Extended caching capability

All cached function calls are now persistent on disk in ~/.visidata_cache

config/visidatarc

@@ -9,6 +9,25 @@ import json
 
 from urllib.parse import unquote_plus
 
+import os.path
+import shelve
+
+cache_path = os.path.expanduser('~/.visidata_cache')
+
+def disk_cache_decorator(func):
+    @functools.lru_cache(maxsize=1000)
+    def get_from_shelve(*args, **kwargs):
+        with shelve.open(cache_path) as cache:
+            key = f"{func.__name__}:{str(args)}:{str(kwargs)}"
+            if key in cache:
+                return cache[key]
+            else:
+                result = func(*args, **kwargs)
+                cache[key] = result
+                return result
+    return get_from_shelve
+
+
 def decode_url_safe(url_safe_string):
     utf8_string = unquote_plus(url_safe_string)
     return utf8_string
@@ -73,7 +92,7 @@ def sym_time(val):
     return datetime.fromtimestamp(b)
 
 
-@functools.lru_cache()
+@disk_cache_decorator
 def vendor(mac):
     try:
         from mac_vendor_lookup import InvalidMacError, MacLookup as mlu
@@ -96,7 +115,7 @@ def _get_vt():
     except:
         return None
 
-@functools.lru_cache()
+@disk_cache_decorator
 def vt_ip(ip):
     vt = _get_vt()
     if vt is None:
@@ -104,7 +123,8 @@ def vt_ip(ip):
     response = vt.get_ip_report(ip)
     return response
 
-@functools.lru_cache()
+
+@disk_cache_decorator
 def vt_file(hash):
     vt = _get_vt()
     if vt is None:
@@ -113,7 +133,7 @@ def vt_file(hash):
     return response
 
 
-@functools.lru_cache(maxsize=1000)
+@disk_cache_decorator
 def dns_lookup(domain, record='A'):
     if len(domain.split(",")) > 1:
         return ",".join([dns_lookup(x, record) for x in domain.split(",")])
@@ -130,7 +150,7 @@ def dns_lookup(domain, record='A'):
     except ModuleNotFoundError:
         return "module not available"
 
-@functools.lru_cache()
+@disk_cache_decorator
 def _asn(ip):
     from bs4 import BeautifulSoup
     import requests
@@ -150,7 +170,7 @@ def _asn(ip):
         res['name']=" ".join(name_split[:-1])
     return res
 
-@functools.lru_cache()
+@disk_cache_decorator
 def asn(ip, type="asn"):
     if len(ip.split(",")) > 1:
         return ",".join([_asn(x, type) for x in ip.split(",")])
@@ -159,7 +179,7 @@ def asn(ip, type="asn"):
     except:
         return ""
 
-@functools.lru_cache(maxsize=1000)
+@disk_cache_decorator
 def _ipinfo(ip):
     try:
         import requests
@@ -172,7 +192,6 @@ def _ipinfo(ip):
         return None
 
 
-@functools.lru_cache()
 def ipinfo(ip, type="country"):
     if len(ip.split(",")) > 1:
         return ",".join([ipinfo(x, type) for x in ip.split(",")])
@@ -191,7 +210,6 @@ def split_number2ip(number):
     else:
         return number
 
-@functools.lru_cache()
 def mx_lookup(domain):
     domain = domain.lstrip("www.")
     try:
@@ -202,10 +220,8 @@ def mx_lookup(domain):
         return str(e)
 
 
-@functools.lru_cache(maxsize=1000)
+@disk_cache_decorator
-def grab_banner(ip, port=25):
+def _grab_banner(ip, port=25):
-    if len(ip.split(",")) > 1:
-        return ",".join([grab_banner(x, port) for x in ip.split(",")])
     try:
         import socket
         sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)  # TCP
@@ -213,8 +229,11 @@ def grab_banner(ip, port=25):
         sock.connect((ip, port))
         ret = sock.recv(1024)
         return str(ret.strip().decode())
-    except:
+    except Exception as e:
-        return ""
+        return f"!Error {ip} {e}"
+
+def grab_banner(ip, port=25):
+    return ",".join([_grab_banner(x.strip(), port) for x in ip.split(",")])
 
 
 def sym_id(val):