Add Last-Modified for easy caching

build.gradle

@@ -7,7 +7,7 @@ plugins {
 }
 
 group = 'com.mangadex'
-version = '1.0.0-rc2'
+version = '1.0.0-rc3'
 mainClassName = 'mdnet.base.MangadexClient'
 
 repositories {

src/main/java/mdnet/base/MangadexClient.java

@@ -37,7 +37,7 @@ public class MangadexClient {
 		this.statistics = new AtomicReference<>();
 
 		try {
-			cache = DiskLruCache.open(new File("cache"), 1, 2,
+			cache = DiskLruCache.open(new File("cache"), 2, 3,
 					clientSettings.getMaxCacheSizeMib() * 1024 * 1024 /* MiB to bytes */);
 		} catch (IOException e) {
 			MangadexClient.dieWithError(e);

src/main/java/mdnet/cache/DiskLruCache.java

@@ -228,9 +228,9 @@ public final class DiskLruCache implements Closeable {
 				cache.readJournal();
 				cache.processJournal();
 				return cache;
-			} catch (IOException journalIsCorrupt) {
+			} catch (IOException e) {
 				if (LOGGER.isWarnEnabled()) {
-					LOGGER.warn("DiskLruCache " + directory + " is corrupt - removing", journalIsCorrupt);
+					LOGGER.warn("DiskLruCache " + directory + " is corrupt/outdated - removing");
 				}
 				cache.delete();
 			}
@@ -600,7 +600,7 @@ public final class DiskLruCache implements Closeable {
 		}
 
 		redundantOpCount++;
-		journalWriter.append(REMOVE + ' ' + key + '\n');
+		journalWriter.append(REMOVE).append(' ').append(key).append('\n');
 		lruEntries.remove(key);
 
 		if (journalRebuildRequired()) {
@@ -694,10 +694,15 @@ public final class DiskLruCache implements Closeable {
 			return ins[index];
 		}
 
-		/** Returns the string value for {@code index}. */
+		/**
+		 * Returns the string value for {@code index}. This consumes the InputStream!
+		 */
 		public String getString(int index) throws IOException {
-			try (InputStream in = getInputStream(index)) {
+			InputStream in = getInputStream(index);
+			try {
 				return IOUtils.toString(in, StandardCharsets.UTF_8);
+			} finally {
+				Util.closeQuietly(in);
 			}
 		}
 

src/main/kotlin/mdnet/base/Application.kt

@@ -14,6 +14,7 @@ import org.http4k.core.Request
 import org.http4k.core.Response
 import org.http4k.core.Status
 import org.http4k.core.then
+import org.http4k.filter.CachingFilters
 import org.http4k.filter.MaxAgeTtl
 import org.http4k.filter.ServerFilters
 import org.http4k.lens.Path
@@ -55,21 +56,38 @@ fun getServer(cache: DiskLruCache, serverSettings: ServerSettings, clientSetting
         statistics.get().requestsServed.incrementAndGet()
 
         // Netty doesn't do Content-Length or Content-Type, so we have the pleasure of doing that ourselves
-        fun respond(input: InputStream, length: String, type: String): Response =
+        fun respondWithImage(input: InputStream, length: String, type: String, lastModified: String): Response =
             Response(Status.OK).header("Content-Length", length)
                 .header("Content-Type", type)
                 .header("X-Content-Type-Options", "nosniff")
+                .header("Last-Modified", lastModified)
+                .header("Cache-Control", listOf("public", MaxAgeTtl(Constants.MAX_AGE_CACHE).toHeaderValue()).joinToString(", "))
+                .header("Timing-Allow-Origin", "https://mangadex.org")
                 .body(input, length.toLong())
 
         val snapshot = cache.get(cacheId)
         if (snapshot != null) {
             statistics.get().cacheHits.incrementAndGet()
+
+            // our files never change, so it's safe to use the browser cache
+            if (request.header("If-Modified-Since") != null) {
+                if (LOGGER.isTraceEnabled) {
+                    LOGGER.trace("Request for $chapterHash/$fileName cached by browser")
+                }
+
+                val lastModified = snapshot.getString(2)
+                snapshot.close()
+
+                Response(Status.NOT_MODIFIED)
+                    .header("Last-Modified", lastModified)
+            } else {
                 if (LOGGER.isTraceEnabled) {
                     LOGGER.trace("Request for $chapterHash/$fileName hit cache")
                 }
 
-            respond(CipherInputStream(snapshot.getInputStream(0), getRc4(cacheId)),
+                respondWithImage(CipherInputStream(snapshot.getInputStream(0), getRc4(cacheId)),
-                snapshot.getLength(0).toString(), snapshot.getString(1))
+                    snapshot.getLength(0).toString(), snapshot.getString(1), snapshot.getString(2))
+            }
         } else {
             statistics.get().cacheMisses.incrementAndGet()
             if (LOGGER.isTraceEnabled) {
@@ -89,6 +107,8 @@ fun getServer(cache: DiskLruCache, serverSettings: ServerSettings, clientSetting
 
                 val editor = cache.edit(cacheId)
 
+                val lastModified = HTTP_TIME_FORMATTER.format(ZonedDateTime.now(ZoneOffset.UTC))
+
                 // A null editor means that this file is being written to
                 // concurrently so we skip the cache process
                 if (editor != null) {
@@ -96,6 +116,7 @@ fun getServer(cache: DiskLruCache, serverSettings: ServerSettings, clientSetting
                         LOGGER.trace("Request for $chapterHash/$fileName is being cached and served")
                     }
                     editor.setString(1, contentType)
+                    editor.setString(2, lastModified)
 
                     val tee = CachingInputStream(mdResponse.body.stream,
                         executor, CipherOutputStream(editor.newOutputStream(0), getRc4(cacheId))) {
@@ -115,18 +136,20 @@ fun getServer(cache: DiskLruCache, serverSettings: ServerSettings, clientSetting
                             editor.abort()
                         }
                     }
-                    respond(tee, contentLength, contentType)
+                    respondWithImage(tee, contentLength, contentType, lastModified)
                 } else {
                     if (LOGGER.isTraceEnabled) {
                         LOGGER.trace("Request for $chapterHash/$fileName is being served")
                     }
 
-                    respond(mdResponse.body.stream, contentLength, contentType)
+                    respondWithImage(mdResponse.body.stream, contentLength, contentType, lastModified)
                 }
             }
         }
     }
 
+    CachingFilters
+
     return catchAllHideDetails()
         .then(ServerFilters.CatchLensFailure)
         .then(addCommonHeaders())
@@ -152,8 +175,6 @@ private fun addCommonHeaders(): Filter {
             val response = next(request)
             response.header("Date", HTTP_TIME_FORMATTER.format(ZonedDateTime.now(ZoneOffset.UTC)))
                 .header("Server", "Mangadex@Home Node")
-                .header("Cache-Control", listOf("public", MaxAgeTtl(Constants.MAX_AGE_CACHE).toHeaderValue()).joinToString(", "))
-                .header("Timing-Allow-Origin", "https://mangadex.org")
         }
     }
 }