Merge pull request #114 from Breakthrough-Energy/jon/nrel-api

Factor out code for interacting with nrel api and add retry logic

prereise/gather/__init__.py

@@ -5,4 +5,5 @@
     "hydrodata",
     "get_monthly_net_generation",
     "trim_eia_form_923",
+    "request_util",
 ]

prereise/gather/request_util.py

@@ -0,0 +1,61 @@
+import functools
+import time
+from datetime import timedelta
+from urllib.error import HTTPError
+
+
+class RateLimit:
+    """Provides a way to call an arbitrary function at most once per interval.
+
+    :param int/float interval: the amount of time in seconds to wait between actions
+    """
+
+    def __init__(self, interval=None):
+        """Constructor"""
+        self.interval = interval
+        self.last_run_at = None if interval is None else time.time() - interval
+
+    def invoke(self, action):
+        """Call the action and return its value, waiting if necessary
+
+        :param callable action: the thing to do
+        :return: (*Any*) -- the return value of the action
+        """
+        if self.interval is None:
+            return action()
+        elapsed = time.time() - self.last_run_at
+        if elapsed < self.interval:
+            time.sleep(self.interval - elapsed)
+        result = action()
+        self.last_run_at = time.time()
+        return result
+
+
+def retry(_func=None, retry_count=5, interval=None, allowed_exceptions=(HTTPError)):
+    """Creates a decorator to handle retry logic.
+
+    :param int retry_count: the max number of retries
+    :param int/float interval: minimum spacing between retries
+    :param tuple allowed_exceptions: exceptions for which the function will be retried, all others will be surfaced to the caller
+
+    :return: (*Any*) -- the return value of the decorated function
+    """
+
+    def decorator(func):
+        limiter = RateLimit(interval)
+
+        @functools.wraps(func)
+        def wrapper(*args, **kwargs):
+            for _ in range(retry_count):
+                try:
+                    return limiter.invoke(lambda: func(*args, **kwargs))
+                except allowed_exceptions as e:
+                    print(str(e))
+                    pass
+            print("Max retries reached!!")
+
+        return wrapper
+
+    if _func is None:
+        return decorator
+    return decorator(_func)

prereise/gather/solardata/nsrdb/__init__.py

@@ -1 +1 @@
-__all__ = ["naive", "sam"]
+__all__ = ["naive", "sam", "nrel_api"]