Added Producer Consumer example code

theories/examples/producer_consumer.v

+From stdpp Require Import sorting.
+From osiris.channel Require Import proto_channel proofmode.
+From iris.heap_lang Require Import proofmode notation.
+From iris.heap_lang Require Import assert.
+From iris.heap_lang.lib Require Import spin_lock.
+From osiris.utils Require Import list compare.
+
+
+Definition qenqueue : val := λ: "q" "v", #().
+Definition qdequeue : val := λ: "q", #().
+Definition qis_empty : val := λ: "q", #().
+
+Definition enq := true.
+Definition deq := false.
+
+Definition cont := true.
+Definition stop := false.
+
+Definition some := true.
+Definition none := false.
+
+Definition dist_queue : val :=
+  rec: "go" "q" "pc" "cc" "c" :=
+    if: "cc" ≤ #0 then #() else 
+    if: recv "c"                (* enq/deq *)
+    then if: recv "c"           (* cont/stop *)
+         then "go" (qenqueue "q" (recv "c")) "pc" "cc" "c"
+         else "go" "q" ("pc"-#1) "cc" "c"
+    else if: (qis_empty "q")
+         then if: "pc" ≤ #0
+              then send "c" #stop;; "go" "q" "pc" ("cc"-#1) "c"
+              else send "c" #cont;; send "c" #none;; "go" "q" "pc" "cc" "c"
+         else send "c" #cont;; send "c" #some;;
+              let: "qv" := qdequeue "q" in
+              send "c" (Snd "qv");; "go" (Fst "qv") "pc" "cc" "c".
+
+Definition producer : val :=
+  rec: "go" "c" "l" "produce" :=
+    match: "produce" #() with
+      SOME "v" =>
+        acquire "l";;
+        send "c" #enq;; send "c" #cont;; send "c" "v";;
+        release "l";;
+        "go" "c" "l" "produce"
+     | NONE =>
+        acquire "l";;
+        send "c" #enq;; send "c" #stop
+        release "l"
+    end.
+        
+Definition consumer : val :=
+  rec: "go" "c" "l" "consume" :=
+    acquire "l";;
+    send "c" #deq;;
+    if: recv "c"             (* cont/stop *)
+    then if: recv "c"        (* some/none *)
+         then let: "v" := recv "c" in
+              release "l";; "produce" "v";; "go" "c" "l" "consume"
+         else release "l";; "go" "c" "l" "consume"
+    else release "l";; #().
+