From: Galen Charlton <gmc@equinoxinitiative.org>
Date: Wed, 3 Jul 2019 21:53:01 +0000 (-0400)
Subject: LP#1777207: teach egGrid how to prepend rows more efficiently
X-Git-Url: https://old-git.evergreen-ils.org/?a=commitdiff_plain;h=59f9d4d7d836b3db37ad5a83fb5573b5934dc9c6;p=working%2FEvergreen.git

LP#1777207: teach egGrid how to prepend rows more efficiently

The checkin and checkout grids in the AngularJS client have
been doing full grid refreshes when adding a checkin or
checkout to their respective grids. While this does not
result in re-fetching data for the loans that were already
processed, as more entries get added to the grid the time
it takes to do a full digest of the grid contents during a
egGrid.collect() (which empties the list of displayed rows,
then refills it), gets progressively longer. Grids that have
only ~40 entries have been observed to take several seconds
purely on the AngularJS rendering phase.

This patch teaches egGrid a new prepend() method that
takes the first element from the underlying data source and
unshifts it onto the list of displayed grid rows, saving much
rendering time. The prepend() method will also force the
grid offset back to 0 if it isn't already.

Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>
---

diff --git a/Open-ILS/web/js/ui/default/staff/circ/checkin/app.js b/Open-ILS/web/js/ui/default/staff/circ/checkin/app.js
index 6d71f6c6dd..965529b4c5 100644
--- a/Open-ILS/web/js/ui/default/staff/circ/checkin/app.js
+++ b/Open-ILS/web/js/ui/default/staff/circ/checkin/app.js
@@ -233,9 +233,13 @@ function($scope , $q , $window , $location , $timeout , egCore , checkinSvc , eg
                     {already_checked_in : final_resp.evt.copy_barcode};
             }
 
-            if ($scope.trim_list && checkinSvc.checkins.length > 20)
+            if ($scope.trim_list && checkinSvc.checkins.length > 20) {
                 //cut array short at 20 items
                 checkinSvc.checkins.length = 20;
+                checkinGrid.prepend(20);
+            } else {
+                checkinGrid.prepend();
+            }
         },
         function() {
             // Checkin was rejected somewhere along the way.
@@ -249,9 +253,7 @@ function($scope , $q , $window , $location , $timeout , egCore , checkinSvc , eg
             checkinSvc.checkins.splice(pos, 1);
 
         })['finally'](function() {
-
-            // when all is said and done, refresh the grid and refocus
-            checkinGrid.refresh();
+            // when all is said and done, refocus
             $scope.focusMe = true;
         });
     }
diff --git a/Open-ILS/web/js/ui/default/staff/circ/patron/checkout.js b/Open-ILS/web/js/ui/default/staff/circ/patron/checkout.js
index f3df2d8ace..d79811c705 100644
--- a/Open-ILS/web/js/ui/default/staff/circ/patron/checkout.js
+++ b/Open-ILS/web/js/ui/default/staff/circ/patron/checkout.js
@@ -189,7 +189,7 @@ function($scope , $q , $routeParams , egCore , egUser , patronSvc ,
         };
 
         $scope.checkouts.unshift(row_item);
-        $scope.gridDataProvider.refresh();
+        $scope.gridDataProvider.prepend();
 
         egCore.hatch.setItem('circ.checkout.strict_barcode', $scope.strict_barcode);
         var options = {check_barcode : $scope.strict_barcode};
diff --git a/Open-ILS/web/js/ui/default/staff/services/grid.js b/Open-ILS/web/js/ui/default/staff/services/grid.js
index 9ee646a47c..a12e47bb25 100644
--- a/Open-ILS/web/js/ui/default/staff/services/grid.js
+++ b/Open-ILS/web/js/ui/default/staff/services/grid.js
@@ -339,6 +339,10 @@ angular.module('egGridMod',
                     grid.collect();
                 }
 
+                controls.prepend = function(limit) {
+                    grid.prepend(limit);
+                }
+
                 controls.setLimit = function(limit,forget) {
                     grid.limit = limit;
                     if (!forget && grid.persistKey) {
@@ -360,6 +364,7 @@ angular.module('egGridMod',
                 }
 
                 grid.dataProvider.refresh = controls.refresh;
+                grid.dataProvider.prepend = controls.prepend;
                 grid.controls = controls;
             }
 
@@ -1322,6 +1327,45 @@ angular.module('egGridMod',
                 });
             }
 
+            grid.prepend = function(limit) {
+                if (grid.offset > 0) {
+                    // if we're prepending, we're forcing the
+                    // offset back to zero to display the top
+                    // of the list
+                    grid.offset = 0;
+                    grid.collect();
+                    return;
+                }
+                if (grid.collecting) return; // avoid parallel collect() or prepend()
+                grid.collecting = true;
+                console.debug('egGrid.prepend() starting');
+                grid.dataProvider.get(0, 1).then(
+                null,
+                null,
+                function(item) {
+                    if (item) {
+                        $scope.items.unshift(item);
+                        if (limit && $scope.items.length > limit) {
+                            // this accommodates the checkin grid that
+                            // allows the user to set a definite limit
+                            // without requiring that entire collect()
+                            $scope.items.length = limit;
+                        }
+                        if ($scope.items.length > grid.limit) {
+                            $scope.items.length = grid.limit;
+                        }
+                        if (grid.controls.itemRetrieved)
+                            grid.controls.itemRetrieved(item);
+                        if ($scope.selectAll)
+                            $scope.selected[grid.indexValue(item)] = true
+                    }
+                }).finally(function() {
+                    console.debug('egGrid.prepend() complete');
+                    grid.collecting = false;
+                    $scope.selected = angular.copy($scope.selected);
+                });
+            }
+
             grid.init();
         }]
     };
@@ -1912,6 +1956,7 @@ angular.module('egGridMod',
             // Calls the grid refresh function.  Once instantiated, the
             // grid will replace this function with it's own refresh()
             gridData.refresh = function(noReset) { }
+            gridData.prepend = function(limit) { }
 
             if (!gridData.get) {
                 // returns a promise whose notify() delivers items