diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/include/storage/bufmgr.h | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h index b8fc87ec57f..82b43006f3e 100644 --- a/src/include/storage/bufmgr.h +++ b/src/include/storage/bufmgr.h @@ -78,20 +78,24 @@ extern PGDLLIMPORT int32 *LocalRefCount; * True iff the given buffer number is valid (either as a shared * or local buffer). * - * This is not quite the inverse of the BufferIsInvalid() macro, since this - * adds sanity rangechecks on the buffer number. - * * Note: For a long time this was defined the same as BufferIsPinned, * that is it would say False if you didn't hold a pin on the buffer. * I believe this was bogus and served only to mask logic errors. * Code should always know whether it has a buffer reference, * independently of the pin state. + * + * Note: For a further long time this was not quite the inverse of the + * BufferIsInvalid() macro, in that it also did sanity checks to verify + * that the buffer number was in range. Most likely, this macro was + * originally intended only to be used in assertions, but its use has + * since expanded quite a bit, and the overhead of making those checks + * even in non-assert-enabled builds can be significant. Thus, we've + * now demoted the range checks to assertions within the macro itself. */ #define BufferIsValid(bufnum) \ ( \ - (bufnum) != InvalidBuffer && \ - (bufnum) >= -NLocBuffer && \ - (bufnum) <= NBuffers \ + AssertMacro((bufnum) <= NBuffers && (bufnum) >= -NLocBuffer), \ + (bufnum) != InvalidBuffer \ ) /* |