Specify eager_t as the default completion token type.

typedef eager_t< Allocator > default_completion_token_type;

Types

Member Functions

The eager object may be passed as the completion token to an asynchronous operation that has an associated I/O executor. The operation is started immediately, and the call returns an eager operation that may be waited on later. For example:

auto op = socket.async_read_some(buffer, boost::asio::eager);

// ... do other work while the read runs ...

std::move(op)([](boost::system::error_code e, std::size_t n) { ... });

An operation with no associated executor, such as one produced by boost::asio::deferred::values, cannot be used with this token, as there would be nowhere to deliver the result of the wait.

Discarding the returned handle without waiting on it detaches from the operation. See basic_eager_async_operation for the requirements this places on the caller.

The optional Allocator is used to allocate the operation's shared state. It is also associated with the handler given to the underlying operation, and so is used for that operation's state as well.

Before C++17, where std::variant is unavailable, this token supports an operation with at most two completion signatures.

The token is idempotent. Applying it to an operation that has already been eagerly initiated yields that same operation, without creating a further shared state, and an allocator specified on the subsequent application is unused.

See Also

Eager operations

Requirements

Header: boost/asio/eager.hpp

Convenience header: boost/asio.hpp