From f402732a333e4fe67494789e9b27d1dfa6f4200d Mon Sep 17 00:00:00 2001
From: Czarna <86512570+Czarna1024@users.noreply.github.com>
Date: Fri, 12 May 2023 23:26:37 +0200
Subject: [PATCH] Optimize the vis_heap_chunks by creating VALID_CHARS once

This commit optimizes the `bin_ascii` function used by the `vis_heap_chunks` command.

That function executed the following line on each call:
```
    valid_chars = list(map(ord, set(printable) - set("\t\r\n\x0c\x0b")))
```

And it could be called thousand times, e.g. 90k on a benchmark.

This commit moves the creation of the `valid_chars` list to the global space so it is computed only once.

As a result, on a simple benchmark we improved the speed of `vis_heap_chunks` command from 4.6s to 3s.
---
 pwndbg/commands/heap.py | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/pwndbg/commands/heap.py b/pwndbg/commands/heap.py
index 1e2c55212..d0503990a 100644
--- a/pwndbg/commands/heap.py
+++ b/pwndbg/commands/heap.py
@@ -1,5 +1,6 @@
 import argparse
 import ctypes
+from string import printable
 from typing import Dict
 from typing import List
 
@@ -973,11 +974,11 @@ def vis_heap_chunks(
         )
 
 
-def bin_ascii(bs):
-    from string import printable
+VALID_CHARS = list(map(ord, set(printable) - set("\t\r\n\x0c\x0b")))
+
 
-    valid_chars = list(map(ord, set(printable) - set("\t\r\n\x0c\x0b")))
-    return "".join(chr(c) if c in valid_chars else "." for c in bs)
+def bin_ascii(bs):
+    return "".join(chr(c) if c in VALID_CHARS else "." for c in bs)
 
 
 def bin_labels_mapping(collections):