Switch to parking_lot::{Mutex, RwLock}

Switch to the `parking_lot` crate's implementations of
`std::sync::Mutex` and `std::sync::RwLock`, which are more efficient.

A writeup on why `parking_lot` is more efficient can be read here:
<https://github.com/Amanieu/parking_lot>

Upgrade path:

Modify `mutex.lock().unwrap()` usage to `mutex.lock()` (not needing to
unwrap or handle a result), and
`rwlock.read().unwrap()`/`rwlock.write().unwrap()` usage to
`rwlock.read()` and `rwlock.write()`.

For example, modify:

```rust
use serenity::CACHE;

println!("{}", CACHE.read().unwrap().user.id);
```

to:

```rust
use serenity::CACHE;

println!("{}", CACHE.read().user.id);
```

1 files changed, 3 insertions, 11 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 612972a..a3710eb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -107,6 +107,7 @@ extern crate serde_json;
 extern crate lazy_static;
 
 extern crate chrono;
+extern crate parking_lot;
 extern crate serde;
 
 #[cfg(feature = "utils")]
@@ -125,8 +126,6 @@ extern crate multipart;
 extern crate native_tls;
 #[cfg(feature = "voice")]
 extern crate opus;
-#[cfg(feature = "client")]
-extern crate parking_lot;
 #[cfg(feature = "voice")]
 extern crate sodiumoxide;
 #[cfg(feature = "threadpool")]
@@ -172,7 +171,7 @@ pub use client::Client;
 #[cfg(feature = "cache")]
 use cache::Cache;
 #[cfg(feature = "cache")]
-use std::sync::RwLock;
+use parking_lot::RwLock;
 
 #[cfg(feature = "cache")]
 lazy_static! {
@@ -197,16 +196,9 @@ lazy_static! {
     /// ```rust,ignore
     /// use serenity::CACHE;
     ///
-    /// println!("{}", CACHE.read().unwrap().user.id);
+    /// println!("{}", CACHE.read().user.id);
     /// ```
     ///
-    /// By `unwrap()`ing, the thread managing an event dispatch will be blocked
-    /// until the guard can be opened.
-    ///
-    /// If you do not want to block the current thread, you may instead use
-    /// `RwLock::try_read`. Refer to `RwLock`'s documentation in the stdlib for
-    /// more information.
-    ///
     /// [`CurrentUser`]: model/struct.CurrentUser.html
     /// [`Cache`]: cache/struct.Cache.html
     /// [cache module documentation]: cache/index.html