Added a timeout value to the ChildProcessSlave and ChildProcessMaster classes.

modules/juce_events/interprocess/juce_ConnectedChildProcess.cpp

@@ -27,7 +27,7 @@ enum { magicMastSlaveConnectionHeader = 0x712baf04 };
 static const char* startMessage = "__ipc_st";
 static const char* killMessage  = "__ipc_k_";
 static const char* pingMessage  = "__ipc_p_";
-enum { specialMessageSize = 8 };
+enum { specialMessageSize = 8, defaultTimeoutMs = 8000 };
 
 static String getCommandLinePrefix (const String& commandLineUniqueID)
 {
@@ -40,7 +40,7 @@ static String getCommandLinePrefix (const String& commandLineUniqueID)
 struct ChildProcessPingThread  : public Thread,
                                  private AsyncUpdater
 {
-    ChildProcessPingThread()  : Thread ("IPC ping"), timeoutMs (8000)
+    ChildProcessPingThread (int timeout)  : Thread ("IPC ping"), timeoutMs (timeout)
     {
         pingReceived();
     }
@@ -84,8 +84,10 @@ private:
 struct ChildProcessMaster::Connection  : public InterprocessConnection,
                                          private ChildProcessPingThread
 {
-    Connection (ChildProcessMaster& m, const String& pipeName)
-        : InterprocessConnection (false, magicMastSlaveConnectionHeader), owner (m)
+    Connection (ChildProcessMaster& m, const String& pipeName, int timeout)
+        : InterprocessConnection (false, magicMastSlaveConnectionHeader),
+          ChildProcessPingThread (timeout),
+          owner (m)
     {
         if (createPipe (pipeName, timeoutMs))
             startThread (4);
@@ -140,7 +142,7 @@ bool ChildProcessMaster::sendMessageToSlave (const MemoryBlock& mb)
     return false;
 }
 
-bool ChildProcessMaster::launchSlaveProcess (const File& executable, const String& commandLineUniqueID)
+bool ChildProcessMaster::launchSlaveProcess (const File& executable, const String& commandLineUniqueID, int timeoutMs)
 {
     connection = nullptr;
     jassert (childProcess.kill());
@@ -153,7 +155,7 @@ bool ChildProcessMaster::launchSlaveProcess (const File& executable, const Strin
 
     if (childProcess.start (args))
     {
-        connection = new Connection (*this, pipeName);
+        connection = new Connection (*this, pipeName, timeoutMs <= 0 ? defaultTimeoutMs : timeoutMs);
 
         if (connection->isConnected())
         {
@@ -171,8 +173,10 @@ bool ChildProcessMaster::launchSlaveProcess (const File& executable, const Strin
 struct ChildProcessSlave::Connection  : public InterprocessConnection,
                                         private ChildProcessPingThread
 {
-    Connection (ChildProcessSlave& p, const String& pipeName)
-        : InterprocessConnection (false, magicMastSlaveConnectionHeader), owner (p)
+    Connection (ChildProcessSlave& p, const String& pipeName, int timeout)
+        : InterprocessConnection (false, magicMastSlaveConnectionHeader),
+          ChildProcessPingThread (timeout),
+          owner (p)
     {
         connectToPipe (pipeName, timeoutMs);
         startThread (4);
@@ -237,7 +241,8 @@ bool ChildProcessSlave::sendMessageToMaster (const MemoryBlock& mb)
 }
 
 bool ChildProcessSlave::initialiseFromCommandLine (const String& commandLine,
-                                                   const String& commandLineUniqueID)
+                                                   const String& commandLineUniqueID,
+                                                   int timeoutMs)
 {
     String prefix (getCommandLinePrefix (commandLineUniqueID));
 
@@ -248,7 +253,7 @@ bool ChildProcessSlave::initialiseFromCommandLine (const String& commandLine,
 
         if (pipeName.isNotEmpty())
         {
-            connection = new Connection (*this, pipeName);
+            connection = new Connection (*this, pipeName, timeoutMs <= 0 ? defaultTimeoutMs : timeoutMs);
 
             if (! connection->isConnected())
                 connection = nullptr;

modules/juce_events/interprocess/juce_ConnectedChildProcess.h

@@ -64,10 +64,16 @@ public:
         The commandLineUniqueID should be a short alphanumeric identifier (no spaces!)
         that matches the string passed to ChildProcessMaster::launchSlaveProcess().
 
+        The timeoutMs parameter lets you specify how long the child process is allowed
+        to run without receiving a ping from the master before the master is considered to
+        have died, and handleConnectionLost() will be called. Passing <= 0 for this timeout
+        makes it use a default value.
+
         Returns true if the command-line matches and the connection is made successfully.
     */
     bool initialiseFromCommandLine (const String& commandLine,
-                                    const String& commandLineUniqueID);
+                                    const String& commandLineUniqueID,
+                                    int timeoutMs);
 
     //==============================================================================
     /** This will be called to deliver messages from the master process.
@@ -141,11 +147,17 @@ public:
         that gets launched must respond by calling ChildProcessSlave::initialiseFromCommandLine()
         in its startup code, and must use a matching ID to commandLineUniqueID.
 
+        The timeoutMs parameter lets you specify how long the child process is allowed
+        to go without sending a ping before it is considered to have died and
+        handleConnectionLost() will be called. Passing <= 0 for this timeout makes
+        it use a default value.
+
         If this all works, the method returns true, and you can begin sending and
         receiving messages with the slave process.
     */
     bool launchSlaveProcess (const File& executableToLaunch,
-                             const String& commandLineUniqueID);
+                             const String& commandLineUniqueID,
+                             int timeoutMs = 0);
 
     /** This will be called to deliver a message from the slave process.
         The call will probably be made on a background thread, so be careful with your thread-safety!