These are extremely useful for ecosystems such as Rust. There are a
couple of reasons why:
1. Rust strongly advises against relying on life before/after main, as
it is difficult to reason about. Most users working in Rust will
generally be quite surprised when encountering this concept.
2. Rust and its package manager makes it easy to use packages (crates)
and somewhat less straightforward to consider the implications of
including a dependency.
In case of the `rust_tracy_client` set of packages, I currently have
to warn throughout the documentation of the package that simply
adding a dependency on the bindings package is sufficient to
potentially accidentally broadcast a lot of information about the
instrumented binary to the broader world. This seems like a major
footgun given how easy is it to forget about having added this
dependency.
Ability to manually manage the lifetime of the profiler would be a great
solution to these problems.
The C++11 spec states in [basic.stc.thread] thread storage duration:
2. A variable with thread storage duration shall be initialized before its
first odr-use (3.2) and, if constructed, shall be destroyed on thread exit.
Previously Tracy relied on the TLS data being initialized:
- During thread creation (MSVC).
- Or during first use in a thread, but the initialization was performed for
the whole TLS block.
It seems that new compilers are more granular with how they perform the
initialization, hence rpmalloc init has to be checked before each allocation,
as it cannot be "folded" into, for example, initialization of the profiler
itself.
This enables better bindings in languages that do not have 0-terminated
strings for source/function name. It does not introduce any additional
overhead in languages that do use 0-terminated strings, either, but it
_is_ a breaking API change.
Fixes https://github.com/wolfpld/tracy/issues/53
This function needs to be called for each non-main thread before calling
the `___tracy_alloc_` functions.
Alternative way to achieve this could be initializing the allocator
transparently in the `___tracy_alloc_*` calls.
