#7136 Increase time out when launching from python.

Added truncated exponential backoff policy to have shorter delays
initially, and longer delay after repeated failures.

ApplicationCode/GrpcInterface/Python/rips/instance.py

@@ -21,7 +21,7 @@ from Definitions_pb2 import Empty
 import RiaVersionInfo
 
 from .project import Project
-from .retry_policy import FixedRetryPolicy
+from .retry_policy import ExponentialBackoffRetryPolicy
 
 class Instance:
     """The ResInsight Instance class. Use to launch or find existing ResInsight instances
@@ -183,7 +183,7 @@ class Instance:
         connection_ok = False
         version_ok = False
 
-        retry_policy = FixedRetryPolicy()
+        retry_policy = ExponentialBackoffRetryPolicy()
         if self.launched:
             for num_tries in range(0, retry_policy.num_retries()):
                 connection_ok, version_ok = self.__check_version()

ApplicationCode/GrpcInterface/Python/rips/retry_policy.py

@@ -1,6 +1,7 @@
 import abc
 
 import time
+import random
 
 
 class RetryPolicy(abc.ABC):
@@ -47,3 +48,36 @@ class FixedRetryPolicy(RetryPolicy):
 
     def num_retries(self):
         return self.max_num_retries
+
+
+class ExponentialBackoffRetryPolicy(RetryPolicy):
+    def __init__(self, min_backoff=200, max_backoff=10000, max_num_retries=20):
+        """
+        Create a truncated exponential backoff policy.
+        See: https://en.wikipedia.org/wiki/Exponential_backoff
+        :param min_backoff: minimum time to sleep in milliseconds.
+        :param max_backoff: maximum time to sleep in milliseconds.
+        :param max_num_retries: max number of retries.
+        """
+        self.min_backoff = min_backoff
+        self.max_backoff = max_backoff
+        self.max_num_retries = max_num_retries
+        self.multiplier = 2
+
+    def sleep(self, retry_num):
+        # Add a random component to avoid synchronized retries
+        wiggle = random.randint(0, 100)
+        sleep_ms = min(
+            self.min_backoff + self.multiplier ** retry_num + wiggle, self.max_backoff
+        )
+        time.sleep(sleep_ms / 1000)
+
+    def time_out_message(self):
+        return (
+            "Tried {} times with increasing delay (from {} to {} milliseconds).".format(
+                self.max_num_retries, self.min_backoff, self.max_backoff
+            )
+        )
+
+    def num_retries(self):
+        return self.max_num_retries