feat: use maxminddb as mmap

Cargo.lock

@@ -1271,6 +1271,7 @@ dependencies = [
  "ipnetwork",
  "log",
  "memchr",
+ "memmap2",
  "serde",
  "thiserror 2.0.12",
 ]
@@ -1281,6 +1282,15 @@ version = "2.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
 
+[[package]]
+name = "memmap2"
+version = "0.9.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fd3f7eed9d3848f8b98834af67102b720745c4ec028fcd0aa0239277e7de374f"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "mime"
 version = "0.3.17"

Cargo.toml

@@ -16,7 +16,7 @@ env_logger = "=0.11.8"
 fancy-regex = "=0.14.0"
 futures = "=0.3.31"
 log = "=0.4.27"
-maxminddb = "=0.26.0"
+maxminddb = { version = "=0.26.0", features = ["mmap"] }
 ratatui = { version = "=0.29.0", optional = true }
 rlimit = "=0.10.2"
 serde = "=1.0.219"

src/output.rs

@@ -47,10 +47,12 @@ pub async fn save_proxies(
         let maybe_mmdb = if config.enable_geolocation {
             let geodb_path =
                 get_geodb_path().await.wrap_err("failed to get GeoDB path")?;
-            let buffer = tokio::fs::read(&geodb_path).await.wrap_err_with(
-                move || format!("failed to read {}", geodb_path.display()),
-            )?;
-            Some(maxminddb::Reader::from_source(buffer)?)
+            Some(
+                tokio::task::spawn_blocking(move || {
+                    maxminddb::Reader::open_mmap(geodb_path)
+                })
+                .await??,
+            )
         } else {
             None
         };