src/system/SystemLayer.cpp

/*
 *
 *    Copyright (c) 2020-2021 Project CHIP Authors
 *    Copyright (c) 2016-2017 Nest Labs, Inc.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

/**
 *    @file
 *      This file contains definitions of the chip::System::Layer
 *      class methods and related data and functions.
 */

// Include module header
#include <system/SystemLayer.h>

// Include common private header
#include "SystemLayerPrivate.h"

// Include local headers
#include <system/SystemClock.h>
#include <system/SystemTimer.h>

// Include additional CHIP headers
#include <platform/LockTracker.h>
#include <support/CHIPMem.h>
#include <support/CodeUtils.h>
#include <support/DLLUtil.h>
#include <support/logging/CHIPLogging.h>

// Include system and language headers
#include <stddef.h>
#include <string.h>

#if CHIP_SYSTEM_CONFIG_USE_SOCKETS || CHIP_SYSTEM_CONFIG_USE_NETWORK_FRAMEWORK
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS

#if CHIP_SYSTEM_CONFIG_POSIX_LOCKING
#include <pthread.h>

// Choose an approximation of PTHREAD_NULL if pthread.h doesn't define one.
#ifndef PTHREAD_NULL
#define PTHREAD_NULL 0
#endif // PTHREAD_NULL
#endif // CHIP_SYSTEM_CONFIG_POSIX_LOCKING

namespace chip {
namespace System {

Layer::Layer() : mLayerState(kLayerState_NotInitialized), mPlatformData(nullptr)
{
#if CHIP_SYSTEM_CONFIG_USE_LWIP
    if (!sSystemEventHandlerDelegate.IsInitialized())
        sSystemEventHandlerDelegate.Init(HandleSystemLayerEvent);

    this->mEventDelegateList = NULL;
    this->mTimerList         = NULL;
    this->mTimerComplete     = false;
#endif // CHIP_SYSTEM_CONFIG_USE_LWIP

#if CHIP_SYSTEM_CONFIG_USE_SOCKETS || CHIP_SYSTEM_CONFIG_USE_NETWORK_FRAMEWORK
#if CHIP_SYSTEM_CONFIG_POSIX_LOCKING
    this->mHandleSelectThread = PTHREAD_NULL;
#endif // CHIP_SYSTEM_CONFIG_POSIX_LOCKING
#endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS || CHIP_SYSTEM_CONFIG_USE_NETWORK_FRAMEWORK
}

CHIP_ERROR Layer::Init()
{
#if CHIP_SYSTEM_CONFIG_USE_SOCKETS
    RegisterPOSIXErrorFormatter();
#endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS
#if CHIP_SYSTEM_CONFIG_USE_LWIP
    RegisterLwIPErrorFormatter();
#endif // CHIP_SYSTEM_CONFIG_USE_LWIP

    if (this->mLayerState != kLayerState_NotInitialized)
        return CHIP_ERROR_INCORRECT_STATE;

#if CHIP_SYSTEM_CONFIG_USE_SOCKETS
    mWatchableEvents.Init(*this);
#endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS
#if CHIP_SYSTEM_CONFIG_USE_LWIP
    this->AddEventHandlerDelegate(sSystemEventHandlerDelegate);
#endif // CHIP_SYSTEM_CONFIG_USE_LWIP

    this->mLayerState = kLayerState_Initialized;

    return CHIP_NO_ERROR;
}

CHIP_ERROR Layer::Shutdown()
{
    if (this->mLayerState == kLayerState_NotInitialized)
        return CHIP_ERROR_INCORRECT_STATE;

    for (size_t i = 0; i < Timer::sPool.Size(); ++i)
    {
        Timer * lTimer = Timer::sPool.Get(*this, i);

        if (lTimer != nullptr)
        {
            lTimer->Cancel();
        }
    }

#if CHIP_SYSTEM_CONFIG_USE_SOCKETS
    mWatchableEvents.Shutdown();
#endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS

    this->mLayerState = kLayerState_NotInitialized;

    return CHIP_NO_ERROR;
}

CHIP_ERROR Layer::NewTimer(Timer *& aTimerPtr)
{
    Timer * lTimer = nullptr;

