pollymc/api/logic/net/HttpMetaCache.cpp

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/* Copyright 2013-2015 MultiMC Contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
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#include "Env.h"
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#include "HttpMetaCache.h"
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#include "FileSystem.h"
#include <QFileInfo>
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#include <QFile>
#include <QDateTime>
#include <QCryptographicHash>
#include <QDebug>
#include <QJsonDocument>
#include <QJsonArray>
#include <QJsonObject>
QString MetaEntry::getFullPath()
{
// FIXME: make local?
return FS::PathCombine(basePath, relativePath);
}
HttpMetaCache::HttpMetaCache(QString path) : QObject()
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{
m_index_file = path;
saveBatchingTimer.setSingleShot(true);
saveBatchingTimer.setTimerType(Qt::VeryCoarseTimer);
connect(&saveBatchingTimer, SIGNAL(timeout()), SLOT(SaveNow()));
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}
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HttpMetaCache::~HttpMetaCache()
{
saveBatchingTimer.stop();
SaveNow();
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}
MetaEntryPtr HttpMetaCache::getEntry(QString base, QString resource_path)
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{
// 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];
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QString real_path = FS::PathCombine(selected_base.base_path, resource_path);
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QFileInfo finfo(real_path);
// is the file really there? if not -> stale
if (!finfo.isFile() || !finfo.isReadable())
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{
// 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);
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}
// if the file changed, check md5sum
qint64 file_last_changed = finfo.lastModified().toUTC().toMSecsSinceEpoch();
if (file_last_changed != entry->local_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->local_changed_timestamp = file_last_changed;
SaveEventually();
}
// entry passed all the checks we cared about.
entry->basePath = getBasePath(base);
return entry;
}
bool HttpMetaCache::updateEntry(MetaEntryPtr stale_entry)
{
if (!m_entries.contains(stale_entry->baseId))
{
qCritical() << "Cannot add entry with unknown base: "
<< stale_entry->baseId.toLocal8Bit();
return false;
}
if (stale_entry->stale)
{
qCritical() << "Cannot add stale entry: " << stale_entry->getFullPath().toLocal8Bit();
return false;
}
m_entries[stale_entry->baseId].entry_list[stale_entry->relativePath] = stale_entry;
SaveEventually();
return true;
}
bool HttpMetaCache::evictEntry(MetaEntryPtr entry)
{
if(entry)
{
entry->stale = true;
SaveEventually();
return true;
}
return false;
}
MetaEntryPtr HttpMetaCache::staleEntry(QString base, QString resource_path)
{
auto foo = new MetaEntry();
foo->baseId = base;
foo->basePath = getBasePath(base);
foo->relativePath = resource_path;
foo->stale = true;
return MetaEntryPtr(foo);
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}
void HttpMetaCache::addBase(QString base, QString base_root)
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{
// TODO: report error
if (m_entries.contains(base))
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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();
}
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void HttpMetaCache::Load()
{
if(m_index_file.isNull())
return;
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QFile index(m_index_file);
if (!index.open(QIODevice::ReadOnly))
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return;
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QJsonDocument json = QJsonDocument::fromJson(index.readAll());
if (!json.isObject())
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return;
auto root = json.object();
// check file version first
auto version_val = root.value("version");
if (!version_val.isString())
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return;
if (version_val.toString() != "1")
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return;
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// read the entry array
auto entries_val = root.value("entries");
if (!entries_val.isArray())
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return;
QJsonArray array = entries_val.toArray();
for (auto element : array)
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{
if (!element.isObject())
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return;
auto element_obj = element.toObject();
QString base = element_obj.value("base").toString();
if (!m_entries.contains(base))
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continue;
auto &entrymap = m_entries[base];
auto foo = new MetaEntry();
foo->baseId = base;
QString path = foo->relativePath = element_obj.value("path").toString();
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foo->md5sum = element_obj.value("md5sum").toString();
foo->etag = element_obj.value("etag").toString();
foo->local_changed_timestamp = element_obj.value("last_changed_timestamp").toDouble();
foo->remote_changed_timestamp =
element_obj.value("remote_changed_timestamp").toString();
// presumed innocent until closer examination
foo->stale = false;
entrymap.entry_list[path] = MetaEntryPtr(foo);
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}
}
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void HttpMetaCache::SaveEventually()
{
// reset the save timer
saveBatchingTimer.stop();
saveBatchingTimer.start(30000);
}
void HttpMetaCache::SaveNow()
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{
if(m_index_file.isNull())
return;
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QJsonObject toplevel;
toplevel.insert("version", QJsonValue(QString("1")));
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QJsonArray entriesArr;
for (auto group : m_entries)
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{
for (auto entry : group.entry_list)
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{
// do not save stale entries. they are dead.
if(entry->stale)
{
continue;
}
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QJsonObject entryObj;
entryObj.insert("base", QJsonValue(entry->baseId));
entryObj.insert("path", QJsonValue(entry->relativePath));
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entryObj.insert("md5sum", QJsonValue(entry->md5sum));
entryObj.insert("etag", QJsonValue(entry->etag));
entryObj.insert("last_changed_timestamp",
QJsonValue(double(entry->local_changed_timestamp)));
if (!entry->remote_changed_timestamp.isEmpty())
entryObj.insert("remote_changed_timestamp",
QJsonValue(entry->remote_changed_timestamp));
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entriesArr.append(entryObj);
}
}
toplevel.insert("entries", entriesArr);
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QJsonDocument doc(toplevel);
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try
{
FS::write(m_index_file, doc.toJson());
}
catch (Exception & e)
{
qWarning() << e.what();
}
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}