allow user to create a custom DiskUsage class (or extend LruDiskUsage class) to implement custom cache keep/delete rules

Author: jpage4500

README.md

@@ -99,6 +99,16 @@ private HttpProxyCacheServer newProxy() {
 }
 ```
 
+or even implement your own `DiskUsage` strategy:
+```java
+private HttpProxyCacheServer newProxy() {
+    return new HttpProxyCacheServer.Builder(this)
+            .diskUsage(new MyCoolDiskUsageStrategy())
+            .build();
+}
+```
+
+
 ### Listen caching progress
 Use `HttpProxyCacheServer.registerCacheListener(CacheListener listener)` method to set listener with callback `onCacheAvailable(File cacheFile, String url, int percentsAvailable)` to be aware of caching progress. Do not forget to to unsubscribe listener with help of `HttpProxyCacheServer.unregisterCacheListener(CacheListener listener)` method to avoid memory leaks.
 

library/src/main/java/com/danikula/videocache/HttpProxyCacheServer.java

@@ -414,6 +414,16 @@ public Builder maxCacheFilesCount(int count) {
             return this;
         }
 
+        /**
+         * Set custom DiskUsage logic for handling when to keep or clean cache.
+         *
+         * @param diskUsage a disk usage strategy, cant be {@code null}.
+         */
+        public Builder diskUsage(DiskUsage diskUsage) {
+            this.diskUsage = checkNotNull(diskUsage);
+            return this;
+        }
+
         /**
          * Builds new instance of {@link HttpProxyCacheServer}.
          *

library/src/main/java/com/danikula/videocache/file/Files.java

@@ -1,11 +1,15 @@
 package com.danikula.videocache.file;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.io.File;
 import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.Date;
 import java.util.LinkedList;
 import java.util.List;
 
@@ -16,6 +20,8 @@
  */
 class Files {
 
+    private static final Logger LOG = LoggerFactory.getLogger("Files");
+
     static void makeDir(File directory) throws IOException {
         if (directory.exists()) {
             if (!directory.isDirectory()) {
@@ -46,7 +52,8 @@ static void setLastModifiedNow(File file) throws IOException {
             if (!modified) {
                 modify(file);
                 if (file.lastModified() < now) {
-                    throw new IOException("Error set last modified date to " + file);
+                    // NOTE: apparently this is a known issue (see: http://stackoverflow.com/questions/6633748/file-lastmodified-is-never-what-was-set-with-file-setlastmodified)
+                    LOG.warn("Last modified date {} is not set for file {}", new Date(file.lastModified()), file.getAbsolutePath());
                 }
             }
         }

library/src/main/java/com/danikula/videocache/file/LruDiskUsage.java

@@ -15,7 +15,7 @@
  *
  * @author Alexey Danilov (danikula@gmail.com).
  */
-abstract class LruDiskUsage implements DiskUsage {
+public abstract class LruDiskUsage implements DiskUsage {
 
     private static final Logger LOG = LoggerFactory.getLogger("LruDiskUsage");
     private final ExecutorService workerThread = Executors.newSingleThreadExecutor();