Struct PageId 

pub struct PageId(/* private fields */);

Identifier of a page in a database file.

PageId is NonZeroU64 so the on-disk value 0 can be used as a sentinel “no page” marker (e.g. the freelist-empty case). This follows power-of-ten Rule 5: encode the invariant in the type so neither the compiler nor a reviewer has to remember it.

Implementations

impl PageId

pub const fn new(raw: u64) -> Option<Self>

Construct a PageId from a raw u64. Returns None if raw is 0. Prefer this over the unsafe NonZeroU64::new_unchecked (Rule 8: no unsafe outside the platform layer).

pub const fn from_nonzero(nz: NonZeroU64) -> Self

Construct a PageId from a NonZeroU64. Total function.

pub const fn get(self) -> u64

Get the underlying u64. Always non-zero.

pub fn byte_offset(self, feature_flags: u32) -> u64

Byte offset at which this page begins in the database file, for a file with the given feature_flags.

#28: the offset is stride-aware. Encrypted files (encryption bit set in feature_flags) use a 4136-byte physical stride for pages 1..N, so a fixed id * PAGE_SIZE computation is wrong for them. This delegates to physical_offset_for, the same helper the pager uses for its real reads/writes (Pager::physical_offset), so the two never diverge. Page 0 is always at offset 0. Pass 0 for plaintext (unencrypted) files.

Trait Implementations

impl Clone for PageId

fn clone(&self) -> PageId

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PageId

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Hash for PageId

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for PageId

fn cmp(&self, other: &PageId) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for PageId

fn eq(&self, other: &PageId) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for PageId

fn partial_cmp(&self, other: &PageId) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for PageId

impl Eq for PageId

impl StructuralPartialEq for PageId