Implement basic logging infrastructure. (#205) r=nalexander,victorporof

Signed-off-by: Paul Lange <palango@gmx.de>

Cargo.toml

@@ -1,11 +1,14 @@
 [package]
+authors = ["Richard Newman <rnewman@twinql.com>", "Nicholas Alexander <nalexander@mozilla.com>"]
 name = "mentat"
 version = "0.4.0"
-authors = ["Richard Newman <rnewman@twinql.com>", "Nicholas Alexander <nalexander@mozilla.com>"]
 
 [dependencies]
 clap = "2.19.3"
 nickel = "0.9.0"
+slog = "1.4.0"
+slog-scope = "0.2.2"
+slog-term = "1.3.4"
 
 [dependencies.rusqlite]
 version = "0.9.3"

src/lib.rs

@@ -8,6 +8,11 @@
 // CONDITIONS OF ANY KIND, either express or implied. See the License for the
 // specific language governing permissions and limitations under the License.
 
+#[macro_use]
+extern crate slog;
+#[macro_use]
+extern crate slog_scope;
+
 extern crate edn;
 extern crate mentat_query;
 extern crate mentat_query_parser;
@@ -18,6 +23,7 @@ use rusqlite::Connection;
 pub mod ident;
 
 pub fn get_name() -> String {
+    info!("Called into mentat library"; "fn" => "get_name");
     return String::from("mentat");
 }
 

src/main.rs

@@ -13,7 +13,16 @@ extern crate clap;
 
 use nickel::{Nickel, HttpRouter};
 
+#[macro_use]
+extern crate slog;
+#[macro_use]
+extern crate slog_scope;
+extern crate slog_term;
+
+extern crate mentat;
+
 use clap::{App, Arg, SubCommand, AppSettings};
+use slog::DrainExt;
 
 use std::u16;
 use std::str::FromStr;
@@ -44,10 +53,29 @@ fn main() {
         let debug = matches.is_present("debug");
         let port = u16::from_str(matches.value_of("port").unwrap()).expect("Port must be an integer");
         if debug {
-            println!("This doesn't do anything yet, but it will eventually serve up the following database: {}",
-                matches.value_of("database").unwrap());
+            println!("This doesn't do anything yet, but it will eventually serve up the following database: {} \
+                      on port: {}.",
+                     matches.value_of("database").unwrap(),
+                     matches.value_of("port").unwrap());
         }
 
+        // Set up logging.
+        let log_level = if debug {
+            slog::Level::Debug
+        } else {
+            slog::Level::Warning
+        };
+        let term_logger = slog_term::streamer().build().fuse();
+        let log = slog::Logger::root(slog::LevelFilter::new(term_logger, log_level),
+                                     o!("version" => env!("CARGO_PKG_VERSION")));
+        slog_scope::set_global_logger(log);
+
+        info!("Serving database"; "database" => matches.value_of("database").unwrap(),
+                                  "port" => port,
+                                  "debug mode" => debug);
+
+        error!("Calling a function: {}", mentat::get_name());
+
         let mut server = Nickel::new();
         server.get("/", middleware!("This doesn't do anything yet"));
         server.listen(("127.0.0.1", port)).expect("Failed to launch server");