but it's safer and saner to put the LL 3ps under the ll:: prefix.
This also allows means it is possible to get rid of that bad "if( TRAGET ...) return() endif()" pattern and rather use include_guard().
Longtime fans will remember that the "dcoroutine" library is a Google Summer
of Code project by Giovanni P. Deretta. He originally called it
"Boost.Coroutine," and we originally added it to our 3p-boost autobuild
package as such. But when the official Boost.Coroutine library came along
(with a very different API), and we still needed the API of the GSoC project,
we renamed the unofficial one "dcoroutine" to allow coexistence.
The "dcoroutine" library had an internal low-level API more or less analogous
to Boost.Context. We later introduced an implementation of that internal API
based on Boost.Context, a step towards eliminating the GSoC code in favor of
official, supported Boost code.
However, recent versions of Boost.Context no longer support the API on which
we built the shim for "dcoroutine." We started down the path of reimplementing
that shim using the current Boost.Context API -- then realized that it's time
to bite the bullet and replace the "dcoroutine" API with the Boost.Fiber API,
which we've been itching to do for literally years now.
Naturally, most of the heavy lifting is in llcoros.{h,cpp} and
lleventcoro.{h,cpp} -- which is good: the LLCoros layer abstracts away most of
the differences between "dcoroutine" and Boost.Fiber.
The one feature Boost.Fiber does not provide is the ability to forcibly
terminate some other fiber. Accordingly, disable LLCoros::kill() and
LLCoprocedureManager::shutdown(). The only known shutdown() call was in
LLCoprocedurePool's destructor.
We also took the opportunity to remove postAndSuspend2() and its associated
machinery: FutureListener2, LLErrorEvent, errorException(), errorLog(),
LLCoroEventPumps. All that dual-LLEventPump stuff was introduced at a time
when the Responder pattern was king, and we assumed we'd want to listen on one
LLEventPump with the success handler and on another with the error handler. We
have never actually used that in practice. Remove associated tests, of course.
There is one other semantic difference that necessitates patching a number of
tests: with "dcoroutine," fulfilling a future IMMEDIATELY resumes the waiting
coroutine. With Boost.Fiber, fulfilling a future merely marks the fiber as
ready to resume next time the scheduler gets around to it. To observe the test
side effects, we've inserted a number of llcoro::suspend() calls -- also in
the main loop.
For a long time we retained a single unit test exercising the raw "dcoroutine"
API. Remove that.
Eliminate llcoro_get_id.{h,cpp}, which provided llcoro::get_id(), which was a
hack to emulate fiber-local variables. Since Boost.Fiber has an actual API for
that, remove the hack.
In fact, use (new alias) LLCoros::local_ptr for LLSingleton's dependency
tracking in place of llcoro::get_id().
In CMake land, replace BOOST_COROUTINE_LIBRARY with BOOST_FIBER_LIBRARY. We
don't actually use the Boost.Coroutine for anything (though there exist
plausible use cases).
Longtime fans will remember that the "dcoroutine" library is a Google Summer
of Code project by Giovanni P. Deretta. He originally called it
"Boost.Coroutine," and we originally added it to our 3p-boost autobuild
package as such. But when the official Boost.Coroutine library came along
(with a very different API), and we still needed the API of the GSoC project,
we renamed the unofficial one "dcoroutine" to allow coexistence.
The "dcoroutine" library had an internal low-level API more or less analogous
to Boost.Context. We later introduced an implementation of that internal API
based on Boost.Context, a step towards eliminating the GSoC code in favor of
official, supported Boost code.
However, recent versions of Boost.Context no longer support the API on which
we built the shim for "dcoroutine." We started down the path of reimplementing
that shim using the current Boost.Context API -- then realized that it's time
to bite the bullet and replace the "dcoroutine" API with the Boost.Fiber API,
which we've been itching to do for literally years now.
Naturally, most of the heavy lifting is in llcoros.{h,cpp} and
lleventcoro.{h,cpp} -- which is good: the LLCoros layer abstracts away most of
the differences between "dcoroutine" and Boost.Fiber.