    if (this->State() != kLayerState_Initialized)
        return CHIP_ERROR_INCORRECT_STATE;

    lTimer    = Timer::sPool.TryCreate(*this);
    aTimerPtr = lTimer;

    if (lTimer == nullptr)
    {
        ChipLogError(chipSystemLayer, "Timer pool EMPTY");
        return CHIP_ERROR_NO_MEMORY;
    }

    return CHIP_NO_ERROR;
}

/**
 * @brief
 *   This method starts a one-shot timer.
 *
 *   @note
 *       Only a single timer is allowed to be started with the same @a aComplete and @a aAppState
 *       arguments. If called with @a aComplete and @a aAppState identical to an existing timer,
 *       the currently-running timer will first be cancelled.
 *
 *   @param[in]  aMilliseconds Expiration time in milliseconds.
 *   @param[in]  aComplete     A pointer to the function called when timer expires.
 *   @param[in]  aAppState     A pointer to the application state object used when timer expires.
 *
 *   @return CHIP_NO_ERROR On success.
 *   @return CHIP_ERROR_NO_MEMORY If a timer cannot be allocated.
 *   @return Other Value indicating timer failed to start.
 *
 */
CHIP_ERROR Layer::StartTimer(uint32_t aMilliseconds, TimerCompleteFunct aComplete, void * aAppState)
{
    CHIP_ERROR lReturn;
    Timer * lTimer;

    this->CancelTimer(aComplete, aAppState);
    lReturn = this->NewTimer(lTimer);
    SuccessOrExit(lReturn);

    lReturn = lTimer->Start(aMilliseconds, aComplete, aAppState);
    if (lReturn != CHIP_NO_ERROR)
    {
        lTimer->Release();
    }

exit:
    return lReturn;
}

/**
 * @brief
 *   This method cancels a one-shot timer, started earlier through @p StartTimer().
 *
 *   @note
 *       The cancellation could fail silently in two different ways. If the timer specified by the combination of the callback
 *       function and application state object couldn't be found, cancellation could fail. If the timer has fired, but not yet
 *       removed from memory, cancellation could also fail.
 *
 *   @param[in]  aOnComplete   A pointer to the callback function used in calling @p StartTimer().
 *   @param[in]  aAppState     A pointer to the application state object used in calling @p StartTimer().
 *
 */
void Layer::CancelTimer(Layer::TimerCompleteFunct aOnComplete, void * aAppState)
{
    if (this->State() != kLayerState_Initialized)
        return;

    for (size_t i = 0; i < Timer::sPool.Size(); ++i)
    {
        Timer * lTimer = Timer::sPool.Get(*this, i);

        if (lTimer != nullptr && lTimer->OnComplete == aOnComplete && lTimer->AppState == aAppState)
        {
            lTimer->Cancel();
            break;
        }
    }
}

/**
 * @brief
 *   Schedules a function with a signature identical to
 *   `TimerCompleteFunct` to be run as soon as possible on the CHIP
 *   thread.
 *
 * @note
 *   This function could, in principle, be implemented as
 *   `StartTimer`.  The specification for
 *   `SystemTimer` however permits certain optimizations that might
 *   make that implementation impossible. Specifically, `SystemTimer`
 *   API may only be called from the thread owning the particular
 *   `SystemLayer`, whereas the `ScheduleWork` may be called from
 *   any thread.  Additionally, whereas the `SystemTimer` API permits
 *   the invocation of the already expired handler in line,
 *   `ScheduleWork` guarantees that the handler function will be
 *   called only after the current CHIP event completes.
 *
 * @param[in] aComplete A pointer to a callback function to be called
 *                      when this timer fires.
 *
 * @param[in] aAppState A pointer to an application state object to be
 *                      passed to the callback function as argument.
 *
 * @retval CHIP_ERROR_INCORRECT_STATE If the SystemLayer has
 *                      not been initialized.
 *
 * @retval CHIP_ERROR_NO_MEMORY If the SystemLayer cannot
 *                      allocate a new timer.
 *
 * @retval CHIP_NO_ERROR On success.
 */
CHIP_ERROR Layer::ScheduleWork(TimerCompleteFunct aComplete, void * aAppState)
{
    assertChipStackLockedByCurrentThread();

