Remove duplicate initialization of dotenv

While doing memory profiling, I noticed that `dotenv` was being
initialized each time the `env` helper function was called.  With my
`.env` file in development it was (temporarily) allocating 9.7MB on
each call to the `env` helper.

The `dotenv::var` helper uses `std::sync::Once` and avoids this
duplicate work.  I don't expect this to improve allocation patterns on
production much, as without a `.env` file, only 1.9kB is
(temporarily) allocated.

Author: jtgeibel

src/controllers/user/session.rs

@@ -133,13 +133,10 @@ pub fn logout(req: &mut dyn Request) -> CargoResult<Response> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use dotenv::dotenv;
-    use std::env;
 
     fn pg_connection() -> PgConnection {
-        let _ = dotenv();
         let database_url =
-            env::var("TEST_DATABASE_URL").expect("TEST_DATABASE_URL must be set to run tests");
+            dotenv::var("TEST_DATABASE_URL").expect("TEST_DATABASE_URL must be set to run tests");
         PgConnection::establish(&database_url).unwrap()
     }
 

src/email.rs

@@ -1,8 +1,6 @@
-use std::env;
 use std::path::Path;
 
 use crate::util::{bad_request, CargoResult};
-use dotenv::dotenv;
 
 use lettre::file::FileTransport;
 use lettre::smtp::authentication::{Credentials, Mechanism};
@@ -19,12 +17,10 @@ pub struct MailgunConfigVars {
 }
 
 pub fn init_config_vars() -> Option<MailgunConfigVars> {
-    dotenv().ok();
-
     match (
-        env::var("MAILGUN_SMTP_LOGIN"),
-        env::var("MAILGUN_SMTP_PASSWORD"),
-        env::var("MAILGUN_SMTP_SERVER"),
+        dotenv::var("MAILGUN_SMTP_LOGIN"),
+        dotenv::var("MAILGUN_SMTP_PASSWORD"),
+        dotenv::var("MAILGUN_SMTP_SERVER"),
     ) {
         (Ok(login), Ok(password), Ok(server)) => Some(MailgunConfigVars {
             smtp_login: login,

src/lib.rs

@@ -100,8 +100,7 @@ pub fn build_handler(app: Arc<App>) -> MiddlewareBuilder {
 /// Panics if the environment variable with the name passed in as an argument is not defined
 /// in the current environment.
 pub fn env(s: &str) -> String {
-    dotenv::dotenv().ok();
-    ::std::env::var(s).unwrap_or_else(|_| panic!("must have `{}` defined", s))
+    dotenv::var(s).unwrap_or_else(|_| panic!("must have `{}` defined", s))
 }
 
 sql_function!(fn lower(x: ::diesel::sql_types::Text) -> ::diesel::sql_types::Text);

src/models/category.rs

@@ -184,13 +184,10 @@ impl<'a> NewCategory<'a> {
 mod tests {
     use super::*;
     use diesel::connection::SimpleConnection;
-    use dotenv::dotenv;
-    use std::env;
 
     fn pg_connection() -> PgConnection {
-        let _ = dotenv();
         let database_url =
-            env::var("TEST_DATABASE_URL").expect("TEST_DATABASE_URL must be set to run tests");
+            dotenv::var("TEST_DATABASE_URL").expect("TEST_DATABASE_URL must be set to run tests");
         let conn = PgConnection::establish(&database_url).unwrap();
         // These tests deadlock if run concurrently
         conn.batch_execute("BEGIN; LOCK categories IN ACCESS EXCLUSIVE MODE")

src/models/keyword.rs

@@ -99,13 +99,10 @@ mod tests {
     use super::*;
     use diesel;
     use diesel::connection::SimpleConnection;
-    use dotenv::dotenv;
-    use std::env;
 
