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authorKartik K. Agaram <vc@akkartik.com>2016-01-26 23:47:23 -0800
committerKartik K. Agaram <vc@akkartik.com>2016-01-26 23:47:23 -0800
commitd009e158803956c76adbf8f58a62884c3e7affb3 (patch)
treeb88198e28d15cd1fc064f5300365a190decc4c50 /html/062scheduler.cc.html
parent2da43c9462c7b7c1bb78d2f2826b3b97b4874973 (diff)
downloadmu-d009e158803956c76adbf8f58a62884c3e7affb3.tar.gz
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+<pre id='vimCodeElement'>
+<span class="Comment">//: Run a second routine concurrently using 'start-running', without any</span>
+<span class="Comment">//: guarantees on how the operations in each are interleaved with each other.</span>
+
+<span class="Delimiter">:(scenario scheduler)</span>
+recipe f1 [
+  start-running f2
+  <span class="Comment"># wait for f2 to run</span>
+  <span class="Delimiter">{</span>
+    jump-unless <span class="Constant">1</span>:number<span class="Delimiter">,</span> -<span class="Constant">1</span>
+  <span class="Delimiter">}</span>
+]
+recipe f2 [
+  <span class="Constant">1</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">1</span>
+]
+<span class="traceContains">+schedule: f1</span>
+<span class="traceContains">+schedule: f2</span>
+
+<span class="Comment">//: first, add a deadline to run(routine)</span>
+<span class="Comment">//: these changes are ugly and brittle; just close your nose and get through the next few lines</span>
+<span class="Delimiter">:(replace &quot;void run_current_routine()&quot;)</span>
+void run_current_routine<span class="Delimiter">(</span>long long int time_slice<span class="Delimiter">)</span>
+<span class="Delimiter">:(replace &quot;while (!Current_routine-&gt;completed())&quot; following &quot;void run_current_routine(long long int time_slice)&quot;)</span>
+long long int ninstrs = <span class="Constant">0</span><span class="Delimiter">;</span>
+while <span class="Delimiter">(</span>Current_routine<span class="Delimiter">-&gt;</span>state == RUNNING &amp;&amp; ninstrs &lt; time_slice<span class="Delimiter">)</span>
+<span class="Delimiter">:(after &quot;Running One Instruction&quot;)</span>
+ninstrs++<span class="Delimiter">;</span>
+
+<span class="Comment">//: now the rest of the scheduler is clean</span>
+
+<span class="Delimiter">:(before &quot;struct routine&quot;)</span>
+enum routine_state <span class="Delimiter">{</span>
+  RUNNING<span class="Delimiter">,</span>
+  COMPLETED<span class="Delimiter">,</span>
+  <span class="Comment">// End routine States</span>
+<span class="Delimiter">};</span>
+<span class="Delimiter">:(before &quot;End routine Fields&quot;)</span>
+enum routine_state state<span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End routine Constructor&quot;)</span>
+state = RUNNING<span class="Delimiter">;</span>
+
+<span class="Delimiter">:(before &quot;End Globals&quot;)</span>
+vector&lt;routine*&gt; Routines<span class="Delimiter">;</span>
+long long int Current_routine_index = <span class="Constant">0</span><span class="Delimiter">;</span>
+long long int Scheduling_interval = <span class="Constant">500</span><span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End Setup&quot;)</span>
+Scheduling_interval = <span class="Constant">500</span><span class="Delimiter">;</span>
+Routines<span class="Delimiter">.</span>clear<span class="Delimiter">();</span>
+<span class="Delimiter">:(replace{} &quot;void run(recipe_ordinal r)&quot;)</span>
+void run<span class="Delimiter">(</span>recipe_ordinal r<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  run<span class="Delimiter">(</span>new routine<span class="Delimiter">(</span>r<span class="Delimiter">));</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(code)</span>
+void run<span class="Delimiter">(</span>routine* rr<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  Routines<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>rr<span class="Delimiter">);</span>
+  Current_routine_index = <span class="Constant">0</span><span class="Delimiter">,</span> Current_routine = Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+  while <span class="Delimiter">(</span>!all_routines_done<span class="Delimiter">())</span> <span class="Delimiter">{</span>
+    skip_to_next_routine<span class="Delimiter">();</span>
+    assert<span class="Delimiter">(</span>Current_routine<span class="Delimiter">);</span>
+    assert<span class="Delimiter">(</span>Current_routine<span class="Delimiter">-&gt;</span>state == RUNNING<span class="Delimiter">);</span>
+    trace<span class="Delimiter">(</span><span class="Constant">9990</span><span class="Delimiter">,</span> <span class="Constant">&quot;schedule&quot;</span><span class="Delimiter">)</span> &lt;&lt; current_routine_label<span class="Delimiter">()</span> &lt;&lt; end<span class="Delimiter">();</span>
+    run_current_routine<span class="Delimiter">(</span>Scheduling_interval<span class="Delimiter">);</span>
+    <span class="Comment">// Scheduler State Transitions</span>
+    if <span class="Delimiter">(</span>Current_routine<span class="Delimiter">-&gt;</span>completed<span class="Delimiter">())</span>
