pub trait Pwm: Sized {
type Error: Error;
type Key;
type Value;
type Iter<'a>: Iterator<Item = (&'a Self::Key, &'a EntryValue<Self::Value>)>
where Self: 'a;
type IntoIter: Iterator<Item = (Self::Key, EntryValue<Self::Value>)>;
type Options;
Show 15 methods
// Required methods
fn new(options: Self::Options) -> Result<Self, Self::Error>;
fn is_empty(&self) -> bool;
fn len(&self) -> usize;
fn validate_entry(
&self,
entry: &Entry<Self::Key, Self::Value>,
) -> Result<(), Self::Error>;
fn max_batch_size(&self) -> u64;
fn max_batch_entries(&self) -> u64;
fn estimate_size(&self, entry: &Entry<Self::Key, Self::Value>) -> u64;
fn get(
&self,
key: &Self::Key,
) -> Result<Option<&EntryValue<Self::Value>>, Self::Error>;
fn get_entry(
&self,
key: &Self::Key,
) -> Result<Option<(&Self::Key, &EntryValue<Self::Value>)>, Self::Error>;
fn contains_key(&self, key: &Self::Key) -> Result<bool, Self::Error>;
fn insert(
&mut self,
key: Self::Key,
value: EntryValue<Self::Value>,
) -> Result<(), Self::Error>;
fn remove_entry(
&mut self,
key: &Self::Key,
) -> Result<Option<(Self::Key, EntryValue<Self::Value>)>, Self::Error>;
fn iter(&self) -> Self::Iter<'_>;
fn into_iter(self) -> Self::IntoIter;
fn rollback(&mut self) -> Result<(), Self::Error>;
}Expand description
A pending writes manager that can be used to store pending writes in a transaction.
By default, there are two implementations of this trait:
- [
IndexMap]: A hash map with consistent ordering and fast lookups. - [
BTreeMap]: A balanced binary tree with ordered keys and fast lookups.
But, users can create their own implementations by implementing this trait. e.g. if you want to implement a recovery transaction manager, you can use a persistent storage to store the pending writes.
Required Associated Types§
Required Methods§
Sourcefn new(options: Self::Options) -> Result<Self, Self::Error>
fn new(options: Self::Options) -> Result<Self, Self::Error>
Create a new pending manager with the given options.
Sourcefn validate_entry(
&self,
entry: &Entry<Self::Key, Self::Value>,
) -> Result<(), Self::Error>
fn validate_entry( &self, entry: &Entry<Self::Key, Self::Value>, ) -> Result<(), Self::Error>
Validate if the entry is valid for this database.
e.g.
- If the entry is expired
- If the key or the value is too large
- If the key or the value is empty
- If the key or the value contains invalid characters
- and etc.
Sourcefn max_batch_size(&self) -> u64
fn max_batch_size(&self) -> u64
Returns the maximum batch size in bytes
Sourcefn max_batch_entries(&self) -> u64
fn max_batch_entries(&self) -> u64
Returns the maximum entries in batch
Sourcefn estimate_size(&self, entry: &Entry<Self::Key, Self::Value>) -> u64
fn estimate_size(&self, entry: &Entry<Self::Key, Self::Value>) -> u64
Returns the estimated size of the entry in bytes when persisted in the database.
Sourcefn get(
&self,
key: &Self::Key,
) -> Result<Option<&EntryValue<Self::Value>>, Self::Error>
fn get( &self, key: &Self::Key, ) -> Result<Option<&EntryValue<Self::Value>>, Self::Error>
Returns a reference to the value corresponding to the key.
Sourcefn get_entry(
&self,
key: &Self::Key,
) -> Result<Option<(&Self::Key, &EntryValue<Self::Value>)>, Self::Error>
fn get_entry( &self, key: &Self::Key, ) -> Result<Option<(&Self::Key, &EntryValue<Self::Value>)>, Self::Error>
Returns a reference to the key-value pair corresponding to the key.
Sourcefn contains_key(&self, key: &Self::Key) -> Result<bool, Self::Error>
fn contains_key(&self, key: &Self::Key) -> Result<bool, Self::Error>
Returns true if the pending manager contains the key.
Sourcefn insert(
&mut self,
key: Self::Key,
value: EntryValue<Self::Value>,
) -> Result<(), Self::Error>
fn insert( &mut self, key: Self::Key, value: EntryValue<Self::Value>, ) -> Result<(), Self::Error>
Inserts a key-value pair into the er.
Sourcefn remove_entry(
&mut self,
key: &Self::Key,
) -> Result<Option<(Self::Key, EntryValue<Self::Value>)>, Self::Error>
fn remove_entry( &mut self, key: &Self::Key, ) -> Result<Option<(Self::Key, EntryValue<Self::Value>)>, Self::Error>
Removes a key from the pending writes, returning the key-value pair if the key was previously in the pending writes.
Dyn Compatibility§
This trait is not dyn compatible.
In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.