Use num_cpus instead of hardcoding the number of threads for dns look_up.

In the next hyper_tls relase it should be possible to use the existing
cpu_pool executor.

hammond-data/Cargo.toml

@@ -25,6 +25,7 @@ tokio-core = "0.1.12"
 hyper-tls = "0.1.2"
 native-tls = "0.1.5"
 futures-cpupool = "0.1.8"
+num_cpus = "1.8.0"
 
 [dependencies.diesel]
 features = ["sqlite", "r2d2"]

hammond-data/src/lib.rs

@@ -44,6 +44,7 @@ extern crate hyper;
 extern crate hyper_tls;
 extern crate itertools;
 extern crate native_tls;
+extern crate num_cpus;
 extern crate rayon;
 extern crate reqwest;
 extern crate rfc822_sanitizer;

hammond-data/src/pipeline.rs

@@ -10,6 +10,7 @@ use hyper::client::HttpConnector;
 use hyper_tls::HttpsConnector;
 use tokio_core::reactor::Core;
 
+use num_cpus;
 use rss;
 
 use Source;
@@ -78,8 +79,7 @@ pub fn run(sources: Vec<Source>, ignore_etags: bool) -> Result<()> {
     let mut core = Core::new()?;
     let handle = core.handle();
     let client = Client::configure()
-        // FIXME: numcpus instead of 4
-        .connector(HttpsConnector::new(4, &handle)?)
+        .connector(HttpsConnector::new(num_cpus::get(), &handle)?)
         .build(&handle);
 
     pipeline(sources, ignore_etags, &mut core, pool, client)