xahaud/modules/beast_core/thread/Stoppable.cpp

//------------------------------------------------------------------------------
/*
    This file is part of rippled: https://github.com/ripple/rippled
    Copyright (c) 2012, 2013 Ripple Labs Inc.

    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.

    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================


Stoppable::Stoppable (char const* name, Stoppable& parent)
    : m_name (name)
    , m_root (false)
    , m_child (this)
    , m_calledStop (false)
    , m_stopped (false)
    , m_childrenStopped (false)
{
    // must not have had stop called
    bassert (! parent.isStopping());

    parent.m_children.push_front (&m_child);
}

Stoppable::Stoppable (char const* name, Stoppable* parent)
    : m_name (name)
    , m_root (parent == nullptr)
    , m_child (this)
    , m_calledStop (false)
    , m_stopped (false)
    , m_childrenStopped (false)
{
    if (parent != nullptr)
    {
        // must not have had stop called
        bassert (! parent->isStopping());

        parent->m_children.push_front (&m_child);
    }
}

Stoppable::~Stoppable ()
{
    // must be stopped
    bassert (m_stopped);

    // children must be stopped
    bassert (m_childrenStopped);
}

void Stoppable::stop (Journal::Stream stream)
{
    // may only be called once
    if (m_calledStop)
        return;

    m_calledStop = true;

    // must be called from a root stoppable
    bassert (m_root);

    // send the notification
    stopAsync ();

    // now block on the tree of Stoppable objects from the leaves up.
    stopRecursive (stream);
}

void Stoppable::stopAsync ()
{
    // must be called from a root stoppable
    bassert (m_root);

    stopAsyncRecursive ();
}

bool Stoppable::isStopping ()
{
    return m_calledStopAsync.get() != 0;
}

bool Stoppable::isStopped ()
{
    return m_stopped;
}

bool Stoppable::areChildrenStopped ()
{
    return m_childrenStopped;
}

void Stoppable::stopped ()
{
    m_stoppedEvent.signal();
}

void Stoppable::onStop()
{
    stopped();
}

void Stoppable::onChildrenStopped ()
{
}

//------------------------------------------------------------------------------

void Stoppable::stopAsyncRecursive ()
{
    // make sure we only do this once
    if (m_root)
    {
        // if this fails, some other thread got to it first
        if (! m_calledStopAsync.compareAndSetBool (1, 0))
            return;
    }
    else
    {
        // can't possibly already be set
        bassert (m_calledStopAsync.get() == 0);

        m_calledStopAsync.set (1);
    }

    // notify this stoppable
    onStop ();

    // notify children
    for (Children::const_iterator iter (m_children.cbegin ());
        iter != m_children.cend(); ++iter)
    {
        iter->stoppable->stopAsyncRecursive();
    }
}

void Stoppable::stopRecursive (Journal::Stream stream)
{
    // Block on each child recursively. Thinking of the Stoppable
    // hierarchy as a tree with the root at the top, we will block
    // first on leaves, and then at each successivly higher level.
    //
    for (Children::const_iterator iter (m_children.cbegin ());
        iter != m_children.cend(); ++iter)
    {
        iter->stoppable->stopRecursive (stream);
    }

    // Once we get here, we either have no children, or all of
    // our children have stopped, so update state accordingly.
    //
    m_childrenStopped = true;

    // Notify derived class that children have stopped.
    onChildrenStopped ();

    // Block until this stoppable stops. First we do a timed wait of 1 second, and
    // if that times out we report to the Journal and then do an infinite wait.
    //
    bool const timedOut (! m_stoppedEvent.wait (1 * 1000)); // milliseconds
    if (timedOut)
    {
        stream << "Waiting for '" << m_name << "' to stop";
        m_stoppedEvent.wait ();
    }

    // once we get here, we know the stoppable has stopped.
    m_stopped = true;
}