    CHIP_ERROR lReturn;
    Timer * lTimer;

    lReturn = this->NewTimer(lTimer);
    SuccessOrExit(lReturn);

    lReturn = lTimer->ScheduleWork(aComplete, aAppState);
    if (lReturn != CHIP_NO_ERROR)
    {
        lTimer->Release();
    }

exit:
    return lReturn;
}

#if CHIP_SYSTEM_CONFIG_USE_SOCKETS || CHIP_SYSTEM_CONFIG_USE_NETWORK_FRAMEWORK

bool Layer::GetTimeout(struct timeval & aSleepTime)
{
    if (this->State() != kLayerState_Initialized)
        return false;

    const Clock::MonotonicMilliseconds kCurrentTime = Clock::GetMonotonicMilliseconds();
    Clock::MonotonicMilliseconds lAwakenTime = kCurrentTime + static_cast<Clock::MonotonicMilliseconds>(aSleepTime.tv_sec) * 1000 +
        static_cast<uint32_t>(aSleepTime.tv_usec) / 1000;

    bool anyTimer = false;
    for (size_t i = 0; i < Timer::sPool.Size(); i++)
    {
        Timer * lTimer = Timer::sPool.Get(*this, i);

        if (lTimer != nullptr)
        {
            anyTimer = true;

            if (!Timer::IsEarlier(kCurrentTime, lTimer->mAwakenTime))
            {
                lAwakenTime = kCurrentTime;
                break;
            }

            if (Timer::IsEarlier(lTimer->mAwakenTime, lAwakenTime))
                lAwakenTime = lTimer->mAwakenTime;
        }
    }

    const Clock::MonotonicMilliseconds kSleepTime = lAwakenTime - kCurrentTime;
    aSleepTime.tv_sec                             = static_cast<time_t>(kSleepTime / 1000);
    aSleepTime.tv_usec                            = static_cast<suseconds_t>((kSleepTime % 1000) * 1000);

    return anyTimer;
}

void Layer::HandleTimeout()
{
    assertChipStackLockedByCurrentThread();

#if CHIP_SYSTEM_CONFIG_POSIX_LOCKING
    this->mHandleSelectThread = pthread_self();
#endif // CHIP_SYSTEM_CONFIG_POSIX_LOCKING

    const Clock::MonotonicMilliseconds kCurrentTime = Clock::GetMonotonicMilliseconds();

    for (size_t i = 0; i < Timer::sPool.Size(); i++)
    {
        Timer * lTimer = Timer::sPool.Get(*this, i);

        if (lTimer != nullptr && !Timer::IsEarlier(kCurrentTime, lTimer->mAwakenTime))
        {
            lTimer->HandleComplete();
        }
    }

#if CHIP_SYSTEM_CONFIG_POSIX_LOCKING
    this->mHandleSelectThread = PTHREAD_NULL;
#endif // CHIP_SYSTEM_CONFIG_POSIX_LOCKING
}

#endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS || CHIP_SYSTEM_CONFIG_USE_NETWORK_FRAMEWORK

#if CHIP_SYSTEM_CONFIG_USE_LWIP
LwIPEventHandlerDelegate Layer::sSystemEventHandlerDelegate;

bool LwIPEventHandlerDelegate::IsInitialized() const
{
    return this->mFunction != NULL;
}

void LwIPEventHandlerDelegate::Init(LwIPEventHandlerFunction aFunction)
{
    this->mFunction     = aFunction;
    this->mNextDelegate = NULL;
}

void LwIPEventHandlerDelegate::Prepend(const LwIPEventHandlerDelegate *& aDelegateList)
{
    this->mNextDelegate = aDelegateList;
    aDelegateList       = this;
}

/**
 * This is the dispatch handler for system layer events.
 *
 *  @param[in,out]  aTarget     A pointer to the CHIP System Layer object making the post request.
 *  @param[in]      aEventType  The type of event to post.
 *  @param[in,out]  aArgument   The argument associated with the event to post.
 */
CHIP_ERROR Layer::HandleSystemLayerEvent(Object & aTarget, EventType aEventType, uintptr_t aArgument)
{
    CHIP_ERROR lReturn = CHIP_NO_ERROR;
    ;

