NotificationsYou must be signed in to change notification settings
Fork5.3k
Star19.2k

Commitd4c0f91

committed

C11 alignas instead of unions -- extended alignments

This replaces some uses of pg_attribute_aligned() with the standardalignas() for cases where extended alignment (larger than max_align_t)is required.This patch stipulates that all supported compilers must supportalignments up to PG_IO_ALIGN_SIZE, but that seems pretty likely.We can then also desupport the case where direct I/O is disabledbecause pg_attribute_aligned is not supported.Reviewed-by: Chao Li <li.evan.chao@gmail.com>Discussion:https://www.postgresql.org/message-id/flat/46f05236-d4d4-4b4e-84d4-faa500f14691%40eisentraut.org

1 parent4b203d4 commitd4c0f91Copy full SHA for d4c0f91

File tree

2 files changed

-17

lines changed

src/include
- c.h
- storage
  - fd.h

2 files changed

-17

lines changed

`‎src/include/c.h‎`

Lines changed: 4 additions & 14 deletions

Original file line number	Diff line number	Diff line change
`@@ -1132,25 +1132,15 @@ typedef struct PGAlignedBlock`
`1132`	`1132`	`* for I/O in general, but may be strictly required on some platforms when`
`1133`	`1133`	`* using direct I/O.`
`1134`	`1134`	`*/`
`1135`		`-typedefunionPGIOAlignedBlock`
	`1135`	`+typedefstructPGIOAlignedBlock`
`1136`	`1136`	`{`
`1137`		`-#ifdefpg_attribute_aligned`
`1138`		`-pg_attribute_aligned(PG_IO_ALIGN_SIZE)`
`1139`		`-#endif`
`1140`		`-chardata[BLCKSZ];`
`1141`		`-doubleforce_align_d;`
`1142`		`-int64force_align_i64;`
	`1137`	`+alignas(PG_IO_ALIGN_SIZE)chardata[BLCKSZ];`
`1143`	`1138`	`}PGIOAlignedBlock;`
`1144`	`1139`
`1145`	`1140`	`/* Same, but for an XLOG_BLCKSZ-sized buffer */`
`1146`		`-typedefunionPGAlignedXLogBlock`
	`1141`	`+typedefstructPGAlignedXLogBlock`
`1147`	`1142`	`{`
`1148`		`-#ifdefpg_attribute_aligned`
`1149`		`-pg_attribute_aligned(PG_IO_ALIGN_SIZE)`
`1150`		`-#endif`
`1151`		`-chardata[XLOG_BLCKSZ];`
`1152`		`-doubleforce_align_d;`
`1153`		`-int64force_align_i64;`
	`1143`	`+alignas(PG_IO_ALIGN_SIZE)chardata[XLOG_BLCKSZ];`
`1154`	`1144`	`}PGAlignedXLogBlock;`
`1155`	`1145`
`1156`	`1146`	`/* msb for char */`

`‎src/include/storage/fd.h‎`

Lines changed: 2 additions & 3 deletions

Original file line number	Diff line number	Diff line change
`@@ -85,10 +85,9 @@ extern PGDLLIMPORT int max_safe_fds;`
`85`	`85`	`* to the appropriate Windows flag in src/port/open.c. We simulate it with`
`86`	`86`	`* fcntl(F_NOCACHE) on macOS inside fd.c's open() wrapper. We use the name`
`87`	`87`	`* PG_O_DIRECT rather than defining O_DIRECT in that case (probably not a good`
`88`		`- * idea on a Unix). We can only use it if the compiler will correctly align`
`89`		`- * PGIOAlignedBlock for us, though.`
	`88`	`+ * idea on a Unix).`
`90`	`89`	`*/`
`91`		`-#if defined(O_DIRECT)&& defined(pg_attribute_aligned)`
	`90`	`+#if defined(O_DIRECT)`
`92`	`91`	`#definePG_O_DIRECT O_DIRECT`
`93`	`92`	`#elif defined(F_NOCACHE)`
`94`	`93`	`#definePG_O_DIRECT 0x80000000`

0 commit comments

Comments

(0)

Movatterモバイル変換

Navigation Menu

Search code, repositories, users, issues, pull requests...

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Commitd4c0f91

File tree

2 files changed

2 files changed

`‎src/include/c.h‎`

`‎src/include/storage/fd.h‎`

0 commit comments