From 18ecbb9b14104e169021f0f245dd84728dceb4e0 Mon Sep 17 00:00:00 2001
From: Christian Kandeler <christian.kandeler@qt.io>
Date: Thu, 14 Nov 2019 10:52:37 +0100
Subject: [PATCH] ProjectExplorer: Speed up FolderNode::addNestedNodes()

... by aggregating the look-up of parent folder nodes.
Also make use of this function in the GenericProjectManager.
As a test case, I added my whole ~/dev directory with ca 600,000 source
files to a generic project. With this patch, the time spent on adding
the new nodes to the tree went down from 15 seconds to two seconds.

Task-number: QTCREATORBUG-20652
Change-Id: If006bce55924feacc071c38ec7a0292d29c51be1
Reviewed-by: hjk <hjk@qt.io>
---
 .../genericprojectmanager/genericproject.cpp  |  4 +++-
 src/plugins/projectexplorer/projectnodes.cpp  | 24 +++++++++++++++++--
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/plugins/genericprojectmanager/genericproject.cpp b/src/plugins/genericprojectmanager/genericproject.cpp
index 00b75d006b8..312a9cfb1ea 100644
--- a/src/plugins/genericprojectmanager/genericproject.cpp
+++ b/src/plugins/genericprojectmanager/genericproject.cpp
@@ -465,12 +465,14 @@ void GenericBuildSystem::refresh(RefreshOptions options)
         // find the common base directory of all source files
         FilePath baseDir = findCommonSourceRoot();
 
+        std::vector<std::unique_ptr<FileNode>> fileNodes;
         for (const QString &f : qAsConst(m_files)) {
             FileType fileType = FileType::Source; // ### FIXME
             if (f.endsWith(".qrc"))
                 fileType = FileType::Resource;
-            newRoot->addNestedNode(std::make_unique<FileNode>(FilePath::fromString(f), fileType), baseDir);
+            fileNodes.emplace_back(std::make_unique<FileNode>(FilePath::fromString(f), fileType));
         }
+        newRoot->addNestedNodes(std::move(fileNodes), baseDir);
 
         newRoot->addNestedNode(std::make_unique<FileNode>(FilePath::fromString(m_filesFileName),
                                                           FileType::Project));
diff --git a/src/plugins/projectexplorer/projectnodes.cpp b/src/plugins/projectexplorer/projectnodes.cpp
index 1424333fcc3..97a4bda4dcd 100644
--- a/src/plugins/projectexplorer/projectnodes.cpp
+++ b/src/plugins/projectexplorer/projectnodes.cpp
@@ -639,8 +639,28 @@ void FolderNode::addNestedNodes(std::vector<std::unique_ptr<FileNode> > &&files,
                                 const Utils::FilePath &overrideBaseDir,
                                 const FolderNode::FolderNodeFactory &factory)
 {
-    for (std::unique_ptr<FileNode> &f : files)
-        addNestedNode(std::move(f), overrideBaseDir, factory);
+    using DirWithNodes = std::pair<Utils::FilePath, std::vector<std::unique_ptr<FileNode>>>;
+    std::vector<DirWithNodes> fileNodesPerDir;
+    for (auto &f : files) {
+        const Utils::FilePath parentDir = f->filePath().parentDir();
+        const auto it = std::lower_bound(fileNodesPerDir.begin(), fileNodesPerDir.end(), parentDir,
+            [](const DirWithNodes &nad, const Utils::FilePath &dir) { return nad.first < dir; });
+        if (it == fileNodesPerDir.end() || it->first < parentDir) {
+            DirWithNodes dirWithNodes;
+            dirWithNodes.first = parentDir;
+            dirWithNodes.second.emplace_back(std::move(f));
+            fileNodesPerDir.insert(it, std::move(dirWithNodes));
+        } else {
+            it->second.emplace_back(std::move(f));
+        }
+    }
+
+    for (DirWithNodes &dirWithNodes : fileNodesPerDir) {
+        FolderNode * const folderNode = recursiveFindOrCreateFolderNode(this, dirWithNodes.first,
+                                                                        overrideBaseDir, factory);
+        for (auto &f : dirWithNodes.second)
+            folderNode->addNode(std::move(f));
+    }
 }
 
 // "Compress" a tree of foldernodes such that foldernodes with exactly one foldernode as a child