Make: Speed up reading compiler flags from build.ninja

Scan through the build.ninja file once for all targets instead once
for each target. This improves CMake project loading speed for
projects with many targets and a large build.ninja considerably.

Change-Id: I857c48a714dbb39a469f81c1f951a77f2f57578e
Reviewed-by: James Legg <jlegg@feralinteractive.com>
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>

src/plugins/cmakeprojectmanager/cmakeproject.cpp

@@ -176,7 +176,26 @@ void CMakeProject::handleKitChanges()
     changeActiveBuildConfiguration(t->activeBuildConfiguration()); // force proper refresh
 }
 
-QStringList CMakeProject::getCXXFlagsFor(const CMakeBuildTarget &buildTarget, QByteArray *cachedBuildNinja)
+QStringList CMakeProject::getCXXFlagsFor(const CMakeBuildTarget &buildTarget,
+                                         QHash<QString, QStringList> &cache)
+{
+    // check cache:
+    auto it = cache.constFind(buildTarget.title);
+    if (it != cache.constEnd())
+        return *it;
+
+    if (extractCXXFlagsFromMake(buildTarget, cache))
+        return cache.value(buildTarget.title);
+
+    if (extractCXXFlagsFromNinja(buildTarget, cache))
+        return cache.value(buildTarget.title);
+
+    cache.insert(buildTarget.title, QStringList());
+    return QStringList();
+}
+
+bool CMakeProject::extractCXXFlagsFromMake(const CMakeBuildTarget &buildTarget,
+                                           QHash<QString, QStringList> &cache)
 {
     QString makeCommand = QDir::fromNativeSeparators(buildTarget.makeCommand);
     int startIndex = makeCommand.indexOf(QLatin1Char('\"'));
@@ -195,55 +214,63 @@ QStringList CMakeProject::getCXXFlagsFor(const CMakeBuildTarget &buildTarget, QB
                 QString line = stream.readLine().trimmed();
                 if (line.startsWith(QLatin1String("CXX_FLAGS ="))) {
                     // Skip past =
-                    return line.mid(11).trimmed().split(QLatin1Char(' '), QString::SkipEmptyParts);
+                    cache.insert(buildTarget.title,
+                                 line.mid(11).trimmed().split(QLatin1Char(' '),
+                                                              QString::SkipEmptyParts));
+                    return true;
                 }
             }
         }
     }
+    return false;
+}
+
+bool CMakeProject::extractCXXFlagsFromNinja(const CMakeBuildTarget &buildTarget,
+                                            QHash<QString, QStringList> &cache)
+{
+    Q_UNUSED(buildTarget)
+    if (!cache.isEmpty()) // We fill the cache in one go!
+        return false;
 
