mpd/src/RemoteTagCache.cxx
Max Kellermann 42d5b05f54 util/IntrusiveHashSet: rename insert() to insert_commit()
Clarify that the method is not a freestanding insertion method but
should only be used after insert_check().
2023-07-21 19:42:26 +02:00

125 lines
2.7 KiB
C++

// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright The Music Player Daemon Project
#include "RemoteTagCache.hxx"
#include "RemoteTagCacheHandler.hxx"
#include "lib/fmt/ExceptionFormatter.hxx"
#include "input/ScanTags.hxx"
#include "util/DeleteDisposer.hxx"
#include "util/Domain.hxx"
#include "Log.hxx"
static constexpr Domain remote_tag_cache_domain("remote_tag_cache");
RemoteTagCache::RemoteTagCache(EventLoop &event_loop,
RemoteTagCacheHandler &_handler) noexcept
:handler(_handler),
defer_invoke_handler(event_loop, BIND_THIS_METHOD(InvokeHandlers))
{
}
RemoteTagCache::~RemoteTagCache() noexcept
{
map.clear_and_dispose(DeleteDisposer());
}
void
RemoteTagCache::Lookup(const std::string &uri) noexcept
{
std::unique_lock<Mutex> lock(mutex);
auto [tag, value] = map.insert_check(uri);
if (value) {
auto item = new Item(*this, uri);
map.insert_commit(tag, *item);
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 (...) {
FmtError(remote_tag_cache_domain,
"Failed to scan tags of '{}': {}",
uri, std::current_exception());
item->scanner.reset();
lock.lock();
ItemResolved(*item);
return;
}
} else if (tag->scanner) {
/* already scanning this one - no-op */
} else {
/* already finished: re-invoke the handler */
idle_list.erase(waiting_list.iterator_to(*tag));
invoke_list.push_back(*tag);
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::scoped_lock<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::scoped_lock<Mutex> lock(parent.mutex);
parent.ItemResolved(*this);
}
void
RemoteTagCache::Item::OnRemoteTagError(std::exception_ptr e) noexcept
{
FmtError(remote_tag_cache_domain,
"Failed to scan tags of '{}': {}", uri, e);
scanner.reset();
const std::scoped_lock<Mutex> lock(parent.mutex);
parent.ItemResolved(*this);
}