From 2bca0d6f2ec866bc9636a4d3113b9673b69a1092 Mon Sep 17 00:00:00 2001
From: Tom Sparrow <793763+sparrowt@users.noreply.github.com>
Date: Tue, 14 Nov 2023 11:24:11 +0000
Subject: [PATCH] Avoid repeatedly re-parsing frames

This should reduce the effort on parsing frames by a factor of 4 when operating on a `--full` trace.

In that case `ms` will be a list of 4 metrics but we only need to parse the frames once because they are the same in all cases.

Also add a couple of comments which weren't obvious to me on first reading.
---
 austin/stats.py | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/austin/stats.py b/austin/stats.py
index 06cf469..9954fe2 100644
--- a/austin/stats.py
+++ b/austin/stats.py
@@ -149,10 +149,10 @@ def parse(metrics: str, metric_type: Optional[MetricType] = None) -> List["Metri
             ms = [int(_) for _ in metrics.split(",")]
             if len(ms) == 3:
                 return [
-                    Metric(MetricType.TIME, ms[0] if ms[1] == 0 else 0),
-                    Metric(MetricType.TIME, ms[0]),
-                    Metric(MetricType.MEMORY, ms[2] if ms[2] >= 0 else 0),
-                    Metric(MetricType.MEMORY, -ms[2] if ms[2] < 0 else 0),
+                    Metric(MetricType.TIME, ms[0] if ms[1] == 0 else 0),  # cpu time
+                    Metric(MetricType.TIME, ms[0]),  # wall time
+                    Metric(MetricType.MEMORY, ms[2] if ms[2] >= 0 else 0),  # memory allocation
+                    Metric(MetricType.MEMORY, -ms[2] if ms[2] < 0 else 0),  # memory deallocation
                 ]
             elif len(ms) != 1:
                 raise ValueError()
@@ -260,14 +260,13 @@ def parse(sample: str, metric_type: Optional[MetricType] = None) -> List["Sample
 
         try:
             ms = Metric.parse(metrics, metric_type)
+            frames = [Frame.parse(frame) for frame in frames.split(";")] if frames else []
             return [
                 Sample(
                     pid=int(pid),
                     thread=thread,
                     metric=metric,
-                    frames=[Frame.parse(frame) for frame in frames.split(";")]
-                    if frames
-                    else [],
+                    frames=frames,
                 )
                 for metric in ms
             ]