From 07452ba2dcd9465d135c7c13addc48c245f77ba3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Krier?= <ced@b2ck.com>
Date: Mon, 3 Jun 2019 15:45:06 +0200
Subject: [PATCH] Reduce number of promises when rendering tree

We preload the first field of the first row if needed. This should ensure that
the following records are also loaded.
And we do not call load if the field is already loaded to avoid to create a
promise.

issue8199
review265411002
---
 src/model.js     |  5 ++-
 src/view/tree.js | 88 +++++++++++++++++++++++++++++-------------------
 2 files changed, 57 insertions(+), 36 deletions(-)

diff --git a/src/model.js b/src/model.js
index ad7546ad0a..b52620b59b 100644
--- a/src/model.js
+++ b/src/model.js
@@ -559,10 +559,13 @@
                 return jQuery.when.apply(jQuery, prms);
             }
         },
+        is_loaded: function(name) {
+            return ((this.id < 0) || (name in this._loaded));
+        },
         load: function(name) {
             var fname;
             var prm;
-            if ((this.id < 0) || (name in this._loaded)) {
+            if (this.is_loaded(name)) {
                 return jQuery.when();
             }
             if (this.group.prm.state() == 'pending') {
diff --git a/src/view/tree.js b/src/view/tree.js
index e8e633fd17..f4f7576928 100644
--- a/src/view/tree.js
+++ b/src/view/tree.js
@@ -806,21 +806,26 @@
     });
 
     function redraw_async(rows, selected, expanded) {
-        var chunk = Sao.config.display_size;
-        var dfd = jQuery.Deferred();
-        var redraw_rows = function(i) {
-            rows.slice(i, i + chunk).forEach(function(row) {
-                row.redraw(selected, expanded);
-            });
-            i += chunk;
-            if (i < rows.length) {
-                setTimeout(redraw_rows, 0, i);
-            } else {
-                dfd.resolve();
+        var dfd= jQuery.Deferred(),
+            i = 0;
+        var redraw = function() {
+            for (; i < rows.length; i++) {
+                var row = rows[i];
+                var record = row.record,
+                    column = row.tree.columns[0];
+                if (!record.is_loaded(column.attributes.name)) {
+                    // Prefetch the first field to prevent promises in
+                    // Cell.render
+                    record.load(column.attributes.name).done(redraw);
+                    return;
+                } else {
+                    row.redraw(selected, expanded);
+                }
             }
+            dfd.resolve();
         };
-        setTimeout(redraw_rows, 0, 0);
-        return dfd;
+        redraw();
+        return dfd.promise();
     }
 
     Sao.View.Tree.Row = Sao.class_(Object, {
@@ -1523,7 +1528,7 @@
             if (!cell) {
                 cell = this.get_cell();
             }
-            record.load(this.attributes.name).done(function() {
+            var render = function() {
                 var value;
                 var field = record.model.fields[this.attributes.name];
                 var invisible = field.get_state_attrs(record).invisible;
@@ -1574,7 +1579,12 @@
                     }
                     cell.text(value);
                 }
-            }.bind(this));
+            }.bind(this);
+            if (!record.is_loaded(this.attributes.name)) {
+                record.load(this.attributes.name).done(render);
+            } else {
+                render();
+            }
             return cell;
         },
         clicked: function(event) {
@@ -1610,7 +1620,7 @@
             if (!cell) {
                 cell = this.get_cell();
             }
-            record.load(this.attributes.name).done(function() {
+            var render = function() {
                 this.update_text(cell, record);
                 this.field.set_state(record);
                 var state_attrs = this.field.get_state_attrs(record);
@@ -1619,7 +1629,12 @@
                 } else {
                     cell.show();
                 }
-            }.bind(this));
+            }.bind(this);
+            if (!record.is_loaded(this.attributes.name)) {
+                record.load(this.attributes.name).done(render);
+            } else {
+                render();
+            }
             return cell;
         }
     });
@@ -1883,18 +1898,8 @@
             if (!cell) {
                 cell = this.get_cell();
             }
-            record.load(this.attributes.name).done(function() {
-                var value = this.field.get_client(record);
-                if (value) {
-                    if (value > Sao.common.BIG_IMAGE_SIZE) {
-                        value = jQuery.when(null);
-                    } else {
-                        value = this.field.get_data(record);
-                    }
-                } else {
-                    value = jQuery.when(null);
-                }
-                value.done(function(data) {
+            var render = function() {
+                var set_src = function(data) {
                     var img_url, blob;
                     if (!data) {
                         img_url = null;
@@ -1903,8 +1908,24 @@
                         img_url = window.URL.createObjectURL(blob);
                     }
                     cell.attr('src', img_url);
-                }.bind(this));
-            }.bind(this));
+                }.bind(this);
+
+                var value = this.field.get_client(record);
+                if (value) {
+                    if (value > Sao.common.BIG_IMAGE_SIZE) {
+                        set_src(null);
+                    } else {
+                        this.field.get_data(record).done(set_src);
+                    }
+                } else {
+                    set_src(null);
+                }
+            }.bind(this);
+            if (!record.is_loaded(this.attributes.name)) {
+                record.load(this.attributes.name).done(render);
+            } else {
+                render();
+            }
             return cell;
         }
     });
@@ -1975,10 +1996,7 @@
                         return undefined;
                     }
                 });
-            // Wait at least one eager field is loaded before evaluating states
-            record.load(fields[0]).done(function() {
-                button.set_state(record);
-            });
+            button.set_state(record);
             return button.el;
         },
         button_clicked: function(event) {