Minor tweak for DrivenEngine

luprex/core/cpp/drivenengine.hpp

@@ -27,11 +27,11 @@
 // functions like "read" or "write" or "connect."  They don't call the operating
 // system at all - not even indirectly, through a wrapper.  Therefore, they
 // can't really do any I/O.  When you use one of these I/O functions to (say)
-// write some data to a communication channel, the only thing that happens
-// is that the data is put into a buffer.  The actual transmission of the
-// data happens elsewhere, in what is called the "Driver."  Likewise, when you
-// use one of these I/O functions to read data, it only returns data that
-// was previously stored by the "Driver."
+// write some data to a communication channel, the only thing that happens is
+// that the data is put into a buffer.  The actual transmission of the data
+// happens elsewhere, in what is called the "Driver."  Likewise, when you use
+// one of these I/O functions to read data, it only returns data that was
+// previously stored by the "Driver."
 //
 // The "Driver" is a module that implements the actual I/O.  It is highly
 // OS-dependent code, because it contains code to manipulate sockets, time
@@ -47,38 +47,64 @@
 // DrivenEngine, it's the other way around: the driver calls into class
 // DrivenEngine to drive it forward.  I/O routines drive computation. 
 //
-// So the upshot of all this is that the DrivenEngine is a deterministic
-// state machine, free of all OS-specific code.
-// 
-//////////////////////////////////////////////////////////////
-//
-//
-//  * List all existing channels using drv_list_channels.
-//
-//  * If there are any new channels in the channel list, use
-//    drv_get_channel_target to fetch the target host, then create a socket and
-//    open the connection.  Associate the socket with the channel.
-//
-//  * Do an OS 'poll'.  The poll should include the sockets for all channels in
-//    the channel list, all listening ports, and stdio.
-//
-//  * If the poll indicates that a listening port has acceptable connections,
-//    accept and call drv_notify_accept.  Associate the accepted socket with the
-//    channel.
-//
-//  * If the poll indicates that a connection can accept outgoing data, use
-//    drv_peek_outgoing to fetch some data to write, and write it.  Use
-//    drv_sent_outgoing_bytes to indicate that the data was sent.
-//
-//  * If the poll indicates that a connection has incoming data, read the data
-//    then push it into the channel using drv_recv_incoming.
-//
-//  * If the poll indicates that STDIO can be read/written, use
-//    drv_peek_outgoing, drv_sent_outgoing, and drv_recv_incoming in the same
-//    manner as you would for a socket.
+// So the upshot of all this is that the DrivenEngine is a deterministic state
+// machine, free of all OS-specific code.
+//
+//////////////////////////////////////////////////////////////
+//
+// Here are the rules for what the driver must do:
+//
+//  * Before doing anything else, the driver must select one of the three
+//    logmodes.
+//
+//  * If 'logmode_replay' is selected, then the driver must proceed to invoke
+//    'drv_step_logfile' over and over until it returns false.  In replay mode,
+//    the driver should not do anything else.
+//
+//  * If 'logmode_write' or 'logmode_none' is selected, the driver must proceed
+//    to drive the application.  Follow the remainder of these steps.
+//
+//  * Read the lua source from disk, and call 'drv_set_lua_source'.
+//
+//  * Invoke the DrivenEngine's init callback by calling
+//    'drv_invoke_engine_init'.
+//
+//  * Open a hardwired list of ports for listening.
+//
+//  * Repeat the following steps over and over:
+//
+//      - List all existing channels using drv_list_channels.
+//
+//      - If there are any new channels in the channel list, use
+//        drv_get_channel_target to fetch the target host, then create a socket
+//        and open the connection.  Associate the socket with the channel.
+//
+//      - If the channel list is missing a previously-known channel, then that
+//        channel was deleted by the engine.  Clean up the channel's data and
+//        close the socket, if any.
+//
+//      - Do an OS 'poll'.  The poll should include the sockets for all channels
+//        in the channel list, all listening ports, and stdio.
+//
+//      - If the poll indicates that a listening port has acceptable
+//        connections, accept and call drv_notify_accept.  Associate the
+//        accepted socket with the channel.
+//
+//      - If the poll indicates that a connection can accept outgoing data, use
+//        drv_peek_outgoing to fetch some data to write, and write it.  Use
+//        drv_sent_outgoing_bytes to indicate that the data was sent.
+//
+//      - If the poll indicates that a connection has incoming data, read the
+//        data then push it into the channel using drv_recv_incoming.
+//
+//      - If the poll indicates that STDIO can be read/written, use
+//        drv_peek_outgoing, drv_sent_outgoing, and drv_recv_incoming in the
+//        same manner as you would for a socket.
+//
+//      - Use 'drv_invoke_engine_update' to invoke the engine's update
+//        callback.
 //
 //////////////////////////////////////////////////////////////
-
 
 #ifndef DRIVENENGINE_HPP
 #define DRIVENENGINE_HPP