From 7610a41afe910df6426aa09eae5aad7431d69e36 Mon Sep 17 00:00:00 2001
From: "Matthias P. Braendli" <matthias.braendli@mpb.li>
Date: Fri, 2 Jun 2017 15:02:56 +0200
Subject: TCP output: do not block in the destructor if one connection stalls

---
 src/TcpSocket.cpp              | 22 ++++++++++++++++++++--
 src/TcpSocket.h                |  5 +++--
 src/dabOutput/dabOutputTcp.cpp | 12 +++++++++++-
 3 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/src/TcpSocket.cpp b/src/TcpSocket.cpp
index b9824fa..40c1c1a 100644
--- a/src/TcpSocket.cpp
+++ b/src/TcpSocket.cpp
@@ -2,7 +2,7 @@
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Her Majesty the Queen in
    Right of Canada (Communications Research Center Canada)
 
-   Copyright (C) 2016
+   Copyright (C) 2017
    Matthias P. Braendli, matthias.braendli@mpb.li
 
     http://www.opendigitalradio.org
@@ -132,8 +132,26 @@ ssize_t TcpSocket::recv(void* data, size_t size)
 }
 
 
-ssize_t TcpSocket::send(const void* data, size_t size)
+ssize_t TcpSocket::send(const void* data, size_t size, int timeout_ms)
 {
+    if (timeout_ms) {
+        struct pollfd fds[1];
+        fds[0].fd = m_sock;
+        fds[0].events = POLLOUT;
+
+        int retval = poll(fds, 1, timeout_ms);
+
+        if (retval == -1) {
+            stringstream ss;
+            ss << "TCP Socket send error on poll(): " << strerror(errno);
+            throw std::runtime_error(ss.str());
+        }
+        else if (retval == 0) {
+            // Timed out
+            return 0;
+        }
+    }
+
     /* Without MSG_NOSIGNAL the process would receive a SIGPIPE and die */
     ssize_t ret = ::send(m_sock, (const char*)data, size, MSG_NOSIGNAL);
 
diff --git a/src/TcpSocket.h b/src/TcpSocket.h
index 660515d..9ff09e5 100644
--- a/src/TcpSocket.h
+++ b/src/TcpSocket.h
@@ -2,7 +2,7 @@
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Her Majesty the Queen in
    Right of Canada (Communications Research Center Canada)
 
-   Copyright (C) 2016
+   Copyright (C) 2017
    Matthias P. Braendli, matthias.braendli@mpb.li
 
     http://www.opendigitalradio.org
@@ -77,9 +77,10 @@ class TcpSocket
         /** Send data over the TCP connection.
          *  @param data The buffer that will be sent.
          *  @param size Number of bytes to send.
+         *  @param timeout_ms number of milliseconds before timeout
          *  return number of bytes sent or -1 if error
          */
-        ssize_t send(const void* data, size_t size);
+        ssize_t send(const void* data, size_t size, int timeout_ms=0);
 
         /** Receive data from the socket.
          *  @param data The buffer that will receive data.
diff --git a/src/dabOutput/dabOutputTcp.cpp b/src/dabOutput/dabOutputTcp.cpp
index 2aab48a..f5aebe0 100644
--- a/src/dabOutput/dabOutputTcp.cpp
+++ b/src/dabOutput/dabOutputTcp.cpp
@@ -89,7 +89,17 @@ class TCPConnection
                 queue.wait_and_pop(data);
 
                 try {
-                    m_sock.send(&data[0], data.size());
+                    ssize_t sent = 0;
+                    do {
+                        const int timeout_ms = 10; // Less than one ETI frame
+                        sent = m_sock.send(&data[0], data.size(), timeout_ms);
+
+                        if (is_overloaded()) {
+                            m_running = false;
+                            break;
+                        }
+                    }
+                    while (sent == 0);
                 }
                 catch (std::runtime_error& e) {
                     m_running = false;
-- 
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