Increase read timeout.

When range interceptor modifies request it also increases read timeout,
that allows server to do transcoding of the response and skip bytes
to offset value.

Signed-off-by: Yahor Berdnikau <egorr.berd@gmail.com>

subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/interceptors/BaseInterceptorTest.kt

@@ -32,4 +32,4 @@ abstract class BaseInterceptorTest {
             .url(mockWebServerRule.mockWebServer.url("/"))
             .also { additionalParams(it) }
             .build()
-}
+}

subsonic-api/src/integrationTest/kotlin/org/moire/ultrasonic/api/subsonic/interceptors/RangeHeaderInterceptorTest.kt

@@ -31,7 +31,7 @@ class RangeHeaderInterceptorTest : BaseInterceptorTest() {
     }
 
     @Test
-    fun `Should not add range header if request doens't contain it`() {
+    fun `Should not add range header if request doesnt contain it`() {
         mockWebServerRule.mockWebServer.enqueue(MockResponse())
         val request = createRequest { }
 
@@ -56,4 +56,4 @@ class RangeHeaderInterceptorTest : BaseInterceptorTest() {
         executedRequest.headers.names() `should contain` "Range"
         executedRequest.headers["Range"]!! `should equal to` "bytes=$offset-"
     }
-}
+}

subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/interceptors/RangeHeaderInterceptor.kt

@@ -3,10 +3,17 @@ package org.moire.ultrasonic.api.subsonic.interceptors
 import okhttp3.Interceptor
 import okhttp3.Interceptor.Chain
 import okhttp3.Response
+import java.util.concurrent.TimeUnit.MILLISECONDS
+
+internal const val SOCKET_READ_TIMEOUT_DOWNLOAD = 30 * 1000
+// Allow 20 seconds extra timeout pear MB offset.
+internal const val TIMEOUT_MILLIS_PER_OFFSET_BYTE = 0.02
 
 /**
  * Modifies request "Range" header to be according to HTTP standard.
  *
+ * Also increases read timeout to allow server to transcode response and offset it.
+ *
  * See [range rfc](https://tools.ietf.org/html/rfc7233).
  */
 internal class RangeHeaderInterceptor : Interceptor {
@@ -14,12 +21,21 @@ internal class RangeHeaderInterceptor : Interceptor {
         val originalRequest = chain.request()
         val headers = originalRequest.headers()
         return if (headers.names().contains("Range")) {
-            val offset = "bytes=${headers["Range"]}-"
-            chain.proceed(originalRequest.newBuilder()
+            val offsetValue = headers["Range"] ?: "0"
+            val offset = "bytes=$offsetValue-"
+            chain.withReadTimeout(getReadTimeout(offsetValue.toInt()), MILLISECONDS)
+                    .proceed(originalRequest.newBuilder()
                     .removeHeader("Range").addHeader("Range", offset)
                     .build())
         } else {
             chain.proceed(originalRequest)
         }
     }
-}
+
+    // Set socket read timeout. Note: The timeout increases as the offset gets larger. This is
+    // to avoid the thrashing effect seen when offset is combined with transcoding/downsampling
+    // on the server. In that case, the server uses a long time before sending any data,
+    // causing the client to time out.
+    private fun getReadTimeout(offset: Int)
+            = (SOCKET_READ_TIMEOUT_DOWNLOAD + offset * TIMEOUT_MILLIS_PER_OFFSET_BYTE).toInt()
+}