Struct matterdb::ReadonlyFork[−][src]

pub struct ReadonlyFork<'a>(_);

Readonly wrapper for a Fork.

This wrapper allows to read from index state from the fork in a type-safe manner (it is impossible to accidentally modify data in the index), and without encountering runtime errors when attempting to concurrently get the same index more than once.

Since the wrapper borrows the Fork immutably, it is still possible to access indexes in the fork directly. In this scenario, the caller should be careful that ReadonlyFork does not access the same indexes as the original Fork: this will result in a runtime error (sort of like attempting both an exclusive and a shared borrow from a RefCell or RwLock).

Examples

let db = TemporaryDB::new();
let fork = db.fork();
fork.get_list("list").push(1_u32);
let readonly: ReadonlyFork<'_> = fork.readonly();
let list = readonly.get_list::<_, u32>("list");
assert_eq!(list.get(0), Some(1));
let same_list = readonly.get_list::<_, u32>("list");
// ^-- Does not result in an error!

// Original fork is still accessible.
let mut map = fork.get_map("map");
map.put(&1_u32, "foo".to_string());

There are no write methods in indexes instantiated from ReadonlyFork:

ⓘ
let db = TemporaryDB::new();
let fork = db.fork();
let readonly: ReadonlyFork<'_> = fork.readonly();
let mut list = readonly.get_list("list");
list.push(1_u32); // Won't compile: no `push` method in `ListIndex<ReadonlyFork, u32>`!

Trait Implementations

impl<'a> AsReadonly for ReadonlyFork<'a>[src]

type Readonly = Self

Readonly version of the access.

fn as_readonly(&self) -> Self::Readonly[src]

Performs the conversion.

impl<'a> Clone for ReadonlyFork<'a>[src]

fn clone(&self) -> ReadonlyFork<'a>[src]

Returns a copy of the value. Read more

fn clone_from(&mut self, source: &Self)1.0.0[src]

Performs copy-assignment from source. Read more

impl<'a> Debug for ReadonlyFork<'a>[src]

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

Formats the value using the given formatter. Read more

impl<'a> From<ReadonlyFork<'a>> for GenericRawAccess<'a>[src]

fn from(ro_fork: ReadonlyFork<'a>) -> Self[src]

Performs the conversion.

impl<'a> IntoErased<'a> for ReadonlyFork<'a>[src]

fn into_erased(self) -> ErasedAccess<'a>[src]

Performs the conversion.

impl<'a> RawAccess for ReadonlyFork<'a>[src]

type Changes = ChangesRef<'a>

Type of the changes() that will be applied to the database.

fn snapshot(&self) -> &dyn Snapshot[src]

Reference to a Snapshot. This is the base relative to which the changes are defined.

fn changes(&self, address: &ResolvedAddress) -> Self::Changes[src]

Returns changes related to specific address compared to the snapshot().

impl<'a> Copy for ReadonlyFork<'a>[src]

Auto Trait Implementations

impl<'a> !RefUnwindSafe for ReadonlyFork<'a>

impl<'a> !Send for ReadonlyFork<'a>

impl<'a> !Sync for ReadonlyFork<'a>

impl<'a> Unpin for ReadonlyFork<'a>

impl<'a> !UnwindSafe for ReadonlyFork<'a>

Blanket Implementations

impl<T> Access for T where
    T: RawAccess, [src]

type Base = T

Raw access serving as the basis for created indexes.

pub fn get_index_metadata(
    Self,
    IndexAddress
) -> Result<Option<IndexMetadata<Vec<u8, Global>>>, AccessError>[src]

Gets index metadata at the specified address, or None if there is no index.

pub fn get_or_create_view(
    Self,
    IndexAddress,
    IndexType
) -> Result<ViewWithMetadata<<T as Access>::Base>, AccessError>[src]

Gets or creates a generic view with the specified address.

pub fn group_keys<K>(Self, IndexAddress) -> GroupKeys<<T as Access>::Base, K> where
    K: BinaryKey + ?Sized,
    <T as Access>::Base: AsReadonly,
    <<T as Access>::Base as AsReadonly>::Readonly == <T as Access>::Base, [src]

Returns an iterator over keys in a group with the specified address. Read more

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

pub fn type_id(&self) -> TypeId[src]

Gets the TypeId of self. Read more

impl<T> Borrow<T> for T where
    T: ?Sized, [src]

pub fn borrow(&self) -> &T[src]

Immutably borrows from an owned value. Read more

impl<T> BorrowMut<T> for T where
    T: ?Sized, [src]

pub fn borrow_mut(&mut self) -> &mut T[src]

Mutably borrows from an owned value. Read more

impl<T> From<T> for T[src]

pub fn from(t: T) -> T[src]

Performs the conversion.

impl<T, U> Into<U> for T where
    U: From<T>, [src]

pub fn into(self) -> U[src]

Performs the conversion.

impl<T> Pointable for T

pub const ALIGN: usize

The alignment of pointer.

type Init = T

The type for initializers.

pub unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more

pub unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more

pub unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more

pub unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more

impl<T> ToOwned for T where
    T: Clone, [src]

type Owned = T

The resulting type after obtaining ownership.

pub fn to_owned(&self) -> T[src]

Creates owned data from borrowed data, usually by cloning. Read more

pub fn clone_into(&self, target: &mut T)[src]

🔬 This is a nightly-only experimental API. (toowned_clone_into)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

impl<T, U> TryFrom<U> for T where
    U: Into<T>, [src]

type Error = Infallible

The type returned in the event of a conversion error.

pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>[src]

Performs the conversion.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, [src]

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

The type returned in the event of a conversion error.

pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>[src]

Performs the conversion.