From 3be3b83c4f383d4e9b81cec2a285adfbb2c37de6 Mon Sep 17 00:00:00 2001
From: gavin <gavin18d@gmail.com>
Date: Fri, 27 May 2022 23:38:52 +0530
Subject: [PATCH] feat: frappe.utils.caching.site_cache

Decorator to cache method calls across requests. The cache is stored in
frappe.utils.caching._SITE_CACHE. The cache persists on the parent process.
It offers a light-weight cache for the current process without the additional
overhead of serializing / deserializing Python objects.

Note: This cache isn't shared among workers. If you need to share data across
workers, use redis (frappe.cache API) instead.

Usage:
    from frappe.utils.caching import site_cache

    @site_cache
    def calculate_pi():
        import math, time
        precision = get_precision("Math Constant", "Pi") # depends on
        site data
	return round(math.pi, precision)

    calculate_pi(10) # will calculate value
    calculate_pi(10) # will return value from cache
    calculate_pi.clear_cache() # clear this function's cache for all sites
    calculate_pi(10) # will calculate value
---
 frappe/utils/caching.py | 56 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 53 insertions(+), 3 deletions(-)

diff --git a/frappe/utils/caching.py b/frappe/utils/caching.py
index d70e660b23..7adfe81606 100644
--- a/frappe/utils/caching.py
+++ b/frappe/utils/caching.py
@@ -2,17 +2,21 @@
 # License: MIT. Check LICENSE
 
 import json
+from collections import defaultdict
 from functools import wraps
+from typing import Callable, Dict, Tuple
 
 import frappe
 
+_SITE_CACHE = defaultdict(lambda: defaultdict(dict))
 
-def __generate_key(func, args, kwargs):
+
+def __generate_request_cache_key(func: Callable, args: Tuple, kwargs: Dict):
 	"""Generate a key for the cache."""
 	return f"{func.__module__}.{func.__name__}{json.dumps((args, kwargs))}"
 
 
-def request_cache(func):
+def request_cache(func: Callable) -> Callable:
 	"""Decorator to cache function calls mid-request. Cache is stored in
 	frappe.local.request_cache. The cache only persists for the current request
 	and is cleared when the request is over. The function is called just once
@@ -42,7 +46,7 @@ def request_cache(func):
 		logger = frappe.logger(module=__name__)
 
 		try:
-			key = __generate_key(func, args, kwargs)
+			key = __generate_request_cache_key(func, args, kwargs)
 		except Exception:
 			logger.warning(f"request_cache: Couldn't generate key for args: {args}, kwargs: {kwargs}")
 			return func(*args, **kwargs)
@@ -54,3 +58,49 @@ def request_cache(func):
 		return frappe.local.request_cache[key]
 
 	return wrapper
+
+
+def site_cache(func: Callable) -> Callable:
+	"""Decorator to cache method calls across requests. The cache is stored in
+	frappe.utils.caching._SITE_CACHE. The cache persists on the parent process.
+	It offers a light-weight cache for the current process without the additional
+	overhead of serializing / deserializing Python objects.
+
+	Note: This cache isn't shared among workers. If you need to share data across
+	workers, use redis (frappe.cache API) instead.
+
+	Usage:
+	        from frappe.utils.caching import site_cache
+
+	        @site_cache
+	        def calculate_pi():
+	                import math, time
+	                precision = get_precision("Math Constant", "Pi") # depends on site data
+	                return round(math.pi, precision)
+
+	        calculate_pi(10) # will calculate value
+	        calculate_pi(10) # will return value from cache
+	        calculate_pi.clear_cache() # clear this function's cache for all sites
+	        calculate_pi(10) # will calculate value
+	"""
+	func_key = f"{func.__module__}.{func.__name__}"
+
+	def clear_cache():
+		"""Clear cache for this function for all sites if not specified."""
+		_SITE_CACHE[func_key].clear()
+
+	func.clear_cache = clear_cache
+
+	@wraps(func)
+	def wrapper(*args, **kwargs):
+		if getattr(frappe.local, "initialised", None):
+			func_call_key = json.dumps((args, kwargs))
+
+			if func_call_key not in _SITE_CACHE[func_key][frappe.local.site]:
+				_SITE_CACHE[func_key][frappe.local.site][func_call_key] = func(*args, **kwargs)
+
+			return _SITE_CACHE[func_key][frappe.local.site][func_call_key]
+
+		return func(*args, **kwargs)
+
+	return wrapper