+      Current_routine<span class="Delimiter">-&gt;</span>state = COMPLETED<span class="Delimiter">;</span>
+    <span class="Comment">// End Scheduler State Transitions</span>
+
+    <span class="Comment">// Scheduler Cleanup</span>
+    <span class="Comment">// End Scheduler Cleanup</span>
+  <span class="Delimiter">}</span>
+<span class="Delimiter">}</span>
+
+bool all_routines_done<span class="Delimiter">()</span> <span class="Delimiter">{</span>
+  for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    if <span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>state == RUNNING<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+      <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
+    <span class="Delimiter">}</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Comment">// skip Current_routine_index past non-RUNNING routines</span>
+void skip_to_next_routine<span class="Delimiter">()</span> <span class="Delimiter">{</span>
+  assert<span class="Delimiter">(</span>!Routines<span class="Delimiter">.</span>empty<span class="Delimiter">());</span>
+  assert<span class="Delimiter">(</span>Current_routine_index &lt; SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">));</span>
+  for <span class="Delimiter">(</span>long long int i = <span class="Delimiter">(</span>Current_routine_index+<span class="Constant">1</span><span class="Delimiter">)</span>%SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">);</span>  i != Current_routine_index<span class="Delimiter">;</span>  i = <span class="Delimiter">(</span>i+<span class="Constant">1</span><span class="Delimiter">)</span>%SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">))</span> <span class="Delimiter">{</span>
+    if <span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>state == RUNNING<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+      Current_routine_index = i<span class="Delimiter">;</span>
+      Current_routine = Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">);</span>
+      <span class="Identifier">return</span><span class="Delimiter">;</span>
+    <span class="Delimiter">}</span>
+  <span class="Delimiter">}</span>
+<span class="Delimiter">}</span>
+
+string current_routine_label<span class="Delimiter">()</span> <span class="Delimiter">{</span>
+  ostringstream result<span class="Delimiter">;</span>
+  const call_stack&amp; calls = Current_routine<span class="Delimiter">-&gt;</span>calls<span class="Delimiter">;</span>
+  for <span class="Delimiter">(</span>call_stack::const_iterator p = calls<span class="Delimiter">.</span>begin<span class="Delimiter">();</span> p != calls<span class="Delimiter">.</span>end<span class="Delimiter">();</span> ++p<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    if <span class="Delimiter">(</span>p != calls<span class="Delimiter">.</span>begin<span class="Delimiter">())</span> result &lt;&lt; <span class="Constant">'/'</span><span class="Delimiter">;</span>
+    result &lt;&lt; get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> p<span class="Delimiter">-&gt;</span>running_recipe<span class="Delimiter">).</span>name<span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">return</span> result<span class="Delimiter">.</span>str<span class="Delimiter">();</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(before &quot;End Teardown&quot;)</span>
+for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span>
+  delete Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">);</span>
+Routines<span class="Delimiter">.</span>clear<span class="Delimiter">();</span>
+Current_routine = <span class="Constant">NULL</span><span class="Delimiter">;</span>
+
+<span class="Comment">//: special case for the very first routine</span>
+<span class="Delimiter">:(replace{} &quot;void run_main(int argc, char* argv[])&quot;)</span>
+void run_main<span class="Delimiter">(</span>int argc<span class="Delimiter">,</span> char* argv[]<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  recipe_ordinal r = get<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;main&quot;</span><span class="Delimiter">);</span>
+  assert<span class="Delimiter">(</span>r<span class="Delimiter">);</span>
+  routine* main_routine = new routine<span class="Delimiter">(</span>r<span class="Delimiter">);</span>
+  <span class="Comment">// pass in commandline args as ingredients to main</span>
+  <span class="Comment">// todo: test this</span>
+  Current_routine = main_routine<span class="Delimiter">;</span>
+  for <span class="Delimiter">(</span>long long int i = <span class="Constant">1</span><span class="Delimiter">;</span> i &lt; argc<span class="Delimiter">;</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    vector&lt;double&gt; arg<span class="Delimiter">;</span>
+    arg<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>new_mu_string<span class="Delimiter">(</span>argv[i]<span class="Delimiter">));</span>
+    current_call<span class="Delimiter">().</span>ingredient_atoms<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>arg<span class="Delimiter">);</span>
+  <span class="Delimiter">}</span>
+  run<span class="Delimiter">(</span>main_routine<span class="Delimiter">);</span>
