Bug 1858807 - Track individual rust crate build times. r=firefox-buil…

…d-system-reviewers,sergesanspaille

As of now, cargo only supports HTML timings output. There is an unstable
flag for a json output, but we can't use that because it requires a
nightly cargo. So we do our best effort to get the data we need off the
HTML, but since the exact details of the format of that file are not
set in stone, we also prevent any error from being unhandled. It's
better not to have the data than break the build.

Differential Revision: https://phabricator.services.mozilla.com/D190884

config/makefiles/rust.mk

@@ -334,7 +334,7 @@ endif
 #
 #   $(call CARGO_BUILD)
 define CARGO_BUILD
-$(call RUN_CARGO,rustc)
+$(call RUN_CARGO,rustc$(if $(BUILDSTATUS), --timings))
 endef
 
 cargo_host_linker_env_var := CARGO_TARGET_$(call varize,$(RUST_HOST_TARGET))_LINKER

python/mozbuild/mozbuild/controller/building.py

@@ -13,6 +13,7 @@
 import sys
 import time
 from collections import Counter, OrderedDict, namedtuple
+from itertools import dropwhile, islice, takewhile
 from textwrap import TextWrapper
 
 import six
@@ -179,6 +180,51 @@ def add_resource_fields_to_dict(self, d):
             return d
 
 
+def record_cargo_timings(resource_monitor, timings_path):
+    cargo_start = 0
+    try:
+        with open(timings_path) as fh:
+            # Extrace the UNIT_DATA list from the cargo timing HTML file.
+            unit_data = dropwhile(lambda l: l.rstrip() != "const UNIT_DATA = [", fh)
+            unit_data = islice(unit_data, 1, None)
+            lines = takewhile(lambda l: l.rstrip() != "];", unit_data)
+            entries = json.loads("[" + "".join(lines) + "]")
+            # Normalize the entries so that any change in data format would
+            # trigger the exception handler that skips this (we don't want the
+            # build to fail in that case)
+            data = [
+                (
+                    "{} v{}{}".format(
+                        entry["name"], entry["version"], entry.get("target", "")
+                    ),
+                    entry["start"] or 0,
+                    entry["duration"] or 0,
+                )
+                for entry in entries
+            ]
+        starts = [
+            start
+            for marker, start in resource_monitor._active_markers.items()
+            if marker.startswith("Rust:")
+        ]
+        # The build system is not supposed to be running more than one cargo
+        # at the same time, which thankfully makes it easier to find the start
+        # of the one we got the timings for.
+        if len(starts) != 1:
+            return
+        cargo_start = starts[0]
+    except Exception:
+        return
+
+    if not cargo_start:
+        return
+
+    for name, start, duration in data:
+        resource_monitor.record_marker(
+            "Rust", cargo_start + start, cargo_start + start + duration, name
+        )
+
+
 class BuildMonitor(MozbuildObject):
     """Monitors the output of the build."""
 
@@ -261,7 +307,7 @@ def on_line(self, line):
         # If the previous line was colored (eg. for a compiler warning), our
         # line will start with the ansi reset sequence. Strip it to ensure it
         # does not interfere with our parsing of the line.
-        plain_line = self._terminal.strip(line) if self._terminal else line
+        plain_line = self._terminal.strip(line) if self._terminal else line.strip()
         if plain_line.startswith("BUILDSTATUS"):
             args = plain_line.split()[1:]
 
@@ -298,6 +344,11 @@ def on_line(self, line):
 
             return BuildOutputResult(None, update_needed, message)
 
+        elif plain_line.startswith("Timing report saved to "):
+            cargo_timings = plain_line[len("Timing report saved to ") :]
+            record_cargo_timings(self.resources, cargo_timings)
+            return BuildOutputResult(None, False, None)
+
         warning = None
 
         try: