[api] static APIClient class

Following @degemer's feedback:
* Make `APIClient` class 100% static
* Rewrite the `resolve_http_client` logic in the `HTTPClient` class

datadog/api/api_client.py

@@ -6,7 +6,7 @@
 from datadog.api import _api_version, _max_timeouts, _backoff_period
 from datadog.api.exceptions import ClientError, ApiError, HttpBackoff, \
     HttpTimeout, ApiNotInitialized
-from datadog.api.http_client import get_http_client
+from datadog.api.http_client import resolve_http_client
 from datadog.util.compat import json, is_p3k
 
 
@@ -25,13 +25,21 @@ class APIClient(object):
     _timeout_counter = 0
     _api_version = _api_version
 
-    def __init__(self):
+    # Plugged HTTP client
+    _http_client = None
+
+    @classmethod
+    def _get_http_client(cls):
         """
-        Instantiate the client. Plug a HTTP client.
+        Getter for the embedded HTTP client.
         """
-        self._http_client = get_http_client()
+        if not cls._http_client:
+            cls._http_client = resolve_http_client()
 
-    def submit(self, method, path, body=None, attach_host_name=False, response_formatter=None,
+        return cls._http_client
+
+    @classmethod
+    def submit(cls, method, path, body=None, attach_host_name=False, response_formatter=None,
                error_formatter=None, **params):
         """
         Make an HTTP API request
@@ -61,8 +69,8 @@ def submit(self, method, path, body=None, attach_host_name=False, response_forma
         """
         try:
             # Check if it's ok to submit
-            if not self._should_submit():
-                _, backoff_time_left = self._backoff_status()
+            if not cls._should_submit():
+                _, backoff_time_left = cls._backoff_status()
                 raise HttpBackoff(backoff_time_left)
 
             # Import API, User and HTTP settings
@@ -103,14 +111,14 @@ def submit(self, method, path, body=None, attach_host_name=False, response_forma
             # Construct the URL
             url = "{api_host}/api/{api_version}/{path}".format(
                   api_host=_api_host,
-                  api_version=self._api_version,
+                  api_version=cls._api_version,
                   path=path.lstrip("/"),
             )
 
             # Process requesting
             start_time = time.time()
 
-            result = self._http_client.request(
+            result = cls._get_http_client().request(
                 method=method, url=url,
                 headers=headers, params=params, data=body,
                 timeout=_timeout, max_retries=_max_retries,
@@ -120,7 +128,7 @@ def submit(self, method, path, body=None, attach_host_name=False, response_forma
             # Request succeeded: log it and reset the timeout counter
             duration = round((time.time() - start_time) * 1000., 4)
             log.info("%s %s %s (%sms)" % (result.status_code, method, url, duration))
-            self._timeout_counter = 0
+            cls._timeout_counter = 0
 
             # Format response content
             content = result.content
@@ -144,7 +152,7 @@ def submit(self, method, path, body=None, attach_host_name=False, response_forma
                 return response_formatter(response_obj)
 
         except HttpTimeout:
-            self._timeout_counter += 1
+            cls._timeout_counter += 1
             raise
         except ClientError as e:
             if _mute:

datadog/api/http_client.py

@@ -9,12 +9,20 @@
 import logging
 import urllib
 
+# 3p
+try:
+    import requests
+except ImportError:
+    requests = None
+
+try:
+    from google.appengine.api import urlfetch, urlfetch_errors
+except ImportError:
+    urlfetch, urlfetch_errors = None, None
+
 # datadog
 from datadog.api.exceptions import ClientError, HTTPError, HttpTimeout
 
-requests = None
-urlfetch = None
-urlfetch_errors = None
 
 log = logging.getLogger('dd.datadogpy')
 
@@ -138,28 +146,19 @@ def raise_on_status(cls, result):
                 raise HTTPError(status_code)
 
 
-HTTP_CLIENTS = [RequestClient, URLFetchClient]
-
-
-def get_http_client():
+def resolve_http_client():
     """
-    Return the appropriate HTTP client based the defined priority and user environment.
+    Resolve an appropriate HTTP client based the defined priority and user environment.
     """
-    global requests
-    global urlfetch
-    global urlfetch_errors
-
-    try:
-        import requests
+    if requests:
+        log.debug(u"Use `requests` based HTTP client.")
         return RequestClient
-    except ImportError:
-        pass
 
