BDE 4.8.0 Release¶

Schedule¶

The BDE team announces that the BDE 4.8.0 production release was completed on Sunday, May 19, 2024.

BDE 4.8.0 Release Highlights¶

Added transparent `try_emplace` to `bsl::map` and `bsl::unordered_map`¶

The transparent overloads of try_emplace that have been added to the standard for C++26 have been added to bsl::map and bsl::unordered_map.

See overloads #3 and #6 on map::try_emplace and unordered_map::try_emplace

Fix link coercion¶

BSL includes link coercion symbols to actively prevent object files compiled with incompatible C++ flags being linked together, as this can result in ABI breaks and undefined behavior.

The new linker (presumably the one from RHEL7) started to actively garbage-collect data sections containing link coercion symbols and successfully link binary incompatible object files and libraries. This release specifically marks those data sections in-use and prevent object files and libraries built with incompatible flags being linked together.

Performance Improvement for Logging¶

This release contains an improvement to how log records are initialized that results in a 50% improvement in the baseline throughput (on Linux) of recording log messages.

The log message recording infrastructure was updated to cache ostream instances across log messages, avoiding contention and other costs for initializing a new ostream.

Thanks to Cameron Desrochers for this contribution.

Updated `bsitzo::TzdfTimezoneUtil` Mapping for TZDF 1¶

Mirroring fixes to Bloomberg’s infrastructure for time zones, the bsitzo_tzdftimezoneutil component, now maps TZDF id 1 to Pacific/Kwajalein rather than Etc/GMT+12.

Etc/GMT+12 was previously specified for TZDF identifier 1 because the TZDF/timesvc data had been incorrect for that time zone. That data has been fixed allowing us to update the mapping.

TZDF uses Enewetak, rather than Kwajalein (both atolls in the Marshall Islands), to identify the time zone. The error in TZDF/timesvc data stemmed from when those atolls changed from UTC-12 to UT+12 in 1993:

From wikipedia:

The Kwajalein Atoll of the Marshall Islands formerly observed

UTC-12:00, which made communicating and trading with the other atolls

observing UTC+12:00 a day ahead highly problematic. Due to this, the

Kwajalein Atoll advanced 24 hours to the Eastern Hemisphere side of the

International Date Line by skipping 21 August 1993.

Thanks to Andrew Paprocki for this contribution.

Fixed DRQSs:¶

Summary
ball::Log::setCategory: tsan race
C++20 work: ‘bslstl_stringview’: Re-enable iterator CTOR and (start\|end)s_with methods
Update ‘bsic_hoststate’ to support node numbers above 64k
stringop-overflow error
Please add transparent try_emplace to ‘bsl::map’ and ‘bsl::unordered_map’
Reuse ‘bsl::ostream’ to reduce locale overhead when logging
Fix UB in ‘bdlb::BitmaskUtil’
Regression in ball logging in BDE 4.6.0
BDE link coercion symbols are not working in recent releases.
‘bsitzo_TzdfTimezoneUtil’: Change TZDF 1 mapping from Etc/GMT+12 to Pacific/Kwajalein