# Wide (Partitioned) Read Write Lock
[](https://crates.io/crates/widerwlock)
[](https://docs.rs/widerwlock)
This crate implements an enterprise-grade read-write lock, typically used for large data structures.
The lock is internally 8x partitioned, which allows it to scale much better with a large number of readers,
as compared to `std::sync::RwLock`.
Even though this is a large lock, it has better performance characteristic for uncontended single reader
or single writer lock than `std::sync::RwLock`.
The lock uses a contiguous 576 byte heap area to store its state, so it's not a light-weight lock.
If you have a complex data structure that holds a GB of data, this would be an appropriate lock.
An interesting feature of this lock, beside its performance, is its Read->Write upgrade mechanics. The `ReadGuard` allows an
upgrade to a write-lock and informs the user whether the upgrade succeeded atomically or not. This enables
the following pattern:
- Read to see if the data structure is in a particular state (e.g. contains a value).
- if not, upgrade to a write lock
- if upgrade was not atomic, perform the (potentially expensive) read again
- write to the structure if needed
- [Documentation](https://docs.rs/widerwlock)
## Usage
Add this to your `Cargo.toml`:
```toml
[dependencies]
widerwlock = "0.5"
```
and this to your crate root:
```rust
extern crate widerwlock;
```
## Rust Version Support
The minimum supported Rust version is 1.28 due to use of allocator api.