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// Copyright (C) 2024 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
#pragma once
#include "algorithm.h"
#include "commandline.h"
#include "environment.h"
#include "filepath.h"
#include "qtcprocess.h"
#include <QDateTime>
#include <QHash>
#include <QMutex>
#include <QMutexLocker>
#include <chrono>
#include <functional>
#include <memory>
#include <optional>
#include <utility>
namespace Utils {
// Use this facility for cached retrieval of data from a tool that always returns the same
// output for the same parameters and is side effect free.
// A prime example is version info via a --version switch.
template<typename Data> class DataFromProcess
{
public:
class Parameters
{
public:
using OutputParser = std::function<
std::optional<Data>(const QString & /* stdOut */, const QString & /* stdErr */)>;
using ErrorHandler = std::function<void(const Process &)>;
using Callback = std::function<void(const std::optional<Data> &)>;
Parameters(const CommandLine &cmdLine, const OutputParser &parser)
: commandLine(cmdLine)
, parser(parser)
{}
CommandLine commandLine;
Environment environment = Environment::systemEnvironment();
std::chrono::seconds timeout = std::chrono::seconds(10);
OutputParser parser;
ErrorHandler errorHandler;
Callback callback;
QList<ProcessResult> allowedResults{ProcessResult::FinishedWithSuccess};
};
// Use the first variant whenever possible.
static void provideData(const Parameters ¶ms);
static std::optional<Data> getData(const Parameters ¶ms);
private:
using Key = std::tuple<FilePath, QStringList, QString>;
using Value = std::pair<std::optional<Data>, QDateTime>;
static std::optional<Data> getOrProvideData(const Parameters ¶ms);
static std::optional<Data> handleProcessFinished(const Parameters ¶ms,
const QDateTime &exeTimestamp,
const Key &cacheKey,
const std::shared_ptr<Process> &process);
static inline QHash<Key, Value> m_cache;
static inline QMutex m_cacheMutex;
};
template<typename Data>
inline void DataFromProcess<Data>::provideData(const Parameters ¶ms)
{
QTC_ASSERT(params.callback, return);
getOrProvideData(params);
}
template<typename Data>
inline std::optional<Data> DataFromProcess<Data>::getData(const Parameters ¶ms)
{
QTC_ASSERT(!params.callback, return {});
return getOrProvideData(params);
}
template<typename Data>
inline std::optional<Data> DataFromProcess<Data>::getOrProvideData(const Parameters ¶ms)
{
if (params.commandLine.executable().isEmpty()) {
if (params.callback)
params.callback({});
return {};
}
const auto key = std::make_tuple(params.commandLine.executable(),
params.environment.toStringList(),
params.commandLine.arguments());
const QDateTime exeTimestamp = params.commandLine.executable().lastModified();
{
QMutexLocker<QMutex> cacheLocker(&m_cacheMutex);
const auto it = m_cache.constFind(key);
if (it != m_cache.constEnd() && it.value().second == exeTimestamp)
return it.value().first;
}
const auto outputRetriever = std::make_shared<Process>();
outputRetriever->setCommand(params.commandLine);
if (params.callback) {
QObject::connect(outputRetriever.get(),
&Process::done,
[params, exeTimestamp, key, outputRetriever] {
handleProcessFinished(params, exeTimestamp, key, outputRetriever);
});
outputRetriever->start();
return {};
}
outputRetriever->runBlocking(params.timeout);
return handleProcessFinished(params, exeTimestamp, key, outputRetriever);
}
template<typename Data>
inline std::optional<Data> DataFromProcess<Data>::handleProcessFinished(
const Parameters ¶ms,
const QDateTime &exeTimestamp,
const Key &cacheKey,
const std::shared_ptr<Process> &process)
{
// Do not store into cache: The next call might succeed.
if (process->result() == ProcessResult::Canceled) {
if (params.callback)
params.callback({});
return {};
}
std::optional<Data> data;
if (params.allowedResults.contains(process->result()))
data = params.parser(process->cleanedStdOut(), process->cleanedStdErr());
else if (params.errorHandler)
params.errorHandler(*process);
QMutexLocker<QMutex> cacheLocker(&m_cacheMutex);
m_cache.insert(cacheKey, std::make_pair(data, exeTimestamp));
if (params.callback) {
params.callback(data);
return {};
}
return data;
}
} // namespace Utils
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