- Reference manual
- SWI-Prolog C-library
- library(process): Create processes and redirect I/O
- library(filesex): Extended operations on files
- library(uid): User and group management on Unix systems
- library(syslog): Unix syslog interface
- library(socket): Network socket (TCP and UDP) library
- The stream_pool library
- library(uri): Process URIs
- CGI Support library
- Password encryption library
- library(uuid): Universally Unique Identifier (UUID) Library
- SHA* Secure Hash Algorithms
- library(md5): MD5 hashes
- library(hash_stream): Maintain a hash on a stream
- Memory files
- Time and alarm library
- library(unix): Unix specific operations
- Limiting process resources
- library(udp_broadcast): A UDP broadcast proxy
- library(prolog_stream): A stream with Prolog callbacks
- SWI-Prolog C-library
library(streampool) library dispatches input from
multiple streams based on wait_for_input/3.
It is part of the clib package as it is used most of the time together
library(socket) library. On non-Unix systems it
often can only be used with socket streams.
With SWI-Prolog 5.1.x, multi-threading often provides a good
alternative to using this library. In this schema one thread watches the
listening socket waiting for connections and either creates a thread per
connection or processes the accepted connections with a pool of
worker threads. The library
provides an example realising a mult-threaded HTTP server.
- add_stream_to_pool(+Stream, :Goal)
- Add Stream, which must be an input stream and ---on non-unix systems--- connected to a socket to the pool. If input is available on Stream, Goal is called.
- Delete the given stream from the pool. Succeeds, even if Stream is no member of the pool. If Stream is unbound the entire pool is emtied but unlike close_stream_pool/0 the streams are not closed.
- Empty the pool, closing all streams that are part of it.
- Wait for maximum of TimeOut for input on any of the streams
in the pool. If there is input, call the Goal associated with
If Goal fails or raises an exception a message is printed. TimeOut
is described with wait_for_input/3.
If Goal is called, there is some input on the associated stream. Goal must be careful not to block as this will block the entire pool.2This is hard to achieve at the moment as none of the Prolog read-commands provide for a timeout.
- Calls dispatch_stream_pool/1 in a loop until the pool is empty.
Below is a very simple example that reads the first line of input and echos it back.
:- use_module(library(streampool)). server(Port) :- tcp_socket(Socket), tcp_bind(Socket, Port), tcp_listen(Socket, 5), tcp_open_socket(Socket, In, _Out), add_stream_to_pool(In, accept(Socket)), stream_pool_main_loop. accept(Socket) :- tcp_accept(Socket, Slave, Peer), tcp_open_socket(Slave, In, Out), add_stream_to_pool(In, client(In, Out, Peer)). client(In, Out, _Peer) :- read_line_to_codes(In, Command), close(In), format(Out, 'Please to meet you: ~s~n', [Command]), close(Out), delete_stream_from_pool(In).