add delay_on_error option

DOCUMENTATION.md

@@ -831,6 +831,14 @@ The maximum number of parallel connections. Set to `0` to disable the limit.
 
 Default: `8`
 
+##### delay_on_error
+
+_(>= 3.7.0)_
+
+Base delay in case of error response (seconds)
+
+Default: `0.01`
+
 ##### max_content_length
 
 The maximum size of the request body. (bytes)

config

@@ -21,6 +21,9 @@
 # Max parallel connections
 #max_connections = 8
 
+# Base delay in case of error response (seconds)
+#delay_on_error = 0.01
+
 # Max size of request body (bytes), default: 100 Mbyte
 # In case of using a reverse proxy in front of check also there related option
 #max_content_length = 100000000

radicale/app/__init__.py

@@ -72,6 +72,7 @@ class Application(ApplicationPartDelete, ApplicationPartHead,
 
     _mask_passwords: bool
     _auth_delay: float
+    _delay_on_error: float
     _internal_server: bool
     _max_content_length: int
     _max_resource_size: int
@@ -97,6 +98,8 @@ class Application(ApplicationPartDelete, ApplicationPartHead,
         """
         super().__init__(configuration)
         self._mask_passwords = configuration.get("logging", "mask_passwords")
+        self._delay_on_error = configuration.get("server", "delay_on_error")
+        logger.info("delay_on_error set to: %.3f seconds", self._delay_on_error)
         self._max_content_length = configuration.get("server", "max_content_length")
         self._max_resource_size = configuration.get("server", "max_resource_size")
         logger.info("max_content_length set to: %d bytes (%sbytes)", self._max_content_length, utils.format_unit(self._max_content_length, binary=True))
@@ -304,6 +307,14 @@ class Application(ApplicationPartDelete, ApplicationPartHead,
                 flags_text = " (" + " ".join(flags) + ")"
             else:
                 flags_text = ""
+            # delay on error
+            if status >= 400:
+                random_delay = self._delay_on_error * (1 + random.random())
+                if status >= 500:
+                    random_delay = 2 * random_delay
+                if logger.isEnabledFor(logging.DEBUG):
+                    logger.debug("Response delay triggered by result code: %d -> %0.3f seconds", status, random_delay)
+                time.sleep(random_delay)
             if answer is not None:
                 logger.info("%s response status for %r%s in %.3f seconds %s %s bytes%s: %s",
                             request_method, unsafe_path, depthinfo,

radicale/config.py

@@ -171,6 +171,10 @@ DEFAULT_CONFIG_SCHEMA: types.CONFIG_SCHEMA = OrderedDict([
             "value": "100000000",
             "help": "maximum size of request body in bytes (default: 100 Mbyte)",
             "type": positive_int}),
+        ("delay_on_error", {
+            "value": "0.01",
+            "help": "base delay in case of error response (seconds)",
+            "type": positive_float}),
         ("max_resource_size", {
             "value": "10000000",
             "help": "maximum size of resource (default: 10 Mbyte)",