86 lines
2.9 KiB
C++
86 lines
2.9 KiB
C++
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/*
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Shared memory barrier, used by OpBarrier.h/.cpp
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*/
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#include "Barrier.h"
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#include <boost/interprocess/sync/scoped_lock.hpp>
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#include <iostream>
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namespace temporal2algebra {
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using boost::interprocess::scoped_lock;
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using boost::interprocess::named_mutex;
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using namespace boost::interprocess;
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using namespace std;
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Barrier::Barrier(std::string id, int num_of_procs) :
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barrier_create_guard(boost::interprocess::open_or_create,
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"mtx_Barrier_CreateGuard"),
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shm_name("temporal2_barrier_" + id){
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scoped_lock<named_mutex>(barrier_create_guard);
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try {
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shm_obj = shared_memory_object(create_only,
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shm_name.c_str(),
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read_write );
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shm_obj.truncate(sizeof(ShmBarrier));
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region = mapped_region(shm_obj, read_write);
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void* addr = region.get_address();
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shmBarrierPtr = new (addr) ShmBarrier(num_of_procs);
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} catch (const boost::interprocess::interprocess_exception ex) {
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cout << "couldn't create shm_obj - someone else did. Try to open.\n";
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cout << ex.what() << endl;
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shm_obj = shared_memory_object(open_only,
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shm_name.c_str(),
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read_write );
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region = mapped_region(shm_obj, read_write);
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void * addr = region.get_address();
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shmBarrierPtr = static_cast<ShmBarrier*>(addr);
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if (shmBarrierPtr->num_procs_to_wait_for != num_of_procs) {
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cout << "Found existing Barrier with num_of_procs: "
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<< shmBarrierPtr->num_procs_to_wait_for
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<< ", but requested num_of_procs: "
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<< num_of_procs << endl;
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}
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} catch (const exception ex) {
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cout << "Ups: MemUpdateStorage::initialize()"
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" - unhandled exeption:\n"
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<< ex.what() << endl;
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throw;
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}
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shmBarrierPtr->numOfUsers++;
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}
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Barrier::~Barrier() {
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scoped_lock<named_mutex>(barrier_create_guard);
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shmBarrierPtr->numOfUsers--;
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if (shmBarrierPtr->numOfUsers == 0) {
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cout << "we are the last remaining user, cleaning up...\n";
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bool shm_remove = shared_memory_object::remove(shm_name.c_str());
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std::cout << "shm_remove = " << shm_remove << std::endl;
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} else {
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cout << "there are other users - skip cleanup...\n";
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}
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}
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int Barrier::wait() {
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cout << "Barrier::wait()\n";
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scoped_lock<interprocess_mutex> lock(shmBarrierPtr->mutex);
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shmBarrierPtr->num_waiting++;
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// the lock is single use: always let pass,
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// once num_procs_to_wait_for has been reached
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if (shmBarrierPtr->num_waiting >= shmBarrierPtr->num_procs_to_wait_for) {
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shmBarrierPtr->cond_everyone_arrived.notify_all();
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} else {
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shmBarrierPtr->cond_everyone_arrived.wait(lock);
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}
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return shmBarrierPtr->num_waiting;
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}
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} /* namespace temporal2algebra */
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