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* MA 02110-1301 USA * |
* MA 02110-1301 USA * |
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***************************************************************************/ |
***************************************************************************/ |
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#ifndef __SYNCHRONIZEDCONFIG_H__ |
#ifndef SYNCHRONIZEDCONFIG_H |
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#define __SYNCHRONIZEDCONFIG_H__ |
#define SYNCHRONIZEDCONFIG_H |
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#include <set> |
#include <set> |
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#include <unistd.h> |
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#include "lsatomic.h" |
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namespace LinuxSampler { |
namespace LinuxSampler { |
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*/ |
*/ |
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template<class T> |
template<class T> |
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class SynchronizedConfig { |
class SynchronizedConfig { |
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struct atomic_t { volatile int word; }; |
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public: |
public: |
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SynchronizedConfig(); |
SynchronizedConfig(); |
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* thread |
* thread |
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*/ |
*/ |
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const T& Lock() { |
const T& Lock() { |
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atomicSet(&lock, 1); |
lock.store(1, memory_order_relaxed); |
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return parent.config[atomicRead(&parent.indexAtomic)]; |
atomic_thread_fence(memory_order_seq_cst); |
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return parent.config[parent.indexAtomic.load( |
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memory_order_acquire)]; |
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} |
} |
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/** |
/** |
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* time threads are locked anymore. |
* time threads are locked anymore. |
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*/ |
*/ |
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void Unlock() { |
void Unlock() { |
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atomicSet(&flag, 0); |
atomic_thread_fence(memory_order_release); |
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atomicSet(&lock, 0); |
lock.store(0, memory_order_relaxed); |
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flag.store(0, memory_order_relaxed); |
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} |
} |
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Reader(SynchronizedConfig& config); |
Reader(SynchronizedConfig& config); |
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private: |
private: |
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friend class SynchronizedConfig; |
friend class SynchronizedConfig; |
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SynchronizedConfig& parent; |
SynchronizedConfig& parent; |
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atomic_t lock; |
atomic<int> lock; |
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atomic_t flag; |
atomic<int> flag; |
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Reader *next; // only used locally in SwitchConfig |
Reader *next; // only used locally in SwitchConfig |
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}; |
}; |
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T& SwitchConfig(); |
T& SwitchConfig(); |
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private: |
private: |
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atomic_t indexAtomic; |
atomic<int> indexAtomic; |
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int updateIndex; |
int updateIndex; |
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T config[2]; |
T config[2]; |
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std::set<Reader*> readers; |
std::set<Reader*> readers; |
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static int atomicRead(atomic_t* pSharedVariable) { |
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return pSharedVariable->word; |
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} |
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static void atomicSet(atomic_t* pSharedVariable, int value) { |
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pSharedVariable->word = value; |
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} |
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}; |
}; |
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template<class T> SynchronizedConfig<T>::SynchronizedConfig() { |
template<class T> SynchronizedConfig<T>::SynchronizedConfig() : |
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atomicSet(&indexAtomic, 0); |
indexAtomic(0) { |
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updateIndex = 1; |
updateIndex = 1; |
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} |
} |
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} |
} |
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template<class T> T& SynchronizedConfig<T>::SwitchConfig() { |
template<class T> T& SynchronizedConfig<T>::SwitchConfig() { |
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atomicSet(&indexAtomic, updateIndex); |
indexAtomic.store(updateIndex, memory_order_release); |
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atomic_thread_fence(memory_order_seq_cst); |
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// first put all locking readers in a linked list |
// first put all locking readers in a linked list |
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Reader* lockingReaders = 0; |
Reader* lockingReaders = 0; |
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for (typename std::set<Reader*>::iterator iter = readers.begin() ; |
for (typename std::set<Reader*>::iterator iter = readers.begin() ; |
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iter != readers.end() ; |
iter != readers.end() ; |
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iter++) { |
iter++) { |
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atomicSet(&(*iter)->flag, 1); |
(*iter)->flag.store(1, memory_order_relaxed); |
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if (atomicRead(&(*iter)->lock) && atomicRead(&(*iter)->flag)) { |
if ((*iter)->lock.load(memory_order_acquire) && |
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(*iter)->flag.load(memory_order_acquire)) { |
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(*iter)->next = lockingReaders; |
(*iter)->next = lockingReaders; |
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lockingReaders = *iter; |
lockingReaders = *iter; |
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} |
} |
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usleep(50000); |
usleep(50000); |
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Reader** prev = &lockingReaders; |
Reader** prev = &lockingReaders; |
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for (Reader* p = lockingReaders ; p ; p = p->next) { |
for (Reader* p = lockingReaders ; p ; p = p->next) { |
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if (atomicRead(&p->lock) && atomicRead(&p->flag)) prev = &p->next; |
if (p->lock.load(memory_order_acquire) && |
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p->flag.load(memory_order_acquire)) prev = &p->next; |
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else *prev = p->next; // unlink |
else *prev = p->next; // unlink |
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} |
} |
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} |
} |
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// ----- Reader ---- |
// ----- Reader ---- |
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template <class T> |
template <class T> |
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SynchronizedConfig<T>::Reader::Reader(SynchronizedConfig& config) : parent(config) { |
SynchronizedConfig<T>::Reader::Reader(SynchronizedConfig& config) : |
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atomicSet(&lock, 0); |
parent(config), lock(0), flag(0) { |
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parent.readers.insert(this); |
parent.readers.insert(this); |
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} |
} |
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