+<span class="Delimiter">}</span>
+
+<span class="SalientComment">//:: To schedule new routines to run, call 'start-running'.</span>
+
+<span class="Comment">//: 'start-running' will return a unique id for the routine that was created.</span>
+<span class="Comment">//: routine id is a number, but don't do any arithmetic on it</span>
+<span class="Delimiter">:(before &quot;End routine Fields&quot;)</span>
+long long int id<span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End Globals&quot;)</span>
+long long int Next_routine_id = <span class="Constant">1</span><span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End Setup&quot;)</span>
+Next_routine_id = <span class="Constant">1</span><span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End routine Constructor&quot;)</span>
+id = Next_routine_id<span class="Delimiter">;</span>
+Next_routine_id++<span class="Delimiter">;</span>
+
+<span class="Comment">//: routines save the routine that spawned them</span>
+<span class="Delimiter">:(before &quot;End routine Fields&quot;)</span>
+<span class="Comment">// todo: really should be routine_id, but that's less efficient.</span>
+long long int parent_index<span class="Delimiter">;</span>  <span class="Comment">// only &lt; 0 if there's no parent_index</span>
+<span class="Delimiter">:(before &quot;End routine Constructor&quot;)</span>
+parent_index = -<span class="Constant">1</span><span class="Delimiter">;</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+START_RUNNING<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;start-running&quot;</span><span class="Delimiter">,</span> START_RUNNING<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+case START_RUNNING: <span class="Delimiter">{</span>
+  if <span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>empty<span class="Delimiter">())</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;'start-running' requires at least one ingredient: the recipe to start running</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  if <span class="Delimiter">(</span>!is_mu_recipe<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;first ingredient of 'start-running' should be a recipe, but got &quot;</span> &lt;&lt; debug_string<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">))</span> &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+case START_RUNNING: <span class="Delimiter">{</span>
+  routine* new_routine = new routine<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">));</span>
+  new_routine<span class="Delimiter">-&gt;</span>parent_index = Current_routine_index<span class="Delimiter">;</span>
+  <span class="Comment">// populate ingredients</span>
+  for <span class="Delimiter">(</span>long long int i = <span class="Constant">1</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    new_routine<span class="Delimiter">-&gt;</span>calls<span class="Delimiter">.</span>front<span class="Delimiter">().</span>ingredient_atoms<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">));</span>
+    reagent ingredient = current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">);</span>
+    canonize_type<span class="Delimiter">(</span>ingredient<span class="Delimiter">);</span>
+    new_routine<span class="Delimiter">-&gt;</span>calls<span class="Delimiter">.</span>front<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>ingredient<span class="Delimiter">);</span>
+  <span class="Delimiter">}</span>
+  Routines<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>new_routine<span class="Delimiter">);</span>
+  products<span class="Delimiter">.</span>resize<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
+  products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>push_back<span class="Delimiter">(</span>new_routine<span class="Delimiter">-&gt;</span>id<span class="Delimiter">);</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(scenario scheduler_runs_single_routine)</span>
+<span class="Special">% Scheduling_interval = 1;</span>
+recipe f1 [
+  <span class="Constant">1</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+  <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+]
+<span class="traceContains">+schedule: f1</span>
+<span class="traceContains">+run: 1:number &lt;- copy 0</span>
+<span class="traceContains">+schedule: f1</span>
+<span class="traceContains">+run: 2:number &lt;- copy 0</span>
+
+<span class="Delimiter">:(scenario scheduler_interleaves_routines)</span>
+<span class="Special">% Scheduling_interval = 1;</span>
+recipe f1 [
+  start-running f2
+  <span class="Constant">1</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+  <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+]
+recipe f2 [
+  <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+  <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+]
+<span class="traceContains">+schedule: f1</span>
+<span class="traceContains">+run: start-running f2</span>
+<span class="traceContains">+schedule: f2</span>
+<span class="traceContains">+run: 3:number &lt;- copy 0</span>
+<span class="traceContains">+schedule: f1</span>
+<span class="traceContains">+run: 1:number &lt;- copy 0</span>
