Semaphore.cc

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/*
 * SWC-DB© Copyright since 2019 Alex Kashirin <kashirin.alex@gmail.com>
 * License details at <https://github.com/kashirin-alex/swc-db/#license>
 */
 
 
#include "swcdb/core/Semaphore.h"
 
 
namespace SWC { namespace Core {
 
 
Semaphore::Semaphore(size_t sz, size_t pre_acquire) noexcept
                    : m_mutex(), m_cv(), m_sz(sz), m_count(pre_acquire) {
}
 
Semaphore::~Semaphore() noexcept { }
 
size_t Semaphore::available() {
  Core::ScopedLock lock(m_mutex);
  return m_sz - m_count;
}
 
bool Semaphore::has_pending() {
  Core::ScopedLock lock(m_mutex);
  return m_count;
}
 
void Semaphore::acquire() {
  Core::UniqueLock lock_wait(m_mutex);
  if(m_count >= m_sz)
    m_cv.wait(lock_wait, [this] {return m_count < m_sz;});
  ++m_count;
}
 
void Semaphore::release() {
  Core::ScopedLock lock(m_mutex);
  --m_count;
  m_cv.notify_all();
}
 
void Semaphore::wait_until_under_and_acquire(size_t sz) {
  Core::UniqueLock lock_wait(m_mutex);
  if(m_count >= sz)
    m_cv.wait(lock_wait, [this, sz] {return m_count < sz;});
  ++m_count;
}
 
void Semaphore::wait_until_under(size_t sz) {
  Core::UniqueLock lock_wait(m_mutex);
  if(m_count >= sz)
    m_cv.wait(lock_wait, [this, sz] {return m_count < sz;});
}
 
size_t Semaphore::wait_available() {
  Core::UniqueLock lock_wait(m_mutex);
  if(m_count >= m_sz)
    m_cv.wait(lock_wait, [this] {return m_count < m_sz;});
  return m_sz - m_count;
}
 
void Semaphore::wait_all() {
  Core::UniqueLock lock_wait(m_mutex);
  if(m_count)
    m_cv.wait(lock_wait, [this] {return !m_count;});
}
 
}}