ci(macrobenchmark): Decode Sauce's JSON-lines device log

The recovery worked on the device but not in the parser. Sauce returns
device.log as JSON lines -- {"tag", "message", "level", ...} -- so the payload
arrives with its quotes escaped and cannot be regexed straight out of the raw
line. Decode each entry and match against its message, falling back to the raw
line so the same parser still handles `adb logcat` output from a local run.

Enable pipefail in the workflow step too. Piping into tee meant the step exited
on tee's status, so this very failure reported success while producing no
results.

Verified against the device.log from run 31117974318: timeToInitialDisplayMs
min 443.5 / median 477.3 / max 571.2 over 12 iterations on a Pixel 9 Pro XL.

Author: runningcode

.github/workflows/integration-tests-macrobenchmark.yml

@@ -70,6 +70,9 @@ jobs:
       - name: Recover benchmark results from the device log
         if: always() && env.SAUCE_USERNAME != null
         run: |
+          # Without pipefail the step passes on `tee`'s exit code, so a failed recovery
+          # would report success while silently producing no results.
+          set -o pipefail
           python3 scripts/parse-macrobenchmark-log.py ./artifacts \
             --json-out ./artifacts/benchmarkData.json | tee -a "$GITHUB_STEP_SUMMARY"
 

scripts/parse-macrobenchmark-log.py

@@ -19,14 +19,33 @@
 CHUNK_RE = re.compile(r"SentryBenchmarkData\s*:\s*\[(\d+)/(\d+)\](.*)$")
 
 
+def log_messages(log_file):
+    """Yields the message text of every log entry.
+
+    Sauce hands back device.log as JSON lines -- {"tag", "message", "level", ...} -- which
+    means the payload arrives with its quotes escaped, so it has to be decoded rather than
+    regexed out of the raw line. Plain-text lines are passed through unchanged so the same
+    parser works on `adb logcat` output from a local run.
+    """
+    # Sauce device logs occasionally carry undecodable bytes; don't die on them.
+    for line in log_file.read_text(errors="replace").splitlines():
+        line = line.strip()
+        if line.startswith("{"):
+            try:
+                yield json.loads(line).get("message", "")
+                continue
+            except json.JSONDecodeError:
+                pass
+        yield line
+
+
 def collect_chunks(log_files):
     """Returns the chunk texts keyed by index, plus the expected total."""
     chunks = {}
     total = None
     for log_file in log_files:
-        # Sauce device logs occasionally carry undecodable bytes; don't die on them.
-        for line in log_file.read_text(errors="replace").splitlines():
-            match = CHUNK_RE.search(line)
+        for message in log_messages(log_file):
+            match = CHUNK_RE.search(message)
             if not match:
                 continue
             index, chunk_total, text = int(match.group(1)), int(match.group(2)), match.group(3)