- * This cache also manages timeout information. - * - * @author niki - */ -public class Cache { - private File dir; - private long tooOldChanging; - private long tooOldStable; - private TraceHandler tracer = new TraceHandler(); - - /** - * Only for inheritance. - */ - protected Cache() { - } - - /** - * Create a new {@link Cache} object. - * - * @param dir - * the directory to use as cache - * @param hoursChanging - * the number of hours after which a cached file that is thought - * to change ~often is considered too old (or -1 for - * "never too old") - * @param hoursStable - * the number of hours after which a cached file that is thought - * to change rarely is considered too old (or -1 for - * "never too old") - * - * @throws IOException - * in case of I/O error - */ - public Cache(File dir, int hoursChanging, int hoursStable) - throws IOException { - this.dir = dir; - this.tooOldChanging = 1000L * 60 * 60 * hoursChanging; - this.tooOldStable = 1000L * 60 * 60 * hoursStable; - - if (dir != null && !dir.exists()) { - dir.mkdirs(); - } - - if (dir == null || !dir.exists()) { - throw new IOException("Cannot create the cache directory: " - + (dir == null ? "null" : dir.getAbsolutePath())); - } - } - - /** - * The traces handler for this {@link Cache}. - * - * @return the traces handler - */ - public TraceHandler getTraceHandler() { - return tracer; - } - - /** - * The traces handler for this {@link Cache}. - * - * @param tracer - * the new traces handler - */ - public void setTraceHandler(TraceHandler tracer) { - if (tracer == null) { - tracer = new TraceHandler(false, false, false); - } - - this.tracer = tracer; - } - - /** - * Check the resource to see if it is in the cache. - * - * @param uniqueID - * the resource to check - * @param allowTooOld - * allow files even if they are considered too old - * @param stable - * a stable file (that dones't change too often) -- parameter - * used to check if the file is too old to keep or not - * - * @return TRUE if it is - * - */ - public boolean check(String uniqueID, boolean allowTooOld, boolean stable) { - return check(getCached(uniqueID), allowTooOld, stable); - } - - /** - * Check the resource to see if it is in the cache. - * - * @param url - * the resource to check - * @param allowTooOld - * allow files even if they are considered too old - * @param stable - * a stable file (that dones't change too often) -- parameter - * used to check if the file is too old to keep or not - * - * @return TRUE if it is - * - */ - public boolean check(URL url, boolean allowTooOld, boolean stable) { - return check(getCached(url), allowTooOld, stable); - } - - /** - * Check the resource to see if it is in the cache. - * - * @param cached - * the resource to check - * @param allowTooOld - * allow files even if they are considered too old - * @param stable - * a stable file (that dones't change too often) -- parameter - * used to check if the file is too old to keep or not - * - * @return TRUE if it is - * - */ - private boolean check(File cached, boolean allowTooOld, boolean stable) { - if (cached.exists() && cached.isFile()) { - if (!allowTooOld && isOld(cached, stable)) { - if (!cached.delete()) { - tracer.error("Cannot delete temporary file: " - + cached.getAbsolutePath()); - } - } else { - return true; - } - } - - return false; - } - - /** - * Clean the cache (delete the cached items). - * - * @param onlyOld - * only clean the files that are considered too old for a stable - * resource - * - * @return the number of cleaned items - */ - public int clean(boolean onlyOld) { - long ms = System.currentTimeMillis(); - - tracer.trace("Cleaning cache from old files..."); - - int num = clean(onlyOld, dir, -1); - - tracer.trace(num + "cache items cleaned in " - + (System.currentTimeMillis() - ms) + " ms"); - - return num; - } - - /** - * Clean the cache (delete the cached items) in the given cache directory. - * - * @param onlyOld - * only clean the files that are considered too old for stable - * resources - * @param cacheDir - * the cache directory to clean - * @param limit - * stop after limit files deleted, or -1 for unlimited - * - * @return the number of cleaned items - */ - private int clean(boolean onlyOld, File cacheDir, int limit) { - int num = 0; - File[] files = cacheDir.listFiles(); - if (files != null) { - for (File file : files) { - if (limit >= 0 && num >= limit) { - return num; - } - - if (file.isDirectory()) { - num += clean(onlyOld, file, limit); - file.delete(); // only if empty - } else { - if (!onlyOld || isOld(file, true)) { - if (file.delete()) { - num++; - } else { - tracer.error("Cannot delete temporary file: " - + file.getAbsolutePath()); - } - } - } - } - } - - return num; - } - - /** - * Open a resource from the cache if it exists. - * - * @param uniqueID - * the unique ID - * @param allowTooOld - * allow files even if they are considered too old - * @param stable - * a stable file (that dones't change too often) -- parameter - * used to check if the file is too old to keep or not - * - * @return the opened resource if found, NULL if not - */ - public InputStream load(String uniqueID, boolean allowTooOld, boolean stable) { - return load(getCached(uniqueID), allowTooOld, stable); - } - - /** - * Open a resource from the cache if it exists. - * - * @param url - * the resource to open - * @param allowTooOld - * allow files even if they are considered