Trait txn_core::sync::Pwm

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;

    // 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 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>;
}

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

type Error: Error

The error type returned by the conflict manager.

type Key

The key type.

type Value

The value type.

type Iter<'a>: Iterator<Item = (&'a Self::Key, &'a EntryValue<Self::Value>)> where Self: 'a

The iterator type.

type IntoIter: Iterator<Item = (Self::Key, EntryValue<Self::Value>)>

The IntoIterator type.

type Options

The options type used to create the pending manager.

Required Methods

fn new(options: Self::Options) -> Result<Self, Self::Error>

Create a new pending manager with the given options.

fn is_empty(&self) -> bool

Returns true if the buffer is empty.

fn len(&self) -> usize

Returns the number of elements in the buffer.

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.

fn max_batch_size(&self) -> u64

Returns the maximum batch size in bytes

fn max_batch_entries(&self) -> u64

Returns the maximum entries in batch

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.

fn get( &self, key: &Self::Key ) -> Result<Option<&EntryValue<Self::Value>>, Self::Error>

Returns a reference to the value corresponding to the key.

fn contains_key(&self, key: &Self::Key) -> Result<bool, Self::Error>

Returns true if the pending manager contains the key.

fn insert( &mut self, key: Self::Key, value: EntryValue<Self::Value> ) -> Result<(), Self::Error>

Inserts a key-value pair into the er.

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.

fn iter(&self) -> Self::Iter<'_>

Returns an iterator over the pending writes.

fn into_iter(self) -> Self::IntoIter

Returns an iterator that consumes the pending writes.

fn rollback(&mut self) -> Result<(), Self::Error>

Rollback the pending writes.

Object Safety

This trait is not object safe.

Implementations on Foreign Types

impl<K, V> Pwm for BTreeMap<K, EntryValue<V>>

where K: Ord,

type Error = Infallible

type Key = K

type Value = V

type Iter<'a> = Iter<'a, K, EntryValue<V>> where Self: 'a

type IntoIter = IntoIter<K, EntryValue<V>>

type Options = ()

fn new(_: 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: &K) -> Result<Option<&EntryValue<Self::Value>>, Self::Error>

fn contains_key(&self, key: &K) -> Result<bool, Self::Error>

fn insert( &mut self, key: K, value: EntryValue<Self::Value> ) -> Result<(), Self::Error>

fn remove_entry( &mut self, key: &K ) -> Result<Option<(K, EntryValue<Self::Value>)>, Self::Error>

fn iter(&self) -> Self::Iter<'_>

fn into_iter(self) -> Self::IntoIter

fn rollback(&mut self) -> Result<(), Self::Error>

impl<K, V, S> Pwm for IndexMap<K, EntryValue<V>, S>

where K: Eq + Hash, S: BuildHasher + Default,

type Error = Infallible

type Key = K

type Value = V

type Iter<'a> = Iter<'a, K, EntryValue<V>> where Self: 'a

type IntoIter = IntoIter<K, EntryValue<V>>

type Options = Option<S>

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: &K) -> Result<Option<&EntryValue<V>>, Self::Error>

fn contains_key(&self, key: &K) -> Result<bool, Self::Error>

fn insert(&mut self, key: K, value: EntryValue<V>) -> Result<(), Self::Error>

fn remove_entry( &mut self, key: &K ) -> Result<Option<(K, EntryValue<V>)>, Self::Error>

fn iter(&self) -> Self::Iter<'_>

fn into_iter(self) -> Self::IntoIter

fn rollback(&mut self) -> Result<(), Self::Error>

Implementors