Struct template spsc_value

boost::lockfree::spsc_value

Synopsis

// In header: <boost/lockfree/spsc_value.hpp>

template<typename T, typename... Options> 
struct spsc_value {

  // public member functions
  explicit spsc_value();
  explicit spsc_value(T);
  void write(T &&);
  void write(const T &);
  bool read(T &);
  std::optional< T > read(uses_optional_t);
  template<typename Functor> bool consume(Functor &&);
};

Description

The spcs_value provides a single-writer/single-reader value, implemented by a triple buffer

Policies:

boost::lockfree::allow_multiple_reads, defaults to boost::lockfree::allow_multiple_reads<false>
If multiple reads are allowed, a value written to the spsc_value can be read multiple times, but not moved out of the instance. If multiple reads are not allowed, the class works as single-element queue that overwrites on write

`spsc_value` public member functions

```
explicit spsc_value();
```
Construct a spsc_value

If configured with boost::lockfree::allow_multiple_reads<true> it is initialized to a default-constructed value
```
explicit spsc_value(T value);
```
Construct a spsc_value, initialized to a value
```
void write(T && value);
```
Writes value to the spsc_value

Note

Thread-safe and wait-free

Requires:

only one thread is allowed to write data to the spsc_value

Postconditions:

object will be written to the spsc_value
```
void write(const T & value);
```
Writes value to the spsc_value

Note

Thread-safe and wait-free

Requires:

only one thread is allowed to write data to the spsc_value

Postconditions:

object will be written to the spsc_value

bool read(T & ret);

Reads content of the spsc_value

	Note
	Thread-safe and wait-free

Requires:	only one thread is allowed to write data to the spsc_value
Postconditions:	if read operation is successful, object will be copied to `ret`.
Returns:	`true`, if the read operation is successful, false if the spsc_value is configured with boost::lockfree::allow_multiple_reads<false> and no value is available for reading

std::optional< T > read(uses_optional_t);

Reads content of the spsc_value, returning an optional

	Note
	Thread-safe and wait-free

Requires:	only one thread is allowed to write data to the spsc_value
Returns:	`std::optional` with value if successful, `std::nullopt` if spsc_value is configured with boost::lockfree::allow_multiple_reads<false> and no value is available for reading

```
template<typename Functor> bool consume(Functor && f);
```
consumes value via a functor

reads element from the spsc_value and applies the functor on this object

Note

Thread-safe and non-blocking, if functor is thread-safe and non-blocking

Returns:

true, if element was consumed

	Note
	Thread-safe and non-blocking, if functor is thread-safe and non-blocking

Boost C++ Libraries

Struct template spsc_value

Synopsis

Description

spsc_value public member functions

`spsc_value` public member functions