Merge branch 'jonathan/cache-cache-size' into 'master'

Jonathan/cache cache size

See merge request BuildStream/buildstream!679

9 files changed, 195 insertions, 82 deletions

diff --git a/buildstream/_artifactcache/__init__.py b/buildstream/_artifactcache/__init__.py
index 07ed52b4b..fad483a57 100644
--- a/buildstream/_artifactcache/__init__.py
+++ b/buildstream/_artifactcache/__init__.py
@@ -17,4 +17,4 @@
 #  Authors:
 #        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
 
-from .artifactcache import ArtifactCache, ArtifactCacheSpec
+from .artifactcache import ArtifactCache, ArtifactCacheSpec, CACHE_SIZE_FILE
diff --git a/buildstream/_artifactcache/artifactcache.py b/buildstream/_artifactcache/artifactcache.py
index d98c291f9..f28fe394f 100644
--- a/buildstream/_artifactcache/artifactcache.py
+++ b/buildstream/_artifactcache/artifactcache.py
@@ -28,6 +28,9 @@ from .. import utils
 from .. import _yaml
 
 
+CACHE_SIZE_FILE = "cache_size"
+
+
 # An ArtifactCacheSpec holds the user configuration for a single remote
 # artifact cache.
 #
@@ -82,7 +85,6 @@ class ArtifactCache():
         self.extractdir = os.path.join(context.artifactdir, 'extract')
         self.tmpdir = os.path.join(context.artifactdir, 'tmp')
 
-        self.max_size = context.cache_quota
         self.estimated_size = None
 
         self.global_remote_specs = []
@@ -90,6 +92,8 @@ class ArtifactCache():
 
         self._local = False
         self.cache_size = None
+        self.cache_quota = None
+        self.cache_lower_threshold = None
 
         os.makedirs(self.extractdir, exist_ok=True)
         os.makedirs(self.tmpdir, exist_ok=True)
@@ -227,7 +231,7 @@ class ArtifactCache():
     def clean(self):
         artifacts = self.list_artifacts()
 
-        while self.calculate_cache_size() >= self.context.cache_quota - self.context.cache_lower_threshold:
+        while self.calculate_cache_size() >= self.cache_quota - self.cache_lower_threshold:
             try:
                 to_remove = artifacts.pop(0)
             except IndexError:
@@ -241,7 +245,7 @@ class ArtifactCache():
                           "Please increase the cache-quota in {}."
                           .format(self.context.config_origin or default_conf))
 
-                if self.calculate_cache_size() > self.context.cache_quota:
+                if self.calculate_cache_size() > self.cache_quota:
                     raise ArtifactError("Cache too full. Aborting.",
                                         detail=detail,
                                         reason="cache-too-full")
@@ -282,7 +286,11 @@ class ArtifactCache():
         # If we don't currently have an estimate, figure out the real
         # cache size.
         if self.estimated_size is None:
-            self.estimated_size = self.calculate_cache_size()
+            stored_size = self._read_cache_size()
+            if stored_size is not None:
+                self.estimated_size = stored_size
+            else:
+                self.estimated_size = self.calculate_cache_size()
 
         return self.estimated_size
 
@@ -541,6 +549,7 @@ class ArtifactCache():
             self.estimated_size = self.calculate_cache_size()
 
         self.estimated_size += artifact_size
+        self._write_cache_size(self.estimated_size)
 
     # _set_cache_size()
     #
@@ -551,6 +560,109 @@ class ArtifactCache():
     def _set_cache_size(self, cache_size):
         self.estimated_size = cache_size
 