+<span class="traceContains">+schedule: f2</span>
+<span class="traceContains">+run: 4:number &lt;- copy 0</span>
+<span class="traceContains">+schedule: f1</span>
+<span class="traceContains">+run: 2:number &lt;- copy 0</span>
+
+<span class="Delimiter">:(scenario start_running_takes_ingredients)</span>
+recipe f1 [
+  start-running f2<span class="Delimiter">,</span> <span class="Constant">3</span>
+  <span class="Comment"># wait for f2 to run</span>
+  <span class="Delimiter">{</span>
+    jump-unless <span class="Constant">1</span>:number<span class="Delimiter">,</span> -<span class="Constant">1</span>
+  <span class="Delimiter">}</span>
+]
+recipe f2 [
+  <span class="Constant">1</span>:number<span class="Special"> &lt;- </span>next-ingredient
+  <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>add <span class="Constant">1</span>:number<span class="Delimiter">,</span> <span class="Constant">1</span>
+]
+<span class="traceContains">+mem: storing 4 in location 2</span>
+
+<span class="Delimiter">:(scenario start_running_returns_routine_id)</span>
+recipe f1 [
+  <span class="Constant">1</span>:number<span class="Special"> &lt;- </span>start-running f2
+]
+recipe f2 [
+  <span class="Constant">12</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">44</span>
+]
+<span class="traceContains">+mem: storing 2 in location 1</span>
+
+<span class="Comment">//: this scenario will require some careful setup in escaped C++</span>
+<span class="Comment">//: (straining our tangle capabilities to near-breaking point)</span>
+<span class="Delimiter">:(scenario scheduler_skips_completed_routines)</span>
+<span class="Special">% recipe_ordinal f1 = load(&quot;recipe f1 [\n1:number &lt;- copy 0\n]\n&quot;).front();</span>
+<span class="Special">% recipe_ordinal f2 = load(&quot;recipe f2 [\n2:number &lt;- copy 0\n]\n&quot;).front();</span>
+<span class="Special">% Routines.push_back(new routine(f1));  // f1 meant to run</span>
+<span class="Special">% Routines.push_back(new routine(f2));</span>
+<span class="Special">% Routines.back()-&gt;state = COMPLETED;  // f2 not meant to run</span>
+<span class="Comment"># must have at least one routine without escaping</span>
+recipe f3 [
+  <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+]
+<span class="Comment"># by interleaving '+' lines with '-' lines, we allow f1 and f3 to run in any order</span>
+<span class="traceContains">+schedule: f1</span>
+<span class="traceContains">+mem: storing 0 in location 1</span>
+<span class="traceAbsent">-schedule: f2</span>
+<span class="traceAbsent">-mem: storing 0 in location 2</span>
+<span class="traceContains">+schedule: f3</span>
+<span class="traceContains">+mem: storing 0 in location 3</span>
+
+<span class="Delimiter">:(scenario scheduler_starts_at_middle_of_routines)</span>
+<span class="Special">% Routines.push_back(new routine(COPY));</span>
+<span class="Special">% Routines.back()-&gt;state = COMPLETED;</span>
+recipe f1 [
+  <span class="Constant">1</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+  <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+]
+<span class="traceContains">+schedule: f1</span>
+<span class="traceAbsent">-run: idle</span>
+
+<span class="SalientComment">//:: Errors in a routine cause it to terminate.</span>
+
+<span class="Delimiter">:(scenario scheduler_terminates_routines_after_errors)</span>
+<span class="Special">% Hide_errors = true;</span>
+<span class="Special">% Scheduling_interval = 2;</span>
+recipe f1 [
+  start-running f2
+  <span class="Constant">1</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+  <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+]
+recipe f2 [
+  <span class="Comment"># divide by 0 twice</span>
+  <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>divide-with-remainder <span class="Constant">4</span><span class="Delimiter">,</span> <span class="Constant">0</span>
+  <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>divide-with-remainder <span class="Constant">4</span><span class="Delimiter">,</span> <span class="Constant">0</span>
+]
+<span class="Comment"># f2 should stop after first divide by 0</span>
+<span class="traceContains">+error: f2: divide by zero in '3:number &lt;- divide-with-remainder 4, 0'</span>
+<span class="traceAbsent">-error: f2: divide by zero in '4:number &lt;- divide-with-remainder 4, 0'</span>
+
+<span class="Delimiter">:(after &quot;operator&lt;&lt;(ostream&amp; os, unused end)&quot;)</span>
+  if <span class="Delimiter">(</span>Trace_stream &amp;&amp; Trace_stream<span class="Delimiter">-&gt;</span>curr_label == <span class="Constant">&quot;error&quot;</span> &amp;&amp; Current_routine<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    Current_routine<span class="Delimiter">-&gt;</span>state = COMPLETED<span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+
+<span class="SalientComment">//:: Routines are marked completed when their parent completes.</span>
+
+<span class="Delimiter">:(scenario scheduler_kills_orphans)</span>
+recipe main [
+  start-running f1
+  <span class="Comment"># f1 never actually runs because its parent completes without waiting for it</span>
+]
+recipe f1 [
