Shared lock pools

#include <x/lockpool.H>

typedef x::sharedlockpool<> sharedpool_t;

sharedpool_t sharedpool(sharedpool_t::create());

sharedpool_t::lockentry rlock(sharedpool->addLockSet(sharedpool_t::create_shared,

sharedpool_t::lockentry rlock(sharedpool->addLockSet(sharedpool_t::create_unique,

x::sharedpool is a specialization of a lock pool that implements the semantics of std::shared_mutex. The single template parameter specifies the lock starvation option. In this specialization, the default starve value is false.

create_shared() creates a shared lock. create_unique() creates a unique lock. Once a unique lock is in the lock pool's waiting list, any subsequent shared locks queue up on the waiting list until all existing shared locks go out of scope, permitting the waiting unique lock to acquire the lock pool. This ensures that the unique lock gets eventually acquired.

Setting starve to true results in shared locks starving any pending unique locks as long as at least one shared lock exists, until all shared locks go out of scope.