+        # set_cache_size is called in cleanup, where it may set the cache to None
+        if self.estimated_size is not None:
+            self._write_cache_size(self.estimated_size)
+
+    # _write_cache_size()
+    #
+    # Writes the given size of the artifact to the cache's size file
+    #
+    def _write_cache_size(self, size):
+        assert isinstance(size, int)
+        size_file_path = os.path.join(self.context.artifactdir, CACHE_SIZE_FILE)
+        with open(size_file_path, "w") as f:
+            f.write(str(size))
+
+    # _read_cache_size()
+    #
+    # Reads and returns the size of the artifact cache that's stored in the
+    # cache's size file
+    #
+    def _read_cache_size(self):
+        size_file_path = os.path.join(self.context.artifactdir, CACHE_SIZE_FILE)
+
+        if not os.path.exists(size_file_path):
+            return None
+
+        with open(size_file_path, "r") as f:
+            size = f.read()
+
+        try:
+            num_size = int(size)
+        except ValueError as e:
+            raise ArtifactError("Size '{}' parsed from '{}' was not an integer".format(
+                size, size_file_path)) from e
+
+        return num_size
+
+    # _calculate_cache_quota()
+    #
+    # Calculates and sets the cache quota and lower threshold based on the
+    # quota set in Context.
+    # It checks that the quota is both a valid expression, and that there is
+    # enough disk space to satisfy that quota
+    #
+    def _calculate_cache_quota(self):
+        # Headroom intended to give BuildStream a bit of leeway.
+        # This acts as the minimum size of cache_quota and also
+        # is taken from the user requested cache_quota.
+        #
+        if 'BST_TEST_SUITE' in os.environ:
+            headroom = 0
+        else:
+            headroom = 2e9
+
+        artifactdir_volume = self.context.artifactdir
+        while not os.path.exists(artifactdir_volume):
+            artifactdir_volume = os.path.dirname(artifactdir_volume)
+
+        try:
+            cache_quota = utils._parse_size(self.context.config_cache_quota, artifactdir_volume)
+        except utils.UtilError as e:
+            raise LoadError(LoadErrorReason.INVALID_DATA,
+                            "{}\nPlease specify the value in bytes or as a % of full disk space.\n"
+                            "\nValid values are, for example: 800M 10G 1T 50%\n"
+                            .format(str(e))) from e
+
+        stat = os.statvfs(artifactdir_volume)
+        available_space = (stat.f_bsize * stat.f_bavail)
+
+        cache_size = self.get_approximate_cache_size()
+
+        # Ensure system has enough storage for the cache_quota
+        #
+        # If cache_quota is none, set it to the maximum it could possibly be.
+        #
+        # Also check that cache_quota is atleast as large as our headroom.
+        #
+        if cache_quota is None:  # Infinity, set to max system storage
+            cache_quota = cache_size + available_space
+        if cache_quota < headroom:  # Check minimum
+            raise LoadError(LoadErrorReason.INVALID_DATA,
+                            "Invalid cache quota ({}): ".format(utils._pretty_size(cache_quota)) +
+                            "BuildStream requires a minimum cache quota of 2G.")
+        elif cache_quota > cache_size + available_space:  # Check maximum
+            raise LoadError(LoadErrorReason.INVALID_DATA,
+                            ("Your system does not have enough available " +
+                             "space to support the cache quota specified.\n" +
+                             "You currently have:\n" +
+                             "- {used} of cache in use at {local_cache_path}\n" +
+                             "- {available} of available system storage").format(
+                                 used=utils._pretty_size(cache_size),
+                                 local_cache_path=self.context.artifactdir,
+                                 available=utils._pretty_size(available_space)))
+
+        # Place a slight headroom (2e9 (2GB) on the cache_quota) into
+        # cache_quota to try and avoid exceptions.
+        #
+        # Of course, we might still end up running out during a build
+        # if we end up writing more than 2G, but hey, this stuff is
+        # already really fuzzy.
+        #
+        self.cache_quota = cache_quota - headroom
+        self.cache_lower_threshold = self.cache_quota / 2
+
 
 # _configured_remote_artifact_cache_specs():
 #
diff --git a/buildstream/_artifactcache/cascache.py b/buildstream/_artifactcache/cascache.py
index 074899d81..d616e293a 100644
--- a/buildstream/_artifactcache/cascache.py
+++ b/buildstream/_artifactcache/cascache.py
@@ -61,6 +61,8 @@ class CASCache(ArtifactCache):
         os.makedirs(os.path.join(self.casdir, 'refs', 'heads'), exist_ok=True)
         os.makedirs(os.path.join(self.casdir, 'objects'), exist_ok=True)
 
+        self._calculate_cache_quota()
+
         self._enable_push = enable_push
 
         # Per-project list of _CASRemote instances.
@@ -330,7 +332,7 @@ class CASCache(ArtifactCache):
                                     request.write_offset = offset
                                     # max. 64 kB chunks
                                     request.data = f.read(chunk_size)
-                                    request.resource_name = resource_name
+                                    request.resource_name = resource_name  # pylint: disable=cell-var-from-loop
                                     request.finish_write = remaining <= 0
                                     yield request
                                     offset += chunk_size
diff --git a/buildstream/_context.py b/buildstream/_context.py
index 8ebb61d23..a94d374cf 100644
--- a/buildstream/_context.py
+++ b/buildstream/_context.py
@@ -64,12 +64,6 @@ class Context():
         # The locations from which to push and pull prebuilt artifacts
         self.artifact_cache_specs = []
 
