOffsetPage(MultiXactId multi)
{
return multi / MULTIXACT_OFFSETS_PER_PAGE;
}
static inline int
MultiXactIdToOffsetEntry(MultiXactId multi)
{
return multi % MULTIXACT_OFFSETS_PER_PAGE;
}
static inline int
MultiXactIdToOffsetSegment(MultiXactId multi)
{
return MultiXactIdToOffsetPage(multi) / SLRU_PAGES_PER_SEGMENT;
}
/*
* The situation for members is a bit more complex: we store one byte of
@ -156,30 +168,59 @@
((uint32) ((0xFFFFFFFF % MULTIXACT_MEMBERS_PER_PAGE) + 1))
/* page in which a member is to be found */
#define MXOffsetToMemberPage(xid) ((xid) / (TransactionId) MULTIXACT_MEMBERS_PER_PAGE)
#define MXOffsetToMemberSegment(xid) (MXOffsetToMemberPage(xid) / SLRU_PAGES_PER_SEGMENT)
static inline int64
MXOffsetToMemberPage(MultiXactOffset offset)
{
return offset / MULTIXACT_MEMBERS_PER_PAGE;
}
static inline int
MXOffsetToMemberSegment(MultiXactOffset offset)
{
return MXOffsetToMemberPage(offset) / SLRU_PAGES_PER_SEGMENT;
}
/* Location (byte offset within page) of flag word for a given member */
#define MXOffsetToFlagsOffset(xid) \
((((xid) / (TransactionId) MULTIXACT_MEMBERS_PER_MEMBERGROUP) % \
(TransactionId) MULTIXACT_MEMBERGROUPS_PER_PAGE) * \
(TransactionId) MULTIXACT_MEMBERGROUP_SIZE)
#define MXOffsetToFlagsBitShift(xid) \
(((xid) % (TransactionId) MULTIXACT_MEMBERS_PER_MEMBERGROUP) * \
MXACT_MEMBER_BITS_PER_XACT)
static inline int
MXOffsetToFlagsOffset(MultiXactOffset offset)
{
MultiXactOffset group = offset / MULTIXACT_MEMBERS_PER_MEMBERGROUP;
int grouponpg = group % MULTIXACT_MEMBERGROUPS_PER_PAGE;
int byteoff = grouponpg * MULTIXACT_MEMBERGROUP_SIZE;
return byteoff;
}
static inline int
MXOffsetToFlagsBitShift(MultiXactOffset offset)
{
int member_in_group = offset % MULTIXACT_MEMBERS_PER_MEMBERGROUP;
int bshift = member_in_group * MXACT_MEMBER_BITS_PER_XACT;
return bshift;
}
/* Location (byte offset within page) of TransactionId of given member */
#define MXOffsetToMemberOffset(xid) \
(MXOffsetToFlagsOffset(xid) + MULTIXACT_FLAGBYTES_PER_GROUP + \
((xid) % MULTIXACT_MEMBERS_PER_MEMBERGROUP) * sizeof(TransactionId))
static inline int
MXOffsetToMemberOffset(MultiXactOffset offset)
{
int member_in_group = offset % MULTIXACT_MEMBERS_PER_MEMBERGROUP;
return MXOffsetToFlagsOffset(offset) +
MULTIXACT_FLAGBYTES_PER_GROUP +
member_in_group * sizeof(TransactionId);
}
/* Multixact members wraparound thresholds. */
#define MULTIXACT_MEMBER_SAFE_THRESHOLD (MaxMultiXactOffset / 2)
#define MULTIXACT_MEMBER_DANGER_THRESHOLD \
(MaxMultiXactOffset - MaxMultiXactOffset / 4)
#define PreviousMultiXactId(xid) \
((xid) == FirstMultiXactId ? MaxMultiXactId : (xid) - 1)
static inline MultiXactId
PreviousMultiXactId(MultiXactId multi)
{
return multi == FirstMultiXactId ? MaxMultiXactId : multi - 1;
}
/*
* Links to shared-memory data structures for MultiXact control