Wrap API and registry requests with common metric timings

Record response times, codes, and rollup non-2XX responses.

util/saas/metricqueue.py

@@ -1,7 +1,11 @@
 import logging
+import time
 
+from functools import wraps
 from Queue import Queue, Full
 
+from flask import g, request
+
 
 logger = logging.getLogger(__name__)
 
@@ -16,4 +20,38 @@ class MetricQueue(object):
       logger.error('Metric queue full')
 
   def get(self):
-    return self._queue.get()
+    v = self._queue.get()
+    return v
+
+def time_blueprint(bp, metric_queue):
+  bp.before_request(time_before_request)
+  bp.after_request(time_after_request(bp.name, metric_queue))
+
+def time_before_request():
+  g._start = time.time()
+
+def time_after_request(name, metric_queue):
+  def f(r):
+    start = getattr(g, '_start', None)
+    if start is None:
+      return r
+    dur = time.time() - start
+    dims = dimensions={'endpoint': request.endpoint}
+    metric_queue.put('ResponseTime', dur, dimensions=dims, unit='Seconds')
+    metric_queue.put('ResponseCode', r.status_code, dimensions=dims)
+    if r.status_code < 200 or r.status_code >= 300:
+      metric_queue.put('Non200Response', 1, dimensions={'name': name})
+    return r
+  return f
+
+def time_decorator(name, metric_queue):
+  after = time_after_request(name, metric_queue)
+  def decorator(func):
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+      time_before_request()
+      rv = func(*args, **kwargs)
+      after(rv)
+      return rv
+    return wrapper
+  return decorator