-        # The artifact cache quota
-        self.cache_quota = None
-
-        # The lower threshold to which we aim to reduce the cache size
-        self.cache_lower_threshold = None
-
         # The directory to store build logs
         self.logdir = None
 
@@ -124,6 +118,8 @@ class Context():
         self._workspaces = None
         self._log_handle = None
         self._log_filename = None
+        self.config_cache_quota = 'infinity'
+        self.artifactdir_volume = None
 
     # load()
     #
@@ -183,71 +179,7 @@ class Context():
         cache = _yaml.node_get(defaults, Mapping, 'cache')
         _yaml.node_validate(cache, ['quota'])
 
-        artifactdir_volume = self.artifactdir
-        while not os.path.exists(artifactdir_volume):
-            artifactdir_volume = os.path.dirname(artifactdir_volume)
-
-        # We read and parse the cache quota as specified by the user
-        cache_quota = _yaml.node_get(cache, str, 'quota', default_value='infinity')
-        try:
-            cache_quota = utils._parse_size(cache_quota, artifactdir_volume)
-        except utils.UtilError as e:
-            raise LoadError(LoadErrorReason.INVALID_DATA,
-                            "{}\nPlease specify the value in bytes or as a % of full disk space.\n"
-                            "\nValid values are, for example: 800M 10G 1T 50%\n"
-                            .format(str(e))) from e
-
-        # Headroom intended to give BuildStream a bit of leeway.
-        # This acts as the minimum size of cache_quota and also
-        # is taken from the user requested cache_quota.
-        #
-        if 'BST_TEST_SUITE' in os.environ:
-            headroom = 0
-        else:
-            headroom = 2e9
-
-        stat = os.statvfs(artifactdir_volume)
-        available_space = (stat.f_bsize * stat.f_bavail)
-
-        # Again, the artifact directory may not yet have been created yet
-        #
-        if not os.path.exists(self.artifactdir):
-            cache_size = 0
-        else:
-            cache_size = utils._get_dir_size(self.artifactdir)
-
-        # Ensure system has enough storage for the cache_quota
-        #
-        # If cache_quota is none, set it to the maximum it could possibly be.
-        #
-        # Also check that cache_quota is atleast as large as our headroom.
-        #
-        if cache_quota is None:  # Infinity, set to max system storage
-            cache_quota = cache_size + available_space
-        if cache_quota < headroom:  # Check minimum
-            raise LoadError(LoadErrorReason.INVALID_DATA,
-                            "Invalid cache quota ({}): ".format(utils._pretty_size(cache_quota)) +
-                            "BuildStream requires a minimum cache quota of 2G.")
-        elif cache_quota > cache_size + available_space:  # Check maximum
-            raise LoadError(LoadErrorReason.INVALID_DATA,
-                            ("Your system does not have enough available " +
-                             "space to support the cache quota specified.\n" +
-                             "You currently have:\n" +
-                             "- {used} of cache in use at {local_cache_path}\n" +
-                             "- {available} of available system storage").format(
-                                 used=utils._pretty_size(cache_size),
-                                 local_cache_path=self.artifactdir,
-                                 available=utils._pretty_size(available_space)))
-
-        # Place a slight headroom (2e9 (2GB) on the cache_quota) into
-        # cache_quota to try and avoid exceptions.
-        #
-        # Of course, we might still end up running out during a build
-        # if we end up writing more than 2G, but hey, this stuff is
-        # already really fuzzy.
-        #
-        self.cache_quota = cache_quota - headroom
-        self.cache_lower_threshold = self.cache_quota / 2
+        self.config_cache_quota = _yaml.node_get(cache, str, 'quota', default_value='infinity')
 
         # Load artifact share configuration
         self.artifact_cache_specs = ArtifactCache.specs_from_config_node(defaults)
diff --git a/buildstream/_frontend/app.py b/buildstream/_frontend/app.py
index 1550fbcb3..1e357f123 100644
--- a/buildstream/_frontend/app.py
+++ b/buildstream/_frontend/app.py
@@ -198,8 +198,10 @@ class App():
             option_value = self._main_options.get(cli_option)
             if option_value is not None:
                 setattr(self.context, context_attr, option_value)
-
-        Platform.create_instance(self.context)
+        try:
+            Platform.create_instance(self.context)
+        except BstError as e:
+            self._error_exit(e, "Error instantiating platform")
 
