Add a queue to the solver worker

roles/solver.py

@@ -6,6 +6,8 @@ import sys
 import time
 import threading
 
+from collections import OrderedDict
+
 class Solver(object):
 
     def __init__(self, config):
@@ -15,7 +17,13 @@ class Solver(object):
         self.address = config['address']
         self.name = config['name']
         self.solver = importlib.import_module(f"solvers.{config['solver']}")
-        self.thread = None
+        self.queue = OrderedDict()
+
+        self.status = 'Ready'
+
+        # self.thread = None
+        self.thread = threading.Thread(name='solver', target=self.solver_thread, daemon=True)
+        self.thread.start()
     
     def __del__(self):
         self.stop_solver()
@@ -23,6 +31,18 @@ class Solver(object):
     def __repr__(self):
         return "Solver"
     
+    def solver_thread(self):
+
+        while True:
+            if len(self.queue) > 0:
+                print("I: Solver started")
+                self.status = 'running'
+                _, params = self.queue.popitem(last=False)
+                self.solve(params)
+            else:
+                self.status = 'ready'
+                time.sleep(0.5)
+    
     def solve(self, params):
 
         start_time = time.time()
@@ -35,7 +55,7 @@ class Solver(object):
             solution['elapsed_time'] = elapsed_time
 
         self.submit_solution(params, solution)
-        self.thread = None
+        # self.thread = None
         return True
     
     def post(self, path, data):
@@ -57,14 +77,18 @@ class Solver(object):
 
     def start_solver(self, params):
 
-        if self.thread is None:
-            print("I: Solver started")
-            # self.thread = StoppableThread(target=self.solve, args=(params, ))
-            self.thread = threading.Thread(name='solver', target=self.solve, args=(params, ), daemon=True)
-            self.thread.start()
-            return {'status': 'started'}
-        else:
-            return {'status': 'busy'}
+        # if self.thread is None:
+            # print("I: Solver started")
+            # self.thread = threading.Thread(name='solver', target=self.solve, args=(params, ), daemon=True)
+            # self.thread.start()
+            # return {'status': 'started'}
+        # else:
+        #     return {'status': 'busy'}
+            
+        print("I: Problem queued")
+        _id = params['request_id']
+        self.queue[_id] = params
+        return {'status': 'queued'}
         
     def stop_solver(self):
 
@@ -80,5 +104,7 @@ class Solver(object):
             return self.start_solver(params)
         elif cmd == 'stop':
             return self.stop_solver()
+        elif cmd == 'status':
+            return self.status
         else:
             return None