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/*
* Copyright 2003-2021 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "RemoteTagCache.hxx"
#include "RemoteTagCacheHandler.hxx"
#include "input/ScanTags.hxx"
#include "util/DeleteDisposer.hxx"
#include "Log.hxx"
RemoteTagCache::RemoteTagCache(EventLoop &event_loop,
RemoteTagCacheHandler &_handler) noexcept
:handler(_handler),
defer_invoke_handler(event_loop, BIND_THIS_METHOD(InvokeHandlers)),
map(typename KeyMap::bucket_traits(&buckets.front(), buckets.size()))
{
}
RemoteTagCache::~RemoteTagCache() noexcept
{
map.clear_and_dispose(DeleteDisposer());
}
void
RemoteTagCache::Lookup(const std::string &uri) noexcept
{
std::unique_lock<Mutex> lock(mutex);
KeyMap::insert_commit_data hint;
auto result = map.insert_check(uri, Item::Hash(), Item::Equal(), hint);
if (result.second) {
auto *item = new Item(*this, uri);
map.insert_commit(*item, hint);
waiting_list.push_back(*item);
lock.unlock();
try {
item->scanner = InputScanTags(uri.c_str(), *item);
if (!item->scanner) {
/* unsupported */
lock.lock();
ItemResolved(*item);
return;
}
item->scanner->Start();
} catch (...) {
FormatError(std::current_exception(),
"Failed to scan tags of '%s'",
uri.c_str());
item->scanner.reset();
lock.lock();
ItemResolved(*item);
return;
}
} else if (result.first->scanner) {
/* already scanning this one - no-op */
} else {
/* already finished: re-invoke the handler */
auto &item = *result.first;
idle_list.erase(waiting_list.iterator_to(item));
invoke_list.push_back(item);
ScheduleInvokeHandlers();
}
}
void
RemoteTagCache::ItemResolved(Item &item) noexcept
{
waiting_list.erase(waiting_list.iterator_to(item));
invoke_list.push_back(item);
ScheduleInvokeHandlers();
}
void
RemoteTagCache::InvokeHandlers() noexcept
{
const std::lock_guard<Mutex> lock(mutex);
while (!invoke_list.empty()) {
auto &item = invoke_list.front();
invoke_list.pop_front();
idle_list.push_back(item);
const ScopeUnlock unlock(mutex);
handler.OnRemoteTag(item.uri.c_str(), item.tag);
}
/* evict items if there are too many */
while (map.size() > MAX_SIZE && !idle_list.empty()) {
auto *item = &idle_list.front();
idle_list.pop_front();
map.erase(map.iterator_to(*item));
delete item;
}
}
void
RemoteTagCache::Item::OnRemoteTag(Tag &&_tag) noexcept
{
tag = std::move(_tag);
scanner.reset();
const std::lock_guard<Mutex> lock(parent.mutex);
parent.ItemResolved(*this);
}
void
RemoteTagCache::Item::OnRemoteTagError(std::exception_ptr e) noexcept
{
FormatError(e, "Failed to scan tags of '%s'", uri.c_str());
scanner.reset();
const std::lock_guard<Mutex> lock(parent.mutex);
parent.ItemResolved(*this);
}
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