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PageHeader

sochdb_kernel::page

Struct PageHeader 

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pub struct PageHeader {
    pub magic: u32,
    pub page_id: PageId,
    pub page_lsn: LogSequenceNumber,
    pub page_type: PageType,
    pub flags: u8,
    pub free_space: u16,
    pub checksum: u32,
}
Expand description

Page header

Every page starts with this header for ARIES recovery support.

Layout (32 bytes):

  • magic: u32 (4 bytes) - validation magic number
  • page_id: u64 (8 bytes) - page identifier
  • page_lsn: u64 (8 bytes) - LSN of last modification (for recovery)
  • page_type: u8 (1 byte) - page type
  • flags: u8 (1 byte) - page flags
  • free_space: u16 (2 bytes) - free space in page
  • checksum: u32 (4 bytes) - page checksum
  • reserved: u32 (4 bytes) - reserved for future use

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§magic: u32

Magic number for validation

§page_id: PageId

Page identifier

§page_lsn: LogSequenceNumber

LSN of last modification

§page_type: PageType

Page type

§flags: u8

Flags

§free_space: u16

Free space in page

§checksum: u32

Checksum

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impl PageHeader

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pub fn new(page_id: PageId, page_type: PageType) -> Self

Create a new page header

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pub fn serialize(&self) -> [u8; 32]

Serialize to bytes

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pub fn deserialize(data: &[u8]) -> KernelResult<Self>

Deserialize from bytes

Trait Implementations§

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impl Clone for PageHeader

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fn clone(&self) -> PageHeader

Returns a duplicate of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for PageHeader

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

Formats the value using the given formatter. Read more
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impl Copy for PageHeader

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dest. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.