The one feature Boost.Fiber does not provide is the ability to forcibly
terminate some other fiber. Accordingly, disable LLCoros::kill() and
LLCoprocedureManager::shutdown(). The only known shutdown() call was in
LLCoprocedurePool's destructor.
We also took the opportunity to remove postAndSuspend2() and its associated
machinery: FutureListener2, LLErrorEvent, errorException(), errorLog(),
LLCoroEventPumps. All that dual-LLEventPump stuff was introduced at a time
when the Responder pattern was king, and we assumed we'd want to listen on one
LLEventPump with the success handler and on another with the error handler. We
have never actually used that in practice. Remove associated tests, of course.
There is one other semantic difference that necessitates patching a number of
tests: with "dcoroutine," fulfilling a future IMMEDIATELY resumes the waiting
coroutine. With Boost.Fiber, fulfilling a future merely marks the fiber as
ready to resume next time the scheduler gets around to it. To observe the test
side effects, we've inserted a number of llcoro::suspend() calls -- also in
the main loop.
For a long time we retained a single unit test exercising the raw "dcoroutine"
API. Remove that.
Eliminate llcoro_get_id.{h,cpp}, which provided llcoro::get_id(), which was a
hack to emulate fiber-local variables. Since Boost.Fiber has an actual API for
that, remove the hack.
In fact, use (new alias) LLCoros::local_ptr for LLSingleton's dependency
tracking in place of llcoro::get_id().
In CMake land, replace BOOST_COROUTINE_LIBRARY with BOOST_FIBER_LIBRARY. We
don't actually use the Boost.Coroutine for anything (though there exist
plausible use cases).
The LLApp API used to consist of init(), mainLoop(), cleanup() methods. This
makes sense -- but on Mac that structure was being subverted. The method
called mainLoop() was in fact being called once per frame. There was
initialization code in the method, which (on Mac) needed to be skipped with an
already-initialized bool. There was a 'while' loop which (on Mac) needed to be
turned into an 'if' instead so the method would return after every frame.
Rename LLApp::mainLoop() to frame(). Propagate through subclasses LLAppViewer
and LLCrashLogger. Document the fact that frame() returns true to mean "done."
(This was always the case, but had to be inferred from the code.)
Rename the Mac Objective-C function mainLoop to oneFrame. Rename the C++ free
function it calls from runMainLoop() to pumpMainLoop(). Add comments to
llappdelegate-objc.mm explaining (inferred) control flow.
Change the Linux viewer main() and the Windows viewer WINMAIN() from a single
LLAppViewer::mainLoop() call to repeatedly call frame() until it returns true.
Move initialization code from the top of LLAppViewer::frame() to the init()
method, where it more properly belongs. Remove corresponding
mMainLoopInitialized flag (and all references) from LLAppViewer.
Remove 'while (! LLApp::isExiting())' (or on Mac, 'if (! LLApp::isExiting())')
from LLAppViewer::frame() -- thus unindenting the whole body of the 'while'
and causing many lines of apparent change. (Apologies to reviewers.)
There are four LLApp states: APP_STATUS_RUNNING, APP_STATUS_QUITTING,
APP_STATUS_STOPPED and APP_STATUS_ERROR. Change LLAppViewer::frame() return
value from (isExiting()) (QUITTING or ERROR) to (! isRunning()). I do not know
under what circumstances the state might transition to STOPPED during a
frame() call, but I'm quite sure that if it does, we don't want to call
frame() again. We only want a subsequent call if the state is RUNNING.
Also rename mainLoop() method in LLCrashLogger subclasses
LLCrashLoggerWindows, LLCrashLoggerMac, LLCrashLoggerLinux. Of course it's
completely up to the frame() method whether to yield control; none of those in
fact do. Honor protocol by returning true (frame() is done), even though each
one's main() caller ignores the return value.
In fact LLCrashLoggerWindows::mainLoop() wasn't using the return protocol
correctly anyway, returning wParam or 0 or 1 -- possibly because the return
protocol was never explicitly documented. It should always return true: "I'm
done, don't call me again."
Ansariel