From 4e3eac1d610a403314d4bb5e21c55f9fe986f14c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=BCrg=20Billeter?= <j@bitron.ch>
Date: Mon, 21 Sep 2020 15:56:46 +0200
Subject: _stream.py: Add query_cache() method

This is preparation for explicit cache query.
---
 src/buildstream/_frontend/cli.py |  2 ++
 src/buildstream/_stream.py       | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/src/buildstream/_frontend/cli.py b/src/buildstream/_frontend/cli.py
index 5e42bda68..3428b3d27 100644
--- a/src/buildstream/_frontend/cli.py
+++ b/src/buildstream/_frontend/cli.py
@@ -551,6 +551,8 @@ def show(app, elements, deps, except_, order, format_):
 
         dependencies = app.stream.load_selection(elements, selection=deps, except_targets=except_)
 
+        app.stream.query_cache(dependencies)
+
         if order == "alpha":
             dependencies = sorted(dependencies)
 
diff --git a/src/buildstream/_stream.py b/src/buildstream/_stream.py
index 0aff5fb94..dc76edad9 100644
--- a/src/buildstream/_stream.py
+++ b/src/buildstream/_stream.py
@@ -163,6 +163,18 @@ class Stream:
 
             return target_objects
 
+    # query_cache()
+    #
+    # Query the artifact and source caches to determine the cache status
+    # of the specified elements.
+    #
+    # Args:
+    #    elements (list of Element): The elements to check
+    #
+    def query_cache(self, elements):
+        # Cache is implicitly queried on demand
+        pass
+
     # shell()
     #
     # Run a shell
@@ -614,6 +626,8 @@ class Stream:
             targets, selection=selection, use_artifact_config=True, load_artifacts=True
         )
 
+        self.query_cache(target_objects)
+
         if self._artifacts.has_fetch_remotes():
             self._pipeline.check_remotes(target_objects)
 
@@ -633,6 +647,8 @@ class Stream:
         # Return list of Element and/or ArtifactElement objects
         target_objects = self.load_selection(targets, selection=_PipelineSelection.NONE, load_artifacts=True)
 
+        self.query_cache(target_objects)
+
         artifact_logs = {}
         for obj in target_objects:
             ref = obj.get_artifact_name()
@@ -661,6 +677,8 @@ class Stream:
         # Return list of Element and/or ArtifactElement objects
         target_objects = self.load_selection(targets, selection=_PipelineSelection.NONE, load_artifacts=True)
 
+        self.query_cache(target_objects)
+
         elements_to_files = {}
         for obj in target_objects:
             ref = obj.get_artifact_name()
-- 
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