-//$$CDS-header$$1
+/*
+ This file is a part of libcds - Concurrent Data Structures library
+
+ (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2017
+
+ Source code repo: http://github.com/khizmax/libcds/
+ Download: http://sourceforge.net/projects/libcds/files/
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice, this
+ list of conditions and the following disclaimer.
+
+ * Redistributions in binary form must reproduce the above copyright notice,
+ this list of conditions and the following disclaimer in the documentation
+ and/or other materials provided with the distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
#ifndef CDSLIB_URCU_DETAILS_GPT_H
#define CDSLIB_URCU_DETAILS_GPT_H
#include <mutex> //unique_lock
+#include <limits>
#include <cds/urcu/details/gp.h>
#include <cds/urcu/dispose_thread.h>
#include <cds/algo/backoff_strategy.h>
This implementation is similar to \ref general_buffered but separate thread is created
for deleting the retired objects. Like \p %general_buffered, the class contains an internal buffer
where retired objects are accumulated. When the buffer becomes full,
- the RCU \p synchronize function is called that waits until all reader/updater threads end up their read-side critical sections,
- i.e. until the RCU quiescent state will come. After that the "work ready" message is sent to reclamation tread.
+ the RCU \p synchronize() function is called that waits until all reader/updater threads end up their read-side critical sections,
+ i.e. until the RCU quiescent state will come. After that the "work ready" message is sent to reclamation thread.
The reclamation thread frees the buffer.
- This synchronization cycle may be called in any thread that calls \ref retire_ptr function.
+ This synchronization cycle may be called in any thread that calls \p retire_ptr() function.
There is a wrapper \ref cds_urcu_general_threaded_gc "gc<general_threaded>" for \p %general_threaded class
that provides unified RCU interface. You should use this wrapper class instead \p %general_threaded
+ The \p Buffer contains items of \ref cds_urcu_retired_ptr "epoch_retired_ptr" type
+
+ and it should support a multiple producer/single consumer queue with the following interface:
+ - <tt> bool push( epoch_retired_ptr& p ) </tt> - places the retired pointer \p p into queue. If the function
+ returns \p false it means that the buffer is full and RCU synchronization cycle must be processed.
+ - <tt>epoch_retired_ptr * front() </tt> - returns a pointer to the top element or \p nullptr if the buffer is empty.
+ - <tt>bool pop_front() </tt> - pops the top element; returns \p false if the buffer is empty.
+ - <tt>size_t size()</tt> - returns queue's item count.
+
+ The buffer is considered as full if \p push() returns \p false or the buffer size reaches the RCU threshold.
+
Template arguments:
- - \p Buffer - buffer type with FIFO semantics. Default is cds::container::VyukovMPMCCycleQueue. See \ref general_buffered
- for description of buffer's interface. The buffer contains the objects of \ref epoch_retired_ptr
+ - \p Buffer - MPSC (muliple producer/single consumer) buffer type with FIFO semantics.
+
+ Default is \p cds::container::VyukovMPSCCycleQueue. The buffer contains the objects of \ref epoch_retired_ptr
type that contains additional \p m_nEpoch field. This field specifies an epoch when the object
has been placed into the buffer. The \p %general_threaded object has a global epoch counter
- that is incremented on each \p synchronize call. The epoch is used internally to prevent early deletion.
+ that is incremented on each \p synchronize() call. The epoch is used internally to prevent early deletion.
- \p Lock - mutex type, default is \p std::mutex
- \p DisposerThread - the reclamation thread class. Default is \ref cds::urcu::dispose_thread,
see the description of this class for required interface.
