Merge pull request #40 from traveltime-dev/throttling

[feature] throttling

docs/reference.md

@@ -145,6 +145,8 @@ The main settings dialog can be open using the ![](images/icons/settings.svg#ico
 
 **Clear cache** : this button allows to clear the request cache. All requests are saved to a cache file, to avoid the need of hitting the API if an identical request was already made. By clearing the cache, all saved queries will be deleted. This shouldn't be necessary unless you have a very high usage of the application and the cache file gets too big.
 
+**Throttle API calls** : when enabled, the plugin will check how many calls were made to the API during the last minute. If above the provided threshold, the plugin will wait before sending the next query to avoid hitting the limit. Use this option if you prefer to avoid API limit errors from interrupting your workflows.
+
 **Log API calls to the message logs** : this settings makes the plugin log all requests and responses to the QGIS Message Log, allowing to inspect what's happening in case you encounter errors.
 
 **Disable HTTPS certificate verification** : under certain circumstances (such as connection from an enterprise network), requests made from Python may fail because the SSL certificates can not be verified. If this happens, you can disable the verification by checking this box. Please be aware that this makes your requests to the API more vulnerable to interception by an attacker.

travel_time_platform_plugin/algorithms/base.py

@@ -1,8 +1,10 @@
 import requests
 import json
+import time
 import os
 import collections
 from qgis.PyQt.QtCore import QSettings
+from qgis.PyQt.QtTest import QTest
 
 from qgis.core import (
     Qgis,
@@ -201,14 +203,23 @@ def processAlgorithmMakeRequest(
                 )
             )
 
-        response = cache.instance.cached_requests.request(
+        request = requests.Request(
             self.method,
             full_url,
             data=json_data,
             params=params,
             headers=headers,
-            verify=not disable_https,
+        ).prepare()
+
+        cached = cache.instance.cached_requests.cache.has_key(
+            cache.instance.cached_requests.cache.create_key(request)
         )
+        if not cached:
+            throttling = cache.instance.throttling_info()
+            log(f"Throttling query ({throttling} s)")
+            QTest.qWait(throttling * 1000)
+
+        response = cache.instance.cached_requests.send(request, verify=not disable_https)
 
         try:
             response_data = json.loads(response.text)

travel_time_platform_plugin/cache.py

@@ -1,6 +1,7 @@
+from datetime import timedelta, datetime
 import os
 
-from qgis.PyQt.QtCore import QCoreApplication, QStandardPaths
+from qgis.PyQt.QtCore import QCoreApplication, QStandardPaths, QSettings
 
 from .libraries import requests_cache
 
@@ -42,5 +43,34 @@ def prepare(self):
             allowable_methods=("GET", "POST"),
         )
 
+    def throttling_info(self):
+        """
+        Returns how long we must wait in seconds before next request according to throttling settings
+        """
+        throttle = QSettings().value("traveltime_platform/throttle_calls_enabled", False, type=bool)
+        throttle_value = QSettings().value("traveltime_platform/throttle_calls_value", 300, type=int)
+
+        if not throttle:
+            return False
+
+        date = datetime.utcnow() - timedelta(seconds=60)
+        oldest = datetime.utcnow()
+        count = 0
+        for key in self.cached_requests.cache.responses:
+            try:
+                response, created_at = self.cached_requests.cache.responses[key]
+            except KeyError:
+                continue
+            if created_at >= date:
+                oldest = min(oldest, created_at)
+                count += 1
+
+        if count < throttle_value:
+            return False
+
+        return (datetime.utcnow() - oldest).seconds
+
+
+
 
 instance = Cache()

travel_time_platform_plugin/metadata.txt

@@ -78,6 +78,8 @@ changelog=- 2019-02-12 : version 0.1-alpha
     - 2021-04-27 : version 1.4.0
         - changed : updated tiles urls
         - fix : geocoder now returns unmatched features
+    - xxxx-xx-xx : version master
+        - feature : added throttling to avoid API overflow
 
 tags=travel,time,platform,api,distance,matrix,geocoder,geocode,geocoding,isochrone,isochrones,routing,polygon,polygons,network analysis,shortest path
 homepage=https://qgis.traveltimeplatform.com/

travel_time_platform_plugin/ui.py

@@ -1,6 +1,6 @@
 import os
 import webbrowser
-from qgis.PyQt.QtCore import Qt, QSettings, QDateTime, QDate, QTime, QUrl
+from qgis.PyQt.QtCore import Qt, QSettings, QDateTime, QDate, QTime, QUrl, QSettings
 from qgis.PyQt.QtWidgets import QDialog, QDateTimeEdit, QWidget
 from qgis.PyQt import uic
 
@@ -38,6 +38,7 @@ def __init__(self):
         self.endpointResetButton.pressed.connect(self.reset_endpoint)
         self.apiKeyHelpLabel.setTextInteractionFlags(Qt.TextBrowserInteraction)
         self.apiKeyHelpLabel.setOpenExternalLinks(True)
+        self.throttleCallsCheckBox.toggled.connect(self.throttleCallsSpinBox.setEnabled)
 
     def showEvent(self, *args, **kwargs):
         super().showEvent(*args, **kwargs)
@@ -62,6 +63,13 @@ def showEvent(self, *args, **kwargs):
         self.disableHttpsCheckBox.setChecked(
             s.value("traveltime_platform/disable_https", False, type=bool)
         )
+        # throttling
+        self.throttleCallsCheckBox.setChecked(
+            s.value("traveltime_platform/throttle_calls_enabled", False, type=bool)
+        )
+        self.throttleCallsSpinBox.setValue(
+            s.value("traveltime_platform/throttle_calls_value", 300, type=int)
+        )
         # refresh current cache
         self.refresh_cache_label()
 
@@ -109,6 +117,9 @@ def accept(self, *args, **kwargs):
         s.setValue(
             "traveltime_platform/disable_https", self.disableHttpsCheckBox.isChecked()
         )
+        # throttling
+        s.setValue("traveltime_platform/throttle_calls_enabled", self.throttleCallsCheckBox.isChecked())
+        s.setValue("traveltime_platform/throttle_calls_value", self.throttleCallsSpinBox.value())
         # endpoint
         s.setValue("traveltime_platform/custom_endpoint", self.endpointLineEdit.text())
 

travel_time_platform_plugin/ui/ConfigDialog.ui

@@ -117,6 +117,50 @@
         </item>
        </layout>
       </item>
+      <item>
+       <layout class="QHBoxLayout" name="horizontalLayout_5">
+        <item>
+         <widget class="QCheckBox" name="throttleCallsCheckBox">
+          <property name="toolTip">
+           <string>If checked, the plugin will throttle API calls to avoid hitting the limit</string>
+          </property>
+          <property name="text">
+           <string>Throttle API calls to </string>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QSpinBox" name="throttleCallsSpinBox">
+          <property name="maximum">
+           <number>10000</number>
+          </property>
+          <property name="value">
+           <number>300</number>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QLabel" name="label_6">
+          <property name="text">
+           <string>per minute</string>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <spacer name="horizontalSpacer">
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+          <property name="sizeHint" stdset="0">
+           <size>
+            <width>40</width>
+            <height>20</height>
+           </size>
+          </property>
+         </spacer>
+        </item>
+       </layout>
+      </item>
       <item>
        <widget class="QCheckBox" name="logCallsCheckBox">
         <property name="text">