Merge branch 'juerg/cache-usage' into 'master'

cascache.py: Fix cache usage monitor on Python older than 3.7

Closes #1131

See merge request BuildStream/buildstream!1597

2 files changed, 36 insertions, 2 deletions

diff --git a/src/buildstream/_cas/cascache.py b/src/buildstream/_cas/cascache.py
index 2d93f0527..1f687669b 100644
--- a/src/buildstream/_cas/cascache.py
+++ b/src/buildstream/_cas/cascache.py
@@ -22,6 +22,7 @@ import os
 import stat
 import errno
 import contextlib
+import ctypes
 import multiprocessing
 import shutil
 import signal
@@ -931,8 +932,8 @@ class _CASCacheUsageMonitor:
         self.cas = cas
 
         # Shared memory (64-bit signed integer) for current disk usage and quota
-        self._disk_usage = multiprocessing.Value('q', -1)
-        self._disk_quota = multiprocessing.Value('q', -1)
+        self._disk_usage = multiprocessing.Value(ctypes.c_longlong, -1)
+        self._disk_quota = multiprocessing.Value(ctypes.c_longlong, -1)
 
         # multiprocessing.Process will fork without exec on Unix.
         # This can't be allowed with background threads or open gRPC channels.
diff --git a/tests/artifactcache/expiry.py b/tests/artifactcache/expiry.py
index 3e252fe2d..d33034813 100644
--- a/tests/artifactcache/expiry.py
+++ b/tests/artifactcache/expiry.py
@@ -21,9 +21,11 @@
 # pylint: disable=redefined-outer-name
 
 import os
+import time
 
 import pytest
 
+from buildstream._cas import CASCache
 from buildstream._exceptions import ErrorDomain, LoadErrorReason
 from buildstream.testing import cli  # pylint: disable=unused-import
 
@@ -36,6 +38,22 @@ DATA_DIR = os.path.join(
 )
 
 
+def get_cache_usage(directory):
+    cas_cache = CASCache(directory)
+    try:
+        wait = 0.1
+        for _ in range(0, int(5 / wait)):
+            used_size = cas_cache.get_cache_usage().used_size
+            if used_size is not None:
+                return used_size
+            time.sleep(wait)
+
+        assert False, "Unable to retrieve cache usage"
+        return None
+    finally:
+        cas_cache.release_resources()
+
+
 # Ensure that the cache successfully removes an old artifact if we do
 # not have enough space left.
 @pytest.mark.datafiles(DATA_DIR)
@@ -388,3 +406,18 @@ def test_cleanup_first(cli, datafiles):
     states = cli.get_element_states(project, ['target.bst', 'target2.bst'])
     assert states['target.bst'] != 'cached'
     assert states['target2.bst'] == 'cached'
+
+
+@pytest.mark.datafiles(DATA_DIR)
+def test_cache_usage_monitor(cli, tmpdir, datafiles):
+    project = str(datafiles)
+    element_path = 'elements'
+
+    assert get_cache_usage(cli.directory) == 0
+
+    ELEMENT_SIZE = 1000000
+    create_element_size('target.bst', project, element_path, [], ELEMENT_SIZE)
+    res = cli.run(project=project, args=['build', 'target.bst'])
+    res.assert_success()
+
+    assert get_cache_usage(cli.directory) >= ELEMENT_SIZE