It is only needed for libuv < 1.19, but since commit c050d6a01e
(string(TIMESTAMP): add %f specifier for microseconds, 2022-01-27,
v3.23.0-rc1~59^2) we require libuv >= 1.28.
Previously if an AUTOGEN process like moc exited with a non-zero exit
code, cmWorkerPool would not populate the result's ErrorMessage
because it mistakenly thought that if the ExitCode / TermSignal had a
non-zero value, the ErrorMessage must have already been set.
This was a wrong assumption.
Instead, check if ErrorMessage is empty, and if it is, set it to
whatever the exit code or term signal number is.
(1) All CV use must hold the corresponding mutex, otherwise race
conditions happen. This is mandated by the C++ standard.
(2) Introduce a separate CV for the thread waiting for other jobs to
finish before running a fence. This avoids waking up all other workers
blindly. Correctly wake that thread up when the processing of outstanding
jobs is done.
(3) Split the waiting for a fence to become runnable from a fence is
pending. This avoids problems if more than one fence can end up on the
queue. The thread that took a fence off the queue is responsible for
clearing the fence processing flag.
Provide a standardized way to handle the C++ "standard" headers
customized to be used with current CMake C++ standard constraints.
Offer under directory `cm` headers which can be used as direct
replacements of the standard ones. For example:
#include <cm/string_view>
can be used safely for CMake development in place of the `<string_view>`
standard header.
Fixes: #19491
This patch is generated by a python script that uses regular expressions to
search for string concatenation patterns of the kind
```
std::string str = <ARG0>;
str += <ARG1>;
str += <ARG2>;
...
```
and replaces them with a single `cmStrCat` call
```
std::string str = cmStrCat(<ARG0>, <ARG1>, <ARG2>, ...);
```
If any `<ARGX>` is itself a concatenated string of the kind
```
a + b + c + ...;
```
then `<ARGX>` is split into multiple arguments for the `cmStrCat` call.
If there's a sequence of literals in the `<ARGX>`, then all literals in the
sequence are concatenated and merged into a single literal argument for
the `cmStrCat` call.
Single character strings are converted to single char arguments for
the `cmStrCat` call.
`std::to_string(...)` wrappings are removed from `cmStrCat` arguments,
because it supports numeric types as well as string types.
`arg.substr(x)` arguments to `cmStrCat` are replaced with
`cm::string_view(arg).substr(x)`
This moves the `cmWorkerPoolInternal::WorkerT` class to `cmWorkerPoolWorker`
and changes the thread start interface to make it independent of the
`cmWorkerPoolInternal` type.
Don't pass the desired worker thread count to the `cmWorkerPool::Process()`
method but set it separately with the new `cmWorkerPool::SetThreadCount`
method. This allows calling `cmWorkerPool::Process()` repeatedly without
having to pass the thread count every time.
This factors out the concurrency framework in `cmQtAutoGeneratorMocUic` to a
dedicated class `cmWorkerPool` which might be reused in other places.
`cmWorkerPool` supports fence jobs that require that
- all other jobs before in the queue have been processed before the fence
job processing gets started,
- no jobs later in the queue will be processed before the fence job processing
has been completed.
Fence jobs are needed where the completion of all previous jobs in the queue
is a requirement for further processing. E.g. in `cmQtAutoGeneratorMocUic`
the generation of `mocs_compilation.cpp` requires that all previous
source file parse jobs have been completed.
