Bug 1918118 - Cache parsing of glean metrics r=mkmelin a=pascalc

Glean metrics are described in yaml, which is notably slow to parse.
Instead of repeatedly parsing the same metrics again and again, cache
the parsing result.

Differential Revision: https://phabricator.services.mozilla.com/D242930

toolkit/components/glean/build_scripts/glean_parser_ext/cache_yaml.py

@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import pickle
+import sys
+
+from run_glean_parser import parse
+
+
+def main(out_fd, *args):
+    parse_result = parse(args)
+    pickle.dump(parse_result, out_fd)
+
+
+if __name__ == "__main__":
+    main(*sys.argv[1:])

toolkit/components/glean/build_scripts/glean_parser_ext/run_glean_parser.py

@@ -5,6 +5,7 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 import os
+import pickle
 import sys
 from pathlib import Path
 
@@ -68,6 +69,11 @@ def parse(args):
     then return the parsed objects for further processing.
     """
 
+    if len(args) == 2 and args[0].endswith(".cached"):
+        cache_file, _ = args
+        with open(cache_file, "rb") as cache:
+            return pickle.load(cache)
+
     # Unfortunately, GeneratedFile appends `flags` directly after `inputs`
     # instead of listifying either, so we need to pull stuff from a *args.
     yaml_array = args[:-1]

toolkit/components/glean/moz.build

@@ -132,6 +132,33 @@ metrics_yamls = ["../../../" + x for x in metrics_yamls]
 pings_yamls = ["../../../" + x for x in pings_yamls]
 tags_yamls = ["../../../" + x for x in tags_yamls]
 
+GeneratedFile(
+    "metrics_yamls.cached",
+    script="build_scripts/glean_parser_ext/cache_yaml.py",
+    flags=[
+        CONFIG["MOZ_APP_VERSION"],
+    ],
+    inputs=metrics_yamls + tags_yamls,
+)
+
+GeneratedFile(
+    "pings_yamls.cached",
+    script="build_scripts/glean_parser_ext/cache_yaml.py",
+    flags=[
+        CONFIG["MOZ_APP_VERSION"],
+    ],
+    inputs=pings_yamls + tags_yamls,
+)
+
+GeneratedFile(
+    "metrics_n_pings_yamls.cached",
+    script="build_scripts/glean_parser_ext/cache_yaml.py",
+    flags=[
+        CONFIG["MOZ_APP_VERSION"],
+    ],
+    inputs=metrics_yamls + pings_yamls + tags_yamls,
+)
+
 GeneratedFile(
     "GleanMetrics.h",
     "GleanJSMetricsLookup.h",
@@ -144,7 +171,7 @@ GeneratedFile(
         "GleanJSMetricsLookup.cpp",
         "api/src/metrics.rs",
     ],
-    inputs=metrics_yamls + tags_yamls,
+    inputs=["!metrics_yamls.cached"],
 )
 
 GeneratedFile(
@@ -159,7 +186,7 @@ GeneratedFile(
         "GleanJSPingsLookup.cpp",
         "api/src/pings.rs",
     ],
-    inputs=pings_yamls + tags_yamls,
+    inputs=["!pings_yamls.cached"],
 )
 
 # Glean Interface For Firefox Telemetry Maps from Glean MetricId to Telemetry ProbeId
@@ -169,7 +196,7 @@ GeneratedFile(
     script="build_scripts/glean_parser_ext/run_glean_parser.py",
     entry_point="gifft_map",
     flags=[CONFIG["MOZ_APP_VERSION"], "Event"],
-    inputs=metrics_yamls + tags_yamls,
+    inputs=["!metrics_yamls.cached"],
 )
 
 GeneratedFile(
@@ -177,7 +204,7 @@ GeneratedFile(
     script="build_scripts/glean_parser_ext/run_glean_parser.py",
     entry_point="gifft_map",
     flags=[CONFIG["MOZ_APP_VERSION"], "Histogram"],
-    inputs=metrics_yamls + tags_yamls,
+    inputs=["!metrics_yamls.cached"],
 )
 
 GeneratedFile(
@@ -185,7 +212,7 @@ GeneratedFile(
     script="build_scripts/glean_parser_ext/run_glean_parser.py",
     entry_point="gifft_map",
     flags=[CONFIG["MOZ_APP_VERSION"], "Scalar"],
-    inputs=metrics_yamls + tags_yamls,
+    inputs=["!metrics_yamls.cached"],
 )
 
 # JOG provides both the Rust factory for building runtime-registered metrics
@@ -197,7 +224,7 @@ GeneratedFile(
     script="build_scripts/glean_parser_ext/run_glean_parser.py",
     entry_point="jog_factory",
     flags=[CONFIG["MOZ_APP_VERSION"]],
-    inputs=pings_yamls + metrics_yamls + tags_yamls,
+    inputs=["!metrics_n_pings_yamls.cached"],
 )
 
 # Only generate jogfile.json in Artifact Builds since
@@ -208,7 +235,7 @@ if CONFIG["MOZ_ARTIFACT_BUILDS"]:
         script="build_scripts/glean_parser_ext/run_glean_parser.py",
         entry_point="jog_file",
         flags=[CONFIG["MOZ_APP_VERSION"]],
-        inputs=pings_yamls + metrics_yamls + tags_yamls,
+        inputs=["!metrics_n_pings_yamls.cached"],
     )
     # Once generated, it needs to be placed in GreD so it can be found.
     FINAL_TARGET_FILES += ["!jogfile.json"]
@@ -221,7 +248,7 @@ GeneratedFile(
     script="build_scripts/glean_parser_ext/run_glean_parser.py",
     entry_point="ohttp_pings",
     flags=[CONFIG["MOZ_APP_VERSION"]],
-    inputs=pings_yamls + tags_yamls,
+    inputs=["!pings_yamls.cached"],
 )
 
 DIRS += [