+  <span class="Constant">1</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+]
+<span class="traceAbsent">-schedule: f1</span>
+
+<span class="Delimiter">:(before &quot;End Scheduler Cleanup&quot;)</span>
+for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  if <span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>state == COMPLETED<span class="Delimiter">)</span> <span class="Identifier">continue</span><span class="Delimiter">;</span>
+  if <span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>parent_index &lt; <span class="Constant">0</span><span class="Delimiter">)</span> <span class="Identifier">continue</span><span class="Delimiter">;</span>  <span class="Comment">// root thread</span>
+  if <span class="Delimiter">(</span>has_completed_parent<span class="Delimiter">(</span>i<span class="Delimiter">))</span> <span class="Delimiter">{</span>
+    Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>state = COMPLETED<span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(code)</span>
+bool has_completed_parent<span class="Delimiter">(</span>long long int routine_index<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  for <span class="Delimiter">(</span>long long int j = routine_index<span class="Delimiter">;</span> j &gt;= <span class="Constant">0</span><span class="Delimiter">;</span> j = Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>j<span class="Delimiter">)-&gt;</span>parent_index<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    if <span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>j<span class="Delimiter">)-&gt;</span>state == COMPLETED<span class="Delimiter">)</span>
+      <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="SalientComment">//:: 'routine-state' can tell if a given routine id is running</span>
+
+<span class="Delimiter">:(scenario routine_state_test)</span>
+<span class="Special">% Scheduling_interval = 2;</span>
+recipe f1 [
+  <span class="Constant">1</span>:number/child-id<span class="Special"> &lt;- </span>start-running f2
+  <span class="Constant">12</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>  <span class="Comment"># race condition since we don't care about location 12</span>
+  <span class="Comment"># thanks to Scheduling_interval, f2's one instruction runs in between here and completes</span>
+  <span class="Constant">2</span>:number/state<span class="Special"> &lt;- </span>routine-state <span class="Constant">1</span>:number/child-id
+]
+recipe f2 [
+  <span class="Constant">12</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
+  <span class="Comment"># trying to run a second instruction marks routine as completed</span>
+]
+<span class="Comment"># recipe f2 should be in state COMPLETED</span>
+<span class="traceContains">+mem: storing 1 in location 2</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+ROUTINE_STATE<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;routine-state&quot;</span><span class="Delimiter">,</span> ROUTINE_STATE<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+case ROUTINE_STATE: <span class="Delimiter">{</span>
+  if <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">)</span> != <span class="Constant">1</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;'routine-state' requires exactly one ingredient, but got &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>to_string<span class="Delimiter">()</span> &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  if <span class="Delimiter">(</span>!is_mu_number<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;first ingredient of 'routine-state' should be a routine id generated by 'start-running', but got &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>original_string &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+case ROUTINE_STATE: <span class="Delimiter">{</span>
+  long long int id = ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+  long long int result = -<span class="Constant">1</span><span class="Delimiter">;</span>
+  for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    if <span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>id == id<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+      result = Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>state<span class="Delimiter">;</span>
+      <span class="Identifier">break</span><span class="Delimiter">;</span>
+    <span class="Delimiter">}</span>
+  <span class="Delimiter">}</span>
+  products<span class="Delimiter">.</span>resize<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
+  products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>push_back<span class="Delimiter">(</span>result<span class="Delimiter">);</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="SalientComment">//:: miscellaneous helpers</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+RESTART<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;restart&quot;</span><span class="Delimiter">,</span> RESTART<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+case RESTART: <span class="Delimiter">{</span>
