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<span class="Comment">//: Routines can be put in a 'waiting' state, from which it will be ready to</span>
<span class="Comment">//: run again when a specific memory location changes its value. This is mu's</span>
<span class="Comment">//: basic technique for orchestrating the order in which different routines</span>
<span class="Comment">//: operate.</span>
<span class="Delimiter">:(scenario wait_for_location)</span>
recipe f1 [
<span class="Constant">1</span>:number<span class="Special"> <- </span>copy <span class="Constant">0</span>:literal
start-running f2:recipe
wait-for-location <span class="Constant">1</span>:number
<span class="Comment"># now wait for f2 to run and modify location 1 before using its value</span>
<span class="Constant">2</span>:number<span class="Special"> <- </span>copy <span class="Constant">1</span>:number
]
recipe f2 [
<span class="Constant">1</span>:number<span class="Special"> <- </span>copy <span class="Constant">34</span>:literal
]
<span class="Comment"># if we got the synchronization wrong we'd be storing 0 in location 2</span>
<span class="traceContains">+mem: storing 34 in location 2</span>
<span class="Comment">//: define the new state that all routines can be in</span>
<span class="Delimiter">:(before "End routine States")</span>
WAITING<span class="Delimiter">,</span>
<span class="Delimiter">:(before "End routine Fields")</span>
<span class="Comment">// only if state == WAITING</span>
long long int waiting_on_location<span class="Delimiter">;</span>
int old_value_of_waiting_location<span class="Delimiter">;</span>
<span class="Delimiter">:(before "End routine Constructor")</span>
waiting_on_location = old_value_of_waiting_location = <span class="Constant">0</span><span class="Delimiter">;</span>
<span class="Comment">//: primitive recipe to put routines in that state</span>
<span class="Delimiter">:(before "End Primitive Recipe Declarations")</span>
WAIT_FOR_LOCATION<span class="Delimiter">,</span>
<span class="Delimiter">:(before "End Primitive Recipe Numbers")</span>
Recipe_number[<span class="Constant">"wait-for-location"</span>] = WAIT_FOR_LOCATION<span class="Delimiter">;</span>
<span class="Delimiter">:(before "End Primitive Recipe Implementations")</span>
case WAIT_FOR_LOCATION: <span class="Delimiter">{</span>
reagent loc = canonize<span class="Delimiter">(</span>current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">));</span>
Current_routine<span class="Delimiter">-></span>state = WAITING<span class="Delimiter">;</span>
Current_routine<span class="Delimiter">-></span>waiting_on_location = loc<span class="Delimiter">.</span>value<span class="Delimiter">;</span>
Current_routine<span class="Delimiter">-></span>old_value_of_waiting_location = Memory[loc<span class="Delimiter">.</span>value]<span class="Delimiter">;</span>
trace<span class="Delimiter">(</span>Primitive_recipe_depth<span class="Delimiter">,</span> <span class="Constant">"run"</span><span class="Delimiter">)</span> << <span class="Constant">"waiting for location "</span> << loc<span class="Delimiter">.</span>value << <span class="Constant">" to change from "</span> << Memory[loc<span class="Delimiter">.</span>value]<span class="Delimiter">;</span>
<span class="CommentedCode">//? trace("schedule") << Current_routine->id << ": waiting for location " << loc.value << " to change from " << Memory[loc.value]; //? 2</span>
<span class="Identifier">break</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
<span class="Comment">//: scheduler tweak to get routines out of that state</span>
<span class="Delimiter">:(before "End Scheduler State Transitions")</span>
for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i < SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span class="CommentedCode">//? trace("schedule") << "wake up loop 1: routine " << Routines.at(i)->id << " has state " << Routines.at(i)->state; //? 1</span>
if <span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>state != WAITING<span class="Delimiter">)</span> <span class="Identifier">continue</span><span class="Delimiter">;</span>
<span class="CommentedCode">//? trace("schedule") << "waiting on location: " << Routines.at(i)->waiting_on_location; //? 1</span>
<span class="CommentedCode">//? if (Routines.at(i)->waiting_on_location) //? 2</span>
<span class="CommentedCode">//? trace("schedule") << "checking routine " << Routines.at(i)->id << " waiting on location " //? 2</span>
<span class="CommentedCode">//? << Routines.at(i)->waiting_on_location << ": " << Memory[Routines.at(i)->waiting_on_location] << " vs " << Routines.at(i)->old_value_of_waiting_location; //? 2</span>
if <span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>waiting_on_location &&
Memory[Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>waiting_on_location] != Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>old_value_of_waiting_location<span class="Delimiter">)</span> <span class="Delimiter">{</span>
trace<span class="Delimiter">(</span><span class="Constant">"schedule"</span><span class="Delimiter">)</span> << <span class="Constant">"waking up routine</span><span class="cSpecial">\n</span><span class="Constant">"</span><span class="Delimiter">;</span>
Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>state = RUNNING<span class="Delimiter">;</span>
Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>waiting_on_location = Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>old_value_of_waiting_location = <span class="Constant">0</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
<span class="Delimiter">}</span>
<span class="Comment">//: also allow waiting on a routine to stop running</span>
<span class="Delimiter">:(scenario wait_for_routine)</span>
recipe f1 [
<span class="Constant">1</span>:number<span class="Special"> <- </span>copy <span class="Constant">0</span>:literal
<span class="Constant">12</span>:number/routine<span class="Special"> <- </span>start-running f2:recipe
wait-for-routine <span class="Constant">12</span>:number/routine
<span class="Comment"># now wait for f2 to run and modify location 1 before using its value</span>
<span class="Constant">3</span>:number<span class="Special"> <- </span>copy <span class="Constant">1</span>:number
]
recipe f2 [
