Multi-counter with embedded SurrealDB database

---

examples/surrealdb/cli-multi-counter/Cargo.toml

[package]
name = "cli-multi-counter"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
serde = { version = "1.0", features = ["derive"] }
surrealdb = { version = "2.0", features = ["kv-rocksdb"] }
tempdir = "0.3"
tokio = { version = "1.35", features = ["macros", "rt-multi-thread"] }

examples/surrealdb/cli-multi-counter/src/main.rs

use serde::{Deserialize, Serialize};
use surrealdb::engine::local::{Db, RocksDb};
use surrealdb::Surreal;

#[derive(Debug, Deserialize, Serialize)]
struct Entry {
    name: String,
    count: u32,
}

#[tokio::main]
async fn main() -> surrealdb::Result<()> {
    let args = std::env::args().collect::<Vec<String>>();

    let database_folder = match std::env::var("DATABASE_PATH") {
        Ok(val) => std::path::PathBuf::from(val),
        Err(_) => {
            let current_dir = std::env::current_dir().unwrap();
            current_dir.join("db")
        }
    };

    let db = Surreal::new::<RocksDb>(database_folder).await?;

    db.use_ns("counter_ns").use_db("counter_db").await?;

    // Maybe do this only when we create the database
    let _response = db
        .query("DEFINE INDEX counter_name ON TABLE counter COLUMNS name UNIQUE")
        .await?;

    if 2 < args.len() {
        eprintln!("Usage: {} NAME     to count NAME", args[0]);
        eprintln!("       {}          to list all the counters", args[0]);
        std::process::exit(1);
    }

    if 2 == args.len() {
        increment(&db, &args[1]).await?;
        return Ok(());
    }

    println!("Listing counters");
    println!("----------------");
    let mut entries = db
        .query("SELECT name, count FROM counter ORDER BY count DESC")
        .await?;
    let entries: Vec<Entry> = entries.take(0)?;
    for entry in entries {
        println!("{}: {}", entry.name, entry.count);
    }

    Ok(())
}

async fn increment(db: &Surreal<Db>, name: &str) -> surrealdb::Result<()> {
    let response = db
        .query("INSERT INTO counter (name, count) VALUES ($name, $count) ON DUPLICATE KEY UPDATE count += 1;")
        .bind(("name", name.to_owned()))
        .bind(("count", 1))
        .await?;

    match response.check() {
        Ok(mut entries) => {
            let entries: Vec<Entry> = entries.take(0)?;
            // fetching the first (and hopefully only) entry
            if let Some(entry) = entries.into_iter().next() {
                println!("{}", entry.count);
            }

            Ok(())
        }
        Err(err) => {
            eprintln!("Could not add entry {}", err);
            std::process::exit(2);
        }
    }
}

examples/surrealdb/cli-multi-counter/tests/tests.rs

use std::{
    os::unix::process::ExitStatusExt,
    process::{Command, ExitStatus},
};
use tempdir::TempDir;

#[test]
fn test_counter() {
    let tmp_dir = TempDir::new("counter").unwrap();
    println!("tmp_dir: {:?}", tmp_dir);

    std::env::set_var("DATABASE_PATH", tmp_dir.path());

    check("foo", "1\n");
    check("foo", "2\n");
    check("foo", "3\n");
    check("bar", "1\n");
    check("bar", "2\n");
    check("foo", "4\n");

    let result = Command::new("cargo")
        .args(["run", "-q"])
        .output()
        .expect("command failed to start");

    assert_eq!(
        std::str::from_utf8(&result.stdout).unwrap(),
        "Listing counters\n----------------\nfoo: 4\nbar: 2\n"
    );
    assert_eq!(std::str::from_utf8(&result.stderr).unwrap(), "");
    assert_eq!(result.status, ExitStatus::from_raw(0));

    drop(tmp_dir);
}

fn check(name: &str, expected_stdout: &str) {
    let result = Command::new("cargo")
        .args(["run", "-q", name])
        .output()
        .expect("command failed to start");

    assert_eq!(
        std::str::from_utf8(&result.stdout).unwrap(),
        expected_stdout
    );
    assert_eq!(std::str::from_utf8(&result.stderr).unwrap(), "");
    assert_eq!(result.status, ExitStatus::from_raw(0));
}