
//          Copyright Oliver Kowalke 2013.
// Distributed under the Boost Software License, Version 1.0.
//    (See accompanying file LICENSE_1_0.txt or copy at
//          http://www.boost.org/LICENSE_1_0.txt)

#include "memoria/fiber/recursive_mutex.hpp"

#include <algorithm>
#include <functional>

#include "memoria/fiber/exceptions.hpp"
#include "memoria/fiber/scheduler.hpp"


namespace memoria {
namespace fibers {

void
recursive_mutex::lock() {
    while ( true) {
        context * active_ctx = context::active();
        // store this fiber in order to be notified later
        detail::spinlock_lock lk{ wait_queue_splk_ };
        if ( active_ctx == owner_) {
            ++count_;
            return;
        } else if ( nullptr == owner_) {
            owner_ = active_ctx;
            count_ = 1;
            return;
        }
        BOOST_ASSERT( ! active_ctx->wait_is_linked() );
        active_ctx->wait_link( wait_queue_);
        // suspend this fiber
        active_ctx->suspend( lk);
        BOOST_ASSERT( ! active_ctx->wait_is_linked() );
    }
}

bool
recursive_mutex::try_lock() noexcept { 
    context * active_ctx = context::active();
    detail::spinlock_lock lk{ wait_queue_splk_ };
    if ( nullptr == owner_) {
        owner_ = active_ctx;
        count_ = 1;
    } else if ( active_ctx == owner_) {
        ++count_;
    }
    lk.unlock();
    // let other fiber release the lock
    context::active()->yield();
    return active_ctx == owner_;
}

void
recursive_mutex::unlock() {
    context * active_ctx = context::active();
    detail::spinlock_lock lk( wait_queue_splk_);
    if ( BOOST_UNLIKELY( active_ctx != owner_) ) {
        throw lock_error(
                std::make_error_code( std::errc::operation_not_permitted),
                "boost fiber: no  privilege to perform the operation");
    }
    if ( 0 == --count_) {
        owner_ = nullptr;
        if ( ! wait_queue_.empty() ) {
            context * ctx = & wait_queue_.front();
            wait_queue_.pop_front();
            active_ctx->schedule( ctx);
        }
    }
}

}}

