Don't wrongly take into account previously downloaded chunks in bitrate calculations

build.sbt

@@ -230,6 +230,8 @@ lazy val cache = project
         // New methdos in Cache.Logger
         ProblemFilters.exclude[MissingMethodProblem]("coursier.Cache#Logger.checkingUpdates"),
         ProblemFilters.exclude[MissingMethodProblem]("coursier.Cache#Logger.checkingUpdatesResult"),
+        // Better overload of Cache.Logger.downloadLength, deprecate previous one
+        ProblemFilters.exclude[MissingMethodProblem]("coursier.Cache#Logger.downloadLength"),
         // Changes to private class TermDisplay#Info
         ProblemFilters.exclude[MissingClassProblem]("coursier.TermDisplay$Info$"),
         ProblemFilters.exclude[AbstractClassProblem]("coursier.TermDisplay$Info"),

cache/src/main/scala/coursier/Cache.scala

@@ -409,7 +409,7 @@ object Cache {
 
                 for (len0 <- Option(conn.getContentLengthLong) if len0 >= 0L) {
                   val len = len0 + (if (partialDownload) alreadyDownloaded else 0L)
-                  logger.foreach(_.downloadLength(url, len))
+                  logger.foreach(_.downloadLength(url, len, alreadyDownloaded))
                 }
 
                 val in = new BufferedInputStream(conn.getInputStream, bufferSize)
@@ -747,9 +747,17 @@ object Cache {
 
   trait Logger {
     def foundLocally(url: String, f: File): Unit = {}
+
     def downloadingArtifact(url: String, file: File): Unit = {}
+
+    @deprecated("Use / override the variant with 3 arguments instead")
     def downloadLength(url: String, length: Long): Unit = {}
+    def downloadLength(url: String, totalLength: Long, alreadyDownloaded: Long): Unit = {
+      downloadLength(url, totalLength)
+    }
+
     def downloadProgress(url: String, downloaded: Long): Unit = {}
+
     def downloadedArtifact(url: String, success: Boolean): Unit = {}
     def checkingUpdates(url: String, currentTimeOpt: Option[Long]): Unit = {}
     def checkingUpdatesResult(url: String, currentTimeOpt: Option[Long], remoteTimeOpt: Option[Long]): Unit = {}

cache/src/main/scala/coursier/TermDisplay.scala

@@ -248,6 +248,7 @@ class TermDisplay(
 
   private case class DownloadInfo(
     downloaded: Long,
+    previouslyDownloaded: Long,
     length: Option[Long],
     startTime: Long,
     updateCheck: Boolean
@@ -258,7 +259,7 @@ class TermDisplay(
     def rate(): Option[Double] = {
       val currentTime = System.currentTimeMillis()
       if (currentTime > startTime)
-        Some(downloaded.toDouble / (System.currentTimeMillis() - startTime) * 1000.0)
+        Some((downloaded - previouslyDownloaded).toDouble / (System.currentTimeMillis() - startTime) * 1000.0)
       else
         None
     }
@@ -387,16 +388,16 @@ class TermDisplay(
   override def downloadingArtifact(url: String, file: File): Unit =
     newEntry(
       url,
-      DownloadInfo(0L, None, System.currentTimeMillis(), updateCheck = false),
+      DownloadInfo(0L, 0L, None, System.currentTimeMillis(), updateCheck = false),
       s"Downloading $url\n"
     )
 
-  override def downloadLength(url: String, length: Long): Unit = {
+  override def downloadLength(url: String, totalLength: Long, alreadyDownloaded: Long): Unit = {
     val info = infos.get(url)
     assert(info != null)
     val newInfo = info match {
       case info0: DownloadInfo =>
-        info0.copy(length = Some(length))
+        info0.copy(length = Some(totalLength), previouslyDownloaded = alreadyDownloaded)
       case _ =>
         throw new Exception(s"Incoherent display state for $url")
     }