Improve dependency resolution time by using cache control

CHANGELOG.md

 # Change Log
 
+## [Unreleased]
+
+### Changes
+
+- Improved dependency resolution time by using cache control.
+
+
 ## [0.7.1] - 2018-04-05
 
 ### Fixed

poetry/repositories/pypi_repository.py

@@ -2,8 +2,10 @@ from pathlib import Path
 from typing import List
 from typing import Union
 
+from cachecontrol import CacheControl
+from cachecontrol.caches.file_cache import FileCache
 from cachy import CacheManager
-from requests import get
+from requests import session
 
 from poetry.locations import CACHE_DIR
 from poetry.packages import dependency_from_pep_508
@@ -21,6 +23,7 @@ class PyPiRepository(Repository):
     def __init__(self, url='https://pypi.org/', disable_cache=False):
         self._url = url
         self._disable_cache = disable_cache
+
         release_cache_dir = Path(CACHE_DIR) / 'cache' / 'repositories' / 'pypi'
         self._cache = CacheManager({
             'default': 'releases',
@@ -35,6 +38,11 @@ class PyPiRepository(Repository):
                 }
             }
         })
+
+        self._session = CacheControl(
+            session(),
+            cache=FileCache(str(release_cache_dir / '_packages'))
+        )
         
         super().__init__()
 
@@ -203,7 +211,7 @@ class PyPiRepository(Repository):
         return data
 
     def _get(self, endpoint: str) -> Union[dict, None]:
-        json_response = get(self._url + endpoint)
+        json_response = self._session.get(self._url + endpoint)
         if json_response.status_code == 404:
             return None
 

pyproject.toml

@@ -32,6 +32,7 @@ requests-toolbelt = "^0.8.0"
 jsonschema = "^2.6"
 pyrsistent = "^0.14.2"
 pyparsing = "^2.2"
+cachecontrol = { version = "^0.12.4", extras = ["filecache"] }
 
 # zipfile36 is needed for Python 3.4 and 3.5
 zipfile36 = { version = "^0.1", python = ">=3.4 <3.6" }
@@ -39,6 +40,12 @@ zipfile36 = { version = "^0.1", python = ">=3.4 <3.6" }
 # The typing module is not in the stdlib in Python 3.4
 typing = { version = "^3.6", python = "~3.4" }
 
+# cachecontrol dependencies are badly set
+# and do not appear in PyPI JSON API
+# So we set them here
+msgpack-python = "^0.5"
+lockfile = "^0.12"
+
 [tool.poetry.dev-dependencies]
 pytest = "^3.4"
 pytest-cov = "^2.5"