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/*
* Ricochet - A minimalist CLI web browser for fast, distraction-free navigation.
* Copyright (C) 2026 Richard Qin
*
* 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 3 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, see <https://www.gnu.org/licenses/>.
*/
#include "mailbox.hh"
#include <algorithm>
#include <cerrno>
#include <sys/eventfd.h>
#include <system_error>
#include <unistd.h>
#include <utility>
namespace ricochet::tui::detail {
Mailbox::Mailbox() : event_fd_( eventfd( 0, EFD_CLOEXEC | EFD_NONBLOCK ) )
{
if ( event_fd_ == -1 ) {
throw std::system_error( errno, std::generic_category(), "eventfd" );
}
}
Mailbox::~Mailbox()
{ ::close( event_fd_ ); }
PostResult Mailbox::post( HostUpdate update )
{
const std::lock_guard lock( mutex_ );
// Closing rejects later producers while existing sender handles remain alive.
if ( closed_ ) {
return PostResult::Closed;
}
updates_.push_back( std::move( update ) );
int result;
do {
result = eventfd_write( event_fd_, 1 );
} while ( result == -1 && errno == EINTR );
// EAGAIN means the counter is already readable, so the loop is already awake.
if ( result == -1 && errno != EAGAIN ) {
const int error = errno;
updates_.pop_back();
throw std::system_error( error, std::generic_category(), "eventfd_write" );
}
return PostResult::Queued;
}
std::vector<HostUpdate> Mailbox::take( std::size_t limit )
{
const std::lock_guard lock( mutex_ );
eventfd_t counter {};
int result;
do {
result = eventfd_read( event_fd_, &counter );
} while ( result == -1 && errno == EINTR );
// An empty queue has no wake token. Other read errors are transport failures.
if ( result == -1 && errno != EAGAIN ) {
throw std::system_error( errno, std::generic_category(), "eventfd_read" );
}
const auto count = std::min( limit, updates_.size() );
std::vector<HostUpdate> batch;
batch.reserve( count );
for ( std::size_t i = 0; i < count; ++i ) {
batch.push_back( std::move( updates_.front() ) );
updates_.pop_front();
}
return batch;
}
int Mailbox::descriptor() const noexcept
{ return event_fd_; }
void Mailbox::close() noexcept
{
const std::lock_guard lock( mutex_ );
closed_ = true;
updates_.clear();
}
} // namespace ricochet::tui::detail
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