+  if <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">)</span> != <span class="Constant">1</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;'restart' requires exactly one ingredient, but got &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>to_string<span class="Delimiter">()</span> &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  if <span class="Delimiter">(</span>!is_mu_number<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;first ingredient of 'restart' should be a routine id generated by 'start-running', but got &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>original_string &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+case RESTART: <span class="Delimiter">{</span>
+  long long int id = ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+  for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    if <span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>id == id<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+      Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>state = RUNNING<span class="Delimiter">;</span>
+      <span class="Identifier">break</span><span class="Delimiter">;</span>
+    <span class="Delimiter">}</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+STOP<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;stop&quot;</span><span class="Delimiter">,</span> STOP<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+case STOP: <span class="Delimiter">{</span>
+  if <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">)</span> != <span class="Constant">1</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;'stop' requires exactly one ingredient, but got &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>to_string<span class="Delimiter">()</span> &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  if <span class="Delimiter">(</span>!is_mu_number<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;first ingredient of 'stop' should be a routine id generated by 'start-running', but got &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>original_string &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+case STOP: <span class="Delimiter">{</span>
+  long long int id = ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+  for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    if <span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>id == id<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+      Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>state = COMPLETED<span class="Delimiter">;</span>
+      <span class="Identifier">break</span><span class="Delimiter">;</span>
+    <span class="Delimiter">}</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+_DUMP_ROUTINES<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;$dump-routines&quot;</span><span class="Delimiter">,</span> _DUMP_ROUTINES<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+case _DUMP_ROUTINES: <span class="Delimiter">{</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+case _DUMP_ROUTINES: <span class="Delimiter">{</span>
+  for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    cerr &lt;&lt; i &lt;&lt; <span class="Constant">&quot;: &quot;</span> &lt;&lt; Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>id &lt;&lt; <span class="Constant">' '</span> &lt;&lt; Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>state &lt;&lt; <span class="Constant">' '</span> &lt;&lt; Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>parent_index &lt;&lt; <span class="cSpecial">'\n'</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="Comment">//: support for stopping routines after some number of cycles</span>
+
+<span class="Delimiter">:(scenario routine_discontinues_past_limit)</span>
+<span class="Special">% Scheduling_interval = 2;</span>
+recipe f1 [
+  <span class="Constant">1</span>:number/child-id<span class="Special"> &lt;- </span>start-running f2
+  limit-time <span class="Constant">1</span>:number/child-id<span class="Delimiter">,</span> <span class="Constant">10</span>
+  <span class="Comment"># padding loop just to make sure f2 has time to completed</span>
+  <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">20</span>
+  <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>subtract <span class="Constant">2</span>:number<span class="Delimiter">,</span> <span class="Constant">1</span>
+  jump-if <span class="Constant">2</span>:number<span class="Delimiter">,</span> -<span class="Constant">2</span>:offset
+]
+recipe f2 [
+  jump -<span class="Constant">1</span>:offset  <span class="Comment"># run forever</span>
+  $print [should never get here]<span class="Delimiter">,</span> <span class="Constant">10</span>/newline
+]
+<span class="Comment"># f2 terminates</span>
+<span class="traceContains">+schedule: discontinuing routine 2</span>
+
+<span class="Delimiter">:(before &quot;End routine States&quot;)</span>
+DISCONTINUED<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Scheduler State Transitions&quot;)</span>
