From e584e3202b4596d62434126c9f5ee0f66133a42a Mon Sep 17 00:00:00 2001
From: Mike Primm <mike@primmhome.com>
Date: Mon, 20 Jun 2011 16:58:07 -0500
Subject: [PATCH] Add delay-retry loop for handling temporarily locked image
 file writes

---
 src/main/java/org/dynmap/flat/FlatMap.java    |  4 +--
 .../dynmap/kzedmap/DefaultTileRenderer.java   |  6 ++--
 .../org/dynmap/utils/FileLockManager.java     | 29 +++++++++++++++++++
 3 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/src/main/java/org/dynmap/flat/FlatMap.java b/src/main/java/org/dynmap/flat/FlatMap.java
index 4a12b507..f97e9add 100644
--- a/src/main/java/org/dynmap/flat/FlatMap.java
+++ b/src/main/java/org/dynmap/flat/FlatMap.java
@@ -281,7 +281,7 @@ public class FlatMap extends MapType {
             if(!outputFile.getParentFile().exists())
                 outputFile.getParentFile().mkdirs();
             try {
-                ImageIO.write(im.buf_img, "png", outputFile);
+                FileLockManager.imageIOWrite(im.buf_img, "png", outputFile);
             } catch (IOException e) {
                 Debug.error("Failed to save image: " + outputFile.getPath(), e);
             } catch (java.lang.NullPointerException e) {
@@ -308,7 +308,7 @@ public class FlatMap extends MapType {
                 if(!dayfile.getParentFile().exists())
                     dayfile.getParentFile().mkdirs();
                 try {
-                    ImageIO.write(im_day.buf_img, "png", dayfile);
+                    FileLockManager.imageIOWrite(im_day.buf_img, "png", dayfile);
                 } catch (IOException e) {
                     Debug.error("Failed to save image: " + dayfile.getPath(), e);
                 } catch (java.lang.NullPointerException e) {
diff --git a/src/main/java/org/dynmap/kzedmap/DefaultTileRenderer.java b/src/main/java/org/dynmap/kzedmap/DefaultTileRenderer.java
index ffc3d39b..d5c068f7 100644
--- a/src/main/java/org/dynmap/kzedmap/DefaultTileRenderer.java
+++ b/src/main/java/org/dynmap/kzedmap/DefaultTileRenderer.java
@@ -265,7 +265,7 @@ public class DefaultTileRenderer implements MapTileRenderer {
             if(!fname.getParentFile().exists())
                 fname.getParentFile().mkdirs();
             try {
-                ImageIO.write(img.buf_img, "png", fname);
+                FileLockManager.imageIOWrite(img.buf_img, "png", fname);
             } catch (IOException e) {
                 Debug.error("Failed to save image: " + fname.getPath(), e);
             } catch (java.lang.NullPointerException e) {
@@ -291,7 +291,7 @@ public class DefaultTileRenderer implements MapTileRenderer {
                 if(!dfname.getParentFile().exists())
                     dfname.getParentFile().mkdirs();
                 try {
-                    ImageIO.write(img_day.buf_img, "png", dfname);
+                    FileLockManager.imageIOWrite(img_day.buf_img, "png", dfname);
                 } catch (IOException e) {
                     Debug.error("Failed to save image: " + dfname.getPath(), e);
                 } catch (java.lang.NullPointerException e) {
@@ -365,7 +365,7 @@ public class DefaultTileRenderer implements MapTileRenderer {
             zoomFile.getParentFile().mkdirs();
 
         try {
-            ImageIO.write(zIm, "png", zoomFile);
+            FileLockManager.imageIOWrite(zIm, "png", zoomFile);
             Debug.debug("Saved zoom-out tile at " + zoomFile.getName());
         } catch (IOException e) {
             Debug.error("Failed to save zoom-out tile: " + zoomFile.getName(), e);
diff --git a/src/main/java/org/dynmap/utils/FileLockManager.java b/src/main/java/org/dynmap/utils/FileLockManager.java
index c60efcf5..c3f4d679 100644
--- a/src/main/java/org/dynmap/utils/FileLockManager.java
+++ b/src/main/java/org/dynmap/utils/FileLockManager.java
@@ -1,6 +1,10 @@
 package org.dynmap.utils;
 import java.io.File;
+import java.io.FileNotFoundException;
 import java.util.HashMap;
+import java.awt.image.BufferedImage;
+import java.io.IOException;
+import javax.imageio.ImageIO;
 
 import org.dynmap.Log;
 /**
@@ -102,4 +106,29 @@ public class FileLockManager {
         }
         //Log.info("releaseReadLock(" + f + ")");
     }
+    private static final int MAX_WRITE_RETRIES = 6;
+    /**
+     * Wrapper for IOImage.write - implements retries for busy files
+     */
+    public static void imageIOWrite(BufferedImage img, String type, File fname) throws IOException {
+        int retrycnt = 0;
+        boolean done = false;
+        
+        while(!done) {
+            try {
+                ImageIO.write(img, type, fname);
+                done = true;
+            } catch (FileNotFoundException fnfx) {  /* This seems to be what we get when file is locked by reader */
+                if(retrycnt < MAX_WRITE_RETRIES) {
+                    Log.info("Image file " + fname.getPath() + " - unable to write - retry #" + retrycnt);
+                    try { Thread.sleep(50 << retrycnt); } catch (InterruptedException ix) { throw fnfx; }
+                    retrycnt++;
+                }
+                else {
+                    Log.info("Image file " + fname.getPath() + " - unable to write - failed");
+                    throw fnfx;
+                }
+            }
+        }
+    }
 }