Implemented a pixbuf cache mechanism.

Since gdk_pixbuf::Pixbuf is refference counted and every episode,
use the cover of the Podcast Feed/Show, We can only create a Pixbuf
cover per show and pass around the Rc pointer.

GObjects do not implement Send trait, so SendCell is a way around that.
Also lazy_static requires Sync trait, so that's what the mutexes are.

hammond-gtk/Cargo.toml

@@ -12,11 +12,13 @@ gdk = "0.7.0"
 gdk-pixbuf = "0.3.0"
 gio = "0.3.0"
 glib = "0.4.0"
+lazy_static = "1.0.0"
 log = "0.3.8"
 loggerv = "0.6.0"
 open = "1.2.1"
 rayon = "0.9.0"
 regex = "0.2.3"
+send-cell = "0.1.2"
 
 [dependencies.diesel]
 features = ["sqlite"]

hammond-gtk/src/main.rs

@@ -12,10 +12,13 @@ extern crate dissolve;
 extern crate hammond_data;
 extern crate hammond_downloader;
 #[macro_use]
+extern crate lazy_static;
+#[macro_use]
 extern crate log;
 extern crate loggerv;
 extern crate open;
 extern crate regex;
+extern crate send_cell;
 // extern crate rayon;
 
 // use rayon::prelude::*;

hammond-gtk/src/utils.rs

@@ -1,3 +1,4 @@
+use send_cell::SendCell;
 use glib;
 use gdk_pixbuf::Pixbuf;
 
@@ -8,7 +9,9 @@ use hammond_downloader::downloader;
 use std::thread;
 use std::cell::RefCell;
 use std::sync::mpsc::{channel, Receiver};
+use std::sync::Mutex;
 use std::rc::Rc;
+use std::collections::HashMap;
 
 use content::Content;
 
@@ -59,10 +62,30 @@ fn refresh_podcasts_view() -> glib::Continue {
     glib::Continue(false)
 }
 
+lazy_static! {
+    static ref CACHED_PIXBUFS: Mutex<HashMap<(i32, u32), Mutex<SendCell<Pixbuf>>>> = {
+        Mutex::new(HashMap::new())
+    };
+}
+
 // FIXME: use something that would just scale?
 pub fn get_pixbuf_from_path(pd: &PodcastCoverQuery, size: u32) -> Option<Pixbuf> {
+    let mut hashmap = CACHED_PIXBUFS.lock().unwrap();
+    {
+        let res = hashmap.get(&(pd.id(), size));
+        if let Some(px) = res {
+            let m = px.lock().unwrap();
+            return Some(m.clone().into_inner());
+        }
+    }
+
     let img_path = downloader::cache_image(pd)?;
-    Pixbuf::new_from_file_at_scale(&img_path, size as i32, size as i32, true).ok()
+    let px = Pixbuf::new_from_file_at_scale(&img_path, size as i32, size as i32, true).ok();
+    if let Some(px) = px {
+        hashmap.insert((pd.id(), size), Mutex::new(SendCell::new(px.clone())));
+        return Some(px);
+    }
+    None
 }
 
 #[cfg(test)]