From 6bca9a8ef435b6b8a5dca917ec848c076c3a971e Mon Sep 17 00:00:00 2001 From: moneromooo-monero Date: Sun, 17 Apr 2016 11:45:38 +0100 Subject: [PATCH] abstract_tcp_server2: avoid deadlock waiting for send queue to drain If we reach the send queue size limit, we need to release the lock, or we will deadlock and it will never drain. If we reach that limit, it's likely there's another problem in the first place though, so it will probably not drain in practice either, unless some kind of transient network timeout. --- contrib/epee/include/net/abstract_tcp_server2.inl | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/contrib/epee/include/net/abstract_tcp_server2.inl b/contrib/epee/include/net/abstract_tcp_server2.inl index b3d4e5fdb..416a24739 100644 --- a/contrib/epee/include/net/abstract_tcp_server2.inl +++ b/contrib/epee/include/net/abstract_tcp_server2.inl @@ -490,7 +490,9 @@ PRAGMA_WARNING_DISABLE_VS(4355) sleep_before_packet(cb, 1, 1); } - epee::critical_region_t send_guard(m_send_que_lock); // *** critical *** + m_send_que_lock.lock(); // *** critical *** + epee::misc_utils::auto_scope_leave_caller scope_exit_handler = epee::misc_utils::create_scope_leave_handler([&](){m_send_que_lock.unlock();}); + long int retry=0; const long int retry_limit = 5*4; while (m_send_que.size() > ABSTRACT_SERVER_SEND_QUE_MAX_COUNT) @@ -504,11 +506,12 @@ PRAGMA_WARNING_DISABLE_VS(4355) long int ms = 250 + (rand()%50); _info_c("net/sleep", "Sleeping because QUEUE is FULL, in " << __FUNCTION__ << " for " << ms << " ms before packet_size="< retry_limit) { - send_guard.unlock(); _erro("send que size is more than ABSTRACT_SERVER_SEND_QUE_MAX_COUNT(" << ABSTRACT_SERVER_SEND_QUE_MAX_COUNT << "), shutting down connection"); // _dbg1_c("net/sleep", "send que size is more than ABSTRACT_SERVER_SEND_QUE_MAX_COUNT(" << ABSTRACT_SERVER_SEND_QUE_MAX_COUNT << "), shutting down connection"); close();