Calculate number of stable crates on crates.io

num-stable-crates.rs

use std::cmp::Reverse;
use std::collections::HashMap;
use std::fs::File;
use std::io::BufRead;
use std::io::BufReader;
use walkdir::WalkDir;

fn get_version(entry: walkdir::Result<walkdir::DirEntry>) -> Option<String> {
    let entry = entry.ok()?;
    let path = entry.path();
    if !path.is_file() {
        return None;
    }

    let file = BufReader::new(File::open(path).ok()?);
    file.lines().last().map(|line| {
        let line = line.ok()?;
        let json: serde_json::Value = serde_json::from_str(&line).ok()?;
        let version = json.as_object()?.get("vers")?.as_str()?;
        Some(version.into())
    })?
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let index_dir = std::env::args()
        .skip(1)
        .next()
        .expect("USAGE: crates-stats <crates.io-index>");

    let mut versions = HashMap::new();
    let mut num_crates = 0;
    for version in WalkDir::new(index_dir).into_iter().filter_map(get_version) {
        let counter = versions.entry(version).or_insert(0);
        *counter += 1;
        num_crates += 1;
    }

    println!("Num crates: {}", num_crates);

    let num_stable_crates: usize = versions
        .iter()
        .map(|(v, &c)| if !v.starts_with('0') { c } else { 0 })
        .sum();
    println!("Num stable crates: {}", num_stable_crates);

    let mut versions: Vec<(usize, String)> = versions.into_iter().map(|(c, v)| (v, c)).collect();
    versions.sort_by_key(|k| Reverse(k.0));

    for (count, version) in &versions {
        println!("{:>width$} {}", count, version, width = 5);
    }

    Ok(())
}