--- /dev/null
+/*
+ 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_GPB_H
+#define CDSLIB_URCU_DETAILS_GPB_H
+
+#include <mutex>
+#include <limits>
+#include <cds/urcu/details/gp.h>
+#include <cds/algo/backoff_strategy.h>
+#include <cds/container/vyukov_mpmc_cycle_queue.h>
+
+namespace cds { namespace urcu {
+
+ /// User-space general-purpose RCU with deferred (buffered) reclamation
+ /**
+ @headerfile cds/urcu/general_buffered.h
+
+ This URCU implementation 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 buffer and all retired objects are freed.
+ This synchronization cycle may be called in any thread that calls \p retire_ptr function.
+
+ The \p Buffer contains items of \ref cds_urcu_retired_ptr "epoch_retired_ptr" type and it should support a queue interface with
+ three function:
+ - <tt> bool push( 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>bool pop( retired_ptr& p ) </tt> - pops queue's head item into \p p parameter; if the queue is empty
+ this function must return \p false
+ - <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.
+
+ There is a wrapper \ref cds_urcu_general_buffered_gc "gc<general_buffered>" for \p %general_buffered class
+ that provides unified RCU interface. You should use this wrapper class instead \p %general_buffered
+
+ Template arguments:
+ - \p Buffer - buffer type. Default is \p cds::container::VyukovMPMCCycleQueue
+ - \p Lock - mutex type, default is \p std::mutex
+ - \p Backoff - back-off schema, default is cds::backoff::Default
+ */
+ template <
+ class Buffer = cds::container::VyukovMPMCCycleQueue< epoch_retired_ptr >
+ ,class Lock = std::mutex
+ ,class Backoff = cds::backoff::Default
+ >
+ class general_buffered: public details::gp_singleton< general_buffered_tag >
+ {
+ //@cond
+ typedef details::gp_singleton< general_buffered_tag > base_class;
+ //@endcond
+ public:
+ typedef general_buffered_tag rcu_tag ; ///< RCU tag
+ typedef Buffer buffer_type ; ///< Buffer type
+ typedef Lock lock_type ; ///< Lock type
+ typedef Backoff back_off ; ///< Back-off type
+
+ typedef base_class::thread_gc thread_gc ; ///< Thread-side RCU part
+ typedef typename thread_gc::scoped_lock scoped_lock ; ///< Access lock class
+
+ //@cond
+ static bool const c_bBuffered = true ; ///< Bufferized RCU
+ //@endcond
+
+ protected:
+ //@cond
+ typedef details::gp_singleton_instance< rcu_tag > singleton_ptr;
+ //@endcond
+
+ protected:
+ //@cond
+ buffer_type m_Buffer;
+ atomics::atomic<uint64_t> m_nCurEpoch;
+ lock_type m_Lock;
+ size_t const m_nCapacity;
+ //@endcond
+
+ public:
+ /// Returns singleton instance
+ static general_buffered * instance()
+ {
+ return static_cast<general_buffered *>( base_class::instance());
+ }
+ /// Checks if the singleton is created and ready to use
+ static bool isUsed()
+ {
+ return singleton_ptr::s_pRCU != nullptr;
+ }
+
+ protected:
+ //@cond
+ general_buffered( size_t nBufferCapacity )
+ : m_Buffer( nBufferCapacity )
+ , m_nCurEpoch(0)
+ , m_nCapacity( nBufferCapacity )
+ {}
+
+ ~general_buffered()
+ {
+ clear_buffer( std::numeric_limits< uint64_t >::max());
+ }
+
+ void flip_and_wait()
+ {
+ back_off bkoff;
+ base_class::flip_and_wait( bkoff );
+ }
+
+ void clear_buffer( uint64_t nEpoch )
+ {
+ epoch_retired_ptr p;
+ while ( m_Buffer.pop( p )) {
+ if ( p.m_nEpoch <= nEpoch ) {
+ p.free();
+ }
+ else {
+ push_buffer( std::move(p));
+ break;
+ }
+ }
+ }
+
+ // Return: \p true - synchronize has been called, \p false - otherwise
+ bool push_buffer( epoch_retired_ptr&& ep )
+ {
+ bool bPushed = m_Buffer.push( ep );
+ if ( !bPushed || m_Buffer.size() >= capacity()) {
+ synchronize();
+ if ( !bPushed ) {
+ ep.free();
+ }
+ return true;
+ }
+ return false;
+ }
+ //@endcond
+
+ public:
+ /// Creates singleton object
+ /**
+ The \p nBufferCapacity parameter defines RCU threshold.
+ */
+ static void Construct( size_t nBufferCapacity = 256 )
+ {
+ if ( !singleton_ptr::s_pRCU )
+ singleton_ptr::s_pRCU = new general_buffered( nBufferCapacity );
+ }
+
+ /// Destroys singleton object
+ static void Destruct( bool bDetachAll = false )
+ {
+ if ( isUsed()) {
+ instance()->clear_buffer( std::numeric_limits< uint64_t >::max());
+ if ( bDetachAll )
+ instance()->m_ThreadList.detach_all();
+ delete instance();
+ singleton_ptr::s_pRCU = nullptr;
+ }
+ }
+
+ public:
+ /// Retire \p p pointer
+ /**
+ The method pushes \p p pointer to internal buffer.
+ When the buffer becomes full \ref synchronize function is called
+ to wait for the end of grace period and then to free all pointers from the buffer.
+ */
+ virtual void retire_ptr( retired_ptr& p ) override
+ {
+ if ( p.m_p )
+ push_buffer( epoch_retired_ptr( p, m_nCurEpoch.load( atomics::memory_order_relaxed )));
+ }
+
+ /// 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 );
+ while ( itFirst != itLast ) {
+ epoch_retired_ptr ep( *itFirst, nEpoch );
+ ++itFirst;
+ 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_relaxed );
+ for ( retired_ptr p{ e() }; p.m_p; ) {
+ epoch_retired_ptr ep( p, nEpoch );
+ p = e();
+ push_buffer( std::move(ep));
+ }
+ }
+
+ /// Wait to finish a grace period and then clear the buffer
+ void synchronize()
+ {
+ epoch_retired_ptr ep( retired_ptr(), m_nCurEpoch.load( atomics::memory_order_relaxed ));
+ synchronize( ep );
+ }
+
+ //@cond
+ bool synchronize( epoch_retired_ptr& ep )
+ {
+ uint64_t nEpoch;
+ {
+ std::unique_lock<lock_type> sl( m_Lock );
+ if ( ep.m_p && m_Buffer.push( ep ))
+ return false;
+ nEpoch = m_nCurEpoch.fetch_add( 1, atomics::memory_order_relaxed );
+ flip_and_wait();
+ flip_and_wait();
+ }
+ clear_buffer( nEpoch );
+ return true;
+ }
+ //@endcond
+
+ /// Returns internal buffer capacity
+ size_t capacity() const
+ {
+ return m_nCapacity;
+ }
+ };
+
+ /// User-space general-purpose RCU with deferred (buffered) reclamation (stripped version)
+ /**
+ @headerfile cds/urcu/general_buffered.h
+
+ This short version of \p general_buffered is intended for stripping debug info.
+ If you use \p %general_buffered with default template arguments you may use
+ this stripped version. All functionality of both classes are identical.
+ */
+ class general_buffered_stripped: public general_buffered<>
+ {};
+
+}} // namespace cds::urcu
+
+#endif // #ifndef CDSLIB_URCU_DETAILS_GPB_H
projects / c11concurrency-benchmarks.git / blobdiff