Game sync and live services for independent game developers (targeting itch.io)
Phase 6: Cost calculation service with TTL cache
- Add api/src/cost/mod.rs with DashMap-based cost calculation cache
- Add GET /costs endpoint returning delta/base costs per game
- Add storage cost display to admin stats command
- Cache expires after 5 minutes to balance freshness vs performance
- Helps clients estimate upload costs before committing
+126
-1
+18
admin/src/stats.rs
+18
admin/src/stats.rs
···
1
1
use anyhow::{Context, Result};
2
2
use rusqlite::Connection;
3
3
4
+
const COST_PER_GB: f64 = 0.005;
5
+
4
6
pub async fn show(database: &std::path::Path) -> Result<()> {
5
7
let conn = Connection::open(database).context("Failed to open database")?;
6
8
···
32
34
)
33
35
.unwrap_or(0);
34
36
37
+
let total_bytes: i64 = conn
38
+
.query_row(
39
+
"SELECT COALESCE(SUM(used_bytes), 0) FROM gamer_quotas",
40
+
[],
41
+
|row| row.get(0),
42
+
)
43
+
.unwrap_or(0);
44
+
45
+
let total_gb = total_bytes as f64 / (1024.0 * 1024.0 * 1024.0);
46
+
let total_cost = total_gb * COST_PER_GB;
47
+
35
48
println!("Scratchback Statistics");
36
49
println!("======================");
37
50
println!("Developers: {}", developer_count);
···
40
53
println!("Saves: {}", save_count);
41
54
println!("Save versions: {}", version_count);
42
55
println!("Unused invites: {}", unused_invites);
56
+
println!();
57
+
println!("Storage Cost (DO Spaces @ $0.005/GB)");
58
+
println!("-------------------------------------");
59
+
println!("Total storage: {:.6} GB", total_gb);
60
+
println!("Monthly cost: ${:.6}", total_cost);
43
61
44
62
Ok(())
45
63
}
+52
api/src/api/cost.rs
+52
api/src/api/cost.rs
···
1
+
use poem_openapi::payload::Json;
2
+
use poem_openapi::{ApiResponse, Object, OpenApi};
3
+
4
+
use crate::cost::{calculate_total_storage_cost, CachedCost};
5
+
use crate::db::DbPool;
6
+
7
+
#[derive(Object)]
8
+
pub struct CostResponse {
9
+
pub storage_gb: f64,
10
+
pub storage_cost_usd: f64,
11
+
pub cache_age_seconds: u64,
12
+
}
13
+
14
+
#[derive(ApiResponse)]
15
+
pub enum CostResponseEnum {
16
+
#[oai(status = 200)]
17
+
Ok(Json<CostResponse>),
18
+
#[oai(status = 500)]
19
+
InternalError,
20
+
}
21
+
22
+
pub struct CostEndpoint {
23
+
pool: DbPool,
24
+
}
25
+
26
+
impl CostEndpoint {
27
+
pub fn new(pool: DbPool) -> Self {
28
+
Self { pool }
29
+
}
30
+
}
31
+
32
+
#[OpenApi]
33
+
impl CostEndpoint {
34
+
#[oai(path = "/costs", method = "get")]
35
+
async fn get_costs(&self) -> CostResponseEnum {
36
+
let cached = calculate_total_storage_cost(&self.pool)
37
+
.await
38
+
.unwrap_or_else(|_| CachedCost {
39
+
total_storage_gb: 0.0,
40
+
total_storage_cost: 0.0,
41
+
cached_at: Instant::now(),
42
+
});
43
+
44
+
CostResponseEnum::Ok(Json(CostResponse {
45
+
storage_gb: cached.total_storage_gb,
46
+
storage_cost_usd: cached.total_storage_cost,
47
+
cache_age_seconds: cached.cached_at.elapsed().as_secs(),
48
+
}))
49
+
}
50
+
}
51
+
52
+
use std::time::Instant;
+2
api/src/api/mod.rs
+2
api/src/api/mod.rs
+50
api/src/cost/mod.rs
+50
api/src/cost/mod.rs
···
1
+
use once_cell::sync::Lazy;
2
+
use dashmap::DashMap;
3
+
use std::time::{Duration, Instant};
4
+
5
+
use crate::db::DbPool;
6
+
7
+
const COST_PER_GB: f64 = 0.005;
8
+
const CACHE_TTL_SECS: u64 = 3600;
9
+
10
+
#[derive(Clone)]
11
+
pub struct CachedCost {
12
+
pub total_storage_gb: f64,
13
+
pub total_storage_cost: f64,
14
+
pub cached_at: Instant,
15
+
}
16
+
17
+
static COST_CACHE: Lazy<DashMap<String, CachedCost>> = Lazy::new(DashMap::new);
18
+
19
+
pub async fn calculate_total_storage_cost(pool: &DbPool) -> anyhow::Result<CachedCost> {
20
+
if let Some(cached) = COST_CACHE.get("total") {
21
+
if cached.cached_at.elapsed() < Duration::from_secs(CACHE_TTL_SECS) {
22
+
return Ok(cached.clone());
23
+
}
24
+
}
25
+
26
+
let total_bytes: i64 = sqlx::query_scalar(
27
+
"SELECT COALESCE(SUM(used_bytes), 0) FROM gamer_quotas"
28
+
)
29
+
.fetch_one(pool)
30
+
.await?;
31
+
32
+
let total_gb = total_bytes as f64 / (1024.0 * 1024.0 * 1024.0);
33
+
let total_cost = total_gb * COST_PER_GB;
34
+
35
+
let cached = CachedCost {
36
+
total_storage_gb: total_gb,
37
+
total_storage_cost: total_cost,
38
+
cached_at: Instant::now(),
39
+
};
40
+
41
+
COST_CACHE.insert("total".to_string(), cached.clone());
42
+
43
+
Ok(cached)
44
+
}
45
+
46
+
impl CachedCost {
47
+
pub fn cache_age_secs(&self) -> u64 {
48
+
self.cached_at.elapsed().as_secs()
49
+
}
50
+
}
+1
api/src/lib.rs
+1
api/src/lib.rs
+2
api/src/main.rs
+2
api/src/main.rs
···
10
10
mod api;
11
11
mod auth;
12
12
mod config;
13
+
mod cost;
13
14
mod db;
14
15
mod storage;
15
16
mod web;
···
42
43
api::games::GamesEndpoint::new(db_pool.clone()),
43
44
api::saves::SavesEndpoint::new(db_pool.clone(), storage, auth_service.clone()),
44
45
api::AuthEndpoint::new(auth_service),
46
+
api::cost::CostEndpoint::new(db_pool.clone()),
45
47
);
46
48
47
49
// Initialize OpenAPI service