sneedmc/logic/net/HttpMetaCache.cpp
2013-10-06 01:13:40 +02:00

232 lines
5.8 KiB
C++

#include "MultiMC.h"
#include "HttpMetaCache.h"
#include <pathutils.h>
#include <QFileInfo>
#include <QFile>
#include <QTemporaryFile>
#include <QSaveFile>
#include <QDateTime>
#include <QCryptographicHash>
#include <logger/QsLog.h>
#include <QJsonDocument>
#include <QJsonArray>
#include <QJsonObject>
QString MetaEntry::getFullPath()
{
return PathCombine(MMC->metacache()->getBasePath(base), path);
}
HttpMetaCache::HttpMetaCache(QString path)
:QObject()
{
m_index_file = path;
saveBatchingTimer.setSingleShot(true);
saveBatchingTimer.setTimerType(Qt::VeryCoarseTimer);
connect(&saveBatchingTimer,SIGNAL(timeout()),SLOT(SaveNow()));
}
HttpMetaCache::~HttpMetaCache()
{
saveBatchingTimer.stop();
SaveNow();
}
MetaEntryPtr HttpMetaCache::getEntry ( QString base, QString resource_path )
{
// no base. no base path. can't store
if(!m_entries.contains(base))
{
// TODO: log problem
return MetaEntryPtr();
}
EntryMap & map = m_entries[base];
if(map.entry_list.contains(resource_path))
{
return map.entry_list[resource_path];
}
return MetaEntryPtr();
}
MetaEntryPtr HttpMetaCache::resolveEntry ( QString base, QString resource_path, QString expected_etag )
{
auto entry = getEntry(base, resource_path);
// it's not present? generate a default stale entry
if(!entry)
{
return staleEntry(base, resource_path);
}
auto & selected_base = m_entries[base];
QString real_path = PathCombine(selected_base.base_path, resource_path);
QFileInfo finfo(real_path);
// is the file really there? if not -> stale
if(!finfo.isFile() || !finfo.isReadable())
{
// if the file doesn't exist, we disown the entry
selected_base.entry_list.remove(resource_path);
return staleEntry(base, resource_path);
}
if(!expected_etag.isEmpty() && expected_etag != entry->etag)
{
// if the etag doesn't match expected, we disown the entry
selected_base.entry_list.remove(resource_path);
return staleEntry(base, resource_path);
}
// if the file changed, check md5sum
qint64 file_last_changed = finfo.lastModified().toUTC().toMSecsSinceEpoch();
if(file_last_changed != entry->last_changed_timestamp)
{
QFile input(real_path);
input.open(QIODevice::ReadOnly);
QString md5sum = QCryptographicHash::hash(input.readAll(), QCryptographicHash::Md5).toHex().constData();
if(entry->md5sum != md5sum)
{
selected_base.entry_list.remove(resource_path);
return staleEntry(base, resource_path);
}
// md5sums matched... keep entry and save the new state to file
entry->last_changed_timestamp = file_last_changed;
SaveEventually();
}
// entry passed all the checks we cared about.
return entry;
}
bool HttpMetaCache::updateEntry ( MetaEntryPtr stale_entry )
{
if(!m_entries.contains(stale_entry->base))
{
QLOG_ERROR() << "Cannot add entry with unknown base: " << stale_entry->base.toLocal8Bit();
return false;
}
if(stale_entry->stale)
{
QLOG_ERROR() << "Cannot add stale entry: " << stale_entry->getFullPath().toLocal8Bit();
return false;
}
m_entries[stale_entry->base].entry_list[stale_entry->path] = stale_entry;
SaveEventually();
return true;
}
MetaEntryPtr HttpMetaCache::staleEntry(QString base, QString resource_path)
{
auto foo = new MetaEntry;
foo->base = base;
foo->path = resource_path;
foo->stale = true;
return MetaEntryPtr(foo);
}
void HttpMetaCache::addBase ( QString base, QString base_root )
{
// TODO: report error
if(m_entries.contains(base))
return;
// TODO: check if the base path is valid
EntryMap foo;
foo.base_path = base_root;
m_entries[base] = foo;
}
QString HttpMetaCache::getBasePath ( QString base )
{
if(m_entries.contains(base))
{
return m_entries[base].base_path;
}
return QString();
}
void HttpMetaCache::Load()
{
QFile index(m_index_file);
if(!index.open(QIODevice::ReadOnly))
return;
QJsonDocument json = QJsonDocument::fromJson(index.readAll());
if(!json.isObject())
return;
auto root = json.object();
// check file version first
auto version_val =root.value("version");
if(!version_val.isString())
return;
if(version_val.toString() != "1")
return;
// read the entry array
auto entries_val =root.value("entries");
if(!entries_val.isArray())
return;
QJsonArray array = entries_val.toArray();
for(auto element: array)
{
if(!element.isObject())
return;
auto element_obj = element.toObject();
QString base = element_obj.value("base").toString();
if(!m_entries.contains(base))
continue;
auto & entrymap = m_entries[base];
auto foo = new MetaEntry;
foo->base = base;
QString path = foo->path = element_obj.value("path").toString();
foo->md5sum = element_obj.value("md5sum").toString();
foo->etag = element_obj.value("etag").toString();
foo->last_changed_timestamp = element_obj.value("last_changed_timestamp").toDouble();
// presumed innocent until closer examination
foo->stale = false;
entrymap.entry_list[path] = MetaEntryPtr( foo );
}
}
void HttpMetaCache::SaveEventually()
{
// reset the save timer
saveBatchingTimer.stop();
saveBatchingTimer.start(30000);
}
void HttpMetaCache::SaveNow()
{
QSaveFile tfile(m_index_file);
if(!tfile.open(QIODevice::WriteOnly | QIODevice::Truncate))
return;
QJsonObject toplevel;
toplevel.insert("version",QJsonValue(QString("1")));
QJsonArray entriesArr;
for(auto group : m_entries)
{
for(auto entry : group.entry_list)
{
QJsonObject entryObj;
entryObj.insert("base", QJsonValue(entry->base));
entryObj.insert("path", QJsonValue(entry->path));
entryObj.insert("md5sum", QJsonValue(entry->md5sum));
entryObj.insert("etag", QJsonValue(entry->etag));
entryObj.insert("last_changed_timestamp", QJsonValue(double(entry->last_changed_timestamp)));
entriesArr.append(entryObj);
}
}
toplevel.insert("entries",entriesArr);
QJsonDocument doc(toplevel);
QByteArray jsonData = doc.toJson();
qint64 result = tfile.write(jsonData);
if(result == -1)
return;
if(result != jsonData.size())
return;
tfile.commit();
}