X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=kern%2Fmsg.h;h=f46b16795f79bad384e5eba2a445a1b5693b005e;hb=5f3952176a4e9a00ca8dd5ec4a6b994958f89e0a;hp=d9b06707cc37d62be7427eaf2824650cc43c4664;hpb=277b540c0764dd376dcf583acdc97a2b2fd3d8e6;p=bertos.git diff --git a/kern/msg.h b/kern/msg.h old mode 100755 new mode 100644 index d9b06707..f46b1679 --- a/kern/msg.h +++ b/kern/msg.h @@ -1,9 +1,9 @@ -/*! +/** * \file * * * \brief Simple inter-process messaging system @@ -18,6 +18,24 @@ /*#* *#* $Log$ + *#* Revision 1.9 2006/07/19 12:56:27 bernie + *#* Convert to new Doxygen style. + *#* + *#* Revision 1.8 2005/11/04 16:20:02 bernie + *#* Fix reference to README.devlib in header. + *#* + *#* Revision 1.7 2005/02/09 21:48:30 bernie + *#* Doxygen fixes. + *#* + *#* Revision 1.6 2005/01/22 04:20:26 bernie + *#* Write extensive documentation; Add simple locking. + *#* + *#* Revision 1.5 2004/11/28 23:20:25 bernie + *#* Remove obsolete INITLIST macro. + *#* + *#* Revision 1.4 2004/10/19 08:22:09 bernie + *#* msg_peek(): New function. + *#* *#* Revision 1.3 2004/08/25 14:12:09 rasky *#* Aggiornato il comment block dei log RCS *#* @@ -35,43 +53,235 @@ #include +/** + * Handle queues of messages associated an action. + * + * A message port is an abstraction used to exchange information + * asynchronously between processes or other entities such as + * interrupts and call-back functions. + * + * This form of IPC is higher-level than bare signals and + * semaphores, because it sets a policy for exchanging + * structured data with well-defined synchronization and + * ownership semantics. + * + * Before using it, a message port must be initialized by + * calling msg_initPort(), which associates the port with + * an Event object, which can be setup to signal a process + * or invoke a call-back hook. + * + * A process or interrupt routine can deliver messages to any + * message port by calling msg_put(). By sending a message, + * the sender temporarly or permanently transfers ownership + * of its associated data to the receiver. + * + * Queuing a message to a port automatically triggers the + * associated Event to notify the receiver. When the + * receiver wakes up, it usually invokes msg_get() to pick + * the next message from the port. + * + * Message ports can hold any number of pending messages, + * and receivers usually process them in FIFO order. + * Other scheduling policies are possible, but not implemented + * in this API. + * + * After the receiver has done processing a message, it replies + * it back to the sender with msg_reply(), which transfer + * ownership back to the original sender. Replies are delivered + * to a reply port, which is nothing more than another MsgPort + * structure designated by the sender. + * + * Returning messages to senders is not mandatory, but it provides + * a convenient way to provide some kind of result and simplify + * the resource allocation scheme at the same time. + * + * When using signals to receive messages in a process, you + * call sig_wait() in an event-loop to wake up when messages + * are delivered to any of your ports. When your process + * wakes up with the port signal active, multiple messages + * may already have queued up at the message port, and the + * process must process them all before returning to sleep. + * Signals don't keep a nesting count. + * + * A simple message loop works like this: + * + * \code + * // Our message port. + * static MsgPort test_port; + * + * // A test message with two parameters and a result. + * typedef struct + * { + * Msg msg; + * + * int x, y; + * int result; + * } TestMsg; + * + * + * // A process that sends two messages and waits for replies. + * static void sender_proc(void) + * { + * MsgPort test_reply_port; + * TestMsg msg1; + * TestMsg msg2; + * Msg *reply; + * + * msg_initPort(&reply_port, + * event_createSignal(proc_current(), SIGF_SINGLE); + * + * // Fill-in first message and send it out. + * msg1.x = 3; + * msg1.y = 2; + * msg1.msg.replyPort = &test_reply_port; + * msg_put(&test_port, &msg1); + * + * // Fill-in second message and send it out too. + * msg2.x = 5; + * msg2.y = 4; + * msg2.msg.replyPort = &test_reply_port; + * msg_put(&test_port, &msg1); + * + * // Wait for a reply... + * sig_wait(SIG_SINGLE); + * + * reply = (TestMsg *)msg_get(&test_reply_port); + * ASSERT(reply != NULL); + * ASSERT(reply->result == 5); + * + * // Get reply to second message. + * while (!