pub const WRITER_LOCK_OFFSET: u64 = 96;Expand description
Byte offset of the WRITER_LOCK (1 byte, exclusive) inside the
<db>.obj-lock sidecar file.
The lock anchor lives at the same offset on every platform
because the sidecar file is never read or written by the pager
— its only purpose is to carry kernel-side lock metadata. On
POSIX this byte exists inside a 128-byte sidecar (see
Db::open’s set_len(128) on the sidecar). OFD locks are
advisory and would tolerate locks past EOF, but giving the byte
a physical existence is the conservative choice across kernels.
On Windows LockFileEx produces mandatory byte-range
locks — the sidecar guarantees pager I/O cannot overlap the
locked region regardless of how large the main DB grows
(issue #1; the previous past-EOF strategy broke at >1 GiB).