too old - * @param stable - * a stable file (that doesn't change too often) -- parameter - * used to check if the file is too old to keep or not in the - * cache - * - * @return the opened resource if found, NULL if not - */ - public InputStream load(URL url, boolean allowTooOld, boolean stable) { - return load(getCached(url), allowTooOld, stable); - } - - /** - * Open a resource from the cache if it exists. - * - * @param cached - * the resource to open - * @param allowTooOld - * allow files even if they are considered too old - * @param stable - * a stable file (that dones't change too often) -- parameter - * used to check if the file is too old to keep or not - * - * @return the opened resource if found, NULL if not - */ - private InputStream load(File cached, boolean allowTooOld, boolean stable) { - if (cached.exists() && cached.isFile() - && (allowTooOld || !isOld(cached, stable))) { - try { - return new MarkableFileInputStream(cached); - } catch (FileNotFoundException e) { - return null; - } - } - - return null; - } - - /** - * Save the given resource to the cache. - * - * @param in - * the input data - * @param uniqueID - * a unique ID used to locate the cached resource - * - * @return the number of bytes written - * - * @throws IOException - * in case of I/O error - */ - public long save(InputStream in, String uniqueID) throws IOException { - File cached = getCached(uniqueID); - cached.getParentFile().mkdirs(); - return save(in, cached); - } - - /** - * Save the given resource to the cache. - * - * @param in - * the input data - * @param url - * the {@link URL} used to locate the cached resource - * - * @return the number of bytes written - * - * @throws IOException - * in case of I/O error - */ - public long save(InputStream in, URL url) throws IOException { - File cached = getCached(url); - return save(in, cached); - } - - /** - * Save the given resource to the cache. - *
- * Will also clean the {@link Cache} from old files. - * - * @param in - * the input data - * @param cached - * the cached {@link File} to save to - * - * @return the number of bytes written - * - * @throws IOException - * in case of I/O error - */ - private long save(InputStream in, File cached) throws IOException { - // We want to force at least an immediate SAVE/LOAD to work for some - // workflows, even if we don't accept cached files (times set to "0" - // -- and not "-1" or a positive value) - clean(true, dir, 10); - cached.getParentFile().mkdirs(); // in case we deleted our own parent - long bytes = IOUtils.write(in, cached); - return bytes; - } - - /** - * Remove the given resource from the cache. - * - * @param uniqueID - * a unique ID used to locate the cached resource - * - * @return TRUE if it was removed - */ - public boolean remove(String uniqueID) { - File cached = getCached(uniqueID); - return cached.delete(); - } - - /** - * Remove the given resource from the cache. - * - * @param url - * the {@link URL} used to locate the cached resource - * - * @return TRUE if it was removed - */ - public boolean remove(URL url) { - File cached = getCached(url); - return cached.delete(); - } - - /** - * Check if the {@link File} is too old according to - * {@link Cache#tooOldChanging}. - * - * @param file - * the file to check - * @param stable - * TRUE to denote stable files, that are not supposed to change - * too often - * - * @return TRUE if it is - */ - private boolean isOld(File file, boolean stable) { - long max = tooOldChanging; - if (stable) { - max = tooOldStable; - } - - if (max < 0) { - return false; - } - - long time = new Date().getTime() - file.lastModified(); - if (time < 0) { - tracer.error("Timestamp in the future for file: " - + file.getAbsolutePath()); - } - - return time < 0 || time > max; - } - - /** - * Return the associated cache {@link File} from this {@link URL}. - * - * @param url - * the {@link URL} - * - * @return the cached {@link File} version of this {@link URL} - */ - private File getCached(URL url) { - File subdir; - - String name = url.getHost(); - if (name == null || name.isEmpty()) { - // File - File file = new File(url.getFile()); - if (file.getParent() == null) { - subdir = new File("+"); - } else { - subdir = new File(file.getParent().replace("..", "__")); - } - subdir = new File(dir, allowedChars(subdir.getPath())); - name = allowedChars(url.getFile()); - } else { - // URL - File subsubDir = new File(dir, allowedChars(url.getHost())); - subdir = new File(subsubDir, "_" + allowedChars(url.getPath())); - name = allowedChars("_" + url.getQuery()); - } - - File cacheFile = new File(subdir, name); - subdir.mkdirs(); - - return cacheFile; - } - - /** - * Get the basic cache resource file corresponding to this unique ID. - *
- * Note that you may need to add a sub-directory in some cases. - * - * @param uniqueID - * the id - * - * @return the cached version if present, NULL if not - */ - private File getCached(String uniqueID) { - File file = new File(dir, allowedChars(uniqueID)); - File subdir = new File(file.getParentFile(), "_"); - return new File(subdir, file.getName()); - } - - /** - * Replace not allowed chars (in a {@link File}) by "_". - * - * @param raw - * the raw {@link String} - * - * @return the sanitised {@link String} - */ - private String allowedChars(String raw) { - return raw.replace('/', '_').replace(':', '_').replace("\\", "_"); - } -} \ No newline at end of file