From 3b9014922986e270f7fde9910603b13de198bf5d Mon Sep 17 00:00:00 2001
From: Ashod Nakashian <ashod.nakashian@collabora.co.uk>
Date: Sat, 19 Nov 2016 10:22:53 -0500
Subject: [PATCH] loolwsd: notify clients of shutdown

Change-Id: I8dbe5752e8e36e2a1f6dee05f5f355f5a7b4d1b6
Reviewed-on: https://gerrit.libreoffice.org/31001
Reviewed-by: Ashod Nakashian <ashnakash@gmail.com>
Tested-by: Ashod Nakashian <ashnakash@gmail.com>
---
 loolwsd/Admin.cpp          |  2 +-
 loolwsd/DocumentBroker.cpp |  1 +
 loolwsd/LOOLWSD.cpp        |  3 +--
 loolwsd/common/SigUtil.cpp | 22 +++++++++++++++++++++-
 loolwsd/common/SigUtil.hpp | 15 +++++++++++++++
 5 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/loolwsd/Admin.cpp b/loolwsd/Admin.cpp
index d24c52426..c9bd23b50 100644
--- a/loolwsd/Admin.cpp
+++ b/loolwsd/Admin.cpp
@@ -149,7 +149,7 @@ bool AdminRequestHandler::adminCommandHandler(const std::vector<char>& payload)
     else if (tokens[0] == "shutdown")
     {
         LOG_INF("Shutdown requested by admin.");
-        ShutdownFlag = true;
+        SigUtil::requestShutdown();
         return false;
     }
     else if (tokens[0] == "set" && tokens.count() > 1)
diff --git a/loolwsd/DocumentBroker.cpp b/loolwsd/DocumentBroker.cpp
index 9e4cc3d6a..52f60c78b 100644
--- a/loolwsd/DocumentBroker.cpp
+++ b/loolwsd/DocumentBroker.cpp
@@ -582,6 +582,7 @@ void DocumentBroker::alertAllUsers(const std::string& msg)
 {
     Util::assertIsLocked(_mutex);
 
+    LOG_DBG("Alerting all users: " << msg);
     for (auto& it : _sessions)
     {
         try
diff --git a/loolwsd/LOOLWSD.cpp b/loolwsd/LOOLWSD.cpp
index 0a345919b..2cdf5d471 100644
--- a/loolwsd/LOOLWSD.cpp
+++ b/loolwsd/LOOLWSD.cpp
@@ -1971,7 +1971,7 @@ int LOOLWSD::main(const std::vector<std::string>& /*args*/)
     while (!TerminationFlag && !ShutdownFlag)
     {
         UnitWSD::get().invokeTest();
-        if (TerminationFlag)
+        if (TerminationFlag || SigUtil::handleShutdownRequest())
         {
             break;
         }
@@ -2078,7 +2078,6 @@ int LOOLWSD::main(const std::vector<std::string>& /*args*/)
     // and wait until sockets close.
     LOG_INF("Stopping server socket listening. ShutdownFlag: " <<
             ShutdownFlag << ", TerminationFlag: " << TerminationFlag);
-    Util::alertAllUsers("close: shutdown");
 
     srv.stop();
     srv2.stop();
diff --git a/loolwsd/common/SigUtil.cpp b/loolwsd/common/SigUtil.cpp
index 8d884bffb..db29de598 100644
--- a/loolwsd/common/SigUtil.cpp
+++ b/loolwsd/common/SigUtil.cpp
@@ -54,6 +54,8 @@ std::atomic<bool> TerminationFlag(false);
 std::atomic<bool> ShutdownFlag(false);
 std::mutex SigHandlerTrap;
 
+static std::atomic<bool> ShutdownRequestFlag(false);
+
 namespace SigUtil
 {
     const char *signalName(const int signo)
@@ -125,7 +127,7 @@ namespace SigUtil
             Log::signalLog(" Shutdown signal received: ");
             Log::signalLog(signalName(signal));
             Log::signalLog("\n");
-            ShutdownFlag = true;
+            SigUtil::requestShutdown();
         }
         else
         {
@@ -242,6 +244,24 @@ namespace SigUtil
         strncpy(FatalGdbString, streamStr.c_str(), sizeof(FatalGdbString));
     }
 
+    void requestShutdown()
+    {
+        ShutdownRequestFlag = true;
+    }
+
+    bool handleShutdownRequest()
+    {
+        if (ShutdownRequestFlag)
+        {
+            LOG_INF("Shutdown requested. Initiating WSD shutdown.");
+            Util::alertAllUsers("close: shutdown");
+            ShutdownFlag = true;
+            return true;
+        }
+
+        return false;
+    }
+
     bool killChild(const int pid)
     {
         LOG_DBG("Killing PID: " << pid);
diff --git a/loolwsd/common/SigUtil.hpp b/loolwsd/common/SigUtil.hpp
index e1221b34d..1d1b0f11d 100644
--- a/loolwsd/common/SigUtil.hpp
+++ b/loolwsd/common/SigUtil.hpp
@@ -37,6 +37,21 @@ namespace SigUtil
     /// Trap all fatal signals to assist debugging.
     void setFatalSignals();
 
+    /// Requests the server to initiate graceful shutdown.
+    /// Shutting down is a multi-stage process, because
+    /// it can be requested via signals.
+    /// Since we need to notify clients, we can't
+    /// invoke the sockets while in a signal handler.
+    /// This flags the server to notify clients first
+    /// then flags for shutdown.
+    void requestShutdown();
+
+    /// Checks for shutdown request and,
+    /// after notifying clients, flags for
+    /// shutting down.
+    /// Returns true if shutdown is requested.
+    bool handleShutdownRequest();
+
     /// Kills a child process and returns true when
     /// child pid is removed from the process table
     /// after a certain (short) timeout.