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// file : butl/process-details -*- C++ -*-
// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#ifndef BUTL_PROCESS_DETAILS
#define BUTL_PROCESS_DETAILS
#include <mutex>
#include <butl/ft/shared_mutex>
#if defined(__cpp_lib_shared_mutex) || defined(__cpp_lib_shared_timed_mutex)
# include <shared_mutex>
#endif
namespace butl
{
#if defined(__cpp_lib_shared_mutex)
using shared_mutex = std::shared_mutex;
using ulock = std::unique_lock<shared_mutex>;
using slock = std::shared_lock<shared_mutex>;
#elif defined(__cpp_lib_shared_timed_mutex)
using shared_mutex = std::shared_timed_mutex;
using ulock = std::unique_lock<shared_mutex>;
using slock = std::shared_lock<shared_mutex>;
#else
// Because we have this fallback, we need to be careful not to create
// multiple shared locks in the same thread.
//
struct shared_mutex: std::mutex
{
using mutex::mutex;
void lock_shared () { lock (); }
void try_lock_shared () { try_lock (); }
void unlock_shared () { unlock (); }
};
using ulock = std::unique_lock<shared_mutex>;
using slock = ulock;
#endif
// Mutex that is acquired to make a sequence of operations atomic in regards
// to child process spawning. Must be aquired for exclusive access for child
// process startup, and for shared access otherwise. Defined in process.cxx.
//
extern shared_mutex process_spawn_mutex;
}
#endif // BUTL_PROCESS_DETAILS
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