NeonLockStore.cxx

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#include <ne_uri.h>
#include <rtl/ustring.hxx>
#include <osl/time.h>
#include <osl/thread.hxx>
#include <sal/log.hxx>
#include <salhelper/thread.hxx>
#include "NeonSession.hxx"
#include "NeonLockStore.hxx"

using namespace webdav_ucp;

namespace webdav_ucp {

class TickerThread : public salhelper::Thread
{
    bool m_bFinish;
    NeonLockStore & m_rLockStore;

public:

    explicit TickerThread( NeonLockStore & rLockStore )
        : Thread( "NeonTickerThread" ), m_bFinish( false )
        , m_rLockStore( rLockStore )
    {
    }

    void finish() { m_bFinish = true; }

private:

    virtual void execute() override;
};

} // namespace webdav_ucp

void TickerThread::execute()
{
    SAL_INFO( "ucb.ucp.webdav", "TickerThread: start." );

    // we have to go through the loop more often to be able to finish ~quickly
    const int nNth = 25;

    int nCount = nNth;
    while ( !m_bFinish )
    {
        if (--nCount < 0)
        {
            m_rLockStore.refreshLocks();
            nCount = nNth;
        }

        salhelper::Thread::wait(TimeValue(0, 1000000000 / nNth));
    }

    SAL_INFO( "ucb.ucp.webdav", "TickerThread: stop." );
}

NeonLockStore::NeonLockStore()
    : m_pNeonLockStore( ne_lockstore_create() )
{
    /*
     * ne_lockstore_create() never returns a NULL; neon calls abort() in case of an out-of-memory
     * situation.
     * Please see:
     * <http://www.webdav.org/neon/doc/html/refneon.html>
     * topic title "Memory handling", copied here verbatim:
     *
     * "neon does not attempt to cope gracefully with an out-of-memory situation;
     *  instead, by default, the abort function is called to immediately terminate
     *  the process. An application may register a custom function which will be
     *  called before abort in such a situation; see ne_oom_callback."
     */
}

NeonLockStore::~NeonLockStore()
{
    {
        osl::ClearableMutexGuard aGuard(m_aMutex);
        stopTicker(aGuard);
    } // actually no threads should even try to access members now

    // release active locks, if any.
    SAL_WARN_IF( !m_aLockInfoMap.empty(), "ucb.ucp.webdav", "NeonLockStore::~NeonLockStore - Releasing active locks!" );

    for ( auto& rLockInfo : m_aLockInfoMap )
    {
        NeonLock * pLock = rLockInfo.first;
        rLockInfo.second.xSession->UNLOCK( pLock );

        ne_lockstore_remove( m_pNeonLockStore, pLock );
        ne_lock_destroy( pLock );
    }

    ne_lockstore_destroy( m_pNeonLockStore );
}

void NeonLockStore::startTicker()
{
    osl::MutexGuard aGuard( m_aMutex );

    if ( !m_pTickerThread.is() )
    {
        m_pTickerThread = new TickerThread( *this );
        m_pTickerThread->launch();
    }
}

void NeonLockStore::stopTicker(osl::ClearableMutexGuard & rGuard)
{
    rtl::Reference<TickerThread> pTickerThread;

    if (m_pTickerThread.is())
    {
        m_pTickerThread->finish(); // needs mutex
        // the TickerThread may run refreshLocks() at most once after this
        pTickerThread = m_pTickerThread;
        m_pTickerThread.clear();
    }

    rGuard.clear();

    if (pTickerThread.is() && pTickerThread->getIdentifier() != osl::Thread::getCurrentIdentifier())
        pTickerThread->join(); // without m_aMutex locked (to prevent deadlock)
}

void NeonLockStore::registerSession( HttpSession * pHttpSession )
{
    osl::MutexGuard aGuard( m_aMutex );

    ne_lockstore_register( m_pNeonLockStore, pHttpSession );
}

NeonLock * NeonLockStore::findByUri( std::u16string_view rUri )
{
    osl::MutexGuard aGuard( m_aMutex );

    ne_uri aUri;
    ne_uri_parse( OUStringToOString(
        rUri, RTL_TEXTENCODING_UTF8 ).getStr(), &aUri );
    return ne_lockstore_findbyuri( m_pNeonLockStore, &aUri );
}

void NeonLockStore::addLock( NeonLock * pLock,
                             rtl::Reference< NeonSession > const & xSession,
                             sal_Int32 nLastChanceToSendRefreshRequest )
{
    osl::MutexGuard aGuard( m_aMutex );

    ne_lockstore_add( m_pNeonLockStore, pLock );
    m_aLockInfoMap[ pLock ]
        = LockInfo( xSession, nLastChanceToSendRefreshRequest );

    startTicker();
}

void NeonLockStore::removeLock( NeonLock * pLock )
{
    osl::ClearableMutexGuard aGuard( m_aMutex );

    m_aLockInfoMap.erase( pLock );
    ne_lockstore_remove( m_pNeonLockStore, pLock );

    if ( m_aLockInfoMap.empty() )
        stopTicker(aGuard);
}

void NeonLockStore::removeLockDeferred(NeonLock* pLock)
{
    osl::MutexGuard aGuard(m_aMutex);

    m_aRemoveDeferred.push_back(pLock);
}

void NeonLockStore::refreshLocks()
{
    osl::MutexGuard aGuard( m_aMutex );

    for ( auto& rLockInfo : m_aLockInfoMap )
    {
        LockInfo & rInfo = rLockInfo.second;
        if ( rInfo.nLastChanceToSendRefreshRequest != -1 )
        {
            // 30 seconds or less remaining until lock expires?
            TimeValue t1;
            osl_getSystemTime( &t1 );
            if ( rInfo.nLastChanceToSendRefreshRequest - 30
                     <= sal_Int32( t1.Seconds ) )
            {
                // refresh the lock.
                sal_Int32 nlastChanceToSendRefreshRequest = -1;
                if ( rInfo.xSession->LOCK(
                         rLockInfo.first,
                         /* out param */ nlastChanceToSendRefreshRequest ) )
                {
                    rInfo.nLastChanceToSendRefreshRequest
                        = nlastChanceToSendRefreshRequest;
                }
                else
                {
                    // refresh failed. stop auto-refresh.
                    rInfo.nLastChanceToSendRefreshRequest = -1;
                }
            }
        }
    }
    // removeLock will not need to actually release the lock, because this is run from TickerThread
    for (auto pLock : m_aRemoveDeferred)
        removeLock(pLock);
    m_aRemoveDeferred.clear();
}

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