fixes saltstack/salt#63982 aptpkg.latest_version calls apt-cache too much

changelog/63982.fixed.md

@@ -0,0 +1 @@
+Fix aptpkg.latest_version performance, reducing number of times to 'shell out'

salt/modules/aptpkg.py

@@ -423,6 +423,8 @@ def parse_arch(name):
 
 def latest_version(*names, **kwargs):
     """
+    .. versionchanged:: 3007.0
+
     Return the latest version of the named package available for upgrade or
     installation. If more than one package name is specified, a dict of
     name/version pairs is returned.
@@ -469,38 +471,47 @@ def latest_version(*names, **kwargs):
     if refresh:
         refresh_db(cache_valid_time)
 
+    cmd = ["apt-cache", "-q", "policy"]
+    cmd.extend(names)
+    if repo is not None:
+        cmd.extend(repo)
+    out = _call_apt(cmd, scope=False)
+
+    short_names = [nom.split(":", maxsplit=1)[0] for nom in names]
+
+    candidates = {}
+    for line in salt.utils.itertools.split(out["stdout"], "\n"):
+        if line.endswith(":") and line[:-1] in short_names:
+            this_pkg = names[short_names.index(line[:-1])]
+        elif "Candidate" in line:
+            candidate = ""
+            comps = line.split()
+            if len(comps) >= 2:
+                candidate = comps[-1]
+                if candidate.lower() == "(none)":
+                    candidate = ""
+            candidates[this_pkg] = candidate
+
     for name in names:
-        cmd = ["apt-cache", "-q", "policy", name]
-        if repo is not None:
-            cmd.extend(repo)
-        out = _call_apt(cmd, scope=False)
-
-        candidate = ""
-        for line in salt.utils.itertools.split(out["stdout"], "\n"):
-            if "Candidate" in line:
-                comps = line.split()
-                if len(comps) >= 2:
-                    candidate = comps[-1]
-                    if candidate.lower() == "(none)":
-                        candidate = ""
-                break
-
         installed = pkgs.get(name, [])
         if not installed:
-            ret[name] = candidate
+            ret[name] = candidates.get(name, "")
         elif installed and show_installed:
-            ret[name] = candidate
-        elif candidate:
+            ret[name] = candidates.get(name, "")
+        elif candidates.get(name):
             # If there are no installed versions that are greater than or equal
             # to the install candidate, then the candidate is an upgrade, so
             # add it to the return dict
             if not any(
                 salt.utils.versions.compare(
-                    ver1=x, oper=">=", ver2=candidate, cmp_func=version_cmp
+                    ver1=x,
+                    oper=">=",
+                    ver2=candidates.get(name, ""),
+                    cmp_func=version_cmp,
                 )
                 for x in installed
             ):
-                ret[name] = candidate
+                ret[name] = candidates.get(name, "")
 
     # Return a string if only one package name passed
     if len(names) == 1:

tests/pytests/unit/modules/test_aptpkg.py

@@ -1401,3 +1401,39 @@ def test_sourceslist_architectures(repo_line):
                     assert source.architectures == ["amd64", "armel"]
                 else:
                     assert source.architectures == ["amd64"]
+
+
+def test_latest_version_calls_aptcache_once_per_run():
+    """
+    Performance Test - don't call apt-cache once for each pkg, call once and parse output
+    """
+    mock_list_pkgs = MagicMock(return_value={"sudo": "1.8.27-1+deb10u5"})
+    apt_cache_ret = {
+        "stdout": textwrap.dedent(
+            """sudo:
+              Installed: 1.8.27-1+deb10u5
+              Candidate: 1.8.27-1+deb10u5
+              Version table:
+             *** 1.8.27-1+deb10u5 500
+                    500 http://security.debian.org/debian-security buster/updates/main amd64 Packages
+                    100 /var/lib/dpkg/status
+                 1.8.27-1+deb10u3 500
+                    500 http://deb.debian.org/debian buster/main amd64 Packages
+            unzip:
+              Installed: (none)
+              Candidate: 6.0-23+deb10u3
+              Version table:
+                 6.0-23+deb10u3 500
+                    500 http://security.debian.org/debian-security buster/updates/main amd64 Packages
+                 6.0-23+deb10u2 500
+                    500 http://deb.debian.org/debian buster/main amd64 Packages
+            """
+        )
+    }
+    mock_apt_cache = MagicMock(return_value=apt_cache_ret)
+    with patch("salt.modules.aptpkg._call_apt", mock_apt_cache), patch(
+        "salt.modules.aptpkg.list_pkgs", mock_list_pkgs
+    ):
+        ret = aptpkg.latest_version("sudo", "unzip", refresh=False)
+    mock_apt_cache.assert_called_once()
+    assert ret == {"sudo": "6.0-23+deb10u3", "unzip": ""}