From 623ac79120a417ec445ce5c106a907fe46734309 Mon Sep 17 00:00:00 2001 From: Nat Goodspeed Date: Thu, 7 Oct 2021 15:32:51 -0400 Subject: SL-16024: Add LL::WorkQueue for passing work items between threads. A typical WorkQueue has a string name, which can be used to find it to post work to it. "Work" is a nullary callable. WorkQueue is a multi-producer, multi-consumer thread-safe queue: multiple threads can service the WorkQueue, multiple threads can post work to it. Work can be scheduled in the future by submitting with a timestamp. In addition, a given work item can be scheduled to run on a recurring basis. A requesting thread servicing a WorkQueue of its own, such as the viewer's main thread, can submit work to another WorkQueue along with a callback to be passed the result (of arbitrary type) of the first work item. The callback is posted to the originating WorkQueue, permitting safe data exchange between participating threads. Methods are provided for different kinds of servicing threads. runUntilClose() is useful for a simple worker thread. runFor(duration) devotes no more than a specified time slice to that WorkQueue, e.g. for use by the main thread. --- indra/llcommon/workqueue.cpp | 114 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 114 insertions(+) create mode 100644 indra/llcommon/workqueue.cpp (limited to 'indra/llcommon/workqueue.cpp') diff --git a/indra/llcommon/workqueue.cpp b/indra/llcommon/workqueue.cpp new file mode 100644 index 0000000000..15e292fb43 --- /dev/null +++ b/indra/llcommon/workqueue.cpp @@ -0,0 +1,114 @@ +/** + * @file workqueue.cpp + * @author Nat Goodspeed + * @date 2021-10-06 + * @brief Implementation for WorkQueue. + * + * $LicenseInfo:firstyear=2021&license=viewerlgpl$ + * Copyright (c) 2021, Linden Research, Inc. + * $/LicenseInfo$ + */ + +// Precompiled header +#include "linden_common.h" +// associated header +#include "workqueue.h" +// STL headers +// std headers +// external library headers +// other Linden headers +#include "llerror.h" +#include "llexception.h" +#include "stringize.h" + +LL::WorkQueue::WorkQueue(const std::string& name): + super(makeName(name)) +{ + // TODO: register for "LLApp" events so we can implicitly close() on + // viewer shutdown. +} + +void LL::WorkQueue::close() +{ + mQueue.close(); +} + +void LL::WorkQueue::runUntilClose() +{ + try + { + for (;;) + { + callWork(mQueue.pop()); + } + } + catch (const Queue::Closed&) + { + } +} + +bool LL::WorkQueue::runPending() +{ + for (Work work; mQueue.tryPop(work); ) + { + callWork(work); + } + return ! mQueue.done(); +} + +bool LL::WorkQueue::runOne() +{ + Work work; + if (mQueue.tryPop(work)) + { + callWork(work); + } + return ! mQueue.done(); +} + +bool LL::WorkQueue::runUntil(const TimePoint& until) +{ + // Should we subtract some slop to allow for typical Work execution time? + // How much slop? + Work work; + while (TimePoint::clock::now() < until && mQueue.tryPopUntil(until, work)) + { + callWork(work); + } + return ! mQueue.done(); +} + +std::string LL::WorkQueue::makeName(const std::string& name) +{ + if (! name.empty()) + return name; + + static thread_local U32 discriminator = 0; + return STRINGIZE("WorkQueue" << discriminator++); +} + +void LL::WorkQueue::callWork(const Queue::DataTuple& work) +{ + // ThreadSafeSchedule::pop() always delivers a tuple, even when + // there's only one data field per item, as for us. + callWork(std::get<0>(work)); +} + +void LL::WorkQueue::callWork(const Work& work) +{ + try + { + work(); + } + catch (...) + { + // No matter what goes wrong with any individual work item, the worker + // thread must go on! Log our own instance name with the exception. + LOG_UNHANDLED_EXCEPTION(getKey()); + } +} + +void LL::WorkQueue::error(const std::string& msg) +{ + LL_ERRS("WorkQueue") << msg << LL_ENDL; +} -- cgit v1.2.3 From c585ddb75e383cdd994d0d99fed8f2de8f955e3c Mon Sep 17 00:00:00 2001 From: Nat Goodspeed Date: Thu, 7 Oct 2021 16:45:15 -0400 Subject: SL-16024: Defend against two threads making "anonymous" WorkQueues. Also make workqueue_test.cpp more robust. --- indra/llcommon/workqueue.cpp | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) (limited to 'indra/llcommon/workqueue.cpp') diff --git a/indra/llcommon/workqueue.cpp b/indra/llcommon/workqueue.cpp index 15e292fb43..ffc9a97dc0 100644 --- a/indra/llcommon/workqueue.cpp +++ b/indra/llcommon/workqueue.cpp @@ -17,10 +17,15 @@ // std headers // external library headers // other Linden headers +#include "llcoros.h" +#include LLCOROS_MUTEX_HEADER #include "llerror.h" #include "llexception.h" #include "stringize.h" +using Mutex = LLCoros::Mutex; +using Lock = LLCoros::LockType; + LL::WorkQueue::WorkQueue(const std::string& name): super(makeName(name)) { @@ -83,8 +88,17 @@ std::string LL::WorkQueue::makeName(const std::string& name) if (! name.empty()) return name; - static thread_local U32 discriminator = 0; - return STRINGIZE("WorkQueue" << discriminator++); + static U32 discriminator = 0; + static Mutex mutex; + U32 num; + { + // Protect discriminator from concurrent access by different threads. + // It can't be thread_local, else two racing threads will come up with + // the same name. + Lock lk(mutex); + num = discriminator++; + } + return STRINGIZE("WorkQueue" << num); } void LL::WorkQueue::callWork(const Queue::DataTuple& work) -- cgit v1.2.3