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.

Cargo.lock

@@ -611,11 +611,13 @@ dependencies = [
  "gtk 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "hammond-data 0.1.0",
  "hammond-downloader 0.1.0",
+ "lazy_static 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "loggerv 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "open 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rayon 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "send-cell 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1280,6 +1282,11 @@ dependencies = [
  "libc 0.2.34 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "send-cell"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "serde"
 version = "1.0.24"
@@ -1746,6 +1753,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum secur32-sys 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3f412dfa83308d893101dd59c10d6fda8283465976c28c287c5c855bf8d216bc"
 "checksum security-framework 0.1.16 (registry+https://github.com/rust-lang/crates.io-index)" = "dfa44ee9c54ce5eecc9de7d5acbad112ee58755239381f687e564004ba4a2332"
 "checksum security-framework-sys 0.1.16 (registry+https://github.com/rust-lang/crates.io-index)" = "5421621e836278a0b139268f36eee0dc7e389b784dc3f79d8f11aabadf41bead"
+"checksum send-cell 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "1c620dd7e056b468b9d374a9f51cfa6bb4bf17a8ca4ee62e5efa0d99aaff2c41"
 "checksum serde 1.0.24 (registry+https://github.com/rust-lang/crates.io-index)" = "1c57ab4ec5fa85d08aaf8ed9245899d9bbdd66768945b21113b84d5f595cb6a1"
 "checksum serde_json 1.0.8 (registry+https://github.com/rust-lang/crates.io-index)" = "7cf5b0b5b4bd22eeecb7e01ac2e1225c7ef5e4272b79ee28a8392a8c8489c839"
 "checksum serde_urlencoded 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "ce0fd303af908732989354c6f02e05e2e6d597152870f2c6990efb0577137480"

hammond-data/src/models/queryables.rs

@@ -513,6 +513,11 @@ impl From<Podcast> for PodcastCoverQuery {
 }
 
 impl PodcastCoverQuery {
+    /// Get the Feed `id`.
+    pub fn id(&self) -> i32 {
+        self.id
+    }
+
     /// Get the Feed `title`.
     pub fn title(&self) -> &str {
         &self.title

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)]