# pragma warning(disable:4251) // C4251: 'identifier' : class 'type' needs to have dll-interface to be used by clients of class 'type2'
#endif
+//@cond
namespace cds { namespace gc {
/// Dynamic Hazard Pointer reclamation schema
/// Internal guard representation
struct guard_data {
- typedef retired_ptr_node * handoff_ptr ; ///< trapped value type
- typedef void * guarded_ptr ; ///< type of value guarded
+ typedef void * guarded_ptr; ///< type of value guarded
- atomics::atomic<guarded_ptr> pPost ; ///< pointer guarded
+ atomics::atomic<guarded_ptr> pPost; ///< pointer guarded
+ atomics::atomic<guard_data *> pGlobalNext; ///< next item of global list of allocated guards
+ atomics::atomic<guard_data *> pNextFree; ///< pointer to the next item in global or thread-local free-list
- atomics::atomic<guard_data *> pGlobalNext ; ///< next item of global list of allocated guards
- atomics::atomic<guard_data *> pNextFree ; ///< pointer to the next item in global or thread-local free-list
+ guard_data * pThreadNext; ///< next item of thread's local list of guards
- guard_data * pThreadNext ; ///< next item of thread's local list of guards
-
- //@cond
guard_data() CDS_NOEXCEPT
: pPost( nullptr )
, pGlobalNext( nullptr )
{
pPost.store( nullptr, atomics::memory_order_relaxed );
}
- //@endcond
/// Checks if the guard is free, that is, it does not contain any pointer guarded
bool isFree() const CDS_NOEXCEPT
details::guard_data * pGuard = m_GuardAllocator.New();
// Link guard to the list
- // m_GuardList is accumulated list and it cannot support concurrent deletion,
+ // m_GuardList is an accumulating list and it cannot support concurrent deletion,
// so, ABA problem is impossible for it
details::guard_data * pHead = m_GuardList.load( atomics::memory_order_acquire );
do {
atomics::atomic<size_t> m_nItemCount; ///< buffer's item count
public:
- //@cond
- CDS_CONSTEXPR retired_ptr_buffer() CDS_NOEXCEPT
+ retired_ptr_buffer() CDS_NOEXCEPT
: m_pHead( nullptr )
, m_nItemCount(0)
{}
{
assert( m_pHead.load( atomics::memory_order_relaxed ) == nullptr );
}
- //@endcond
/// Pushes new node into the buffer. Returns current buffer size
size_t push( retired_ptr_node& node ) CDS_NOEXCEPT
cds::details::Allocator< block, Alloc > m_BlockAllocator ; ///< block allocator
private:
- //@cond
void allocNewBlock()
{
// allocate new block
{
return (m_nCurEpoch.load(atomics::memory_order_acquire) - 1) & (c_nEpochCount - 1);
}
- //@endcond
public:
- //@cond
retired_ptr_pool()
: m_pBlockListHead( nullptr )
, m_nCurEpoch(0)
m_nCurEpoch.fetch_add( 1, atomics::memory_order_acq_rel );
}
- //@endcond
-
/// Allocates new retired pointer
retired_ptr_node& alloc()
{
friend class ThreadGC;
protected:
details::guard_data * m_pGuard ; ///< Pointer to guard data
+
public:
/// Initialize empty guard.
CDS_CONSTEXPR guard() CDS_NOEXCEPT
: m_pGuard( nullptr )
{}
- /// The object is not copy-constructible
+ /// Ñopy-ctor is disabled
guard( guard const& ) = delete;
+ /// Move-ctor is disabled
+ guard( guard&& ) = delete;
+
/// Object destructor, does nothing
~guard() CDS_NOEXCEPT
{}
+ /// Get current guarded pointer
+ void * get( atomics::memory_order order = atomics::memory_order_acquire ) const CDS_NOEXCEPT
+ {
+ assert( m_pGuard != nullptr );
+ return m_pGuard->pPost.load( order );
+ }
+
/// Guards pointer \p p
- void set( void * p ) CDS_NOEXCEPT
+ void set( void * p, atomics::memory_order order = atomics::memory_order_release ) CDS_NOEXCEPT
{
assert( m_pGuard != nullptr );
- m_pGuard->pPost.store( p, atomics::memory_order_release );
- //CDS_COMPILER_RW_BARRIER;
+ m_pGuard->pPost.store( p, order );
}
/// Clears the guard
- void clear() CDS_NOEXCEPT
+ void clear( atomics::memory_order order = atomics::memory_order_relaxed ) CDS_NOEXCEPT
{
assert( m_pGuard != nullptr );
- m_pGuard->pPost.store( nullptr, atomics::memory_order_relaxed );
- CDS_STRICT_DO( CDS_COMPILER_RW_BARRIER );
+ m_pGuard->pPost.store( nullptr, order );
}
/// Guards pointer \p p
return p;
}
- //@cond
std::nullptr_t operator=(std::nullptr_t) CDS_NOEXCEPT
{
clear();
return nullptr;
}
- //@endcond
public: // for ThreadGC.
