Merge pull request #326 from rmkraus/fix_pip

Fix pip installation issues.

homeassistant/util/package.py

@@ -1,19 +1,53 @@
 """Helpers to install PyPi packages."""
 import os
+import logging
+import pkg_resources
 import subprocess
 import sys
+import threading
+
+_LOGGER = logging.getLogger(__name__)
+INSTALL_LOCK = threading.Lock()
 
 
-def install_package(package, upgrade=False, target=None):
+def install_package(package, upgrade=True, target=None):
     """Install a package on PyPi. Accepts pip compatible package strings.
     Return boolean if install successfull."""
     # Not using 'import pip; pip.main([])' because it breaks the logger
     args = [sys.executable, '-m', 'pip', 'install', '--quiet', package]
+
     if upgrade:
         args.append('--upgrade')
     if target:
         args += ['--target', os.path.abspath(target)]
+
+    with INSTALL_LOCK:
+        if check_package_exists(package, target):
+            return True
+
+        _LOGGER.info('Attempting install of %s', package)
         try:
             return 0 == subprocess.call(args)
         except subprocess.SubprocessError:
             return False
+
+
+def check_package_exists(package, target=None):
+    """Check if a package exists.
+    Returns True when the requirement is met.
+    Returns False when the package is not installed or doesn't meet req."""
+    req = pkg_resources.Requirement.parse(package)
+
+    if target:
+        work_set = pkg_resources.WorkingSet([target])
+        search_fun = work_set.find
+
+    else:
+        search_fun = pkg_resources.get_distribution
+
+    try:
+        result = search_fun(req)
+    except (pkg_resources.DistributionNotFound, pkg_resources.VersionConflict):
+        return False
+
+    return bool(result)