my-website-v2/backend/public/src/state.rs

use fred::interfaces::KeysInterface;
use fred::{clients::Pool, prelude::*};
use sqlx::PgPool;

pub type AppState = std::sync::Arc<tokio::sync::Mutex<AppInternalState>>;

pub struct AppInternalState {
    pub database: sqlx::postgres::PgPool,
    pub cache: Cache,
}

pub struct Cache {
    pub inmem: Pool,
}

impl AppInternalState {
    pub fn new(database: PgPool, cache: Pool) -> Self {
        AppInternalState {
            database,
            cache: Cache { inmem: cache },
        }
    }
}

impl Cache {
    pub async fn get<T>(&mut self, key: String) -> Result<Option<T>, Box<dyn std::error::Error>>
    where
        T: for<'de> serde::Deserialize<'de>,
    {
        self.is_connected()?;
        let value: Option<String> = self.inmem.get(&key).await?;

        match value {
            Some(json_str) => match serde_json::from_str::<T>(&json_str) {
                Ok(deserialized) => Ok(Some(deserialized)),
                Err(_) => Ok(None),
            },
            None => Ok(None),
        }
    }

    pub async fn set<T>(
        &mut self,
        key: String,
        contents: &T,
        expiration: Option<Expiration>,
        set_opts: Option<SetOptions>,
        get: bool,
    ) -> Result<(), Box<dyn std::error::Error>>
    where
        T: for<'de> serde::Deserialize<'de> + serde::Serialize,
    {
        self.is_connected()?;
        let json_string = match serde_json::to_string::<T>(contents) {
            Ok(s) => s,
            Err(_) => {
                return Err(Box::new(std::io::Error::new(
                    std::io::ErrorKind::Other,
                    "Unable to deserialize contents passed to cache".to_string(),
                )))
            }
        };

        Ok(self
            .inmem
            .set(key, json_string, expiration, set_opts, get)
            .await?)
    }

    pub async fn del(&mut self, key: String) -> Result<(), Box<dyn std::error::Error>> {
        Ok(self.inmem.del(key).await?)
    }

    fn is_connected(&mut self) -> Result<(), Box<dyn std::error::Error>> {
        match self.inmem.is_connected() {
            true => Ok(()),
            false => Err(Box::new(std::io::Error::new(
                std::io::ErrorKind::Other,
                "Not connected to cache".to_string(),
            ))),
        }
    }
}