    // Dispatch logic specific to the event type
    switch (aEventType)
    {
    case kEvent_ReleaseObj:
        aTarget.Release();
        break;

    case kEvent_ScheduleWork:
        static_cast<Timer &>(aTarget).HandleComplete();
        break;

    default:
        lReturn = CHIP_ERROR_UNEXPECTED_EVENT;
        break;
    }

    return lReturn;
}

/**
 * This adds an event handler delegate to the system layer to extend its ability to handle LwIP events.
 *
 *  @param[in]  aDelegate   An uninitialied LwIP event handler delegate structure
 *
 *  @retval     CHIP_NO_ERROR                 On success.
 *  @retval     CHIP_ERROR_INVALID_ARGUMENT   If the function pointer contained in aDelegate is NULL
 */
CHIP_ERROR Layer::AddEventHandlerDelegate(LwIPEventHandlerDelegate & aDelegate)
{
    CHIP_ERROR lReturn;

    VerifyOrExit(aDelegate.mFunction != NULL, lReturn = CHIP_ERROR_INVALID_ARGUMENT);
    aDelegate.Prepend(this->mEventDelegateList);
    lReturn = CHIP_NO_ERROR;

exit:
    return lReturn;
}

/**
 * This posts an event / message of the specified type with the provided argument to this instance's platform-specific event
 * queue.
 *
 *  @param[in,out]  aTarget     A pointer to the CHIP System Layer object making the post request.
 *  @param[in]      aEventType  The type of event to post.
 *  @param[in,out]  aArgument   The argument associated with the event to post.
 *
 *  @retval    CHIP_NO_ERROR                  On success.
 *  @retval    CHIP_ERROR_INCORRECT_STATE     If the state of the Layer object is incorrect.
 *  @retval    CHIP_ERROR_NO_MEMORY           If the event queue is already full.
 *  @retval    other Platform-specific errors generated indicating the reason for failure.
 */
CHIP_ERROR Layer::PostEvent(Object & aTarget, EventType aEventType, uintptr_t aArgument)
{
    CHIP_ERROR lReturn = CHIP_NO_ERROR;
    VerifyOrExit(this->State() == kLayerState_Initialized, lReturn = CHIP_ERROR_INCORRECT_STATE);

    // Sanity check that this instance and the target layer haven't been "crossed".
    VerifyOrDieWithMsg(aTarget.IsRetained(*this), chipSystemLayer, "wrong poster! [target %p != this %p]", &(aTarget.SystemLayer()),
                       this);

    lReturn = Platform::Eventing::PostEvent(*this, aTarget, aEventType, aArgument);
    if (lReturn != CHIP_NO_ERROR)
    {
        ChipLogError(chipSystemLayer, "Failed to queue CHIP System Layer event (type %d): %s", aEventType, ErrorStr(lReturn));
    }
    SuccessOrExit(lReturn);

exit:
    return lReturn;
}

/**
 * This is a syntactic wrapper around a platform-specific hook that effects an event loop, waiting on a queue that services this
 * instance, pulling events off of that queue, and then dispatching them for handling.
 *
 *  @return #CHIP_NO_ERROR on success; otherwise, a specific error indicating the reason for initialization failure.
 */
CHIP_ERROR Layer::DispatchEvents()
{
    CHIP_ERROR lReturn = CHIP_NO_ERROR;
    VerifyOrExit(this->State() == kLayerState_Initialized, lReturn = CHIP_ERROR_INCORRECT_STATE);

    lReturn = Platform::Eventing::DispatchEvents(*this);
    SuccessOrExit(lReturn);

exit:
    return lReturn;
}

/**
 * This dispatches the specified event for handling by this instance.
 *
 *  The unmarshalling of the type and arguments from the event is handled by a platform-specific hook which should then call
 * back to Layer::HandleEvent for the actual dispatch.
 *
 *  @param[in]  aEvent  The platform-specific event object to dispatch for handling.
 *
 * @return CHIP_NO_ERROR on success; otherwise, a specific error indicating the reason for initialization failure.
 */
CHIP_ERROR Layer::DispatchEvent(Event aEvent)
{
    CHIP_ERROR lReturn = CHIP_NO_ERROR;
    VerifyOrExit(this->State() == kLayerState_Initialized, lReturn = CHIP_ERROR_INCORRECT_STATE);

