From 4c8bf0dec2f279cb5a5014098c3b3526b53ff521 Mon Sep 17 00:00:00 2001
From: Philipp Schneider <github-commit@phil-schneider.de>
Date: Thu, 6 Dec 2012 22:14:47 +0100
Subject: [PATCH] =?UTF-8?q?DATAMONGO-583=20-=20Using=20while=20(=E2=80=A6)?=
 =?UTF-8?q?=20instead=20of=20for=20(=E2=80=A6)=20for=20DBCursors=20to=20av?=
 =?UTF-8?q?oid=20memory=20leak.?=
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Instead of iterating over the DBCursor using a for-loop we now use a while-loop to avoid the potential memory leak outlined in [0].

[0] https://jira.mongodb.org/browse/JAVA-664
---
 .../data/mongodb/core/MongoTemplate.java      | 59 +++++++++++++------
 1 file changed, 42 insertions(+), 17 deletions(-)

diff --git a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoTemplate.java b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoTemplate.java
index 2dd85c7f4..8f7425ce5 100644
--- a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoTemplate.java
+++ b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MongoTemplate.java
@@ -1513,19 +1513,32 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 			CursorPreparer preparer, DbObjectCallback<T> objectCallback, String collectionName) {
 
 		try {
-			DBCursor cursor = collectionCallback.doInCollection(getAndPrepareCollection(getDb(), collectionName));
 
-			if (preparer != null) {
-				cursor = preparer.prepare(cursor);
+			DBCursor cursor = null;
+
+			try {
+
+				cursor = collectionCallback.doInCollection(getAndPrepareCollection(getDb(), collectionName));
+
+				if (preparer != null) {
+					cursor = preparer.prepare(cursor);
+				}
+
+				List<T> result = new ArrayList<T>();
+
+				while (cursor.hasNext()) {
+					DBObject object = cursor.next();
+					result.add(objectCallback.doWith(object));
+				}
+
+				return result;
+
+			} finally {
+
+				if (cursor != null) {
+					cursor.close();
+				}
 			}
-
-			List<T> result = new ArrayList<T>();
-
-			for (DBObject object : cursor) {
-				result.add(objectCallback.doWith(object));
-			}
-
-			return result;
 		} catch (RuntimeException e) {
 			throw potentiallyConvertRuntimeException(e);
 		}
@@ -1535,15 +1548,27 @@ public class MongoTemplate implements MongoOperations, ApplicationContextAware {
 			DocumentCallbackHandler callbackHandler, String collectionName) {
 
 		try {
-			DBCursor cursor = collectionCallback.doInCollection(getAndPrepareCollection(getDb(), collectionName));
 
-			if (preparer != null) {
-				cursor = preparer.prepare(cursor);
+			DBCursor cursor = null;
+
+			try {
+				cursor = collectionCallback.doInCollection(getAndPrepareCollection(getDb(), collectionName));
+
+				if (preparer != null) {
+					cursor = preparer.prepare(cursor);
+				}
+
+				while (cursor.hasNext()) {
+					DBObject dbobject = cursor.next();
+					callbackHandler.processDocument(dbobject);
+				}
+
+			} finally {
+				if (cursor != null) {
+					cursor.close();
+				}
 			}
 
-			for (DBObject dbobject : cursor) {
-				callbackHandler.processDocument(dbobject);
-			}
 		} catch (RuntimeException e) {
 			throw potentiallyConvertRuntimeException(e);
 		}