[C++] Integrate std::span support for flyweight API#1027
Closed
mspdt22 wants to merge 1 commit intoaeron-io:masterfrom
Closed
[C++] Integrate std::span support for flyweight API#1027mspdt22 wants to merge 1 commit intoaeron-io:masterfrom
mspdt22 wants to merge 1 commit intoaeron-io:masterfrom
Conversation
mspdt22
force-pushed
the
std-span
branch
3 times, most recently
from
a185e4e to
60af6f0
Compare
The impetus was a bug that we ran into when writing a string-literal to a fixed-width char field:
```c++
flyweight.putFixedChar("hello");
```
This is unsafe:
- If the field size is less than 6, we overrun the buffer and corrupt it.
- If the field size is more than 6, we don't zero pad the rest of it.
Instead, we build on support for the std::string_view getters and setters, which do length checking.
std::span generalizes this to fixed-width fields of all types. Notably, if the size of the std::span
is knowable at compile time, we pay no runtime cost for the length checking, and we should get
similar performance to the existing API which takes a raw pointer.
Further, we add a sbetool option to disable accepting arrays by raw pointer, which should prevent
memcpy operation without bounds checking. This is off by default to avoid a breaking change.
Merged
Contributor
|
#1038 was merged instead. |
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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
The impetus was a bug that we ran into when writing a string-literal to a fixed-width char field:
flyweight.putFixedChar("hello");This is unsafe:
Instead, we build on support for the std::string_view getters and setters, which do length checking. std::span generalizes this to fixed-width fields of all types. Notably, if the size of the std::span is knowable at compile time, we pay no runtime cost for the length checking, and we should get similar performance to the existing API which takes a raw pointer.
Further, we add a sbetool option to disable accepting arrays by raw pointer, which should prevent memcpy operation without bounds checking. This is off by default to avoid a breaking change.