From 6a441e8c63b6d0f48577b65e3f47ee7205f2716e Mon Sep 17 00:00:00 2001
From: Sven Augustin <sven.augustin@psi.ch>
Date: Sun, 2 Nov 2025 16:50:16 +0100
Subject: [PATCH] added cooldown to avoid checking for a non-existent file at
 100 Hz

---
 dap/algos/custom.py         |  3 ++
 dap/algos/utils/__init__.py |  1 +
 dap/algos/utils/cooldown.py | 84 +++++++++++++++++++++++++++++++++++++
 3 files changed, 88 insertions(+)
 create mode 100644 dap/algos/utils/cooldown.py

diff --git a/dap/algos/custom.py b/dap/algos/custom.py
index 214c7eb..3e9c689 100644
--- a/dap/algos/custom.py
+++ b/dap/algos/custom.py
@@ -2,6 +2,8 @@ import functools
 import importlib.util as ilu
 from pathlib import Path
 
+from .utils import cooldown
+
 
 BASE = "/gpfs/photonics/swissfel/buffer/dap/custom_dap_scripts"
 BASE = Path(BASE)
@@ -28,6 +30,7 @@ def calc_custom(results, image, pixel_mask):
     results.update(res)
 
 
+@cooldown(30)
 @functools.cache
 def load_custom(script):
     beamline, name = script.split(":")
diff --git a/dap/algos/utils/__init__.py b/dap/algos/utils/__init__.py
index 9efc8a4..161b45e 100644
--- a/dap/algos/utils/__init__.py
+++ b/dap/algos/utils/__init__.py
@@ -1,4 +1,5 @@
 
+from .cooldown import cooldown
 from .npmemo import npmemo
 
 
diff --git a/dap/algos/utils/cooldown.py b/dap/algos/utils/cooldown.py
new file mode 100644
index 0000000..bdb34fe
--- /dev/null
+++ b/dap/algos/utils/cooldown.py
@@ -0,0 +1,84 @@
+import functools
+from time import time
+
+
+class cooldown:
+
+    def __init__(self, seconds):
+        self.seconds = seconds
+        self.last_fail_time = 0
+        self.last_fail_exc = None
+
+
+    def __call__(self, func):
+        @functools.wraps(func)
+        def wrapper(*args, **kwargs):
+            remaining = self.get_remaining()
+            if remaining > 0:
+                raise CooldownActive(func, args, kwargs, remaining) from self.last_fail_exc
+
+            try:
+                return func(*args, **kwargs)
+            except Exception as exc:
+                self.last_fail_time = time()
+                self.last_fail_exc = exc
+                raise exc
+
+        return wrapper
+
+
+    def get_remaining(self):
+        now = time()
+        elapsed = now - self.last_fail_time
+        return self.seconds - elapsed
+
+
+
+class CooldownActive(Exception):
+
+    def __init__(self, func, args, kwargs, remaining):
+        call = format_call(func, args, kwargs)
+        msg = f"function call is on cooldown ({remaining:.3g}s remaining): {call}"
+        super().__init__(msg)
+
+
+
+def format_call(func, args, kwargs):
+    fargs = [truncated_repr(i) for i in args]
+    fargs += [f"{k}={truncated_repr(v)}" for k, v in kwargs.items()]
+    fargs = ", ".join(fargs)
+    return f"{func.__name__}({fargs})"
+
+def truncated_repr(x, length=10, ellipsis="..."):
+    thresh = 2 * length + len(ellipsis)
+    x = repr(x)
+    if len(x) <= thresh:
+        return x
+    return x[:length] + ellipsis + x[-length:]
+
+
+
+
+
+if __name__ == "__main__":
+    from time import sleep
+
+
+    @cooldown(seconds=5)
+    def load(fn):
+        return open(fn).read()
+
+
+    print(load(__file__))
+
+
+    while True:
+        try:
+            load("does_not_exist.txt")
+        except Exception as e:
+            en = type(e).__name__
+            print(f"{en}: {e}")
+        sleep(0.1)
+
+
+