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New
WatchService based on Java 7's WatchService
The goal of this is to add an abstraction layer so that we can define new kinds of `WatchService`s. This way, we can use the default `WatchService` provided by the JDK on certain platform (e.g. Windows), and revert back to the `PollingWatchService` that existed before, on machine where there's no native support for monitoring the file system (e.g. macOS). This commit includes an adapter for the `WatchService` from Java NIO to our new interface, and a port of the existing `PollingWatchService`.
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| Original file line number | Diff line number | Diff line change |
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@@ -3,6 +3,6 @@ scala: | |
| - 2.10.6 | ||
| - 2.11.11 | ||
| - 2.12.2 | ||
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| - 2.13.0-M1 | ||
| jdk: | ||
| - oraclejdk8 | ||
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,165 @@ | ||
| package sbt.io | ||
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| import java.nio.file.{ClosedWatchServiceException, Files, Path => JPath, Watchable, WatchKey, WatchEvent} | ||
| import java.nio.file.StandardWatchEventKinds._ | ||
| import java.util.{List => JList} | ||
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| import sbt.io.syntax._ | ||
| import scala.collection.mutable | ||
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| /** A `WatchService` that polls the filesystem every `delayMs` milliseconds. */ | ||
| class PollingWatchService(delayMs: Long) extends WatchService { | ||
| private var closed: Boolean = false | ||
| private val thread: PollingThread = new PollingThread(delayMs) | ||
| private val keys: mutable.Map[JPath, PollingWatchKey] = mutable.Map.empty | ||
| private val pathLengthOrdering: Ordering[JPath] = | ||
| Ordering.fromLessThan { | ||
| case (null, _) | (_, null) => true | ||
| case (a, b) => | ||
| a.toString.length < b.toString.length | ||
| } | ||
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| private val watched: mutable.Map[JPath, Seq[WatchEvent.Kind[JPath]]] = | ||
| mutable.Map.empty | ||
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| override def close(): Unit = | ||
| closed = true | ||
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| override def init(): Unit = { | ||
| ensureNotClosed() | ||
| thread.start() | ||
| while (!thread.initDone) { | ||
| Thread.sleep(100) | ||
| } | ||
| } | ||
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| override def poll(timeoutMs: Long): WatchKey = thread.keysWithEvents.synchronized { | ||
| ensureNotClosed() | ||
| thread.keysWithEvents.headOption.map { k => | ||
| thread.keysWithEvents -= k | ||
| k | ||
| }.orNull | ||
| } | ||
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| override def pollEvents(): Map[WatchKey, Seq[WatchEvent[JPath]]] = thread.keysWithEvents.synchronized { | ||
| import scala.collection.JavaConverters._ | ||
| ensureNotClosed() | ||
| val events = thread.keysWithEvents.map { k => | ||
| k -> k.pollEvents().asScala.asInstanceOf[Seq[WatchEvent[JPath]]] | ||
| } | ||
| thread.keysWithEvents.clear() | ||
| events.toMap | ||
| } | ||
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| override def register(path: JPath, events: WatchEvent.Kind[JPath]*): WatchKey = { | ||
| ensureNotClosed() | ||
| val key = new PollingWatchKey(thread, path, new java.util.ArrayList[WatchEvent[_]]) | ||
| keys += path -> key | ||
| watched += path -> events | ||
| key | ||
| } | ||
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| private def ensureNotClosed(): Unit = | ||
| if (closed) throw new ClosedWatchServiceException | ||
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| private class PollingThread(delayMs: Long) extends Thread { | ||
| private var fileTimes: Map[JPath, Long] = Map.empty | ||
| var initDone = false | ||
| val keysWithEvents = mutable.LinkedHashSet.empty[WatchKey] | ||
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| override def run(): Unit = | ||
| while (!closed) { | ||
| populateEvents() | ||
| initDone = true | ||
| Thread.sleep(delayMs) | ||
| } | ||
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| def getFileTimes(): Map[JPath, Long] = { | ||
| val results = mutable.Map.empty[JPath, Long] | ||
| watched.toSeq.sortBy(_._1)(pathLengthOrdering).foreach { | ||
| case (p, _) => | ||
| if (!results.contains(p)) | ||
| p.toFile.allPaths.get.foreach(f => results += f.toPath -> f.lastModified) | ||
| } | ||
| results.toMap | ||
| } | ||
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| private def addEvent(path: JPath, ev: WatchEvent[JPath]): Unit = keysWithEvents.synchronized { | ||
| keys.get(path).foreach { k => | ||
| keysWithEvents += k | ||
| k.events.add(ev) | ||
| } | ||
| } | ||
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| private def populateEvents(): Unit = { | ||
| val newFileTimes = getFileTimes() | ||
| val newFiles = newFileTimes.keySet | ||
| val oldFiles = fileTimes.keySet | ||
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| val deletedFiles = (oldFiles -- newFiles).toSeq | ||
| val createdFiles = (newFiles -- oldFiles).toSeq | ||
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| val modifiedFiles = fileTimes.collect { | ||
| case (p, oldTime) if newFileTimes.getOrElse(p, 0L) > oldTime => p | ||
| } | ||
| fileTimes = newFileTimes | ||
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| deletedFiles.foreach { deleted => | ||
| val parent = deleted.getParent | ||
| if (watched.getOrElse(parent, Seq.empty).contains(ENTRY_DELETE)) { | ||
| val ev = new PollingWatchEvent(parent.relativize(deleted), ENTRY_DELETE) | ||
| addEvent(parent, ev) | ||
| } | ||
| watched -= deleted | ||
| } | ||
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| createdFiles.sorted(pathLengthOrdering).foreach { | ||
| case dir if Files.isDirectory(dir) => | ||
| val parent = dir.getParent | ||
| val parentEvents = watched.getOrElse(parent, Seq.empty) | ||
| if (parentEvents.contains(ENTRY_CREATE)) { | ||
| val ev = new PollingWatchEvent(parent.relativize(dir), ENTRY_CREATE) | ||
| addEvent(parent, ev) | ||
| } | ||
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| case file => | ||
| val parent = file.getParent | ||
| if (watched.getOrElse(parent, Seq.empty).contains(ENTRY_CREATE)) { | ||
| val ev = new PollingWatchEvent(parent.relativize(file), ENTRY_CREATE) | ||
| addEvent(parent, ev) | ||
| } | ||
| } | ||
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| modifiedFiles.foreach { | ||
| case file => | ||
| val parent = file.getParent | ||
| if (watched.getOrElse(parent, Seq.empty).contains(ENTRY_MODIFY)) { | ||
| val ev = new PollingWatchEvent(parent.relativize(file), ENTRY_MODIFY) | ||
| addEvent(parent, ev) | ||
| } | ||
| } | ||
| } | ||
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| } | ||
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| private class PollingWatchKey(origin: PollingThread, | ||
| override val watchable: Watchable, | ||
| val events: JList[WatchEvent[_]]) extends WatchKey { | ||
| override def cancel(): Unit = () | ||
| override def isValid(): Boolean = true | ||
| override def pollEvents(): java.util.List[WatchEvent[_]] = origin.keysWithEvents.synchronized { | ||
| origin.keysWithEvents -= this | ||
| val evs = new java.util.ArrayList[WatchEvent[_]](events) | ||
| events.clear() | ||
| evs | ||
| } | ||
| override def reset(): Boolean = true | ||
| } | ||
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| } | ||
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| private class PollingWatchEvent(override val context: JPath, | ||
| override val kind: WatchEvent.Kind[JPath]) extends WatchEvent[JPath] { | ||
| override val count: Int = 1 | ||
| } | ||
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