-    try:
-        from google.appengine.api import urlfetch, urlfetch_errors
+    if urlfetch and urlfetch_errors:
+        log.debug(u"Use `urlfetch` based HTTP client.")
         return URLFetchClient
-    except ImportError:
-        raise ImportError(
-            u"Datadog API client was unable to resolve a HTTP client. "
-            u" Please install `requests` library."
-        )
+
+    raise ImportError(
+        u"Datadog API client was unable to resolve a HTTP client. "
+        u" Please install `requests` library."
+    )

datadog/api/resources.py

@@ -40,13 +40,13 @@ def create(cls, attach_host_name=False, method='POST', id=None, params=None, **b
         if params is None:
             params = {}
         if method == 'GET':
-            return APIClient().submit('GET', cls._class_url, **body)
+            return APIClient.submit('GET', cls._class_url, **body)
         if id is None:
-            return APIClient().submit('POST', cls._class_url, body,
-                                      attach_host_name=attach_host_name, **params)
+            return APIClient.submit('POST', cls._class_url, body,
+                                    attach_host_name=attach_host_name, **params)
         else:
-            return APIClient().submit('POST', cls._class_url + "/" + str(id), body,
-                                      attach_host_name=attach_host_name, **params)
+            return APIClient.submit('POST', cls._class_url + "/" + str(id), body,
+                                    attach_host_name=attach_host_name, **params)
 
 
 class SendableAPIResource(object):
@@ -70,11 +70,11 @@ def send(cls, attach_host_name=False, id=None, **body):
         :returns: JSON response from HTTP API request
         """
         if id is None:
-            return APIClient().submit('POST', cls._class_url, body,
-                                      attach_host_name=attach_host_name)
+            return APIClient.submit('POST', cls._class_url, body,
+                                    attach_host_name=attach_host_name)
         else:
-            return APIClient().submit('POST', cls._class_url + "/" + str(id), body,
-                                      attach_host_name=attach_host_name)
+            return APIClient.submit('POST', cls._class_url + "/" + str(id), body,
+                                    attach_host_name=attach_host_name)
 
 
 class UpdatableAPIResource(object):
@@ -96,7 +96,7 @@ def update(cls, id, params=None, **body):
         """
         if params is None:
             params = {}
-        return APIClient().submit('PUT', cls._class_url + "/" + str(id), body, **params)
+        return APIClient.submit('PUT', cls._class_url + "/" + str(id), body, **params)
 
 
 class DeletableAPIResource(object):
@@ -113,7 +113,7 @@ def delete(cls, id, **params):
 
         :returns: JSON response from HTTP API request
         """
-        return APIClient().submit('DELETE', cls._class_url + "/" + str(id), **params)
+        return APIClient.submit('DELETE', cls._class_url + "/" + str(id), **params)
 
 
 class GetableAPIResource(object):
@@ -133,7 +133,7 @@ def get(cls, id, **params):
 
         :returns: JSON response from HTTP API request
         """
-        return APIClient().submit('GET', cls._class_url + "/" + str(id), **params)
+        return APIClient.submit('GET', cls._class_url + "/" + str(id), **params)
 
 
 class ListableAPIResource(object):
@@ -150,7 +150,7 @@ def get_all(cls, **params):
 
         :returns: JSON response from HTTP API request
         """
-        return APIClient().submit('GET', cls._class_url, **params)
+        return APIClient.submit('GET', cls._class_url, **params)
 
 
 class SearchableAPIResource(object):
@@ -167,7 +167,7 @@ def _search(cls, **params):
 
         :returns: JSON response from HTTP API request
         """
-        return APIClient().submit('GET', cls._class_url, **params)
+        return APIClient.submit('GET', cls._class_url, **params)
 
 
 class ActionAPIResource(object):
@@ -194,9 +194,9 @@ def _trigger_class_action(cls, method, name, id=None, **params):
         :returns: JSON response from HTTP API request
         """
         if id is None:
-            return APIClient().submit(method, cls._class_url + "/" + name, params)
+            return APIClient.submit(method, cls._class_url + "/" + name, params)
         else:
-            return APIClient().submit(method, cls._class_url + "/" + str(id) + "/" + name, params)
+            return APIClient.submit(method, cls._class_url + "/" + str(id) + "/" + name, params)
 
     @classmethod
     def _trigger_action(cls, method, name, id=None, **params):
@@ -218,6 +218,6 @@ def _trigger_action(cls, method, name, id=None, **params):
         :returns: JSON response from HTTP API request
         """
         if id is None:
-            return APIClient().submit(method, name, params)
+            return APIClient.submit(method, name, params)
         else:
-            return APIClient().submit(method, name + "/" + str(id), params)
+            return APIClient.submit(method, name + "/" + str(id), params)