eck 0.0.4

A fast, simple file & folder encryption manager, written in Rust
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use crate::context::{
    LOW_BOUNDARY, MID_INFERIOR_BOUNDARY, MID_SUPERIOR_BOUNDARY, SUPERIOR_BOUNDARY,
};
use crate::errors::EnkryptitError;
use crate::types::ParallelismType;

/// Given the **size** of a buffer or file, it infers the [`ParallelismType`] to use.
/// Its flow is :
/// - Gets an estimate of the default amount of parallelism a program should use.
/// - **Matches** the size of the buffer or file, and return the [`ParallelismType`] that corresponds.
pub fn infer_parallelism(size: u64) -> Result<ParallelismType, EnkryptitError> {
    let cpus = std::thread::available_parallelism()
        .map(|n| n.get())
        .unwrap_or(1);

    Ok(match size {
        0..LOW_BOUNDARY => ParallelismType::Single,
        LOW_BOUNDARY..MID_INFERIOR_BOUNDARY => ParallelismType::MultiThread(8.min(cpus) as u8),
        MID_INFERIOR_BOUNDARY..MID_SUPERIOR_BOUNDARY => {
            ParallelismType::MultiThread(12.min(cpus) as u8)
        }
        MID_SUPERIOR_BOUNDARY..SUPERIOR_BOUNDARY => {
            ParallelismType::MultiThread(16.min(cpus) as u8)
        }
        _ => ParallelismType::MultiThread(cpus as u8),
    })
}