From 0b2cbd1916c276345d1f71f27bba209672195236 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=BCrg=20Billeter?= <j@bitron.ch>
Date: Tue, 23 Jan 2018 12:28:07 +0000
Subject: Keep track of failed pull operations

Do not consider pull as pending if pull failed. This is required to
allow fallback to fetch and build after pull failure.
---
 buildstream/_scheduler/pullqueue.py |  3 +++
 buildstream/element.py              | 13 +++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/buildstream/_scheduler/pullqueue.py b/buildstream/_scheduler/pullqueue.py
index e879b4689..4cc0f8a1b 100644
--- a/buildstream/_scheduler/pullqueue.py
+++ b/buildstream/_scheduler/pullqueue.py
@@ -56,6 +56,9 @@ class PullQueue(Queue):
         if returncode != 0:
             return False
 
+        if not result:
+            element._pull_failed()
+
         element._update_state()
 
         # Element._pull() returns True if it downloaded an artifact,
diff --git a/buildstream/element.py b/buildstream/element.py
index 11e27ad89..d74007b6b 100644
--- a/buildstream/element.py
+++ b/buildstream/element.py
@@ -143,6 +143,7 @@ class Element(Plugin):
         self.__strong_cached = None             # Whether we have a cached artifact
         self.__remotely_cached = None           # Whether we have a remotely cached artifact
         self.__remotely_strong_cached = None    # Whether we have a remotely cached artifact
+        self.__pull_failed = False              # Whether pull was attempted but failed
         self.__log_path = None                  # Path to dedicated log file or None
         self.__splits = None
 
@@ -1370,6 +1371,11 @@ class Element(Plugin):
     #   (bool): Whether a pull operation is pending
     #
     def _pull_pending(self):
+        if self.__pull_failed:
+            # Consider this equivalent to artifact being unavailable in
+            # remote cache
+            return False
+
         if not self.__strong_cached and self.__remotely_strong_cached:
             # Pull pending using strict cache key
             return True
@@ -1380,6 +1386,13 @@ class Element(Plugin):
             # No pull pending
             return False
 
+    # _pull_failed()
+    #
+    # Indicate that pull was attempted but failed.
+    #
+    def _pull_failed(self):
+        self.__pull_failed = True
+
     # _update_state()
     #
     # Keep track of element state. Calculate cache keys if possible and
-- 
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