postIfOpen() provides a no-exception alternative to post(), which blocks if
full but throws if closed. postIfOpen() likewise blocks if full, but returns
true if able to post and false if the queue was closed.
ThreadSafeSchedule::tryPopUntil() (and therefore tryPopFor()) was simply
delegating to LLThreadSafeQueue::tryPopUntil(), with an adjusted timeout since
we want to wake up as soon as the head item, if any, becomes ready. But then
we have to loop back to retry the pop to actually deal with that head item.
In addition, ThreadSafeSchedule::popWithTime() was spinning rather than
properly blocking on a timed condition variable. Fixed.
ThreadSafeSchedule orders its items by timestamp, which can be passed either
implicitly or explicitly. The timestamp specifies earliest delivery time: an
item cannot be popped until that time.
Add initial tests.
Tweak the LLThreadSafeQueue base class to support ThreadSafeSchedule:
introduce virtual canPop() method to report whether the current head item is
available to pop. The base class unconditionally says yes, ThreadSafeSchedule
says it depends on whether its timestamp is still in the future.
This replaces the protected pop_() overload accepting a predicate. Rather than
explicitly passing a predicate through a couple levels of function call, use
canPop() at the level it matters. Runtime behavior that varies depending on
an object's leaf class is what virtual functions were invented for.
Give pop_() a three-state enum return so pop() can distinguish between "closed
and empty" (throws exception) versus "closed, not yet drained because we're
not yet ready to pop the head item" (waits).
Also break out protected tryPopUntil_() method, the body logic of
tryPopUntil(). The public method locks the data structure, the protected
method requires that its caller has already done so.
Add chrono.h with a more full-featured LL::time_point_cast() function than the
one found in <chrono>, which only converts between time_point durations, not
between time_points based on different clocks.
Add LL::PriorityQueueAdapter, a wrapper for std::priority_queue to make its
API more closely resemble std::queue for drop-in use as LLThreadSafeQueue's
underlying QueueT container.
Support move-only element types.
Factor out some implementation redundancy: wrap actual push semantics as
push_(), actual pop semantics as pop_(). push(), tryPush() and tryPushUntil()
now call push_(); pop(), tryPop() and tryPopUntil() now call pop_().
Break out tryLock() and tryLockUntil() methods that, if they can lock, run the
passed callable. Then tryPush(), tryPushUntil(), tryPop() and tryPopUntil()
pass lambdas containing the meat of the original method body to tryLock() or
tryLockUntil(), as appropriate.
First, parameterize LLThreadSafeQueue's queue type. This allows us to
substitute (e.g.) a std::priority_queue for a particular instance.
Use std::queue for the default queue type, changing the operations invoked on
the queue type from std::deque methods to std::queue methods.
Rename published methods from (e.g.) pushFront() and popBack() to simple
push() and pop(), retaining legacy names as aliases. Not only are the overt
Front and Back unnecessary; they're the opposite of how std::queue uses
std::deque or std::list, so they only confuse the reader.
Break out tryPushUntil() method. We already use that logic internally to
tryPushFor(), so it's just as easy to publish it as its own entry point.
Add tryPopFor() and tryPopUntil() to allow limiting the time we'll wait for a
queue item to become available.
Specifically:
LLCoros::Mutex means boost::fibers::mutex
LLCoros::LockType means std::unique_lock<boost::fibers::mutex>
LLCoros::ConditionVariable means boost::fibers::condition_variable
LLCoros::cv_status means boost::fibers::cv_status
So as not to drag in all of boost::fibers::mutex.hpp or condition_variable.hpp
for each consumer of llcoros.h, instead #define LLCOROS_MUTEX_HEADER and
LLCOROS_CONDVAR_HEADER. Those who need them can #include the relevant macro.
Update llcond.h and llthreadsafequeue.h accordingly.
Also isClosed() and explicit operator bool() to detect closed state.
close() causes every subsequent pushFront() to throw
LLThreadSafeQueueInterrupt. Once the queue is drained, it causes popBack() to
throw likewise.
This also introduces LLContinueError for exceptions which should interrupt
some part of viewer processing (e.g. the current coroutine) but should attempt
to let the viewer session proceed.
Derive all existing viewer exception classes from LLException rather than from
std::runtime_error or std::logic_error.
Use BOOST_THROW_EXCEPTION() rather than plain 'throw' to enrich the thrown
exception with source file, line number and containing function.
Nat Goodspeed