[thread.thread.id] (original) (raw)

32 Thread support library [thread]

32.4 Threads [thread.threads]

32.4.2 Class thread [thread.thread.class]

32.4.2.1 Class thread​::​id [thread.thread.id]

namespace std { class thread::id { public: id() noexcept; };

bool operator==(thread::id x, thread::id y) noexcept; strong_ordering operator<=>(thread::id x, thread::id y) noexcept;

template<class charT, class traits> basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& out, thread::id id);

template struct hash; template<> struct hashthread::id; }

An object of type thread​::​id provides a unique identifier for each thread of execution and a single distinct value for all threadobjects that do not represent a thread of execution ([thread.thread.class]).

Each thread of execution has an associated thread​::​id object that is not equal to thethread​::​id object of any other thread of execution and that is not equal to the thread​::​id object of any thread object that does not represent threads of execution.

thread​::​id is a trivially copyable class ([class.prop]).

The library may reuse the value of a thread​::​id of a terminated thread that can no longer be joined.

[ Note

:

Relational operators allow thread​::​id objects to be used as keys in associative containers.

— end note

]

Postconditions:The constructed object does not represent a thread of execution.

bool operator==(thread::id x, thread::id y) noexcept;

Returns: true only if x and y represent the same thread of execution or neither x nor y represents a thread of execution.

strong_ordering operator<=>(thread::id x, thread::id y) noexcept;

Let be an unspecified total ordering over thread​::​idas described in [alg.sorting].

Returns: strong_­ordering​::​less if is true.

Otherwise, strong_­ordering​::​greaterif is true.

Otherwise, strong_­ordering​::​equal.

template<class charT, class traits> basic_ostream<charT, traits>& operator<< (basic_ostream<charT, traits>& out, thread::id id);

Effects:Inserts an unspecified text representation of id intoout.

For two objects of type thread​::​id x and y, if x == y the thread​::​id objects have the same text representation and if x != y the thread​::​id objects have distinct text representations.

template<> struct hash<thread::id>;