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mobile/cleanup: use a mutex to protect storage access

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Instead of the crude and error prone bool, let's just use the right tool
for this job.

In order to avoid issues with a goto across a mutex boundary, this
slightly restructures the code in one place - 'git show -w' makes it
clear that this is really rather simple in its changes.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
This commit is contained in:
Dirk Hohndel 2020-03-28 18:14:00 -07:00
parent d482108f8c
commit d12e86cb2b
2 changed files with 43 additions and 45 deletions
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33
mobile-widgets/qmlmanager.cpp
View file

@ -17,6 +17,7 @@
#include <QtConcurrent>
#include <QFuture>
#include <QUndoStack>
#include <QMutexLocker>
#include <QBluetoothLocalDevice>
@ -163,7 +164,6 @@ void QMLManager::usbRescan()
QMLManager::QMLManager() : m_locationServiceEnabled(false),
m_verboseEnabled(false),
alreadySaving(false),
m_pluggedInDeviceName(""),
m_showNonDiveComputers(false),
undoAction(Command::undoAction(this)),
@ -300,8 +300,6 @@ void QMLManager::applicationStateChanged(Qt::ApplicationState state)
}
stateText.prepend("AppState changed to ");
stateText.append(" with ");
stateText.append((alreadySaving ? QLatin1String("") : QLatin1String("no ")) + QLatin1String("save ongoing"));
stateText.append(" and ");
stateText.append((unsaved_changes() ? QLatin1String("") : QLatin1String("no ")) + QLatin1String("unsaved changes"));
appendTextToLog(stateText);
@ -317,9 +315,8 @@ int QMLManager::openAndMaybeSync(const char *filename)
{
// parse_file will potentially sync with the git server - so make sure we don't start
// a save in the middle of that (for example if the user switches away from the app)
alreadySaving = true;
QMutexLocker lockAlreadySaving(&alreadySaving);
int error = parse_file(filename, &dive_table, &trip_table, &dive_site_table);
alreadySaving = false;
return error;
}
@ -665,8 +662,7 @@ void QMLManager::loadDivesWithValidCredentials()
int error;
if (check_git_sha(fileNamePrt.data(), &git, &branch) == 0) {
appendTextToLog("Cloud sync shows local cache was current");
goto successful_exit;
}
} else {
appendTextToLog("Cloud sync brought newer data, reloading the dive list");
// if we aren't switching from no-cloud mode, let's clear the dive data
@ -677,7 +673,9 @@ void QMLManager::loadDivesWithValidCredentials()
appendTextToLog("Switching from no cloud mode; keep in memory dive data");
}
// this might sync with the remote server and therefore change our git repo
alreadySaving = true;
// we need a block to enforce a short lifetime for the QMutexLocker (otherwise
// we get an error with the 'goto' above)
QMutexLocker lockAlreadySaving(&alreadySaving);
if (git != dummy_git_repository) {
appendTextToLog(QString("have repository and branch %1").arg(branch));
error = git_load_dives(git, branch, &dive_table, &trip_table, &dive_site_table);
@ -685,7 +683,7 @@ void QMLManager::loadDivesWithValidCredentials()
appendTextToLog(QString("didn't receive valid git repo, try again"));
error = parse_file(fileNamePrt.data(), &dive_table, &trip_table, &dive_site_table);
}
alreadySaving = false;
lockAlreadySaving.unlock();
if (!error) {
report_error("filename is now %s", fileNamePrt.data());
set_filename(fileNamePrt.data());
@ -697,8 +695,7 @@ void QMLManager::loadDivesWithValidCredentials()
return;
}
consumeFinishedLoad();
successful_exit:
}
setLoadFromCloud(true);
// if we came from local storage mode, let's merge the local data into the local cache
// for the remote data - which then later gets merged with the remote data if necessary
@ -1290,9 +1287,8 @@ void QMLManager::openNoCloudRepo()
if (git == dummy_git_repository) {
// repo doesn't exist, create it and write the empty dive list to it
git_create_local_repo(qPrintable(filename));
alreadySaving = true;
QMutexLocker lockAlreadySaving(&alreadySaving);
save_dives(qPrintable(filename));
alreadySaving = false;
set_filename(qPrintable(filename));
auto s = qPrefLog::instance();
s->set_default_filename(qPrintable(filename));
@ -1319,15 +1315,15 @@ void QMLManager::saveChangesLocal()
appendTextToLog("Don't save dives without loading from the cloud, first.");
return;
}
if (alreadySaving) {
// try for 10ms, move on if we can't get the lock
if (!alreadySaving.tryLock(10)) {
appendTextToLog("save operation already in progress, can't save locally");
return;
}
bool glo = git_local_only;
git_local_only = true;
alreadySaving = true;
int error = save_dives(existing_filename);
alreadySaving = false;
alreadySaving.unlock();
git_local_only = glo;
if (error) {
setNotificationText(consumeError());
@ -1346,14 +1342,15 @@ void QMLManager::saveChangesCloud(bool forceRemoteSync)
appendTextToLog("asked to save changes but no unsaved changes");
return;
}
if (alreadySaving) {
// try for 10ms, move on if we can't get the lock
if (!alreadySaving.tryLock(10)) {
appendTextToLog("save operation in progress already");
return;
}
// first we need to store any unsaved changes to the local repo
gitProgressCB("Save changes to local cache");
saveChangesLocal();
alreadySaving.unlock();
// if the user asked not to push to the cloud we are done
if (git_local_only && !forceRemoteSync)
return;

3
mobile-widgets/qmlmanager.h
View file

@ -9,6 +9,7 @@
#include <QElapsedTimer>
#include <QColor>
#include <QFile>
#include <QMutex>
#include "core/btdiscovery.h"
#include "core/gpslocation.h"
@ -255,7 +256,7 @@ private:
QString m_notificationText;
qreal m_lastDevicePixelRatio;
QElapsedTimer timer;
bool alreadySaving;
QMutex alreadySaving;
bool checkDate(const DiveObjectHelper &myDive, struct dive *d, QString date);
bool checkLocation(DiveSiteChange &change, const DiveObjectHelper &myDive, struct dive *d, QString location, QString gps);
bool checkDuration(const DiveObjectHelper &myDive, struct dive *d, QString duration);