Downloader Rewrite (#437)

* Downloader rewrite
- Rewrite downloader to use coroutines instead of a thread
- Remove unused Page functions
- Add page progress
- Add ProgressResponseBody
- Add support for canceling a download in the middle of downloading
- Fix clear download queue

* Minor fix

* Minor improvements
- notifyAllClients now launches in another thread and only sends new data every second
- Better handling of download queue checker in step()
- Minor improvements and fixes

* Reorder downloads

* Download in parallel by source

* Remove TODO

server/src/main/kotlin/eu/kanade/tachiyomi/network/OkHttpExtensions.kt

@@ -116,13 +116,13 @@ fun Call.asObservableSuccess(): Observable<Response> {
 @Suppress("UNUSED_PARAMETER")
 fun OkHttpClient.newCallWithProgress(request: Request, listener: ProgressListener): Call {
     val progressClient = newBuilder()
-//        .cache(null)
-//        .addNetworkInterceptor { chain ->
-//            val originalResponse = chain.proceed(chain.request())
-//            originalResponse.newBuilder()
-//                .body(ProgressResponseBody(originalResponse.body!!, listener))
-//                .build()
-//        }
+        .cache(null)
+        .addNetworkInterceptor { chain ->
+            val originalResponse = chain.proceed(chain.request())
+            originalResponse.newBuilder()
+                .body(ProgressResponseBody(originalResponse.body!!, listener))
+                .build()
+        }
         .build()
 
     return progressClient.newCall(request)

server/src/main/kotlin/eu/kanade/tachiyomi/network/ProgressResponseBody.kt

@@ -0,0 +1,44 @@
+package eu.kanade.tachiyomi.network
+
+import okhttp3.MediaType
+import okhttp3.ResponseBody
+import okio.Buffer
+import okio.BufferedSource
+import okio.ForwardingSource
+import okio.Source
+import okio.buffer
+import java.io.IOException
+
+class ProgressResponseBody(private val responseBody: ResponseBody, private val progressListener: ProgressListener) : ResponseBody() {
+
+    private val bufferedSource: BufferedSource by lazy {
+        source(responseBody.source()).buffer()
+    }
+
+    override fun contentType(): MediaType? {
+        return responseBody.contentType()
+    }
+
+    override fun contentLength(): Long {
+        return responseBody.contentLength()
+    }
+
+    override fun source(): BufferedSource {
+        return bufferedSource
+    }
+
+    private fun source(source: Source): Source {
+        return object : ForwardingSource(source) {
+            var totalBytesRead = 0L
+
+            @Throws(IOException::class)
+            override fun read(sink: Buffer, byteCount: Long): Long {
+                val bytesRead = super.read(sink, byteCount)
+                // read() returns the number of bytes read, or -1 if this source is exhausted.
+                totalBytesRead += if (bytesRead != -1L) bytesRead else 0
+                progressListener.update(totalBytesRead, responseBody.contentLength(), bytesRead == -1L)
+                return bytesRead
+            }
+        }
+    }
+}