Improve run_gurobi to wait for available token

doc/release_notes.rst

@@ -33,6 +33,8 @@ Version 0.3.9
 
 * Up to now the `rhs` argument in the `add_constraints` function was not supporting an expression as an input type. This is now added.
 
+* Improve `run_gurobi` to optionally wait for an available token.
+
 * Linopy now supports python 3.12.
 
 **Deprecations**

linopy/solvers.py

@@ -583,6 +583,25 @@
     return Result(status, solution, m)
 
 
+def start_gurobi_env(wait=60):
+    """
+    Try (forever!) to create an environment. Return the environment once started. Waiting time is in seconds.
+    """
+    # see https://support.gurobi.com/hc/en-us/articles/360029879251-How-do-I-check-the-availability-of-floating-license-tokens
+    import time
+
+    while True:
+        try:
+            # Attempt to construct a Gurobi environment
+            env = gurobipy.Env()
+            logging.debug("Gurobi: Token retrieved!")
+            return env
+        except gurobipy.GurobiError:
+            logging.debug("Gurobi: No tokens available...")
+            # Wait x seconds
+            time.sleep(wait)
+
+
 def run_gurobi(
     model,
     io_api=None,
@@ -627,7 +646,10 @@
 
     with contextlib.ExitStack() as stack:
         if env is None:
-            env = stack.enter_context(gurobipy.Env())
+            if solver_options.get("WaitTime"):
+                env = stack.enter_context(start_gurobi_env(solver_options["WaitTime"]))
+            else:
+                env = stack.enter_context(gurobipy.Env())
 
         if io_api is None or io_api in FILE_IO_APIS:
             problem_fn = model.to_file(problem_fn, io_api=io_api)
@@ -643,7 +665,8 @@
 
         if solver_options is not None:
             for key, value in solver_options.items():
-                m.setParam(key, value)
+                if key != "WaitTime":
+                    m.setParam(key, value)
         if log_fn is not None:
             m.setParam("logfile", log_fn)