/*
GCC cannot compile code for template versions of ThreasGC::allocGuard/freeGuard,
the compiler produces error: \91cds::gc::dhp::details::guard_data* cds::gc::dhp::details::guard::m_pGuard\92 is protected
despite the fact that ThreadGC is declared as friend for guard class.
- We should not like to declare m_pGuard member as public one.
Therefore, we have to add set_guard/get_guard public functions
*/
/// Set guard data
{
return m_pGuard;
}
+
+ details::guard_data * release_guard() CDS_NOEXCEPT
+ {
+ details::guard_data * p = m_pGuard;
+ m_pGuard = nullptr;
+ return p;
+ }
+
+ bool is_initialized() const
+ {
+ return m_pGuard != nullptr;
+ }
};
} // namespace details
*/
class Guard: public details::guard
{
- //@cond
typedef details::guard base_class;
friend class ThreadGC;
- //@endcond
ThreadGC& m_gc ; ///< ThreadGC object of current thread
public:
/// Allocates a guard from \p gc GC. \p gc must be ThreadGC object of current thread
- Guard( ThreadGC& gc ) CDS_NOEXCEPT;
+ Guard( ThreadGC& gc );
/// Returns guard allocated back to pool of free guards
- ~Guard() CDS_NOEXCEPT; // inline after GarbageCollector
+ ~Guard(); // inline after GarbageCollector
/// Returns DHP GC object
ThreadGC& getGC() CDS_NOEXCEPT
return base_class::operator =<T>( p );
}
- //@cond
std::nullptr_t operator=(std::nullptr_t) CDS_NOEXCEPT
{
return base_class::operator =(nullptr);
}
- //@endcond
};
/// Array of guards
public:
/// Allocates array of guards from \p gc which must be the ThreadGC object of current thread
- GuardArray( ThreadGC& gc ) CDS_NOEXCEPT; // inline below
+ GuardArray( ThreadGC& gc ); // inline below
/// The object is not default-constructible
GuardArray() = delete;
GuardArray( GuardArray const& ) = delete;
/// Returns guards allocated back to pool
- ~GuardArray() CDS_NOEXCEPT; // inline below
+ ~GuardArray(); // inline below
/// Returns the capacity of array
CDS_CONSTEXPR size_t capacity() const CDS_NOEXCEPT
class CDS_EXPORT_API GarbageCollector
{
private:
- //@cond
friend class ThreadGC;
/// Internal GC statistics
, m_nFreeGuardCount(0)
{}
};
- //@endcond
public:
/// Exception "No GarbageCollector object is created"
size_t m_nGuardCount ; ///< Total guard count
size_t m_nFreeGuardCount ; ///< Count of free guard
- //@cond
InternalState()
: m_nGuardCount(0)
, m_nFreeGuardCount(0)
return *this;
}
- //@endcond
};
private:
}
private:
- //@cond none
GarbageCollector( size_t nLiberateThreshold, size_t nInitialThreadGuardCount );
~GarbageCollector();
- //@endcond
};
/// Thread GC
public:
/// Initializes guard \p g
- void allocGuard( Guard& g )
+ void allocGuard( dhp::details::guard& g )
{
assert( m_pList != nullptr );
- if ( m_pFree ) {
- g.m_pGuard = m_pFree;
- m_pFree = m_pFree->pNextFree.load(atomics::memory_order_relaxed);
- }
- else {
- g.m_pGuard = m_gc.allocGuard();
- g.m_pGuard->pThreadNext = m_pList;
- m_pList = g.m_pGuard;
+ if ( !g.m_pGuard ) {
+ if ( m_pFree ) {
+ g.m_pGuard = m_pFree;
+ m_pFree = m_pFree->pNextFree.load( atomics::memory_order_relaxed );
+ }
+ else {
+ g.m_pGuard = m_gc.allocGuard();
+ g.m_pGuard->pThreadNext = m_pList;
+ m_pList = g.m_pGuard;
+ }
}
}
/// Frees guard \p g
- void freeGuard( Guard& g )
+ void freeGuard( dhp::details::guard& g )
{
assert( m_pList != nullptr );
- g.m_pGuard->pPost.store( nullptr, atomics::memory_order_relaxed );
- g.m_pGuard->pNextFree.store( m_pFree, atomics::memory_order_relaxed );
- m_pFree = g.m_pGuard;
+ if ( g.m_pGuard ) {
+ g.m_pGuard->pPost.store( nullptr, atomics::memory_order_relaxed );
+ g.m_pGuard->pNextFree.store( m_pFree, atomics::memory_order_relaxed );
+ m_pFree = g.m_pGuard;
+ g.m_pGuard = nullptr;
+ }
}
/// Initializes guard array \p arr
m_gc.retirePtr( p, pFunc );
}
- //@cond
void scan()
{
m_gc.scan();
}
- //@endcond
-
};
//////////////////////////////////////////////////////////
} // namespace dhp
}} // namespace cds::gc
+//@endcond
#if CDS_COMPILER == CDS_COMPILER_MSVC
# pragma warning(pop)
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