GeoTiffRasterSource Thread Safety

CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 - VLM: Correct incomplete reads when using `MosaicRasterSource`
+- VLM: `GeoTiffRasterSource` reads are now thread safe
 
 ### Removed
 - Summary: Subproject removed. The polygonal summary prototype was moved to GeoTrellis core for the 3.0 release. See: https://github.com/locationtech/geotrellis/blob/master/docs/guide/rasters.rst#polygonal-summary

vlm/src/main/scala/geotrellis/contrib/vlm/geotiff/GeoTiffRasterSource.scala

@@ -57,24 +57,31 @@ case class GeoTiffRasterSource(
       // TODO: shouldn't GridExtent give me Extent for types other than N ?
       Raster(tile, gridExtent.extentFor(gb.toGridType[Long], clamp = false))
     }
-    if (it.hasNext) Some(convertRaster(it.next)) else None
+
+    // We want to use this tiff in different `RasterSource`s, so we
+    // need to lock it in order to garuntee the state of tiff when
+    // it's being accessed by a thread.
+    tiff.synchronized { if (it.hasNext) Some(convertRaster(it.next)) else None }
   }
 
   def read(bounds: GridBounds[Long], bands: Seq[Int]): Option[Raster[MultibandTile]] = {
     val it = readBounds(List(bounds), bands)
-    if (it.hasNext) Some(it.next) else None
+
+    tiff.synchronized { if (it.hasNext) Some(it.next) else None }
   }
 
   override def readExtents(extents: Traversable[Extent], bands: Seq[Int]): Iterator[Raster[MultibandTile]] = {
     val bounds = extents.map(gridExtent.gridBoundsFor(_, clamp = true))
+
     readBounds(bounds, bands)
   }
 
   override def readBounds(bounds: Traversable[GridBounds[Long]], bands: Seq[Int]): Iterator[Raster[MultibandTile]] = {
     val geoTiffTile = tiff.tile.asInstanceOf[GeoTiffMultibandTile]
     val intersectingBounds: Seq[GridBounds[Int]] =
-      bounds.flatMap(_.intersection(this.gridBounds)).
-        toSeq.map(b => b.toGridType[Int])
+      bounds
+        .flatMap(_.intersection(this.gridBounds)).toSeq
+        .map(b => b.toGridType[Int])
 
     geoTiffTile.crop(intersectingBounds, bands.toArray).map { case (gb, tile) =>
       convertRaster(Raster(tile, gridExtent.extentFor(gb.toGridType[Long], clamp = true)))

vlm/src/main/scala/geotrellis/contrib/vlm/geotiff/GeoTiffReprojectRasterSource.scala

@@ -44,12 +44,9 @@ case class GeoTiffReprojectRasterSource(
   protected lazy val backTransform = Transform(crs, baseCRS)
 
   override lazy val gridExtent: GridExtent[Long] = reprojectOptions.targetRasterExtent match {
-      case Some(targetRasterExtent) =>
-        targetRasterExtent.toGridType[Long]
-
-        case None =>
-        ReprojectRasterExtent(baseGridExtent, transform, reprojectOptions)
-    }
+    case Some(targetRasterExtent) => targetRasterExtent.toGridType[Long]
+    case None => ReprojectRasterExtent(baseGridExtent, transform, reprojectOptions)
+  }
 
   lazy val resolutions: List[GridExtent[Long]] =
       gridExtent :: tiff.overviews.map(ovr => ReprojectRasterExtent(ovr.rasterExtent.toGridType[Long], transform))
@@ -72,17 +69,19 @@ case class GeoTiffReprojectRasterSource(
 
   def read(extent: Extent, bands: Seq[Int]): Option[Raster[MultibandTile]] = {
     val bounds = gridExtent.gridBoundsFor(extent, clamp = false)
-    val it = readBounds(List(bounds), bands)
-    if (it.hasNext) Some(it.next) else None
+
+    read(bounds, bands)
   }
 
   def read(bounds: GridBounds[Long], bands: Seq[Int]): Option[Raster[MultibandTile]] = {
     val it = readBounds(List(bounds), bands)
-    if (it.hasNext) Some(it.next) else None
+
+    closestTiffOverview.synchronized { if (it.hasNext) Some(it.next) else None }
   }
 
   override def readExtents(extents: Traversable[Extent], bands: Seq[Int]): Iterator[Raster[MultibandTile]] = {
     val bounds = extents.map(gridExtent.gridBoundsFor(_, clamp = true))
+
     readBounds(bounds, bands)
   }
 
