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Diffstat (limited to 'src/VBox/Main/glue/EventQueue.cpp')
| -rw-r--r-- | src/VBox/Main/glue/EventQueue.cpp | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/src/VBox/Main/glue/EventQueue.cpp b/src/VBox/Main/glue/EventQueue.cpp new file mode 100644 index 00000000..4f5a4a36 --- /dev/null +++ b/src/VBox/Main/glue/EventQueue.cpp @@ -0,0 +1,257 @@ +/* $Id: EventQueue.cpp $ */ +/** @file + * Event queue class declaration. + */ + +/* + * Copyright (C) 2013-2022 Oracle and/or its affiliates. + * + * This file is part of VirtualBox base platform packages, as + * available from https://www.virtualbox.org. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, in version 3 of the + * License. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <https://www.gnu.org/licenses>. + * + * SPDX-License-Identifier: GPL-3.0-only + */ + +/** @todo Adapt / update documentation! */ + +#include "VBox/com/EventQueue.h" + +#include <iprt/asm.h> +#include <new> /* For bad_alloc. */ + +#include <iprt/err.h> +#include <iprt/semaphore.h> +#include <iprt/time.h> +#include <iprt/thread.h> +#include <iprt/log.h> + +namespace com +{ + +// EventQueue class +//////////////////////////////////////////////////////////////////////////////// + +EventQueue::EventQueue(void) + : mUserCnt(0), + mShutdown(false) +{ + int rc = RTCritSectInit(&mCritSect); + AssertRC(rc); + + rc = RTSemEventCreate(&mSemEvent); + AssertRC(rc); +} + +EventQueue::~EventQueue(void) +{ + int rc = RTCritSectDelete(&mCritSect); + AssertRC(rc); + + rc = RTSemEventDestroy(mSemEvent); + AssertRC(rc); + + EventQueueListIterator it = mEvents.begin(); + while (it != mEvents.end()) + { + (*it)->Release(); + it = mEvents.erase(it); + } +} + +/** + * Process events pending on this event queue, and wait up to given timeout, if + * nothing is available. + * + * Must be called on same thread this event queue was created on. + * + * @param cMsTimeout The timeout specified as milliseconds. Use + * RT_INDEFINITE_WAIT to wait till an event is posted on the + * queue. + * + * @returns VBox status code + * @retval VINF_SUCCESS if one or more messages was processed. + * @retval VERR_TIMEOUT if cMsTimeout expired. + * @retval VERR_INVALID_CONTEXT if called on the wrong thread. + * @retval VERR_INTERRUPTED if interruptEventQueueProcessing was called. + * On Windows will also be returned when WM_QUIT is encountered. + * On Darwin this may also be returned when the native queue is + * stopped or destroyed/finished. + * @retval VINF_INTERRUPTED if the native system call was interrupted by a + * an asynchronous event delivery (signal) or just felt like returning + * out of bounds. On darwin it will also be returned if the queue is + * stopped. + */ +int EventQueue::processEventQueue(RTMSINTERVAL cMsTimeout) +{ + size_t cNumEvents; + int rc = RTCritSectEnter(&mCritSect); + if (RT_SUCCESS(rc)) + { + if (mUserCnt == 0) /* No concurrent access allowed. */ + { + mUserCnt++; + + cNumEvents = mEvents.size(); + if (!cNumEvents) + { + int rc2 = RTCritSectLeave(&mCritSect); + AssertRC(rc2); + + rc = RTSemEventWaitNoResume(mSemEvent, cMsTimeout); + + rc2 = RTCritSectEnter(&mCritSect); + AssertRC(rc2); + + if (RT_SUCCESS(rc)) + { + if (mShutdown) + rc = VERR_INTERRUPTED; + cNumEvents = mEvents.size(); + } + } + + if (RT_SUCCESS(rc)) + rc = processPendingEvents(cNumEvents); + + Assert(mUserCnt); + mUserCnt--; + } + else + rc = VERR_WRONG_ORDER; + + int rc2 = RTCritSectLeave(&mCritSect); + if (RT_SUCCESS(rc)) + rc = rc2; + } + + Assert(rc != VERR_TIMEOUT || cMsTimeout != RT_INDEFINITE_WAIT); + return rc; +} + +/** + * Processes all pending events in the queue at the time of + * calling. Note: Does no initial locking, must be done by the + * caller! + * + * @return IPRT status code. + */ +int EventQueue::processPendingEvents(size_t cNumEvents) +{ + if (!cNumEvents) /* Nothing to process? Bail out early. */ + return VINF_SUCCESS; + + int rc = VINF_SUCCESS; + + EventQueueListIterator it = mEvents.begin(); + for (size_t i = 0; + i < cNumEvents + && it != mEvents.end(); i++) + { + Event *pEvent = *it; + AssertPtr(pEvent); + + mEvents.erase(it); + + int rc2 = RTCritSectLeave(&mCritSect); + AssertRC(rc2); + + pEvent->handler(); + pEvent->Release(); + + rc2 = RTCritSectEnter(&mCritSect); + AssertRC(rc2); + + it = mEvents.begin(); + if (mShutdown) + { + rc = VERR_INTERRUPTED; + break; + } + } + + return rc; +} + +/** + * Interrupt thread waiting on event queue processing. + * + * Can be called on any thread. + * + * @returns VBox status code. + */ +int EventQueue::interruptEventQueueProcessing(void) +{ + ASMAtomicWriteBool(&mShutdown, true); + + return RTSemEventSignal(mSemEvent); +} + +/** + * Posts an event to this event loop asynchronously. + * + * @param pEvent the event to post, must be allocated using |new| + * @return TRUE if successful and false otherwise + */ +BOOL EventQueue::postEvent(Event *pEvent) +{ + int rc = RTCritSectEnter(&mCritSect); + if (RT_SUCCESS(rc)) + { + try + { + if (pEvent) + { + pEvent->AddRef(); + mEvents.push_back(pEvent); + } + else /* No locking, since we're already in our crit sect. */ + mShutdown = true; + + size_t cEvents = mEvents.size(); + if (cEvents > _1K) /** @todo Make value configurable? */ + { + static int s_cBitchedAboutLotEvents = 0; + if (s_cBitchedAboutLotEvents < 10) + LogRel(("Warning: Event queue received lots of events (%zu), expect delayed event handling (%d/10)\n", + cEvents, ++s_cBitchedAboutLotEvents)); + } + + /* Leave critical section before signalling event. */ + rc = RTCritSectLeave(&mCritSect); + if (RT_SUCCESS(rc)) + { + int rc2 = RTSemEventSignal(mSemEvent); + AssertRC(rc2); + } + } + catch (std::bad_alloc &ba) + { + NOREF(ba); + rc = VERR_NO_MEMORY; + } + + if (RT_FAILURE(rc)) + { + int rc2 = RTCritSectLeave(&mCritSect); + AssertRC(rc2); + } + } + + return RT_SUCCESS(rc) ? TRUE : FALSE; +} + +} +/* namespace com */ |