implement lru cache for tiles

Cargo.lock

@@ -305,6 +305,11 @@ dependencies = [
  "time 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "lru"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "mapbox_expressions_to_sql"
 version = "0.1.0"
@@ -324,6 +329,7 @@ dependencies = [
  "lazy_static 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "logger 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lru 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "mapbox_expressions_to_sql 0.1.0 (git+https://github.com/stepankuzmin/rust-mapbox-expressions-to-sql)",
  "persistent 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "postgres 0.15.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -933,6 +939,7 @@ dependencies = [
 "checksum log 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)" = "e19e8d5c34a3e0e2223db8e060f9e8264aeeb5c5fc64a4ee9965c062211c024b"
 "checksum log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)" = "89f010e843f2b1a31dbd316b3b8d443758bc634bed37aabade59c686d644e0a2"
 "checksum logger 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "6c9172cb4c2f6c52117e25570983edcbb322f130b1031ae5d5d6b1abe7eeb493"
+"checksum lru 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "f1422de50f19f1e08676a563ba667974c0fe487a5c02eea23890983997c0184a"
 "checksum mapbox_expressions_to_sql 0.1.0 (git+https://github.com/stepankuzmin/rust-mapbox-expressions-to-sql)" = "<none>"
 "checksum matches 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "100aabe6b8ff4e4a7e32c1c13523379802df0772b82466207ac25b013f193376"
 "checksum md5 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "b6d9aab58e540f50b59d5cfa7f0da4c3d437476890e1e0b6206e230dce55a23c"

Cargo.toml

@@ -18,6 +18,7 @@ iron-test = "0.6.0"
 lazy_static = "0.2.11"
 log = "0.4.1"
 logger = "0.4.0"
+lru = "0.1.7"
 mapbox_expressions_to_sql = { git = "https://github.com/stepankuzmin/rust-mapbox-expressions-to-sql" }
 persistent = "0.4.0"
 postgres = { version = "0.15", features = ["with-time", "with-uuid", "with-serde_json"] }

src/main.rs

@@ -12,7 +12,11 @@ fn main() {
     let conn_string: String = env::var("DATABASE_URL")
         .expect("DATABASE_URL must be set");
 
-    let chain = martin_lib::chain(conn_string);
+    let cache_size = env::var("CACHE_SIZE").ok()
+        .and_then(|cache_size| cache_size.parse::<usize>().ok())
+        .unwrap_or(16384);
+
+    let chain = martin_lib::chain(conn_string, cache_size);
 
     let port = 3000;
     let bind_addr = format!("0.0.0.0:{}", port);

src/martin/lib.rs

@@ -1,6 +1,7 @@
 extern crate iron_test;
 extern crate iron;
 extern crate logger;
+extern crate lru;
 extern crate mapbox_expressions_to_sql;
 extern crate persistent;
 extern crate r2d2_postgres;
@@ -16,15 +17,17 @@ extern crate urlencoded;
 
 use iron::prelude::Chain;
 use logger::Logger;
-use persistent::Read;
+use lru::LruCache;
+use persistent::{Read, State};
 use rererouter::RouterBuilder;
 
+mod cache;
 mod cors;
 mod db;
 mod routes;
 mod tileset;
 
-pub fn chain(conn_string: String) -> iron::Chain {
+pub fn chain(conn_string: String, cache_size: usize) -> iron::Chain {
     let mut router_builder = RouterBuilder::new();
     router_builder.get(r"/index.json", routes::index);
     router_builder.get(r"/(?P<tileset>[\w|\.]*)\.json", routes::tileset);
@@ -51,6 +54,9 @@ pub fn chain(conn_string: String) -> iron::Chain {
         }
     };
 
+    let tile_cache = LruCache::new(cache_size);
+    chain.link(State::<cache::TileCache>::both(tile_cache));
+
     chain.link_after(cors::Middleware);
     chain.link_after(logger_after);
 

src/martin/routes.rs

@@ -1,13 +1,15 @@
 use iron::{status, mime, Request, Response, IronResult};
 use iron::headers::{Headers, parsing};
 use iron::prelude::{Plugin};
+use iron::url::Url;
 use mapbox_expressions_to_sql;
-use persistent::Read;
+use persistent::{Read, State};
 use regex::{Regex, Captures};
 use serde_json;
 use urlencoded::UrlEncodedQuery;
 
 use super::db;
+use super::cache;
 use super::tileset;
 use tilejson::TileJSONBuilder;
 
@@ -72,6 +74,22 @@ fn get_filter<'a>(req: &'a mut Request) -> Option<&'a String> {
 }
 
 pub fn tile(req: &mut Request, caps: Captures) -> IronResult<Response> {
+    let url: Url = req.url.clone().into();
+    let lock = req.get::<State<cache::TileCache>>().unwrap();
+    let cached_tile = lock.write().ok().and_then(|mut guard|
+        guard.get(&url).cloned()
+    );
+
+    let content_type = "application/x-protobuf".parse::<mime::Mime>().unwrap();
+    if let Some(tile) = cached_tile {
+        debug!("{} hit", url);
+        return match tile.len() {
+            0 => Ok(Response::with((content_type, status::NoContent))),
+            _ => Ok(Response::with((content_type, status::Ok, tile)))
+        }
+    };
+
+    debug!("{} miss", url);
     let tilesets = req.get::<Read<tileset::Tilesets>>().unwrap();
     let tileset = match tilesets.get(&caps["tileset"]) {
         Some(tileset) => tileset,
@@ -112,7 +130,9 @@ pub fn tile(req: &mut Request, caps: Captures) -> IronResult<Response> {
         }
     };
 
-    let content_type = "application/x-protobuf".parse::<mime::Mime>().unwrap();
+    let mut guard = lock.write().unwrap();
+    guard.put(req.url.clone().into(), tile.clone());
+
     match tile.len() {
         0 => Ok(Response::with((content_type, status::NoContent))),
         _ => Ok(Response::with((content_type, status::Ok, tile)))