@@ -95,8 +94,12 @@ case class GeoTiffReprojectRasterSource(
       val targetRasterExtent = RasterExtent(
         extent = gridExtent.extentFor(targetPixelBounds, clamp = true),
         cols = targetPixelBounds.width.toInt,
-        rows = targetPixelBounds.height.toInt)
-      val sourceExtent = targetRasterExtent.extent.reprojectAsPolygon(backTransform, 0.001).envelope
+        rows = targetPixelBounds.height.toInt
+      )
+
+      // A tmp workaround for https://github.com/locationtech/proj4j/pull/29
+      // Stacktrace details: https://github.com/geotrellis/geotrellis-contrib/pull/206#pullrequestreview-260115791
+      val sourceExtent = Proj4Transform.synchronized(targetRasterExtent.extent.reprojectAsPolygon(backTransform, 0.001).envelope)
       val sourcePixelBounds = closestTiffOverview.rasterExtent.gridBoundsFor(sourceExtent, clamp = true)
       (sourcePixelBounds, targetRasterExtent)
     }}.toMap

vlm/src/main/scala/geotrellis/contrib/vlm/geotiff/GeoTiffResampleRasterSource.scala

@@ -43,13 +43,13 @@ case class GeoTiffResampleRasterSource(
 
   override lazy val gridExtent: GridExtent[Long] = resampleGrid(tiff.rasterExtent.toGridType[Long])
   lazy val resolutions: List[GridExtent[Long]] = {
-      val ratio = gridExtent.cellSize.resolution / tiff.rasterExtent.cellSize.resolution
-      gridExtent :: tiff.overviews.map { ovr =>
-        val re = ovr.rasterExtent
-        val CellSize(cw, ch) = re.cellSize
-        new GridExtent[Long](re.extent, CellSize(cw * ratio, ch * ratio))
-      }
+    val ratio = gridExtent.cellSize.resolution / tiff.rasterExtent.cellSize.resolution
+    gridExtent :: tiff.overviews.map { ovr =>
+      val re = ovr.rasterExtent
+      val CellSize(cw, ch) = re.cellSize
+      new GridExtent[Long](re.extent, CellSize(cw * ratio, ch * ratio))
     }
+  }
 
   @transient protected lazy val closestTiffOverview: GeoTiff[MultibandTile] =
     tiff.getClosestOverview(gridExtent.cellSize, strategy)
@@ -70,13 +70,14 @@ case class GeoTiffResampleRasterSource(
 
   def read(extent: Extent, bands: Seq[Int]): Option[Raster[MultibandTile]] = {
     val bounds = gridExtent.gridBoundsFor(extent, clamp = false)
-    val it = readBounds(List(bounds), bands)
-    if (it.hasNext) Some(it.next) else None
+
+    read(bounds, bands)
   }
 
   def read(bounds: GridBounds[Long], bands: Seq[Int]): Option[Raster[MultibandTile]] = {
     val it = readBounds(List(bounds), bands)
-    if (it.hasNext) Some(it.next) else None
+
+    closestTiffOverview.synchronized { if (it.hasNext) Some(it.next) else None }
   }
 
   override def readExtents(extents: Traversable[Extent], bands: Seq[Int]): Iterator[Raster[MultibandTile]] = {

vlm/src/test/scala/geotrellis/contrib/vlm/geotiff/GeoTiffRasterSourceMultiThreadingSpec.scala

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2019 Azavea
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package geotrellis.contrib.vlm.geotiff
+
+import geotrellis.contrib.vlm.{RasterSource, Resource}
+import geotrellis.proj4.CRS
+import geotrellis.raster.resample._
+
+import cats.instances.future._
+import cats.instances.list._
+import cats.syntax.traverse._
+import org.scalatest.{AsyncFunSpec, Matchers}
+
+import scala.concurrent.{ExecutionContext, Future}
+
+class GeoTiffRasterSourceMultiThreadingSpec extends AsyncFunSpec with Matchers {
+  val url = Resource.path("img/aspect-tiled.tif")
+  val source = GeoTiffRasterSource(url)
+
+  implicit val ec = ExecutionContext.global
+
+  val iterations = (0 to 100).toList
+
+  /**
+    * readBounds and readExtends are not covered by these tests since these methods return an [[Iterator]].
+    * Due to the [[Iterator]] lazy nature, the lock in these cases should be done on the user side.
+    * */
+  def testMultithreading(rs: RasterSource): Unit = {
+    it("read") {
+      val res = iterations.map { _ => Future { rs.read() } }.sequence.map(_.flatten)
+      res.map { rasters => rasters.length shouldBe iterations.length }
+    }
+
+    it("readBounds - Option") {
+      val res =
+        iterations
+          .map { _ => Future { rs.read(rs.gridBounds, 0 until rs.bandCount) } }
+          .sequence
+          .map(_.flatten)
+
+      res.map { rasters => rasters.length shouldBe iterations.length }
+    }
+  }
+
+  describe("GeoTiffRasterSource should be threadsafe") {
+    testMultithreading(source)
+  }
+
+  describe("GeoTiffRasterReprojectSource should be threadsafe") {
+    testMultithreading(source.reproject(CRS.fromEpsgCode(4326)))
+  }
+
+  describe("GeoTiffRasterResampleSource should be threadsafe") {
+    testMultithreading(source.resample((source.cols * 0.95).toInt , (source.rows * 0.95).toInt, NearestNeighbor))
+  }
+}