Optimized and refined bounds checking for delimited fields. #24494
+318
−215
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Prior to this CL, whenever we parsed a size we would immediately verify that size against the current EpsCopyInputStream limit. This was correct but was unnecessarily expensive, especially since it was redundant with other checks we perform when parsing sub-messages or strings. In this CL, we remove the eager check when parsing a size, and we perform more targeted and optimized bounds checks at the points where these checks are actually needed. This brings us more into line with how EpsCopyInputStream works in C++. In particular: - We never need to check against the pushed limit, because `IsDone()` is already checking to make sure we ended at the correct limit. - When reading a string (either to alias or to copy), we only need to check against the buffer end, not the limit. This could result in us reading a string that extends beyond the current limit, but the parse will then fail, and the string fields will still be safe to read (even if nonsense). PiperOrigin-RevId: 826744003
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Optimized and refined bounds checking for delimited fields.
Prior to this CL, whenever we parsed a size we would immediately verify that size against the current EpsCopyInputStream limit. This was correct but was unnecessarily expensive, especially since it was redundant with other checks we perform when parsing sub-messages or strings.
In this CL, we remove the eager check when parsing a size, and we perform more targeted and optimized bounds checks at the points where these checks are actually needed. This brings us more into line with how EpsCopyInputStream works in C++.
In particular:
IsDone()is already checking to make sure we ended at the correct limit.