I have a fundamental doubt wrt boost signaling used in bitcoin. As far as I understand the following happens between main.cpp and init.cpp:

• StartNode() spawns a thread ThreadMessageHandler
• ThreadMessageHandler issues a boost signal SendMessages
• SendMessages() does the sending of messages (like PING or INV)

Is my understanding correct? Why do we invoke a boost signal and complicate ? Why not a simple function call to SendMessages() in main.cpp would not do the equivalent?

Any expert please explain the flow of code here.

Update

Code Snippet1 (Original Bitcoin)

if (lockSend)
     g_signals.SendMessages(pnode);

Code Snippet2 (My Attempt):

if (lockSend)
     SendMessages(pnode);