multihandle

Multihandle is a software abstraction used in some programming libraries to manage multiple operation handles as a single object. A multihandle encapsulates a collection of sub-handles and provides mechanisms to initiate, monitor, and complete the operations associated with those sub-handles in a coordinated fashion. This promotes concurrency and reduces overhead by avoiding separate control paths for each operation.

In practice, a multihandle supports operations such as adding and removing sub-handles, starting processing of all sub-handles, polling or waiting for events, and collecting results or completion statuses. Depending on the library, the multihandle may use an event loop, a poll mechanism, or callbacks to notify when individual operations finish.

Example: libcurl. libcurl offers a multi interface that uses a CURLM handle to manage several easy handles (CURL*). Applications create a multi handle with curl_multi_init, add easy transfers with curl_multi_add_handle, drive progress with curl_multi_perform or curl_multi_wait, and retrieve completed messages via curl_multi_info_read before cleaning up.

Design considerations for multihandles include thread-safety, resource management, error handling, fairness among sub-handles, and compatibility with both synchronous and asynchronous programming models. The approach chosen can affect performance, complexity, and portability across platforms and libraries.

See also multiplexing, event-driven I/O, handle, resource manager.