     fn pg_connection() -> PgConnection {
-        let _ = dotenv();
         let database_url =
-            env::var("TEST_DATABASE_URL").expect("TEST_DATABASE_URL must be set to run tests");
+            dotenv::var("TEST_DATABASE_URL").expect("TEST_DATABASE_URL must be set to run tests");
         let conn = PgConnection::establish(&database_url).unwrap();
         // These tests deadlock if run concurrently
         conn.batch_execute("BEGIN;").unwrap();

src/tests/all.rs

@@ -20,7 +20,6 @@ use cargo_registry::{
 };
 use std::{
     borrow::Cow,
-    env,
     sync::{
         atomic::{AtomicUsize, Ordering},
         Arc,
@@ -112,15 +111,13 @@ fn app() -> (
     Arc<App>,
     conduit_middleware::MiddlewareBuilder,
 ) {
-    dotenv::dotenv().ok();
-
     let (proxy, bomb) = record::proxy();
     let uploader = Uploader::S3 {
         bucket: s3::Bucket::new(
             String::from("alexcrichton-test"),
             None,
-            std::env::var("S3_ACCESS_KEY").unwrap_or_default(),
-            std::env::var("S3_SECRET_KEY").unwrap_or_default(),
+            dotenv::var("S3_ACCESS_KEY").unwrap_or_default(),
+            dotenv::var("S3_SECRET_KEY").unwrap_or_default(),
             // When testing we route all API traffic over HTTP so we can
             // sniff/record it, but everywhere else we use https
             "http",
@@ -140,8 +137,8 @@ fn simple_app(uploader: Uploader) -> (Arc<App>, conduit_middleware::MiddlewareBu
         session_key: "test this has to be over 32 bytes long".to_string(),
         git_repo_checkout: git::checkout(),
         index_location: Url::from_file_path(&git::bare()).unwrap(),
-        gh_client_id: env::var("GH_CLIENT_ID").unwrap_or_default(),
-        gh_client_secret: env::var("GH_CLIENT_SECRET").unwrap_or_default(),
+        gh_client_id: dotenv::var("GH_CLIENT_ID").unwrap_or_default(),
+        gh_client_secret: dotenv::var("GH_CLIENT_SECRET").unwrap_or_default(),
         db_url: env("TEST_DATABASE_URL"),
         env: Env::Test,
         max_upload_size: 3000,
@@ -160,7 +157,7 @@ fn simple_app(uploader: Uploader) -> (Arc<App>, conduit_middleware::MiddlewareBu
 
 // Return the environment variable only if it has been defined
 fn env(var: &str) -> String {
-    match env::var(var) {
+    match dotenv::var(var) {
         Ok(ref s) if s == "" => panic!("environment variable `{}` must not be empty", var),
         Ok(s) => s,
         _ => panic!(

src/tests/categories.rs

@@ -1,8 +1,6 @@
 use cargo_registry::schema::categories;
-use std::env;
 
 use diesel::*;
-use dotenv::dotenv;
 
 const ALGORITHMS: &str = r#"
 [algorithms]
@@ -40,9 +38,8 @@ description = "Another category ho hum"
 "#;
 
 fn pg_connection() -> PgConnection {
-    let _ = dotenv();
     let database_url =
-        env::var("TEST_DATABASE_URL").expect("TEST_DATABASE_URL must be set to run tests");
+        dotenv::var("TEST_DATABASE_URL").expect("TEST_DATABASE_URL must be set to run tests");
     let conn = PgConnection::establish(&database_url).unwrap();
     conn.begin_test_transaction().unwrap();
     conn

src/tests/util.rs

@@ -48,7 +48,6 @@ pub struct TestApp(Rc<TestAppInner>);
 impl TestApp {
     /// Initialize an application with an `Uploader` that panics
     pub fn init() -> TestAppBuilder {
-        dotenv::dotenv().ok();
         let (app, middle) = crate::simple_app(Uploader::Panic);
         let inner = Rc::new(TestAppInner {
             app,