diff options
Diffstat (limited to 'src/backend/access/transam/slru.c')
| -rw-r--r-- | src/backend/access/transam/slru.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c index 5a8f654fb73..5e53593a8f2 100644 --- a/src/backend/access/transam/slru.c +++ b/src/backend/access/transam/slru.c @@ -563,6 +563,50 @@ SimpleLruWritePage(SlruCtl ctl, int slotno) SlruInternalWritePage(ctl, slotno, NULL); } +/* + * Return whether the given page exists on disk. + * + * A false return means that either the file does not exist, or that it's not + * large enough to contain the given page. + */ +bool +SimpleLruDoesPhysicalPageExist(SlruCtl ctl, int pageno) +{ + int segno = pageno / SLRU_PAGES_PER_SEGMENT; + int rpageno = pageno % SLRU_PAGES_PER_SEGMENT; + int offset = rpageno * BLCKSZ; + char path[MAXPGPATH]; + int fd; + bool result; + off_t endpos; + + SlruFileName(ctl, path, segno); + + fd = OpenTransientFile(path, O_RDWR | PG_BINARY, S_IRUSR | S_IWUSR); + if (fd < 0) + { + /* expected: file doesn't exist */ + if (errno == ENOENT) + return false; + + /* report error normally */ + slru_errcause = SLRU_OPEN_FAILED; + slru_errno = errno; + SlruReportIOError(ctl, pageno, 0); + } + + if ((endpos = lseek(fd, 0, SEEK_END)) < 0) + { + slru_errcause = SLRU_OPEN_FAILED; + slru_errno = errno; + SlruReportIOError(ctl, pageno, 0); + } + + result = endpos >= (off_t) (offset + BLCKSZ); + + CloseTransientFile(fd); + return result; +} /* * Physical read of a (previously existing) page into a buffer slot |