From 5b06e2dd0a77a5faf2c52558d825ed52d3cb6ed0 Mon Sep 17 00:00:00 2001
From: James Ennis <james.ennis@codethink.com>
Date: Tue, 15 Jan 2019 15:07:15 +0000
Subject: WIP: cli.py: Spawn pull jobs in another process to isolate gRPC calls

---
 buildstream/_frontend/cli.py | 59 ++++++++++++++++++++++++++++++++++++++------
 1 file changed, 51 insertions(+), 8 deletions(-)

diff --git a/buildstream/_frontend/cli.py b/buildstream/_frontend/cli.py
index 24012ba79..1752b8f2d 100644
--- a/buildstream/_frontend/cli.py
+++ b/buildstream/_frontend/cli.py
@@ -1,4 +1,6 @@
+import multiprocessing
 import os
+import signal
 import sys
 from contextlib import ExitStack
 from fnmatch import fnmatch
@@ -973,6 +975,9 @@ def artifact_pull(app, artifacts, deps, remote):
         none:  No dependencies, just the element itself
         all:   All dependencies
     """
+    from .. import _signals
+    from .. import utils
+    from .._exceptions import CASError
 
     with app.initialized(session_name="Pull"):
         cache = app.context.artifactcache
@@ -1016,14 +1021,52 @@ def artifact_pull(app, artifacts, deps, remote):
             # Pull buildtrees?
             excluded_subdirs = ["buildtree"] if app.context.pull_buildtrees else None
 
-            # Try to pull the artifact from one of the remotes
-            remotes = [cache.create_remote(spec) for spec in remotes]
-            for ref in artifacts:
-                if cache.contains_ref(ref):
-                    continue
-                for remote in remotes:
-                    if cache.pull_ref(ref, remote, exclude_subdirs=exclude_subdirs):
-                        break
+            # Define function to be used by multiprocessing
+            def _pull_artifact(artifact_cache_obj, remote_specs, refs, excluded_subdirs, queue):
+                remotes = [artifact_cache_obj.create_remote(spec) for spec in remote_specs]
+                pull_attempts = {'skipped': [], 'pulled': [], 'failed': []}
+                for ref in refs:
+                    if artifact_cache_obj.contains_ref(ref):
+                        pull_attempts['skipped'].append(ref)
+                        continue
+
+                    pulled = False
+                    for remote in remotes:
+                        try:
+                            if artifact_cache_obj.pull_ref(ref, remote, excluded_subdirs=excluded_subdirs):
+                                pull_attempts['pulled'].append((ref, remote.spec.url))
+                                break
+                        except CASError as e:
+                            queue.put(e)
+                            raise
+                        if not pulled:
+                            pull_attempts['failed'].append(ref)
+
+                queue.put(pull_attempts)
+
+            q = multiprocessing.Queue()
+            p = multiprocessing.Process(target=_pull_artifact, args=(cache, remotes, artifacts, excluded_subdirs, q))
+            try:
+                with _signals.blocked([signal.SIGINT], ignore=False):
+                    p.start()
+
+                result = q.get()
+                p.join()
+            except KeyboardInterrupt:
+                utils._kill_process_tree(p.pid)
+                raise
+
+            # Output to user
+            if isinstance(result, dict):
+                for ref in result['skipped']:
+                    click.echo("'{}' already available - pull skipped.".format(ref))
+                for ref, remote in result['pulled']:
+                    click.echo("'{}' pulled from '{}'.".format(ref, remote))
+                for ref in result['failed']:
+                    urls = [remote.url for remote in remotes]
+                    click.echo("'{}' not available in remotes: {}".format(ref, urls))  # Ugly list print
+            else:
+                raise result
 
 
 ##################################################################
-- 
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