     // Attempt to find build.ninja file and obtain FLAGS (CXX_FLAGS) from there if no suitable flags.make were
     // found
     // Get "all" target's working directory
-    if (!buildTargets().empty()) {
+    QByteArray ninjaFile;
-        if (cachedBuildNinja->isNull()) {
+    QString buildNinjaFile = QDir::fromNativeSeparators(buildTargets().at(0).workingDirectory);
-            QString buildNinjaFile = QDir::fromNativeSeparators(buildTargets().at(0).workingDirectory);
+    buildNinjaFile += QLatin1String("/build.ninja");
-            buildNinjaFile += QLatin1String("/build.ninja");
+    QFile buildNinja(buildNinjaFile);
-            QFile buildNinja(buildNinjaFile);
+    if (buildNinja.exists()) {
-            if (buildNinja.exists()) {
+        buildNinja.open(QIODevice::ReadOnly | QIODevice::Text);
-                buildNinja.open(QIODevice::ReadOnly | QIODevice::Text);
+        ninjaFile = buildNinja.readAll();
-                *cachedBuildNinja = buildNinja.readAll();
+        buildNinja.close();
-                buildNinja.close();
-            } else {
-                *cachedBuildNinja = QByteArray();
-            }
-        }
-
-        if (cachedBuildNinja->isEmpty())
-            return QStringList();
-
-        QTextStream stream(cachedBuildNinja);
-        bool targetFound = false;
-        bool cxxFound = false;
-        QString targetSearchPattern = QString::fromLatin1("target %1").arg(buildTarget.title);
-
-        while (!stream.atEnd()) {
-            // 1. Look for a block that refers to the current target
-            // 2. Look for a build rule which invokes CXX_COMPILER
-            // 3. Return the FLAGS definition
-            QString line = stream.readLine().trimmed();
-            if (line.startsWith(QLatin1String("#"))) {
-                if (!line.startsWith(QLatin1String("# Object build statements for"))) continue;
-                targetFound = line.endsWith(targetSearchPattern);
-            } else if (targetFound && line.startsWith(QLatin1String("build"))) {
-                cxxFound = line.indexOf(QLatin1String("CXX_COMPILER")) != -1;
-            } else if (cxxFound && line.startsWith(QLatin1String("FLAGS ="))) {
-                // Skip past =
-                return line.mid(7).trimmed().split(QLatin1Char(' '), QString::SkipEmptyParts);
-            }
-        }
-
     }
-    return QStringList();
+
+    if (ninjaFile.isEmpty())
+        return false;
+
+    QTextStream stream(ninjaFile);
+    bool cxxFound = false;
+    const QString targetSignature = QLatin1String("# Object build statements for ");
+    QString currentTarget;
+
+    while (!stream.atEnd()) {
+        // 1. Look for a block that refers to the current target
+        // 2. Look for a build rule which invokes CXX_COMPILER
+        // 3. Return the FLAGS definition
+        QString line = stream.readLine().trimmed();
+        if (line.startsWith(QLatin1Char('#'))) {
+            if (line.startsWith(targetSignature)) {
+                int pos = line.lastIndexOf(QLatin1Char(' '));
+                currentTarget = line.mid(pos + 1);
+            }
+        } else if (!currentTarget.isEmpty() && line.startsWith(QLatin1String("build"))) {
+            cxxFound = line.indexOf(QLatin1String("CXX_COMPILER")) != -1;
+        } else if (cxxFound && line.startsWith(QLatin1String("FLAGS ="))) {
+            // Skip past =
+            cache.insert(currentTarget, line.mid(7).trimmed().split(QLatin1Char(' '), QString::SkipEmptyParts));
+        }
+    }
+    return !cache.isEmpty();
 }
 
 void CMakeProject::parseCMakeOutput()
@@ -283,13 +310,13 @@ void CMakeProject::parseCMakeOutput()
 
     ppBuilder.setQtVersion(activeQtVersion);
 
-    QByteArray cachedBuildNinja;
+    QHash<QString, QStringList> targetDataCache;
     foreach (const CMakeBuildTarget &cbt, buildTargets()) {
         // This explicitly adds -I. to the include paths
         QStringList includePaths = cbt.includeFiles;
         includePaths += projectDirectory().toString();
         ppBuilder.setIncludePaths(includePaths);
-        QStringList cxxflags = getCXXFlagsFor(cbt, &cachedBuildNinja);
+        QStringList cxxflags = getCXXFlagsFor(cbt, targetDataCache);
         ppBuilder.setCFlags(cxxflags);
         ppBuilder.setCxxFlags(cxxflags);
         ppBuilder.setDefines(cbt.defines);

src/plugins/cmakeprojectmanager/cmakeproject.h

@@ -145,7 +145,9 @@ private:
     QString uiHeaderFile(const QString &uiFile);
     void updateTargetRunConfigurations(ProjectExplorer::Target *t);
     void updateApplicationAndDeploymentTargets();
-    QStringList getCXXFlagsFor(const CMakeBuildTarget &buildTarget, QByteArray *cachedBuildNinja);
+    QStringList getCXXFlagsFor(const CMakeBuildTarget &buildTarget, QHash<QString, QStringList> &cache);
+    bool extractCXXFlagsFromMake(const CMakeBuildTarget &buildTarget, QHash<QString, QStringList> &cache);
+    bool extractCXXFlagsFromNinja(const CMakeBuildTarget &buildTarget, QHash<QString, QStringList> &cache);
 
     ProjectExplorer::Target *m_activeTarget = 0;
     Internal::BuildDirManager *m_buildDirManager = 0;