clang allows us to specify, as a default function parameter, an expression
involving a preceding parameter, e.g. (char* ptr, size_t len=strlen(ptr)). The
Microsoft compiler produces errors, requiring more overloads to address that.
Also #undef llstring.h's declaration helper macros at the bottom of the file.
Once we've used them to declare stuff, they need not (should not) be visible
to the consuming source file.
Use new ll_convert_forms() macro in llstring.h to declare, for each
wide-string conversion function of interest, four overloads. The real one, the
nontrivial one, is (const char*, size_t len), implemented in llstring.cpp. Then
(const string&, size_t len), (const char*) and (const string&) are each
trivially implemented with an inline call to (const char*, size_t len).
Notably, we change all S32 len parameters to size_t. Using S32 is old skool.
Tweak each nontrivial implementation in llstring.cpp to accept (const char*,
size_t len) instead of (const string&) with or without explicit length.
Eliminate from llstring.cpp trivial overloads (deriving length from either a
const char* or from a string), since those are now inline in the header.
Of course three of those overloads will be unified once we enable C++17 and
change each relevant parameter to std::string_view, but we're not yet there.
Meanwhile, this suite of overloads minimizes, to the best of our ability, new
string allocations solely for parameter passing. And use of a macro means we
need only change the macro once we get std::string_view.
We take this step because some use cases require (const char*), some require
(const string&, size_t len), others (const char*, size_t len) ... We were
missing some key overloads, and had to work around them by instantiating new
string objects (necessitating both allocation and character copying) just to
pass the desired parameter. Using the macro ensures this consistent set of
overloads for every wide-string conversion function.
Additionally, knowing that the ugly-name overloads exist, ll_convert_forms()
implicitly defines corresponding ll_convert<TARGET>() overloads.
Streamline declarations of utf16str_to_wstring(), wstring_to_utf16str(),
utf8str_to_utf16str(), utf16str_to_utf8str(), utf8str_to_wstring(),
wstring_to_utf8str(), ll_convert_wide_to_wstring() and
ll_convert_wstring_to_wide() using ll_convert_forms().
Use corresponding new ll_convert_cp_forms() macro to declare consistent
overloads for conversion functions accepting an optional unsigned int
code_page parameter. We used to delegate to the .cpp file the implementation
of each overload accepting code_page so llstring.h need not include the
Windows header defining the CP_UTF8 default; this is more simply accomplished
by introducing a small ll_wstring_default_code_page() function to retrieve it
from the .cpp file. That lets us specify the code_page parameter as optional,
using that function as its default value.
Use ll_convert_cp_forms() to streamline declarations of
ll_convert_wide_to_string() and ll_convert_string_to_wide().
Introduce real implementations of ll_convert_wide_to_wstring() and
ll_convert_wstring_to_wide(). The previous implementations merely copied
individual characters, which is wrong: when we convert UTF16LE to UTF32, we
can and should fold multi-character UTF16LE encodings to the corresponding
single UTF32 character. The real implemenations leverage our awareness that
both llutf16string and Windows std::wstring (either variant) use UTF16LE
encoding, so we can reuse the corresponding llutf16string conversions.
Introduce generic ll_convert_length() function, specialized as either
std::strlen() or std::wcslen() depending on parameter type. (Even if
std::wcslen() is derived from classic C, why doesn't the C++ standard library
define a std::strlen(const wchar_t*) overload to call it?)
Fix ll_convert_alias()'s ll_convert_impl specialization's operator() to accept
boost::call_traits::param_type, so we can pass (e.g.) const std::wstring& but
also const wchar_t* instead of const wchar_t*&.
Now that we've enabled -std=c++14 for the whole viewer source tree, that CMake
directive is actually a step backwards -- since it introduces -std=gnu++11 on
the compiler command line, after the one we want, which apparently overrides
c++14 with gnu++11 and causes errors with legitimate C++14 constructs.
In llpreprocessor.h, consider the case of clang on Windows: #define
LL_WCHAR_T_NATIVE there as well as for the Microsoft compiler with /Zc:wchar_t
switch.
In stdtypes.h, inject a LLWCHAR_IS_WCHAR_T symbol to allow the preprocessor to
make decisions about when the types are identical.
llstring.h's conversion logic deals with three types of wide strings
(LLWString, std::wstring and utf16string) based on three types of wide char
(llwchar, wchar_t and U16, respectively). Sometimes they're three distinct
types, sometimes wchar_t is identical to llwchar and sometimes wchar_t is
identical to U16. Rationalize the three cases using ll_convert_u16_alias() and
new ll_convert_wstr_alias() macros.
stringize.h was directly calling wstring_to_utf8str() and utf8str_to_wstring(),
which was producing errors with VS 2019 clang since there isn't actually a
wstring_to_utf8str(std::wstring) overload. Use ll_convert<std::string>()
instead, since that redirects to the relevant ll_convert_wide_to_string()
function. (And now you see why we've been trying to migrate to the uniform
ll_convert<target>() wrapper!) Similarly, call ll_convert<std::wstring>()
instead of a two-step conversion from utf8str_to_wstring(), producing LLWString,
then a character-by-character copy from LLWString to std::wstring. That
isn't even correct: on Windows, we should be encoding from UTF32 to UTF16.
postTo() sets up two-way communication: the caller asks to run work on some
other WorkQueue, expecting an eventual callback on the originating WorkQueue.
That permits us to transport any exception thrown by the work callable back to
rethrow on the originating WorkQueue.
In addition to the name making the blocking explicit, we changed the
signature: instead of specifying a target WorkQueue on which to run,
waitForResult() runs the passed callable on its own WorkQueue.
Why is that? Because, unlike postTo(), we do not require a handshake between
two different WorkQueues. postTo() allows running arbitrary callback code,
setting variables or whatever, on the originating WorkQueue (presumably on the
originating thread). waitForResult() synchronizes using Promise/Future, which
are explicitly designed for cross-thread communication. We need not call
set_value() on the originating thread, so we don't need a postTo() callback
lambda.
The idea is that you can call runOn(target, callable) from a (non-default)
coroutine and block that coroutine until the result becomes available.
As a safety check, we forbid calling runOn() from a thread's default
coroutine, assuming that a given thread's default coroutine is the one
servicing the relevant WorkQueue.
ThreadPool bundles a WorkQueue with the specified number of worker threads to
service it. Each ThreadPool has a name that can be used to locate its
WorkQueue.
Each worker thread calls WorkQueue::runUntilClose().
ThreadPool listens on the "LLApp" LLEventPump for shutdown notification. On
receiving that, it closes its WorkQueue and then join()s each of its worker
threads for orderly shutdown.
Add a settings.xml entry "ThreadPoolSizes", the first LLSD-valued settings
entry to expect a map: pool name->size. The expectation is that usually code
instantiating a particular ThreadPool will have a default size in mind, but it
should check "ThreadPoolSizes" for a user override.
Make idle_startup()'s STATE_SEED_CAP_GRANTED state instantiate a "General"
ThreadPool. This is function-static for lazy initialization.
Eliminate LLMainLoopRepeater, which is completely unreferenced. Any potential
future use cases are better addressed by posting to the main loop's WorkQueue.
Eliminate llappviewer.cpp's private LLDeferredTaskList class, which
implemented LLAppViewer::addOnIdleCallback(). Make addOnIdleCallback() post
work to the main loop's WorkQueue instead.
Nat Goodspeed