(reply = (TestMsg *)msg_get(&test_reply_port)) + * { + * // Not yet, be patient and wait some more. + * sig_wait(SIG_SINGLE); + * } + * + * ASSERT(reply->result == 9); + * } + * + * + * // Receive messages and do something boring with them. + * static void receiver_proc(void) + * { + * msg_initPort(&test_port, + * event_createSignal(proc_current(), SIGF_EXAMPLE); + * + * proc_new(sender_proc, (iptr_t)&test_port, + * sender_stack, sizeof(sender_stack); + * + * for (;;) + * { + * sigmask_t sigs = sig_wait(SIGF_EXAMPLE | more_signals); + * + * if (sigs & SIGF_EXAMPLE) + * { + * TestMsg *emsg; + * while (emsg = (TestMsg *)msg_get(&test_port) + * { + * // Do something with the message + * emsg->result = emsg->x + emsg->y; + * msg_reply((Msg *)msg); + * } + * } + * } + * } + * \endcode + */ typedef struct MsgPort { - List queue; /*!< Messages queued at this port */ - Event evn; /*!< Event to trigger when a message arrives */ + List queue; /**< Messages queued at this port. */ + Event event; /**< Event to trigger when a message arrives. */ } MsgPort; typedef struct Msg { - Node link; /*!< Link into message port queue */ - MsgPort *replyPort; /*!< Port to which the msg is to be replied */ + Node link; /**< Link into message port queue. */ + MsgPort *replyPort; /**< Port to which the msg is to be replied. */ /* User data may follow */ } Msg; -/*! Initialize a message port */ -INLINE void msg_initPort(MsgPort* port, Event event) +/** + * Lock a message port. + * + * This is required before reading or manipulating + * any field of the MsgPort structure. + * + * \note Ports may be locked multiple times and each + * call to msg_lockPort() must be paired with + * a corresponding call to msg_unlockPort(). + * + * \todo Add a configurable policy for locking against + * interrupts and locking with semaphorse. + * + * \see msg_unlockPort() + */ +INLINE void msg_lockPort(MsgPort *port) { - INITLIST(&port->queue); - port->evn = event; + proc_forbid(); } -/*! Queue \a msg into \a port, triggering the associated event */ -INLINE void msg_put(MsgPort* port, Msg* msg) +/** + * Unlock a message port. + * + * \see msg_lockPort() + */ +INLINE void msg_unlockPort(MsgPort *port) { + proc_permit(); +} + + +/** Initialize a message port */ +INLINE void msg_initPort(MsgPort *port, Event event) +{ + LIST_INIT(&port->queue); + port->event = event; +} + +/** Queue \a msg into \a port, triggering the associated event */ +INLINE void msg_put(MsgPort *port, Msg *msg) +{ + msg_portLock(port); ADDTAIL(&port->queue, &msg->link); - event_do(&port->evn); + msg_portUnlock(port); + + event_do(&port->event); +} + +/** + * Get the first message from the queue of \a port. + * + * \return Pointer to the message or NULL if the port was empty. + */ +INLINE Msg *msg_get(MsgPort *port) +{ + Msg *msg; + + msg_portLock(port); + msg = (Msg *)REMHEAD(&port->queue); + msg_portUnlock(port); + + return msg; } -/* Get the first message from the queue of \a port, or NULL if the port is empty */ -INLINE Msg* msg_get(MsgPort* port) +/** Peek the first message in the queue of \a port, or NULL if the port is empty. */ +INLINE Msg *msg_peek(MsgPort *port) { - return (Msg*)REMHEAD(&port->queue); + Msg *msg; + + msg_portLock(port); + msg = (Msg *)port->queue.head; + if (ISLISTEMPTY(&port->queue)) + msg = NULL; + msg_portUnlock(port); + + return msg; } -/*! Send back (reply) \a msg to its sender */ -INLINE void msg_reply(Msg* msg) +/** Send back (reply) \a msg to its sender. */ +INLINE void msg_reply(Msg *msg) { msg_put(msg->replyPort, msg); }