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Optimize initial size in ContentCachingRequestWrapper when contentCacheLimit set #29775

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Optimize initial size in ContentCachingRequestWrapper when contentCacheLimit set #29775

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9 changes: 7 additions & 2 deletions spring-web/src/main/java/org/springframework/web/util/ContentCachingRequestWrapper.java
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,8 @@
*/
public class ContentCachingRequestWrapper extends HttpServletRequestWrapper {

private static final int DEFAULT_INITIAL_BUFFER_SIZE_WHEN_UNKNOWN = 1024;

private final ByteArrayOutputStream cachedContent;

@Nullable
Expand All @@ -74,7 +76,8 @@ public class ContentCachingRequestWrapper extends HttpServletRequestWrapper {
public ContentCachingRequestWrapper(HttpServletRequest request) {
super(request);
int contentLength = request.getContentLength();
this.cachedContent = new ByteArrayOutputStream(contentLength >= 0 ? contentLength : 1024);
this.cachedContent = new ByteArrayOutputStream(contentLength >= 0 ?
contentLength : DEFAULT_INITIAL_BUFFER_SIZE_WHEN_UNKNOWN);
this.contentCacheLimit = null;
}

Expand All @@ -87,7 +90,9 @@ public ContentCachingRequestWrapper(HttpServletRequest request) {
*/
public ContentCachingRequestWrapper(HttpServletRequest request, int contentCacheLimit) {
super(request);
this.cachedContent = new ByteArrayOutputStream(contentCacheLimit);
int contentLength = request.getContentLength();
int guessedInitBufferSize = contentLength >= 0 ? contentLength : DEFAULT_INITIAL_BUFFER_SIZE_WHEN_UNKNOWN;
this.cachedContent = new ByteArrayOutputStream(Math.min(guessedInitBufferSize, contentCacheLimit));
this.contentCacheLimit = contentCacheLimit;
}

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40 changes: 39 additions & 1 deletion spring-web/src/test/java/org/springframework/web/util/ContentCachingRequestWrapperTests.java
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Original file line number Diff line number Diff line change
Expand Up @@ -48,13 +48,15 @@ public class ContentCachingRequestWrapperTests {

@Test
void cachedContent() throws Exception {
byte[] contentPayload = "Hello World".getBytes(CHARSET);
this.request.setMethod(GET);
this.request.setCharacterEncoding(CHARSET);
this.request.setContent("Hello World".getBytes(CHARSET));
this.request.setContent(contentPayload);

ContentCachingRequestWrapper wrapper = new ContentCachingRequestWrapper(this.request);
byte[] response = FileCopyUtils.copyToByteArray(wrapper.getInputStream());
assertThat(wrapper.getContentAsByteArray()).isEqualTo(response);
assertThat(wrapper.getContentAsByteArray()).isEqualTo(contentPayload);
}

@Test
Expand Down Expand Up @@ -117,4 +119,40 @@ void inputStreamFormPostRequest() throws Exception {
assertThat(wrapper.getContentAsByteArray()).isEqualTo(response);
}

/**
* When content limiting, if the content length is known and is lower than the content limit, the internal
* buffer should allocate that size. This exaggerates this scenario by using a very large content limit that
* would cause an OOM Error likely otherwise.
*/
@Test
void cachedContentWithLimitKnownLengthAvoidOverAllocation() throws Exception {
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@ryanrupp ryanrupp Jan 5, 2023 •
edited
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This is a bit awkward to test without exposing some internals in a package private method or something (maybe reflection to grab the byte array size). Basically, using a really large content limit before this change could cause an OOM Error if you ran this test with < 2GB heap or so. After this change it wouldn't use the 2GB limit, it would just allow growing to it (but the tests don't exercise growing to it as that's not relevant here).

byte[] contentPayload = "Hello World".getBytes(CHARSET);
this.request.setMethod(POST);
this.request.setCharacterEncoding(CHARSET);
this.request.setContent(contentPayload);

ContentCachingRequestWrapper wrapper = new ContentCachingRequestWrapper(this.request, Integer.MAX_VALUE);

byte[] contents = FileCopyUtils.copyToByteArray(wrapper.getInputStream());
assertThat(contents).isEqualTo(contentPayload);
assertThat(wrapper.getContentAsByteArray()).isEqualTo(contentPayload);
}

/**
* When content limiting, if the content length is unknown, rather than allocating the content limit upfront
* (which may be quite a bit larger than the actual request), a smaller initial buffer should be used that is
* allowed to grow as needed up to the limit. This exaggerates this scenario by using a very large content limit
* that would cause an OOM Error likely otherwise.
*/
@Test
void cachedContentWithLimitUnknownLengthAvoidOverAllocation() throws Exception {
this.request.setMethod(POST);
this.request.setCharacterEncoding(CHARSET);

ContentCachingRequestWrapper wrapper = new ContentCachingRequestWrapper(this.request, Integer.MAX_VALUE);

byte[] contents = FileCopyUtils.copyToByteArray(wrapper.getInputStream());
assertThat(contents).isEmpty();
assertThat(wrapper.getContentAsByteArray()).isEmpty();
}
}