From: Frédéric Perrin <frederic.perrin@att.com>
Date: Thu, 30 Jan 2020 11:14:46 +0000 (+0000)
Subject: Download tiles in chunks
X-Git-Tag: v19.2.fp6~1^2~2
X-Git-Url: http://gitweb.fperrin.net/?p=GpsPrune.git;a=commitdiff_plain;h=860ae36b24e22ff49b23cc5e3b51e9bd5520712b

Download tiles in chunks

Reading byte-per-byte makes the download CPU-limited, while that change
makes it closer to bandwidth-limited
---

diff --git a/src/tim/prune/function/srtm/Srtm3Source.java b/src/tim/prune/function/srtm/Srtm3Source.java
index 14fad59..cc0da79 100644
--- a/src/tim/prune/function/srtm/Srtm3Source.java
+++ b/src/tim/prune/function/srtm/Srtm3Source.java
@@ -110,7 +110,6 @@ public class Srtm3Source extends SrtmSource {
 	public boolean downloadTile(SrtmTile inTile)
 		throws SrtmSourceException
 	{
-		int redirects = 5;
 		URL tileUrl = buildUrl(inTile);
 		File outputFile = getCacheFileName(inTile);
 		System.out.println("Download: Need to download: " + tileUrl);
@@ -120,7 +119,6 @@ public class Srtm3Source extends SrtmSource {
 			HttpURLConnection conn = (HttpURLConnection) tileUrl.openConnection();
 
 			// Define streams
-			FileOutputStream outStream = null;
 			InputStream inStream = null;
 
 			conn.setRequestProperty("User-Agent", "GpsPrune v" + GpsPrune.VERSION_NUMBER);
@@ -138,18 +136,7 @@ public class Srtm3Source extends SrtmSource {
 			{
 				throw new SrtmSourceException("Invalid response from server: " +status+conn.getContent());
 			}
-
-			outStream = new FileOutputStream(outputFile);
-
-			int c;
-			while ((c = inStream.read()) != -1)
-			{
-				outStream.write(c);
-			}
-			// Make sure streams are closed
-			try {inStream.close();} catch (Exception e) {}
-			try {outStream.close();} catch (Exception e) {}
-			return true;
+			return downloadToFile(inStream, outputFile);
 		}
 		catch (IOException e)
 		{
diff --git a/src/tim/prune/function/srtm/SrtmGl1Source.java b/src/tim/prune/function/srtm/SrtmGl1Source.java
index 51e6d77..f8639b7 100644
--- a/src/tim/prune/function/srtm/SrtmGl1Source.java
+++ b/src/tim/prune/function/srtm/SrtmGl1Source.java
@@ -88,10 +88,7 @@ public class SrtmGl1Source extends SrtmSource {
 		try
 		{
 			HttpURLConnection conn = (HttpURLConnection) tileUrl.openConnection();
-			long fileLength = 0L;
-
 			// Define streams
-			FileOutputStream outStream = null;
 			InputStream inStream = null;
 
 			// Documentation about HTTP interface at:
@@ -114,7 +111,6 @@ public class SrtmGl1Source extends SrtmSource {
 				{
 					// Found the tile, we're good
 					inStream = conn.getInputStream();
-					fileLength = conn.getContentLengthLong();
 					break;
 				}
 				else if (status == 302)
@@ -133,22 +129,7 @@ public class SrtmGl1Source extends SrtmSource {
 				}
 			}
 
-			// _progress.setValue(t * 10 + 1);
-			outStream = new FileOutputStream(outputFile);
-
-			// Copy all the bytes to the file
-			int c;
-			long written = 0L;
-			while ((c = inStream.read()) != -1)
-			{
-				outStream.write(c);
-				written++;
-				// _progress.setValue(t * 10 + 1 + (int) ((10 * written) / fileLength));
-			}
-			// Make sure streams are closed
-			try {inStream.close();} catch (Exception e) {}
-			try {outStream.close();} catch (Exception e) {}
-			return true;
+			return downloadToFile(inStream, outputFile);
 		}
 		catch (IOException e)
 		{
diff --git a/src/tim/prune/function/srtm/SrtmSource.java b/src/tim/prune/function/srtm/SrtmSource.java
index 44ceccf..6e49ad1 100644
--- a/src/tim/prune/function/srtm/SrtmSource.java
+++ b/src/tim/prune/function/srtm/SrtmSource.java
@@ -3,11 +3,13 @@ package tim.prune.function.srtm;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
+import java.io.InputStream;
 import java.io.IOException;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipInputStream;
 
 public abstract class SrtmSource {
+	// methods implemented by each source
 	public abstract String getName();
 	public abstract boolean isReadyToUse();
 	public abstract boolean downloadTile(SrtmTile inTile)
@@ -15,6 +17,24 @@ public abstract class SrtmSource {
 	public abstract int getRowSize(SrtmTile inTile);
 	protected abstract String getSourceExtension();
 
+	protected boolean downloadToFile(InputStream inStream, File outputFile)
+		throws IOException
+	{
+		FileOutputStream outStream = new FileOutputStream(outputFile);
+
+		byte[] buffer = new byte[4096];
+		int read = 0;
+		while ((read = inStream.read(buffer)) != -1)
+		{
+			outStream.write(buffer, 0, read);
+		}
+		// Make sure streams are closed
+		try {inStream.close();} catch (Exception e) {}
+		try {outStream.close();} catch (Exception e) {}
+		return true;
+
+	}
+
 	protected int[] slurpTileHeigths(ZipInputStream inStream, int tileSize)
 		throws IOException
 	{
diff --git a/src/tim/prune/function/srtm/SrtmViewfinderSource.java b/src/tim/prune/function/srtm/SrtmViewfinderSource.java
index 17790ae..a25e9c4 100644
--- a/src/tim/prune/function/srtm/SrtmViewfinderSource.java
+++ b/src/tim/prune/function/srtm/SrtmViewfinderSource.java
@@ -130,15 +130,12 @@ public class SrtmViewfinderSource extends SrtmSource {
 		throws SrtmSourceException
 	{
 		URL tileUrl = buildUrl(inTile);
-		File outputFile = getCacheFileName(inTile);
 		System.out.println("Download: Need to download: " + tileUrl);
-
 		try
 		{
 			HttpURLConnection conn = (HttpURLConnection) tileUrl.openConnection();
 
 			// Define streams
-			FileOutputStream outStream = null;
 			InputStream inStream = null;
 
 			conn.setRequestProperty("User-Agent", "GpsPrune v" + GpsPrune.VERSION_NUMBER);
@@ -157,17 +154,7 @@ public class SrtmViewfinderSource extends SrtmSource {
 				throw new SrtmSourceException("Invalid response from server: " +status+conn.getContent());
 			}
 
-			outStream = new FileOutputStream(outputFile);
-
-			int c;
-			while ((c = inStream.read()) != -1)
-			{
-				outStream.write(c);
-			}
-			// Make sure streams are closed
-			try {inStream.close();} catch (Exception e) {}
-			try {outStream.close();} catch (Exception e) {}
-			return true;
+			return downloadToFile(inStream, getCacheFileName(inTile));
 		}
 		catch (IOException e)
 		{