From 8e173eab88e234683b808764d6232f3e75b23f7e Mon Sep 17 00:00:00 2001
From: jokob-sk <jokob.sk@gmail.com>
Date: Thu, 4 Aug 2022 22:45:12 +1000
Subject: [PATCH] optimisations #2, basic session cache for some dropdowns

---
 back/pialert.py         |  4 ++
 front/deviceDetails.php | 99 +++++++++++++++++++++++++++++------------
 2 files changed, 74 insertions(+), 29 deletions(-)

diff --git a/back/pialert.py b/back/pialert.py
index 3f6c3852..0321b70d 100644
--- a/back/pialert.py
+++ b/back/pialert.py
@@ -1576,6 +1576,9 @@ def upgradeDB ():
       ALTER TABLE "Devices" ADD "dev_Network_Node_port" INTEGER 
       """)
 
+    # don't hog DB access  
+    closeDB ()
+
 #-------------------------------------------------------------------------------
 
 def openDB ():
@@ -1591,6 +1594,7 @@ def openDB ():
 
     # Open DB and Cursor
     sql_connection = sqlite3.connect (DB_PATH, isolation_level=None)
+    sql_connection.execute('pragma journal_mode=wal') #
     sql_connection.text_factory = str
     sql_connection.row_factory = sqlite3.Row
     sql = sql_connection.cursor()
diff --git a/front/deviceDetails.php b/front/deviceDetails.php
index e4319171..03ea31a5 100644
--- a/front/deviceDetails.php
+++ b/front/deviceDetails.php
@@ -815,44 +815,85 @@ function initializeiCheck () {
 // -----------------------------------------------------------------------------
 function initializeCombos () {
   // Initialize combos with queries
-  initializeCombo ( $('#dropdownOwner')[0],                      'getOwners',       'txtOwner');
-  initializeCombo ( $('#dropdownDeviceType')[0],                 'getDeviceTypes',  'txtDeviceType');
-  initializeCombo ( $('#dropdownGroup')[0],                      'getGroups',       'txtGroup');
-  initializeCombo ( $('#dropdownLocation')[0],                   'getLocations',    'txtLocation');
-  initializeCombo ( $('#dropdownNetworkNodeMac')[0],             'getNetworkNodes', 'txtNetworkNodeMac');
+  initializeCombo ( '#dropdownOwner',                      'getOwners',       'txtOwner', true);
+  initializeCombo ( '#dropdownDeviceType',                 'getDeviceTypes',  'txtDeviceType', true);
+  initializeCombo ( '#dropdownGroup',                      'getGroups',       'txtGroup', true);
+  initializeCombo ( '#dropdownLocation',                   'getLocations',    'txtLocation', true);
+  initializeCombo ( '#dropdownNetworkNodeMac',             'getNetworkNodes', 'txtNetworkNodeMac', false);
 
   // Initialize static combos
   initializeComboSkipRepeated ();
 }
 
-function initializeCombo (HTMLelement, queryAction, txtDataField) {
-  // get data from server
-  $.get('php/server/devices.php?action='+queryAction, function(data) {
-    var listData = JSON.parse(data);
-    var order = 1;
+function initializeCombo (dropdownId, queryAction, txtDataField, useCache) {
 
-    HTMLelement.innerHTML = ''
-    // for each item
-    listData.forEach(function (item, index) {
-      // insert line divisor
-      if (order != item['order']) {
-        HTMLelement.innerHTML += '<li class="divider"></li>';
-        order = item['order'];
-      }
+  // check if we have the value cached already
+  var dropdownHtmlContent = useCache ? getCache(dropdownId) : ""; 
 
-      id = item['name'];
-      // use explicitly specified id (value) if avaliable
-      if(item['id'])
-      {
-        id = item['id'];
-      }
+  if(dropdownHtmlContent == "")
+  {
+    // get data from server
+    $.get('php/server/devices.php?action='+queryAction, function(data) {
+      var listData = JSON.parse(data);
+      var order = 1;
+      
 
-      // add dropdown item
-      HTMLelement.innerHTML +=
-        '<li><a href="javascript:void(0)" onclick="setTextValue(\''+
-        txtDataField +'\',\''+ id +'\')">'+ item['name'] + '</a></li>'
+      // for each item
+      listData.forEach(function (item, index) {
+        // insert line divisor
+        if (order != item['order']) {
+          dropdownHtmlContent += '<li class="divider"></li>';
+          order = item['order'];
+        }
+
+        id = item['name'];
+        // use explicitly specified id (value) if avaliable
+        if(item['id'])
+        {
+          id = item['id'];
+        }
+
+        // add dropdown item
+        dropdownHtmlContent +=
+          '<li><a href="javascript:void(0)" onclick="setTextValue(\''+
+          txtDataField +'\',\''+ id +'\')">'+ item['name'] + '</a></li>'
+      });
+
+      writeDropdownHtml(dropdownId, dropdownHtmlContent)
     });
-  });
+  } else
+  {
+    writeDropdownHtml(dropdownId, dropdownHtmlContent)
+  }
+}
+
+// write out the HTML for the dropdown
+function writeDropdownHtml(dropdownId, dropdownHtmlContent)
+{
+  // cache
+  setCache(dropdownId, dropdownHtmlContent);
+
+  // write HTML for the dropdown
+  var HTMLelement = $(dropdownId)[0];
+  HTMLelement.innerHTML = ''
+  HTMLelement.innerHTML += dropdownHtmlContent;
+}
+
+function getCache(key)
+{
+  // check cache
+  if(sessionStorage.getItem(key))
+  {
+    return sessionStorage.getItem(key);
+  } else
+  {
+    return "";
+  }
+}
+
+function setCache(key, data)
+{
+  sessionStorage.setItem(key, data); 
 }