    lReturn = Platform::Eventing::DispatchEvent(*this, aEvent);
    SuccessOrExit(lReturn);

exit:
    return lReturn;
}

/**
 * This implements the actual dispatch and handling of a CHIP System Layer event.
 *
 *  @param[in,out]  aTarget     A reference to the layer object to which the event is targeted.
 *  @param[in]      aEventType  The event / message type to handle.
 *  @param[in]      aArgument   The argument associated with the event / message.
 *
 *  @retval   CHIP_NO_ERROR                 On success.
 *  @retval   CHIP_ERROR_INCORRECT_STATE    If the state of the InetLayer object is incorrect.
 *  @retval   CHIP_ERROR_UNEXPECTED_EVENT   If the event type is unrecognized.
 */
CHIP_ERROR Layer::HandleEvent(Object & aTarget, EventType aEventType, uintptr_t aArgument)
{
    const LwIPEventHandlerDelegate * lEventDelegate;
    CHIP_ERROR lReturn;
    VerifyOrExit(this->State() == kLayerState_Initialized, lReturn = CHIP_ERROR_INCORRECT_STATE);

    // Sanity check that this instance and the target layer haven't been "crossed".
    VerifyOrDieWithMsg(aTarget.IsRetained(*this), chipSystemLayer, "wrong handler! [target %p != this %p]",
                       &(aTarget.SystemLayer()), this);

    lReturn        = CHIP_ERROR_UNEXPECTED_EVENT;
    lEventDelegate = this->mEventDelegateList;

    // Prevent the target object from being freed while dispatching the event.
    aTarget.Retain();

    while (lReturn == CHIP_ERROR_UNEXPECTED_EVENT && lEventDelegate != NULL)
    {
        lReturn        = lEventDelegate->mFunction(aTarget, aEventType, aArgument);
        lEventDelegate = lEventDelegate->mNextDelegate;
    }

    if (lReturn == CHIP_ERROR_UNEXPECTED_EVENT)
    {
        ChipLogError(chipSystemLayer, "Unexpected event type %d", aEventType);
    }

    /*
      Release the reference to the target object. When the object's lifetime finally comes to an end, in most cases this will be
      the release call that decrements the ref count to zero.
      */
    aTarget.Release();

exit:
    return lReturn;
}

/**
 * Start the platform timer with specified millsecond duration.
 *
 *  @brief
 *      Calls the Platform specific API to start a platform timer. This API is called by the chip::System::Timer class when
 *      one or more timers are active and require deferred execution.
 *
 *  @param[in]  aDelayMilliseconds  The timer duration in milliseconds.
 *
 *  @return CHIP_NO_ERROR on success, error code otherwise.
 *
 */
CHIP_ERROR Layer::StartPlatformTimer(uint32_t aDelayMilliseconds)
{
    CHIP_ERROR lReturn = CHIP_NO_ERROR;
    VerifyOrExit(this->State() == kLayerState_Initialized, lReturn = CHIP_ERROR_INCORRECT_STATE);

    lReturn = Platform::Eventing::StartTimer(*this, aDelayMilliseconds);
    SuccessOrExit(lReturn);

exit:
    return lReturn;
}

/**
 * Handle the platform timer expiration event.
 *
 *  @brief
 *      Calls chip::System::Timer::HandleExpiredTimers to handle any expired timers.  It is assumed that this API is called
 *      only while on the thread which owns the CHIP System Layer object.
 *
 *  @return CHIP_NO_ERROR on success, error code otherwise.
 *
 */
CHIP_ERROR Layer::HandlePlatformTimer()
{
    CHIP_ERROR lReturn = CHIP_NO_ERROR;
    VerifyOrExit(this->State() == kLayerState_Initialized, lReturn = CHIP_ERROR_INCORRECT_STATE);

    lReturn = Timer::HandleExpiredTimers(*this);

    SuccessOrExit(lReturn);

exit:
    return lReturn;
}
#endif // CHIP_SYSTEM_CONFIG_USE_LWIP

} // namespace System
} // namespace chip