Do not leak TcpAcceptor job on reconfiguration
by monitoring and reacting to the listening socket closure.

Every job that waits for Comm I/O must have a FD closure handler.
Unfortunately, we currently cannot enforce that rule automatically.

=== modified file 'src/comm/TcpAcceptor.cc'
--- src/comm/TcpAcceptor.cc	2014-04-14 06:50:31 +0000
+++ src/comm/TcpAcceptor.cc	2014-04-24 20:12:30 +0000
@@ -105,40 +105,46 @@ Comm::TcpAcceptor::doneAll() const
 {
     // stop when FD is closed
     if (!IsConnOpen(conn)) {
         return AsyncJob::doneAll();
     }
 
     // stop when handlers are gone
     if (theCallSub == NULL) {
         return AsyncJob::doneAll();
     }
 
     // open FD with handlers...keep accepting.
     return false;
 }
 
 void
 Comm::TcpAcceptor::swanSong()
 {
     debugs(5,5, HERE);
     unsubscribe("swanSong");
+    if (IsConnOpen(conn)) {
+        if (closer_ != NULL)
+            comm_remove_close_handler(conn->fd, closer_);
+        conn->close();
+    }
+
     conn = NULL;
     AcceptLimiter::Instance().removeDead(this);
     AsyncJob::swanSong();
 }
 
 const char *
 Comm::TcpAcceptor::status() const
 {
     if (conn == NULL)
         return "[nil connection]";
 
     static char ipbuf[MAX_IPSTRLEN] = {'\0'};
     if (ipbuf[0] == '\0')
         conn->local.toHostStr(ipbuf, MAX_IPSTRLEN);
 
     static MemBuf buf;
     buf.reset();
     buf.Printf(" FD %d, %s",conn->fd, ipbuf);
 
     const char *jobStatus = AsyncJob::status();
@@ -165,42 +171,57 @@ Comm::TcpAcceptor::setListen()
     }
 
     if (Config.accept_filter && strcmp(Config.accept_filter, "none") != 0) {
 #ifdef SO_ACCEPTFILTER
         struct accept_filter_arg afa;
         bzero(&afa, sizeof(afa));
         debugs(5, DBG_IMPORTANT, "Installing accept filter '" << Config.accept_filter << "' on " << conn);
         xstrncpy(afa.af_name, Config.accept_filter, sizeof(afa.af_name));
         if (setsockopt(conn->fd, SOL_SOCKET, SO_ACCEPTFILTER, &afa, sizeof(afa)) < 0)
             debugs(5, DBG_CRITICAL, "WARNING: SO_ACCEPTFILTER '" << Config.accept_filter << "': '" << xstrerror());
 #elif defined(TCP_DEFER_ACCEPT)
         int seconds = 30;
         if (strncmp(Config.accept_filter, "data=", 5) == 0)
             seconds = atoi(Config.accept_filter + 5);
         if (setsockopt(conn->fd, IPPROTO_TCP, TCP_DEFER_ACCEPT, &seconds, sizeof(seconds)) < 0)
             debugs(5, DBG_CRITICAL, "WARNING: TCP_DEFER_ACCEPT '" << Config.accept_filter << "': '" << xstrerror());
 #else
         debugs(5, DBG_CRITICAL, "WARNING: accept_filter not supported on your OS");
 #endif
     }
+
+    typedef CommCbMemFunT<Comm::TcpAcceptor, CommCloseCbParams> Dialer;
+    closer_ = JobCallback(5, 4, Dialer, this, Comm::TcpAcceptor::handleClosure);
+    comm_add_close_handler(conn->fd, closer_);
 }
 
+/// called when listening descriptor is closed by an external force
+/// such as clientHttpConnectionsClose()
+void
+Comm::TcpAcceptor::handleClosure(const CommCloseCbParams &io)
+{
+    closer_ = NULL;
+    conn = NULL;
+    Must(done());
+}
+
+
 /**
  * This private callback is called whenever a filedescriptor is ready
  * to dupe itself and fob off an accept()ed connection
  *
  * It will either do that accept operation. Or if there are not enough FD
  * available to do the clone safely will push the listening FD into a list
  * of deferred operations. The list gets kicked and the dupe/accept() actually
  * done later when enough sockets become available.
  */
 void
 Comm::TcpAcceptor::doAccept(int fd, void *data)
 {
     try {
         debugs(5, 2, HERE << "New connection on FD " << fd);
 
         Must(isOpen(fd));
         TcpAcceptor *afd = static_cast<TcpAcceptor*>(data);
 
         if (!okToAccept()) {
             AcceptLimiter::Instance().defer(afd);

=== modified file 'src/comm/TcpAcceptor.h'
--- src/comm/TcpAcceptor.h	2013-10-25 00:13:46 +0000
+++ src/comm/TcpAcceptor.h	2014-04-24 20:12:30 +0000
@@ -1,29 +1,31 @@
 #ifndef SQUID_COMM_TCPACCEPTOR_H
 #define SQUID_COMM_TCPACCEPTOR_H
 
 #include "base/AsyncJob.h"
 #include "base/CbcPointer.h"
 #include "base/Subscription.h"
 #include "comm/forward.h"
 #include "comm_err_t.h"
 
+class CommCloseCbParams;
+
 namespace Comm
 {
 
 class AcceptLimiter;
 
 /**
  * Listens on a Comm::Connection for new incoming connections and
  * emits an active Comm::Connection descriptor for the new client.
  *
  * Handles all event limiting required to quash inbound connection
  * floods within the global FD limits of available Squid_MaxFD and
  * client_ip_max_connections.
  *
  * Fills the emitted connection with all connection details able to
  * be looked up. Currently these are the local/remote IP:port details
  * and the listening socket transparent-mode flag.
  */
 class TcpAcceptor : public AsyncJob
 {
 public:
@@ -56,37 +58,41 @@ public:
      */
     void acceptNext();
 
     /// Call the subscribed callback handler with details about a new connection.
     void notify(const comm_err_t flag, const Comm::ConnectionPointer &details) const;
 
     /// errno code of the last accept() or listen() action if one occurred.
     int errcode;
 
 protected:
     friend class AcceptLimiter;
     int32_t isLimited;                   ///< whether this socket is delayed and on the AcceptLimiter queue.
 
 private:
     Subscription::Pointer theCallSub;    ///< used to generate AsyncCalls handling our events.
 
     /// conn being listened on for new connections
     /// Reserved for read-only use.
     ConnectionPointer conn;
 
+    AsyncCall::Pointer closer_; ///< listen socket closure handler
+
     /// Method to test if there are enough file descriptors to open a new client connection
     /// if not the accept() will be postponed
     static bool okToAccept();
 
     /// Method callback for whenever an FD is ready to accept a client connection.
     static void doAccept(int fd, void *data);
 
     void acceptOne();
     comm_err_t oldAccept(Comm::ConnectionPointer &details);
     void setListen();
 
+    void handleClosure(const CommCloseCbParams &io);
+
     CBDATA_CLASS2(TcpAcceptor);
 };
 
 } // namespace Comm
 
 #endif /* SQUID_COMM_TCPACCEPTOR_H */