<span class="Constant">1</span>:number<span class="Special"> <- </span>copy <span class="Constant">34</span>:literal
]
<span class="traceContains">+schedule: f1</span>
<span class="traceContains">+run: waiting for routine 2</span>
<span class="traceContains">+schedule: f2</span>
<span class="traceContains">+schedule: waking up routine 1</span>
<span class="traceContains">+schedule: f1</span>
<span class="Comment"># if we got the synchronization wrong we'd be storing 0 in location 3</span>
<span class="traceContains">+mem: storing 34 in location 3</span>
<span class="Delimiter">:(before "End routine Fields")</span>
<span class="Comment">// only if state == WAITING</span>
long long int waiting_on_routine<span class="Delimiter">;</span>
<span class="Delimiter">:(before "End routine Constructor")</span>
waiting_on_routine = <span class="Constant">0</span><span class="Delimiter">;</span>
<span class="Delimiter">:(before "End Primitive Recipe Declarations")</span>
WAIT_FOR_ROUTINE<span class="Delimiter">,</span>
<span class="Delimiter">:(before "End Primitive Recipe Numbers")</span>
Recipe_number[<span class="Constant">"wait-for-routine"</span>] = WAIT_FOR_ROUTINE<span class="Delimiter">;</span>
<span class="Delimiter">:(before "End Primitive Recipe Implementations")</span>
case WAIT_FOR_ROUTINE: <span class="Delimiter">{</span>
Current_routine<span class="Delimiter">-></span>state = WAITING<span class="Delimiter">;</span>
assert<span class="Delimiter">(</span>scalar<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)));</span>
Current_routine<span class="Delimiter">-></span>waiting_on_routine = 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>
trace<span class="Delimiter">(</span>Primitive_recipe_depth<span class="Delimiter">,</span> <span class="Constant">"run"</span><span class="Delimiter">)</span> << <span class="Constant">"waiting for routine "</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>
<span class="Identifier">break</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
<span class="Delimiter">:(before "End Scheduler State Transitions")</span>
<span class="Comment">// Wake up any routines waiting for other routines to go to sleep.</span>
<span class="Comment">// Important: this must come after the scheduler loop above giving routines</span>
<span class="Comment">// waiting for locations to change a chance to wake up.</span>
for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i < 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">)-></span>state != WAITING<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">)-></span>waiting_on_routine<span class="Delimiter">)</span> <span class="Identifier">continue</span><span class="Delimiter">;</span>
long long int id = Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>waiting_on_routine<span class="Delimiter">;</span>
assert<span class="Delimiter">(</span>id != Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>id<span class="Delimiter">);</span>
for <span class="Delimiter">(</span>long long int j = <span class="Constant">0</span><span class="Delimiter">;</span> j < SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">);</span> ++j<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">)-></span>id == id && Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>j<span class="Delimiter">)-></span>state != RUNNING<span class="Delimiter">)</span> <span class="Delimiter">{</span>
trace<span class="Delimiter">(</span><span class="Constant">"schedule"</span><span class="Delimiter">)</span> << <span class="Constant">"waking up routine "</span> << Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>id<span class="Delimiter">;</span>
Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>state = RUNNING<span class="Delimiter">;</span>
Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>waiting_on_routine = <span class="Constant">0</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
<span class="Delimiter">}</span>
<span class="Delimiter">}</span>
<span class="Delimiter">:(before "End Primitive Recipe Declarations")</span>
SWITCH<span class="Delimiter">,</span>
<span class="Delimiter">:(before "End Primitive Recipe Numbers")</span>
Recipe_number[<span class="Constant">"switch"</span>] = SWITCH<span class="Delimiter">;</span>
<span class="Delimiter">:(before "End Primitive Recipe Implementations")</span>
case SWITCH: <span class="Delimiter">{</span>
long long int id = some_other_running_routine<span class="Delimiter">();</span>
if <span class="Delimiter">(</span>id<span class="Delimiter">)</span> <span class="Delimiter">{</span>
assert<span class="Delimiter">(</span>id != Current_routine<span class="Delimiter">-></span>id<span class="Delimiter">);</span>
<span class="CommentedCode">//? cerr << "waiting on " << id << " from " << Current_routine->id << '\n'; //? 1</span>
Current_routine<span class="Delimiter">-></span>state = WAITING<span class="Delimiter">;</span>
Current_routine<span class="Delimiter">-></span>waiting_on_routine = id<span class="Delimiter">;</span>
<span class="Delimiter">}</span>
<span class="Identifier">break</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
<span class="Delimiter">:(code)</span>
long long int some_other_running_routine<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 < SIZE<span class="Delimiter">(</span>Routines<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
if <span class="Delimiter">(</span>i == Current_routine_index<span class="Delimiter">)</span> <span class="Identifier">continue</span><span class="Delimiter">;</span>
assert<span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)</span> != Current_routine<span class="Delimiter">);</span>
assert<span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>id != Current_routine<span class="Delimiter">-></span>id<span class="Delimiter">);</span>
if <span class="Delimiter">(</span>Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>state == RUNNING<span class="Delimiter">)</span>
<span class="Identifier">return</span> Routines<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)-></span>id<span class="Delimiter">;</span>
<span class="Delimiter">}</span>
<span class="Identifier">return</span> <span class="Constant">0</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
</pre>
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