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[helm.git] / helm / software / DEVEL / ocaml-http / examples / threads.ml

diff --git a/helm/software/DEVEL/ocaml-http/examples/threads.ml b/helm/software/DEVEL/ocaml-http/examples/threads.ml
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+
+(*
+  OCaml HTTP - do it yourself (fully OCaml) HTTP daemon
+
+  Copyright (C) <2002-2004> Stefano Zacchiroli <zack@cs.unibo.it>
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+*)
+
+open Http_types
+
+let m = Mutex.create ()
+let m_locked = ref true
+
+let critical f =
+  Mutex.lock m;
+    m_locked := true;
+    Lazy.force f;
+    m_locked := false;
+  Mutex.unlock m
+
+  (** ocaml's Thread.unlock suspend the invoking process if the mutex is already
+  * unlocked, therefore we unlock it only if we know that it's currently locked
+  *)
+let safe_unlock _ _ = if !m_locked then Mutex.unlock m
+
+let i = ref 10
+let dump_i outchan =
+  Http_daemon.respond ~body:(Printf.sprintf "i = %d\n" !i) outchan
+
+let callback req outchan =
+  match req#path with
+  | "/incr" -> critical (lazy (incr i; dump_i outchan; Unix.sleep 5))
+  | "/decr" -> critical (lazy (decr i; dump_i outchan; Unix.sleep 5))
+  | "/get"  -> critical (lazy (dump_i outchan))
+  | bad_request -> Http_daemon.respond_error outchan
+
+let spec =
+  { Http_daemon.default_spec with
+      port = 9999;
+      mode = `Thread;
+      callback = callback;
+      exn_handler = Some safe_unlock;
+        (** ocaml-http's default exn_handler is Pervasives.ignore. This means
+        * that threads holding the "m" mutex above may die without unlocking it.
+        * Using safe_unlock as an exception handler we ensure that "m" mutex is
+        * unlocked in case of exceptions (e.g. SIGPIPE) *)
+  }
+
+let _ = Http_daemon.main spec
+