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.

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:

   pub fn sizeof_val(v: &serde_json::Value) -> usize {
       std::mem::size_of::<serde_json::Value>()
           + match v {
               serde_json::Value::Null => 0,
               serde_json::Value::Bool(_) => 0,
               serde_json::Value::Number(_) => 0,
               serde_json::Value::String(s) => s.capacity(),
               serde_json::Value::Array(a) => a.iter().map(sizeof_val).sum(),
               serde_json::Value::Object(o) => o
                   .iter()
                   .map(|(k, v)| {
                       std::mem::size_of::<String>()
                           + k.capacity()
                           + sizeof_val(v)
                           + std::mem::size_of::<usize>() * 3 // crude approximation 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.