add cache for qm monitor functions

src/pvecommon/__init__.py

@@ -1,7 +1,33 @@
+import time
+import random
 import pexpect
+from functools import wraps
 
 global_qm_timeout = 10
+qm_max_ttl = 600
+qm_rand = 60
 
+def ttl_cache_with_randomness(max_ttl, randomness_factor):
+    cache = {}
+    def decorator(func):
+        @wraps(func)
+        def wrapper(*args, **kwargs):
+            # Create a key based on the args and kwargs
+            key = str(args) + str(kwargs)
+            # Check if the key is in the cache and not expired
+            if key in cache:
+                result, timestamp = cache[key]
+                elapsed_time = time.time() - timestamp
+                if elapsed_time < max_ttl + random.uniform(-randomness_factor, randomness_factor):
+                    return result
+            # Call the actual function and store the result in cache
+            result = func(*args, **kwargs)
+            cache[key] = (result, time.time())
+            return result
+        return wrapper
+    return decorator
+
+@ttl_cache_with_randomness(qm_max_ttl, qm_rand)
 def qm_term_cmd(vm_id, cmd, timeout=global_qm_timeout):
     child = pexpect.spawn(f'qm monitor {vm_id}')
     try: