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https://issues.apache.org/jira/browse/THRIFT-1188?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Roger Meier resolved THRIFT-1188.
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Resolution: Fixed
Fix Version/s: 0.9.2
Assignee: Roger Meier
committed
> C++: Use bit fields for a more compact __isset struct
> -----------------------------------------------------
>
> Key: THRIFT-1188
> URL: https://issues.apache.org/jira/browse/THRIFT-1188
> Project: Thrift
> Issue Type: New Feature
> Components: C++ - Compiler
> Affects Versions: 0.6.1, 0.7
> Reporter: Eric Rannaud
> Assignee: Roger Meier
> Fix For: 0.9.2
>
> Attachments: thrift-cpp-isset-bitfield.patch
>
>
> With the C++ generator, the __isset structure is made of bool fields.
> For Thrift objects with many optional fields, the memory impact of the
> __isset structure with respect to the actual data payload can be significant.
> This patch simply turns each member of __isset into a 1-bit field.
> This patch does not pack the structure as I'm not sure how this should be
> handled in general. As is, it will depend on the compiler whether there is a
> real size gain (with GCC 4.5 the struct is packed at all optimization levels).
> To enforce packing in all cases, should I define a T_ATTRIBUTE_PACKED macro
> in Thrift.h? That wouldn't work for compilers that use #pragma, however.
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