Struct MemoryStorage 

pub struct MemoryStorage { /* private fields */ }

Main storage engine implementing Redis-like functionality

Provides thread-safe storage with transaction support and caching. All keys are case-insensitive and stored in lowercase.

Implementations

impl MemoryStorage

pub fn new() -> Self

Creates a new empty storage instance with default cache settings

pub fn save_snapshot(&self, path: &str) -> Result<()>

Saves the current storage state to a file

Arguments

• path - Path to save the snapshot file

pub fn load_snapshot(&mut self, path: &str) -> Result<()>

Loads storage state from a snapshot file

Arguments

• path - Path to the snapshot file to load

pub fn start_transaction(&mut self)

Starts a new transaction

Creates a new transaction layer that will track changes until committed or rolled back.

pub fn commit_transaction(&mut self) -> Result<Vec<String>, String>

Commits the current transaction

Returns

• Ok(Vec<String>) - Results of operations in the transaction
• Err(String) - Error message if no transaction is active

pub fn rollback_transaction(&mut self) -> Result<(), String>

Rolls back the current transaction

Returns

• Ok(()) - Transaction successfully rolled back
• Err(String) - Error message if no transaction is active

pub fn set(&mut self, key: String, value: String)

Sets a key-value pair in the storage

If a transaction is active, the change is recorded in the current transaction layer. Otherwise, it’s applied directly to the main storage. The value is also cached.

Arguments

• key - The key (case-insensitive)
• value - The value to store

pub fn get(&mut self, key: &str) -> Option<String>

Retrieves a value by its key

Checks the cache first, then active transactions from newest to oldest, finally falling back to main storage. Found values are cached for future access.

Arguments

• key - The key to look up (case-insensitive)

Returns

• Some(String) - The value if found
• None - If the key doesn’t exist

pub fn del(&mut self, key: &str) -> bool

Deletes a key-value pair from storage

In a transaction, marks the key for deletion. Otherwise, removes it from main storage immediately. Also removes the key from cache if it existed.

Arguments

• key - The key to delete (case-insensitive)

Returns

true if the key existed and was marked for deletion or removed

pub fn incr(&mut self, key: &str) -> i64

Increments the numeric value stored at the given key

If the key doesn’t exist, it’s initialized with “0” before incrementing. Non-numeric values are treated as 0.

Arguments

• key - The key storing the numeric value (case-insensitive)

Returns

The new value after incrementing

pub fn decr(&mut self, key: &str) -> i64

Decrements the numeric value stored at the given key

If the key doesn’t exist, it’s initialized with “0” before decrementing. Non-numeric values are treated as 0.

Arguments

• key - The key storing the numeric value (case-insensitive)

Returns

The new value after decrementing

pub fn lpush(&mut self, key: &str, value: String) -> usize

Pushes a value to the front of a list

Creates the list if it doesn’t exist.

Arguments

• key - The list’s key (case-insensitive)
• value - The value to push

Returns

The new length of the list

pub fn rpush(&mut self, key: &str, value: String) -> usize

Pushes a value to the end of a list

Creates the list if it doesn’t exist.

Arguments

• key - The list’s key (case-insensitive)
• value - The value to push

Returns

The new length of the list

pub fn lpop(&mut self, key: &str) -> Option<String>

Removes and returns the first element from a list

Arguments

• key - The list’s key (case-insensitive)

Returns

• Some(String) - The removed value
• None - If the list is empty or doesn’t exist

pub fn rpop(&mut self, key: &str) -> Option<String>

Removes and returns the last element from a list

Arguments

• key - The list’s key (case-insensitive)

Returns

• Some(String) - The removed value
• None - If the list is empty or doesn’t exist

pub fn llen(&self, key: &str) -> usize

Returns the length of a list

If in a transaction, returns the length from the most recent transaction layer that has the list. Otherwise, returns the length from main storage.

Arguments

• key - The list’s key (case-insensitive)

Returns

The length of the list, or 0 if it doesn’t exist