Python: cache the module path for executable

This reduces ui freezes when switching the interpreter for a python
project.

Change-Id: Iaa8ce8ed8d51666f8696eb96f504aaf8c4a11822
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

1 files changed, 11 insertions, 3 deletions

diff --git a/src/plugins/python/pythonutils.cpp b/src/plugins/python/pythonutils.cpp
index aa7051b396..dced51518b 100644
--- a/src/plugins/python/pythonutils.cpp
+++ b/src/plugins/python/pythonutils.cpp
@@ -94,6 +94,11 @@ static QString pythonName(const FilePath &pythonPath)
 
 FilePath getPylsModulePath(CommandLine pylsCommand)
 {
+    static QMap<FilePath, FilePath> cache;
+    const FilePath &modulePath = cache.value(pylsCommand.executable());
+    if (!modulePath.isEmpty())
+        return modulePath;
+
     pylsCommand.addArg("-h");
     SynchronousProcess pythonProcess;
     pythonProcess.setEnvironment(pythonProcess.environment() + QStringList("PYTHONVERBOSE=x"));
@@ -111,8 +116,11 @@ FilePath getPylsModulePath(CommandLine pylsCommand)
     const QString &output = response.allOutput();
     for (auto regex : {regexCached, regexNotCached}) {
         QRegularExpressionMatch result = regex.match(output);
-        if (result.hasMatch())
-            return FilePath::fromUserInput(result.captured(1));
+        if (result.hasMatch()) {
+            const FilePath &modulePath = FilePath::fromUserInput(result.captured(1));
+            cache[pylsCommand.executable()] = modulePath;
+            return modulePath;
+        }
     }
     return {};
 }
@@ -146,7 +154,7 @@ static PythonLanguageServerState checkPythonLanguageServer(const FilePath &pytho
             }
         }
 
-        return {PythonLanguageServerState::AlreadyInstalled, getPylsModulePath(pythonLShelpCommand)};
+        return {PythonLanguageServerState::AlreadyInstalled, modulePath};
     }
 
     const CommandLine pythonPipVersionCommand(python, {"-m", "pip", "-V"});