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# 1brc

## Intro

As I was going through my usual morning routine reading [hackernews](https://news.ycombinator.com/).  
I stumbled upon this announcement [1brc](https://www.morling.dev/blog/one-billion-row-challenge/) and thought it to be a cool idea to do it. I chose to use [rustlang](https://www.rust-lang.org) as its something I am want to be proficient in.

## The challenge

The challenge is to create a java program that retrieves temperature values from a text file. Then calculates the min, mean, and max temperature per weather station. The core of the challenge is to come up with the fastest program to process a file with 1 billion rows. The 1 billion file is approximately 12 GB in size.

## My Approach

Read the file using a buffered reader. And as I read, aggregate the min, mean and max and store in a Hashmap keyed by city name.  
Then sort the HashMap and print the results.

Sample code.

```
let file = File::open(filename)?;
// uses a reader buffer
let mut reader = BufReader::new(file);
let mut line = String::new();
loop {
    match reader.read_line(&mut line) {
        Ok(bytes_read) => {
            if bytes_read == 0 {
                info!("EOF Reached");
                break;
            }

            load_cities(&line, cities);

            line.clear();
        }
        Err(err) => {
            error!("err");
            return Err(err);
        }
    };
}
    ....
let city: Vec<&str> = line.trim().split(';').collect();
let city_name: String = city[0].to_string();
let t: f32 = city[1].parse::<f32>().unwrap();
cities
    .entry(city_name)
    .and_modify(|temps| {
        let (_mi, avg, _ma, total, count) = temps;
        let t1 = t;
        let t2 = t;
        *_mi = cmp::min_by(t1, *_mi, |a, b| a.total_cmp(b));
        *_ma = cmp::max_by(t2, *_ma, |a, b| a.total_cmp(b));
        *total += t;
        *count += 1.0;
        *avg = *total / *count;
    })
    .or_insert((t, t, t, t, 1.0));

```

I later figured out that I can remove the sort step by using [BTreeMap](https://doc.rust-lang.org/std/collections/struct.BTreeMap.html), which is a sorted hashmap.

## Conclusion

My code isn't optimized and tested to complete the challenge but you can access it from [github](https://github.com/denniswambua/rusty_1brc). 
Completed rust implementation from other developers can be checked from [here](https://github.com/gunnarmorling/1brc/discussions)  
The general optimal route is to:

1.  Use MMAP. Maps the file directly into memory. Avoid reading speed penalties.
2.  SIMD (Single Instruction Multiple Data) Parallel processing technique.  
3.  Multi-process the file, collect and merge the results.

## Todo
1. Next step is to benchmark the current implementation with the full dataset.
2. Implement the above optimizations.
3. Compare the results.


The One Billion Challenge


I will answer this after laying out some information on forex trading.
For my background with forex. I first studied forex trading on [https://www.babypips.com/](https://www.babypips.com/) website. 
Traded on demo accounts and then moved to trading on a live account.
I was trading under a mentorship of a profitable forex trader and I managed to be a breakeven trader.
I am not trading at the moment because of my day job and for forex you need a lot of chart time to be better.

1. Forex trading is a zero sum game. For evey money you gain someone has to lose.
2. Above 80% lose their account by the first 3 months. Market makers and brokers targets to take all your money by 3 months.
3. Market makers use know human weakness like _fomo_ to manipulate you on taking trades. Fomo means fear of missing out
4. Most Forex broker take the other side of the trades, knowing that most traders will lose money.
5. Market makers can access all the positions of retail traders and they take advantage of that.
6. Mastering your own psychology and the use of proper risk management can make you profitable.
7. No one can predict the future so trade with money you can afford to loose.
8. It takes more than 3 years of break even trading to be come profitable.
9. People who make money forex trading don't shout about it. Be cautious of those you see who market their rich lifestyle. Most of them are sponsored by the brokerage firm to get more retail traders into forex trading.
10. Market maker moves the market and not the retail trader as they want you to believe.

If you don't use proper money management then you are gambling.
If you are using high leverage on your account you are gambling.
If you are not taking human psychology into account as you trade then you are gambling.


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