LruDiskUsage.java
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package com.danikula.videocache.file;
import com.danikula.videocache.Logger;
import java.io.File;
import java.io.IOException;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
/**
* {@link DiskUsage} that uses LRU (Least Recently Used) strategy to trim cache.
*
* @author Alexey Danilov (danikula@gmail.com).
*/
public abstract class LruDiskUsage implements DiskUsage {
private final ExecutorService workerThread = Executors.newSingleThreadExecutor();
@Override
public void touch(File file) throws IOException {
workerThread.submit(new TouchCallable(file));
}
private void touchInBackground(File file) throws IOException {
Files.setLastModifiedNow(file);
List<File> files = Files.getLruListFiles(file.getParentFile());
trim(files);
}
protected abstract boolean accept(File file, long totalSize, int totalCount);
private void trim(List<File> files) {
long totalSize = countTotalSize(files);
int totalCount = files.size();
for (File file : files) {
boolean accepted = accept(file, totalSize, totalCount);
if (!accepted) {
long fileSize = file.length();
boolean deleted = file.delete();
if (deleted) {
totalCount--;
totalSize -= fileSize;
Logger.info("Cache file " + file + " is deleted because it exceeds cache limit");
} else {
Logger.error("Error deleting file " + file + " for trimming cache");
}
}
}
}
private long countTotalSize(List<File> files) {
long totalSize = 0;
for (File file : files) {
totalSize += file.length();
}
return totalSize;
}
private class TouchCallable implements Callable<Void> {
private final File file;
public TouchCallable(File file) {
this.file = file;
}
@Override
public Void call() throws Exception {
touchInBackground(file);
return null;
}
}
}