LogSinkStream.md

LogSinkStream

Network stream sink for the Log module. Writes formatted log lines to an open m2stream handle over TCP or TLS. Designed for forwarding structured logs to a remote log collector or aggregation service.

Behavior

Uses Stream.TryWrite internally for synchronous, non-blocking output. If the write would block (TLS renegotiation) or fails (connection closed, I/O error), the log line is silently dropped. This is intentional -- logging must never block the event loop or crash the program. Each line is terminated with a newline character.

The stream handle is not owned by the sink. The caller is responsible for creating the stream, keeping it alive for the sink's lifetime, and destroying it afterward.

Dependencies

Requires the m2stream library and its transitive dependencies (m2futures, m2evloop, m2sockets). Only import this module if your program already uses networking -- it pulls in the full async I/O stack.

Procedures

Create

PROCEDURE Create(streamHandle: ADDRESS; VAR out: Sink);

Create a sink that writes formatted log lines to an open stream. streamHandle must be a valid Stream handle (from Stream.CreateTCP or Stream.CreateTLS) in the Open state. The returned sink is ready to pass to Log.AddSink.

Unlike LogSinkFile.Create, this procedure does not return a success/failure flag -- the stream is assumed to already be connected and valid. Errors during individual writes are handled silently per the non-blocking policy.

Example

MODULE StreamLogDemo;

FROM SYSTEM IMPORT ADDRESS;
FROM Log IMPORT Logger, Init, AddSink, Sink, Info;
FROM LogSinkStream IMPORT Create;
FROM Stream IMPORT Stream, CreateTCP, Destroy, OK;
FROM Sockets IMPORT Connect;

VAR
  lg: Logger;
  ss: Sink;
  s: Stream;
  fd: INTEGER;

BEGIN
  (* Assume fd is a connected TCP socket to a log server *)
  IF CreateTCP(loop, sched, fd, s) = OK THEN
    Init(lg);
    Create(s, ss);
    IF AddSink(lg, ss) THEN END;

    Info(lg, "connected to log server");
    Info(lg, "processing started");

    (* When done, destroy the stream (sink becomes a no-op) *)
    Destroy(s)
  END
END StreamLogDemo.