Add a package listing API to cipd.

appengine/chrome_infra_packages/cipd/impl.py

Index: appengine/chrome_infra_packages/cipd/impl.py
diff --git a/appengine/chrome_infra_packages/cipd/impl.py b/appengine/chrome_infra_packages/cipd/impl.py
index 451a0377cef1445f1698575efb196aa621fb0940..bbd6458fd504b054bfcf1b887501b53a7b83fa4b 100644
--- a/appengine/chrome_infra_packages/cipd/impl.py
+++ b/appengine/chrome_infra_packages/cipd/impl.py
@@ -165,6 +165,31 @@ class RepoService(object):
     """
     return package_key(package_name).get()
 
+  def list_packages(self, prefix):
+    """Returns list of Packages with the given prefix.
+
+    Args:
+      prefix: string prefix of the packages to list.
+
+    Returns:
+      [Package, ...].
+    """
+    query = Package.query().order(Package.key)
+
+    # Only apply the filtering if a prefix was given. The empty string isn't a
+    # valid key and will result in an exception.
+    if prefix:
+      query = query.filter(
+          # Prefix match using the operators available to us. Packages can only
+          # contain lowercase ascii, numbers, and '/' so '\uffff' will always
+          # be larger.
+          ndb.AND(Package.key >= ndb.Key(Package, prefix),

[Vadim Sh., 2015/06/19 21:12:03]

this thing may require additional composite index (in index.yaml). The simplest
way to find out is to deploy  it to chrome-infra-packages-dev.appspot.com (I'll
send you invite) and try the call.

[estaab, 2015/06/20 02:25:25]

Sounds good.

+                  Package.key <= ndb.Key(Package, prefix + u'\uffff')))
+    pkgs = []
+    for pkg in query:

[Vadim Sh., 2015/06/19 21:12:03]

use keys_only=True query and extract package_name from the key. Will be much
faster that way (index-only query).

[estaab, 2015/06/20 02:25:25]

Done.

+      pkgs.append(pkg.package_name)
+    return pkgs

[Vadim Sh., 2015/06/19 21:12:03]

return sorted(pkgs)

[estaab, 2015/06/20 02:25:25]

Done

+
   def get_processing_result(self, package_name, instance_id, processor_name):
     """Returns results of some asynchronous processor or None if not ready.