- \p Backoff - back-off schema, default is cds::backoff::Default
*/
template <
- class Buffer = cds::container::VyukovMPMCCycleQueue< epoch_retired_ptr >
+ class Buffer = cds::container::VyukovMPSCCycleQueue< epoch_retired_ptr >
,class Lock = std::mutex
,class DisposerThread = dispose_thread<Buffer>
,class Backoff = cds::backoff::Default
protected:
//@cond
- buffer_type m_Buffer;
- atomics::atomic<uint64_t> m_nCurEpoch;
- lock_type m_Lock;
- size_t const m_nCapacity;
- disposer_thread m_DisposerThread;
+ buffer_type m_Buffer;
+ atomics::atomic<uint64_t> m_nCurEpoch;
+ lock_type m_Lock;
+ size_t const m_nCapacity;
+ disposer_thread m_DisposerThread;
//@endcond
public:
/// Returns singleton instance
static general_threaded * instance()
{
- return static_cast<general_threaded *>( base_class::instance() );
+ return static_cast<general_threaded *>( base_class::instance());
}
/// Checks if the singleton is created and ready to use
static bool isUsed()
}
// Return: true - synchronize has been called, false - otherwise
- bool push_buffer( epoch_retired_ptr& p )
+ bool push_buffer( epoch_retired_ptr&& p )
{
bool bPushed = m_Buffer.push( p );
- if ( !bPushed || m_Buffer.size() >= capacity() ) {
+ if ( !bPushed || m_Buffer.size() >= capacity()) {
synchronize();
- if ( !bPushed ) {
- CDS_TSAN_ANNOTATE_IGNORE_RW_BEGIN;
+ if ( !bPushed )
p.free();
- CDS_TSAN_ANNOTATE_IGNORE_RW_END;
- }
return true;
}
return false;
static void Construct( size_t nBufferCapacity = 256 )
{
if ( !singleton_ptr::s_pRCU ) {
- std::unique_ptr< general_threaded, scoped_disposer > pRCU( new general_threaded( nBufferCapacity ) );
+ std::unique_ptr< general_threaded, scoped_disposer > pRCU( new general_threaded( nBufferCapacity ));
pRCU->m_DisposerThread.start();
singleton_ptr::s_pRCU = pRCU.release();
/// Destroys singleton object and terminates internal reclamation thread
static void Destruct( bool bDetachAll = false )
{
- if ( isUsed() ) {
+ if ( isUsed()) {
general_threaded * pThis = instance();
if ( bDetachAll )
pThis->m_ThreadList.detach_all();
- pThis->m_DisposerThread.stop( pThis->m_Buffer, pThis->m_nCurEpoch.load( atomics::memory_order_acquire ));
+ pThis->m_DisposerThread.stop( pThis->m_Buffer, std::numeric_limits< uint64_t >::max());
delete pThis;
singleton_ptr::s_pRCU = nullptr;
*/
virtual void retire_ptr( retired_ptr& p )
{
- if ( p.m_p ) {
- epoch_retired_ptr ep( p, m_nCurEpoch.load( atomics::memory_order_acquire ) );
- push_buffer( ep );
- }
+ if ( p.m_p )
+ push_buffer( epoch_retired_ptr( p, m_nCurEpoch.load( atomics::memory_order_acquire )));
}
/// Retires the pointer chain [\p itFirst, \p itLast)
template <typename ForwardIterator>
void batch_retire( ForwardIterator itFirst, ForwardIterator itLast )
{
- uint64_t nEpoch = m_nCurEpoch.load( atomics::memory_order_relaxed );
+ uint64_t nEpoch = m_nCurEpoch.load( atomics::memory_order_acquire );
while ( itFirst != itLast ) {
- epoch_retired_ptr p( *itFirst, nEpoch );
+ epoch_retired_ptr ep( *itFirst, nEpoch );
++itFirst;
- push_buffer( p );
+ push_buffer( std::move(ep));
+ }
+ }
+
+ /// Retires the pointer chain until \p Func returns \p nullptr retired pointer
+ template <typename Func>
+ void batch_retire( Func e )
+ {
+ uint64_t nEpoch = m_nCurEpoch.load( atomics::memory_order_acquire );
+ for ( retired_ptr p{ e() }; p.m_p; ) {
+ epoch_retired_ptr ep( p, nEpoch );
+ p = e();
+ push_buffer( std::move(ep));
}
}
void synchronize( bool bSync )
{
uint64_t nPrevEpoch = m_nCurEpoch.fetch_add( 1, atomics::memory_order_release );
-
- atomics::atomic_thread_fence( atomics::memory_order_acquire );
{
std::unique_lock<lock_type> sl( m_Lock );
flip_and_wait();
flip_and_wait();
-
- m_DisposerThread.dispose( m_Buffer, nPrevEpoch, bSync );
}
- atomics::atomic_thread_fence( atomics::memory_order_release );
+ m_DisposerThread.dispose( m_Buffer, nPrevEpoch, bSync );
}
void force_dispose()
{
return m_nCapacity;
}
};
+
+ /// User-space general-purpose RCU with deferred threaded reclamation (stripped version)
+ /**
+ @headerfile cds/urcu/general_threaded.h
+
+ This short version of \p general_threaded is intended for stripping debug info.
+ If you use \p %general_threaded with default template arguments you may use
+ this stripped version. All functionality of both classes are identical.
+ */
+ class general_threaded_stripped: public general_threaded<>
+ {};
+
}} // namespace cds::urcu
#endif // #ifndef CDSLIB_URCU_DETAILS_GPT_H
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