+if <span class="Delimiter">(</span>Current_routine<span class="Delimiter">-&gt;</span>limit &gt;= <span class="Constant">0</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+  if <span class="Delimiter">(</span>Current_routine<span class="Delimiter">-&gt;</span>limit &lt;= Scheduling_interval<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    trace<span class="Delimiter">(</span><span class="Constant">9999</span><span class="Delimiter">,</span> <span class="Constant">&quot;schedule&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;discontinuing routine &quot;</span> &lt;&lt; Current_routine<span class="Delimiter">-&gt;</span>id &lt;&lt; end<span class="Delimiter">();</span>
+    Current_routine<span class="Delimiter">-&gt;</span>state = DISCONTINUED<span class="Delimiter">;</span>
+    Current_routine<span class="Delimiter">-&gt;</span>limit = <span class="Constant">0</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  else <span class="Delimiter">{</span>
+    Current_routine<span class="Delimiter">-&gt;</span>limit -= Scheduling_interval<span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+<span class="Delimiter">}</span>
+
+<span class="Delimiter">:(before &quot;End routine Fields&quot;)</span>
+long long int limit<span class="Delimiter">;</span>
+<span class="Delimiter">:(before &quot;End routine Constructor&quot;)</span>
+limit = -<span class="Constant">1</span><span class="Delimiter">;</span>  <span class="Comment">/*</span><span class="Comment"> no limit </span><span class="Comment">*/</span>
+
+<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
+LIMIT_TIME<span class="Delimiter">,</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
+put<span class="Delimiter">(</span>Recipe_ordinal<span class="Delimiter">,</span> <span class="Constant">&quot;limit-time&quot;</span><span class="Delimiter">,</span> LIMIT_TIME<span class="Delimiter">);</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Checks&quot;)</span>
+case LIMIT_TIME: <span class="Delimiter">{</span>
+  if <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">)</span> != <span class="Constant">2</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;'limit-time' requires exactly two ingredient, but got &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>to_string<span class="Delimiter">()</span> &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  if <span class="Delimiter">(</span>!is_mu_number<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;first ingredient of 'limit-time' should be a routine id generated by 'start-running', but got &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>original_string &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  if <span class="Delimiter">(</span>!is_mu_number<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">)))</span> <span class="Delimiter">{</span>
+    raise_error &lt;&lt; maybe<span class="Delimiter">(</span>get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">).</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;second ingredient of 'limit-time' should be a number (of instructions to run for), but got &quot;</span> &lt;&lt; inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>original_string &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
+    <span class="Identifier">break</span><span class="Delimiter">;</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
+case LIMIT_TIME: <span class="Delimiter">{</span>
+  long long int id = ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+  for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+    if <span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>id == id<span class="Delimiter">)</span> <span class="Delimiter">{</span>
+      Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-&gt;</span>limit = ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
+      <span class="Identifier">break</span><span class="Delimiter">;</span>
+    <span class="Delimiter">}</span>
+  <span class="Delimiter">}</span>
+  <span class="Identifier">break</span><span class="Delimiter">;</span>
+<span class="Delimiter">}</span>
+
+<span class="SalientComment">//:: make sure that each routine gets a different alloc to start</span>
+
+<span class="Delimiter">:(scenario new_concurrent)</span>
+recipe f1 [
+  start-running f2
+  <span class="Constant">1</span>:address:shared:number/<span class="Special">raw &lt;- </span>new number:type
+  <span class="Comment"># wait for f2 to complete</span>
+  <span class="Delimiter">{</span>
+    loop-unless <span class="Constant">4</span>:number/<span class="Special">raw</span>
+  <span class="Delimiter">}</span>
+]
+recipe f2 [
+  <span class="Constant">2</span>:address:shared:number/<span class="Special">raw &lt;- </span>new number:type
+  <span class="Comment"># hack: assumes scheduler implementation</span>
+  <span class="Constant">3</span>:boolean/<span class="Special">raw &lt;- </span>equal <span class="Constant">1</span>:address:shared:number/<span class="Special">raw</span><span class="Delimiter">,</span> <span class="Constant">2</span>:address:shared:number/<span class="Special">raw</span>
+  <span class="Comment"># signal f2 complete</span>
+  <span class="Constant">4</span>:number/<span class="Special">raw &lt;- </span>copy <span class="Constant">1</span>
+]
+<span class="traceContains">+mem: storing 0 in location 3</span>
+</pre>
+</body>
+</html>
+<!-- vim: set foldmethod=manual : -->