         # Create the logger right before setting the message handler
         self.logger = LogLine(self.context,
diff --git a/buildstream/_scheduler/queues/buildqueue.py b/buildstream/_scheduler/queues/buildqueue.py
index 5967fbf76..2009fce97 100644
--- a/buildstream/_scheduler/queues/buildqueue.py
+++ b/buildstream/_scheduler/queues/buildqueue.py
@@ -97,7 +97,7 @@ class BuildQueue(Queue):
             cache = element._get_artifact_cache()
             cache._add_artifact_size(artifact_size)
 
-            if cache.get_approximate_cache_size() > self._scheduler.context.cache_quota:
+            if cache.get_approximate_cache_size() > cache.cache_quota:
                 self._scheduler._check_cache_size_real()
 
     def done(self, job, element, result, success):
diff --git a/buildstream/_scheduler/scheduler.py b/buildstream/_scheduler/scheduler.py
index 3d1d79b61..38d38be48 100644
--- a/buildstream/_scheduler/scheduler.py
+++ b/buildstream/_scheduler/scheduler.py
@@ -29,6 +29,7 @@ from contextlib import contextmanager
 # Local imports
 from .resources import Resources, ResourceType
 from .jobs import CacheSizeJob, CleanupJob
+from .._platform import Platform
 
 
 # A decent return code for Scheduler.run()
@@ -316,7 +317,8 @@ class Scheduler():
         self._sched()
 
     def _run_cleanup(self, cache_size):
-        if cache_size and cache_size < self.context.cache_quota:
+        platform = Platform.get_platform()
+        if cache_size and cache_size < platform.artifactcache.cache_quota:
             return
 
         job = CleanupJob(self, 'cleanup', 'cleanup',
diff --git a/tests/artifactcache/cache_size.py b/tests/artifactcache/cache_size.py
new file mode 100644
index 000000000..0d12cda8c
--- /dev/null
+++ b/tests/artifactcache/cache_size.py
@@ -0,0 +1,62 @@
+import os
+import pytest
+
+from buildstream import _yaml
+from buildstream._artifactcache import CACHE_SIZE_FILE
+
+from tests.testutils import cli, create_element_size
+
+# XXX: Currently lacking:
+#      * A way to check whether it's faster to read cache size on
+#        successive invocations.
+#      * A way to check whether the cache size file has been read.
+
+
+def create_project(project_dir):
+    project_file = os.path.join(project_dir, "project.conf")
+    project_conf = {
+        "name": "test"
+    }
+    _yaml.dump(project_conf, project_file)
+    element_name = "test.bst"
+    create_element_size(element_name, project_dir, ".", [], 1024)
+
+
+def test_cache_size_roundtrip(cli, tmpdir):
+    # Builds (to put files in the cache), then invokes buildstream again
+    # to check nothing breaks
+
+    # Create project
+    project_dir = str(tmpdir)
+    create_project(project_dir)
+
+    # Build, to populate the cache
+    res = cli.run(project=project_dir, args=["build", "test.bst"])
+    res.assert_success()
+
+    # Show, to check that nothing breaks while reading cache size
+    res = cli.run(project=project_dir, args=["show", "test.bst"])
+    res.assert_success()
+
+
+def test_cache_size_write(cli, tmpdir):
+    # Builds (to put files in the cache), then checks a number is
+    # written to the cache size file.
+
+    project_dir = str(tmpdir)
+    create_project(project_dir)
+
+    # Artifact cache must be in a known place
+    artifactdir = os.path.join(project_dir, "artifacts")
+    cli.configure({"artifactdir": artifactdir})
+
+    # Build, to populate the cache
+    res = cli.run(project=project_dir, args=["build", "test.bst"])
+    res.assert_success()
+
+    # Inspect the artifact cache
+    sizefile = os.path.join(artifactdir, CACHE_SIZE_FILE)
+    assert os.path.isfile(sizefile)
+    with open(sizefile, "r") as f:
+        size_data = f.read()
+    size = int(size_data)
diff --git a/tests/testutils/artifactshare.py b/tests/testutils/artifactshare.py
index 76b729e33..05e87a499 100644
--- a/tests/testutils/artifactshare.py
+++ b/tests/testutils/artifactshare.py
@@ -140,6 +140,7 @@ class ArtifactShare():
 
         return statvfs_result(f_blocks=self.total_space,
                               f_bfree=self.free_space - repo_size,
+                              f_bavail=self.free_space - repo_size,
                               f_bsize=1)
 
 
@@ -156,4 +157,4 @@ def create_artifact_share(directory, *, total_space=None, free_space=None):
         share.close()
 
 
-statvfs_result = namedtuple('statvfs_result', 'f_blocks f_bfree f_bsize')
+statvfs_result = namedtuple('statvfs_result', 'f_blocks f_bfree f_bsize f_bavail')