sizeof_val - Estimate JSON Value Size

sizeof_val is a Rust function that calculates an approximate size of a serde_json::Value in bytes. It estimates the memory consumption of various types of JSON data and their nested structures. Original code

Usage

Adding Dependencies

Add the following dependencies to your Cargo.toml file:

[dependencies]
serde = "1.0"
serde_json = "1.0"

Importing and Using the Function

To use the sizeof_val function, follow these steps:

1. Import the necessary modules:

   use serde_json::{Value, json};

2. Define the sizeof_val function:

   use serde_json::Value;
   use std::mem::size_of;
   pub fn sizeof_val(v: &serde_json::Value) -> usize {
    size_of::<serde_json::Value>()
        + match v {
            Value::Null => 0,
            Value::Bool(_) => 0,
            Value::Number(_) => 0, // incorrect if arbitrary_precision is enabled
            Value::String(s) => s.capacity(),
            Value::Array(a) => a.iter().map(sizeof_val).sum(),
            Value::Object(o) => o
                .iter()
                .map(|(k, v)| {
                    size_of::<String>() + k.capacity() + sizeof_val(v) + size_of::<usize>() * 3
                    //crude approximation, each map entry has 3 words of overhead
                })
                .sum(),
        }
   }

3. Use the function to estimate the size of a JSON value:

   fn main() {
       let val = json!({
           "name": "OpenAI",
           "founded": 2015,
           "services": ["chatbot", "API"]
       });
   
       let size = sizeof_val(&val);
       println!("Estimated size: {} bytes", size);
   }

Example

The following example demonstrates the use of the sizeof_val function:

use serde_json::{Value, json};

fn main() {
    let val = json!({
        "name": "bread",
        "amount": 2,

    });

    let size = sizeof_val(&val);
    println!("Estimated size: {} bytes", size);
}

Caveats

• The estimation might not be precise for objects using arbitrary precision numbers.
• The estimation might vary depending on the specific architecture and implementation of the serde_json crate.

Contributing

Feel free to submit pull requests or open issues for any improvements or bugs related to the sizeof_val function.

License

This project is licensed under the MIT License.