LLThread::currentID() used to return a U32, a distinct unsigned value
incremented by explicitly constructing LLThread or by calling LLThread::
registerThreadID() early in a thread launched by other means. The latter
imposed an unobvious requirement on new code based on std::thread. Using
std:🧵:id instead delegates to the compiler/library the problem of
distinguishing threads launched by any means.
Change lots of explicit U32 declarations. Introduce LLThread::id_t typedef to
avoid having to run around fixing uses again if we later revisit this decision.
LLMutex, which stores an LLThread::id_t, wants a distinguished value meaning
NO_THREAD, and had an enum with that name. But as std:🧵:id promises
that the default-constructed value is distinct from every valid value,
NO_THREAD becomes unnecessary and goes away.
Because LLMutex now stores LLThread::id_t instead of U32, make llmutex.h
#include "llthread.h" instead of the other way around. This makes LLMutex an
incomplete type within llthread.h, so move LLThread::lockData() and
unlockData() to the .cpp file. Similarly, remove llrefcount.h's #include
"llmutex.h" to break circularity; instead forward-declare LLMutex.
It turns out that a number of source files assumed that #include "llthread.h"
would get the definition for LLMutex. Sprinkle #include "llmutex.h" as needed.
In the SAFE_SSL code in llcorehttp/httpcommon.cpp, there's an ssl_thread_id()
callback that returns an unsigned long to the SSL library. When LLThread::
currentID() was U32, we could simply return that. But std:🧵:id is very
deliberately opaque, and can't be reinterpret_cast to unsigned long.
Fortunately it can be hashed because std::hash is specialized with that type.
The new LLCoros::Stop exception is intended to terminate long-lived coroutines
-- not interrupt mainstream shutdown processing. Only throw it on an
explicitly-launched coroutine.
Make LLCoros::getName() (used by the above test) static. As with other LLCoros
methods, it might be called after the LLCoros LLSingleton instance has been
deleted. Requiring the caller to call instance() implies a possible need to
also call wasDeleted(). Encapsulate that nuance into a static method instead.
The new close(void) method simply acquires the logic from
~LLCoprocedureManager() (which now calls close()). It's useful, even if only
in test programs, to be able to shut down all existing LLCoprocedurePools
without having to name them individually -- and without having to destroy the
LLCoprocedureManager singleton instance. Deleting an LLSingleton should be
done only once per process, whereas test programs want to reset the
LLCoprocedureManager after each test.
Reinstate LLCoprocedureManager::countPending() and count() methods. These were
removed because boost::fibers::buffered_channel has no size() method, but
since all users run within a single thread, it works to increment and
decrement a simple counter.
Add count information and max queue size to log messages.
Since the consuming coroutine LLCoprocedurePool::coprocedureInvokerCoro() has
been observed to outlive the LLCoprocedurePool instance that owns the
CoprocQueue_t, closing that queue isn't enough to keep the coroutine from
crashing at shutdown: accessing a deleted CoprocQueue_t is fatal whether or
not it's been closed.
Make LLCoprocedurePool store a shared_ptr to a heap CoprocQueue_t instance,
and pass that shared_ptr by value to consuming coroutines. That way the
CoprocQueue_t instance is guaranteed to live as long as the last interested
party.
By the time "LLApp" listeners are notified that the app is quitting, the
mainloop is no longer running. Even though those listeners do things like
close work queues and inject exceptions into pending promises, any coroutines
waiting on those resources must regain control before they can notice and shut
down properly. Add a final "LLApp" listener that resumes ready coroutines a
few more times.
Make sure every other "LLApp" listener is positioned before that new one.
Add LLCoros::TempStatus instances around known suspension points so
printActiveCoroutines() can report what each suspended coroutine is waiting
for.
Similarly, sprinkle checkStop() calls at known suspension points.
Make LLApp::setStatus() post an event to a new LLEventPump "LLApp" with a
string corresponding to the status value being set, but only until
~LLEventPumps() -- since setStatus() also gets called very late in the
application's lifetime.
Make postAndSuspendSetup() (used by postAndSuspend(), suspendUntilEventOn(),
postAndSuspendWithTimeout(), suspendUntilEventOnWithTimeout()) add a listener
on the new "LLApp" LLEventPump that pushes the new LLCoros::Stopping exception
to the coroutine waiting on the LLCoros::Promise. Make it return the new
LLBoundListener along with the previous one.
Accordingly, make postAndSuspend() and postAndSuspendWithTimeout() store the
new LLBoundListener returned by postAndSuspendSetup() in a LLTempBoundListener
(as with the previous one) so it will automatically disconnect once the wait
is over.
Make each LLCoprocedurePool instance listen on "LLApp" with a listener that
closes the queue on which new work items are dispatched. Closing the queue
causes the waiting dispatch coroutine to terminate. Store the connection in an
LLTempBoundListener on the LLCoprocedurePool so it will disconnect
automatically on destruction.
Refactor the loop in coprocedureInvokerCoro() to instantiate TempStatus around
the suspending call.
Change a couple spammy LL_INFOS() calls to LL_DEBUGS(). Give all logging calls
in that module a "CoProcMgr" tag to make it straightforward to re-enable the
LL_DEBUGS() calls as desired.
Using boost::fibers::unbuffered_channel can block the mainthread when calling mPendingCoprocs.push (LLCoprocedurePool::enqueueCoprocedure)
From the documentation:
- If a fiber attempts to send a value through an unbuffered channel and no fiber is waiting to receive the value, the channel will block the sending fiber.
This can happen if LLCoprocedurePool::coprocedureInvokerCoro is running a coroutine and this coroutine calls yield, resuming the viewers main loop. If inside
the main loop someone calls LLCoprocedurePool::enqueueCoprocedure now push will block, as there's no one waiting for a result right now.
The wait would be in LLCoprocedurePool::coprocedureInvokerCoro at the start of the while loop, but we have not reached that yet again as LLCoprocedurePool::coprocedureInvokerCoro
did yield before reaching pop_wait_for.
The result is a deadlock.
boost::fibers::buffered_channel will not block as long as there's space in the channel. A size of 4096 (DEFAULT_QUEUE_SIZE) should be plenty enough for this.
Use LLStringUtil::getenv() or getoptenv() whenever we fetch a string that will
be used as a pathname.
Use LLFile::tmpdir() instead of getenv("TEMP").
As an added extra-special bonus, finally clean up $TMP/llcontrol-test-zzzzzz
directories that have been accumulating every time we run a local build!
Nat Goodspeed