Working simple caching of the images used to hash. Needs some additional work, but much better than on dry runs.

.gitignore

@@ -12,3 +12,6 @@
 
 # Building a library, so ignore the lock file
 Cargo.lock
+
+# Cache Directory
+.hash_cache/

Cargo.toml

@@ -9,4 +9,4 @@ rustc-serialize = "*"
 image = "*"
 complex = "*"
 dft = "*"
-rust-crypto = "*"
+sha1 = "*"

src/cache.rs

@@ -3,28 +3,99 @@
 // Licensed under the MIT license<LICENSE-MIT or http://opensource.org/licenses/MIT>.
 // This file may not be copied, modified, or distributed except according to those terms.
 
-extern image;
+extern crate image;
+extern crate sha1;
 
 use self::image::ImageBuffer;
+use self::sha1::Sha1;
 use std::path::Path;
+use std::fs::{File, create_dir_all};
+use std::io::{Read, Error};
+use std::option::Option;
+use std::result::Result;
+
+const CACHE_DIR: &'static str = "./.hash_cache";
+const CACHE_FILE_EXT: &'static str = "png";
+
+// Creates the required directories 
+pub fn prep_cache() -> Result<(), Error> {
+    create_dir_all(CACHE_DIR)
+}
 
 /**
  * Get the hash of the desired file and return it as a hex string
  */
-fn get_file_hash(path: &Path) -> String {
-    
+fn get_file_hash(path: &Path) -> Result<String, Error> {
+    let mut source = try!(File::open(&path));
+    let mut buf: Vec<u8> = Vec::new();
+    try!(source.read_to_end(&mut buf));
+    let mut sha1 = Sha1::new();
+    sha1.update(&buf);
+    // Return the hex result of the hash
+    Ok(sha1.hexdigest())
 }
 
 /**
  * Put an image buffer in the cache
  */
-pub fn put_in_cache(path: &Path, image: &ImageBuffer)  {
-
+pub fn put_in_cache(path: &Path, image: &ImageBuffer<image::Luma<u8>, Vec<u8>>)  {
+    let hash = get_file_hash(&path);
+    match hash {
+        Ok(sha1) => {
+            let cache_path_str = format!("{}/{}.{}",CACHE_DIR, sha1, CACHE_FILE_EXT);
+            let cached_path = Path::new(&cache_path_str);
+            // Save the file into the cache
+            match image.save(cached_path) {
+                Ok(_) => {},
+                Err(e) => println!("Error: {}", e),
+            }
+        },
+        Err(e) =>  println!("Error: {}", e),
+    }
 }
 
 /**
  * Get an image buffer out of the cache
  */
-pub fn get_from_cache(path: &Path) -> Some(ImageBuffer) {
+pub fn get_from_cache(path: &Path) -> Option<ImageBuffer<image::Luma<u8>, Vec<u8>>> {
+    let hash = get_file_hash(&path);
+    match hash {
+        Ok(sha1) => {
+            // Check if the file exists in the cache
+            let cache_path_str = format!("{}/{}.{}",CACHE_DIR, sha1, CACHE_FILE_EXT);
+            let cached_path = Path::new(&cache_path_str);
+            // Try to open, if it does, then we can read the image in
+            match File::open(&cached_path) {
+                Ok(_) => {
+                    let image = image::open(&cached_path).unwrap();
+                    Some(image.to_luma())
+                },
+                Err(e) => {
+                    println!("Error: {}", e);
+                    None
+                },
+            }
+        },
+        Err(e) => {
+            println!("Error: {}", e);
+            None
+        },
+    }
+}
 
+#[test]
+fn test_get_file_hash() {
+    let target = "test_images/sample_01_large.jpg";
+    let target_path = Path::new(target);
+    let hash = get_file_hash(&target_path);
+    match hash {
+        Ok(v) => {
+            println!("Hash: {}", v);
+            assert!(v == "4beb6f2d852b75a313863916a1803ebad13a3196");
+        }
+        Err(e) => {
+            println!("Error: {:?}", e);
+            assert!(false);
+        }
+    }
 }

src/hash.rs

@@ -16,6 +16,7 @@ use self::image::{
 };
 use self::dft::real;
 use self::complex::*;
+use cache;
 
 /**
  * Prepared image that can be used to generate hashes
@@ -52,13 +53,19 @@ pub struct PerceptualHashes<'a> {
 pub fn prepare_image(path: &Path, size: u32) -> PreparedImage {
     let image_path = path.to_str().unwrap();
     // Check if we have the already converted image in a cache and use that if possible.
-    
-
-    // Otherwise let's do that work now and store it.
-    let image = image::open(path).unwrap();
-    let small_image = image.resize_exact(size, size, FilterType::Lanczos3);
-    let grey_image = small_image.to_luma();
-    PreparedImage { orig_path: &*image_path, image: grey_image }
+    match cache::get_from_cache(&path) {
+        Some(image) => {
+            PreparedImage { orig_path: &*image_path, image: image }
+        },
+        None => {
+            // Otherwise let's do that work now and store it.
+            let image = image::open(path).unwrap();
+            let small_image = image.resize_exact(size, size, FilterType::Lanczos3);
+            let grey_image = small_image.to_luma();
+            cache::put_in_cache(&path, &grey_image);
+            PreparedImage { orig_path: &*image_path, image: grey_image }
+        },
+    }
 }
 
 /**

src/lib.rs

@@ -8,6 +8,18 @@ use std::path::Path;
 mod hash;
 mod cache;
 
+/**
+ * Prepare the library for work.
+ *
+ * Not performing this step may cause parts to fail.
+ */
+pub fn init() {
+    match cache::prep_cache() {
+        Ok(_) => {},
+        Err(e) => println!("Error: {}", e),
+    }
+}
+
 pub fn get_phashes(path: &Path) -> hash::PerceptualHashes {
     hash::get_perceptual_hashes(path, 8)
 }

src/main.rs

@@ -38,6 +38,9 @@ fn main() {
     let args: Args = Docopt::new(USAGE)
                                 .and_then(|d| d.decode())
                                 .unwrap_or_else(|e| e.exit());
+    // Init the hashing library
+    pihash::init();
+
     //println!("{:?}", args);
     // All flags set or, no flags set
     if (args.flag_ahash && args.flag_dhash && args.flag_phash)