--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Nominal/activities/tphols09/IDW/FI-Ex.thy	Wed Mar 30 17:27:34 2016 +0100
@@ -0,0 +1,264 @@
+theory Ex
+imports Main
+begin
+
+section {* Sledgehammer *}
+lemma "inj f ==> inj g ==> inj (f o g)"
+sledgehammer e
+apply (metis comp_inj_on inj_on_inverseI inv_f_eq top_set_eq) done
+
+
+
+
+section {* Threads in ML *}
+
+text {* some helper functions *}
+
+ML {* fun sleep time = OS.Process.sleep (Time.fromSeconds time) *}
+ML {* sleep 5 *}
+
+ML {* val count = ref 0 *}
+ML {*
+fun slow_inc name time =
+  let
+  val a = !count
+  val _ = sleep time
+  val result = a + 1
+  val _ = count := result
+  in
+    priority (name ^ ": " ^ string_of_int result)
+  end
+*}
+ML {* slow_inc "incremented" 10 *}
+
+ML {* SimpleThread.fork *}
+ML {*
+SimpleThread.fork true (fn () =>
+  slow_inc "parallel counter" 10)
+*}
+
+
+
+
+section {* Synchronization *}
+
+text{* Example: lost update *}
+ML {*
+count := 0;
+
+SimpleThread.fork true (fn () =>
+  slow_inc "counter1" 10);
+
+SimpleThread.fork true (fn () =>
+  slow_inc "counter2" 10)
+*}
+
+
+
+
+subsection {* pthreads-primitives *}
+
+text {* functions for mutexes *}
+ML {* Mutex.mutex *}
+ML {* Mutex.lock *}
+ML {* Mutex.unlock *}
+
+ML {*
+(* protecting count *)
+val mutex = Mutex.mutex()
+*}
+
+ML {*
+fun fork_inc name time =
+  SimpleThread.fork true (fn () =>
+    let
+      val _ = Mutex.lock mutex
+      val _ = slow_inc name time
+      val _ = Mutex.unlock mutex
+    in () end);
+*}
+
+ML {*
+fork_inc "A" 5;
+fork_inc "B" 5;
+*}
+
+text {* CAUTION: mutex stays locked after interrupt! *}
+ML {* fork_inc "C" 10000 *}
+ML {* SimpleThread.interrupt it *}
+ML {* fork_inc "D" 1 *}
+ML {* Mutex.unlock mutex (* actually undefined behaviour!! *) *}
+
+
+
+
+text {* Condition Variables *}
+ML {*
+val mutex = Mutex.mutex()
+val cond = ConditionVar.conditionVar()
+val state = ref 0
+*}
+
+text {* double state when signalled *}
+ML {*
+SimpleThread.fork true (fn () =>
+  let 
+  val _ = Mutex.lock mutex
+  val _ = ConditionVar.wait (cond, mutex)
+  val _ = state := (!state) * 2
+  val _ = sleep 1
+  val _ = priority ("Changed to: " ^ string_of_int (!state))
+  val _ = Mutex.unlock mutex
+  in () end)
+*}
+
+text {* change state and signal condition variable*}
+ML {* Mutex.lock mutex *}
+ML {* state := 21 *}
+ML {* ConditionVar.signal cond *}
+ML {* Mutex.unlock mutex*}
+
+
+
+
+subsection{* Isabelle/ML combinators*}
+
+ML {* SimpleThread.synchronized *}
+
+text {* protect count *}
+ML {*
+fun fork_inc_safe name time =
+  SimpleThread.fork true (fn () =>
+    SimpleThread.synchronized name mutex (fn () =>
+      slow_inc name time))
+*}
+
+ML {* val e = fork_inc_safe "E" 10000 *}
+ML {* SimpleThread.interrupt e *}
+ML {* fork_inc_safe "F" 1 *}
+
+
+
+
+subsection {* State Variables with synchronized access *}
+
+ML {* Synchronized.var *}
+
+ML {* val state = Synchronized.var "goods" 0 *}
+ML {* Synchronized.value state *}
+
+text{* modifying state *}
+ML {* Synchronized.change *}
+ML {* Synchronized.change state (fn i => i + 1) *}
+ML {* Synchronized.value state *}
+
+text{* change with result *}
+ML {* Synchronized.change;
+      Synchronized.change_result *}
+ML {*
+val previous_state_string =
+  Synchronized.change_result state (fn i =>
+    (string_of_int i, i + 1))
+*}
+
+
+text{* change (with result) when state meets some property *}
+
+ML {* Synchronized.change_result;
+      Synchronized.guarded_access *}
+
+
+text{* example: producer consumer *}
+
+ML {* Synchronized.change state (K 0) *}
+
+ML {* fun produce k = Synchronized.change state (fn i => i + k) *}
+
+ML {*
+fun consume () = Synchronized.guarded_access state (fn i =>
+  if i <= 0
+  then NONE
+  else SOME(i - 1, i - 1));
+*}
+
+ML {*
+fun consumer name = SimpleThread.fork true (fn () =>
+  while true do
+    let
+    val amount = consume ()
+    val _ = sleep 1
+    in priority (name ^ " consumed; " ^ string_of_int amount ^ " left") end)
+*}
+
+ML {* val a = consumer "A" *}
+ML {* produce 3 *}
+ML {* val b = consumer "B" *}
+ML {* produce 4 *}
+
+ML {* map SimpleThread.interrupt [a,b] *}
+
+
+text {* timeout while waiting on signal *}
+ML {* Synchronized.guarded_access;
+      Synchronized.timed_access*}
+
+ML {*
+fun consume_t timeout =
+  Synchronized.timed_access
+    state
+    (* absolute time! *)
+    (fn _ => SOME (Time.+ (Time.now (),Time.fromSeconds (timeout))))
+    (fn i => if i <= 0 then NONE else SOME(i - 1, i - 1))
+*}
+
+ML {* produce 2 *}
+ML {* consume_t 3 *}
+ML {* consume_t 3 *}
+ML {* consume_t 3 *}
+
+
+
+
+section{* Thread Attributes *}
+
+ML {*
+fun start_work () = SimpleThread.fork true (fn () =>
+  uninterruptible (fn restore_attributes => fn () =>
+    let
+    val _ = sleep 5
+    val _ = priority "... initialized"
+    val _ = restore_attributes (fn () =>
+      (sleep 5; priority "done work")) ()
+    in () end) ())
+*}
+
+ML {* val thread = start_work () *}
+ML {* SimpleThread.interrupt thread *}
+
+
+
+
+section{* External processes *}
+
+ML {* system_out *}
+
+ML {* val bash_script = "sleep 10; echo woke up" *}
+ML {* system_out bash_script *}
+
+ML {* val bash_script = "while [ 0 ]; do x=$x; done" *}
+ML {*
+val thread = SimpleThread.fork true (fn () =>
+  let val _ = system_out bash_script
+  in () end)
+*}
+ML {*SimpleThread.interrupt thread*}
+
+
+ML {* val path_to_isabelle = Path.explode "~~/bin/isabelle" *}
+
+text {* File in File.shell_path (spaces!) *}
+ML {* val command = File.shell_path path_to_isabelle ^ " version" *}
+ML {* system_out command *}
+
+end
+