First part of efficiency fixes for message sending to pid's (cutting down

the amount of time we hold tdb locks). Gulp down all messages at once rather
than reading/re-writing one at a time. NOTE: All dispatch routines *must*
be able to cope with incoming message on *odd* byte boundaries (all current
handlers do).
Jeremy.
(This used to be commit b752c0340f96669b2b2573cf7d3d10f99580b070)

1 files changed, 95 insertions, 48 deletions

diff --git a/source3/lib/messages.c b/source3/lib/messages.c
index 8200b2f8c3..555a55569e 100644
--- a/source3/lib/messages.c
+++ b/source3/lib/messages.c
@@ -3,6 +3,7 @@
    Samba internal messaging functions
    Copyright (C) Andrew Tridgell 2000
    Copyright (C) 2001 by Martin Pool
+   Copyright (C) 2002 by Jeremy Allison
    
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -35,6 +36,9 @@
    use that to reply by message_send_pid().  See ping_message() for a
    simple example.
 
+   *NOTE*: Dispatch functions must be able to cope with incoming
+   messages on an *odd* byte boundary.
+
    This system doesn't have any inherent size limitations but is not
    very efficient for large messages or when messages are sent in very
    quick succession.
@@ -87,6 +91,16 @@ static void ping_message(int msg_type, pid_t src, void *buf, size_t len)
 }
 
 /****************************************************************************
+ Return current debug level.
+****************************************************************************/
+
+void debuglevel_message(int msg_type, pid_t src, void *buf, size_t len)
+{
+	DEBUG(1,("INFO: Received REQ_DEBUGLEVEL message from PID %u\n",(unsigned int)src));
+	message_send_pid(src, MSG_DEBUGLEVEL, DEBUGLEVEL_CLASS, sizeof(DEBUGLEVEL_CLASS), True);
+}
+
+/****************************************************************************
  Initialise the messaging functions. 
 ****************************************************************************/
 
@@ -106,6 +120,7 @@ BOOL message_init(void)
 	CatchSignal(SIGUSR1, SIGNAL_CAST sig_usr1);
 
 	message_register(MSG_PING, ping_message);
+	message_register(MSG_REQ_DEBUGLEVEL, debuglevel_message);
 
 	return True;
 }
@@ -133,9 +148,13 @@ static TDB_DATA message_key_pid(pid_t pid)
 
 static BOOL message_notify(pid_t pid)
 {
-	/* Doing kill with a non-positive pid causes messages to be
-	 * sent to places we don't want. */
+	/*
+	 * Doing kill with a non-positive pid causes messages to be
+	 * sent to places we don't want.
+	 */
+
 	SMB_ASSERT(pid > 0);
+
 	if (kill(pid, SIGUSR1) == -1) {
 		if (errno == ESRCH) {
 			DEBUG(2,("pid %d doesn't exist - deleting messages record\n", (int)pid));
@@ -160,16 +179,19 @@ BOOL message_send_pid(pid_t pid, int msg_type, const void *buf, size_t len,
 	struct message_rec rec;
 	void *p;
 
+	/*
+	 * Doing kill with a non-positive pid causes messages to be
+	 * sent to places we don't want.
+	 */
+
+	SMB_ASSERT(pid > 0);
+
 	rec.msg_version = MESSAGE_VERSION;
 	rec.msg_type = msg_type;
 	rec.dest = pid;
 	rec.src = sys_getpid();
 	rec.len = len;
 
-	/* Doing kill with a non-positive pid causes messages to be
-	 * sent to places we don't want. */
-	SMB_ASSERT(pid > 0);
-
 	kbuf = message_key_pid(pid);
 
 	/* lock the record for the destination */
@@ -241,111 +263,136 @@ BOOL message_send_pid(pid_t pid, int msg_type, const void *buf, size_t len,
 
  failed:
 	tdb_chainunlock(tdb, kbuf);
+	SAFE_FREE(dbuf.dptr);
 	errno = 0;                    /* paranoia */
 	return False;
 }
 
 /****************************************************************************
- Retrieve the next message for the current process.
+ Retrieve all messages for the current process.
 ****************************************************************************/
 
-static BOOL message_recv(int *msg_type, pid_t *src, void **buf, size_t *len)
+static BOOL retrieve_all_messages(char **msgs_buf, size_t *total_len)
 {
 	TDB_DATA kbuf;
 	TDB_DATA dbuf;
-	struct message_rec rec;
+	TDB_DATA null_dbuf;
+
+	ZERO_STRUCT(null_dbuf);
+
+	*msgs_buf = NULL;
+	*total_len = 0;
 
 	kbuf = message_key_pid(sys_getpid());
 
 	tdb_chainlock(tdb, kbuf);
-	
 	dbuf = tdb_fetch(tdb, kbuf);
-	if (dbuf.dptr == NULL || dbuf.dsize == 0)
-		goto failed;
+	/*
+	 * Replace with an empty record to keep the allocated
+	 * space in the tdb.
+	 */
+	tdb_store(tdb, kbuf, null_dbuf, TDB_REPLACE);
+	tdb_chainunlock(tdb, kbuf);
+
+	if (dbuf.dptr == NULL || dbuf.dsize == 0) {
+		SAFE_FREE(dbuf.dptr);
+		return False;
+	}
+
+	*msgs_buf = dbuf.dptr;
+	*total_len = dbuf.dsize;
+
+	return True;
+}
+
+/****************************************************************************
+ Parse out the next message for the current process.
+****************************************************************************/
+
+static BOOL message_recv(char *msgs_buf, size_t total_len, int *msg_type, pid_t *src, char **buf, size_t *len)
+{
+	struct message_rec rec;
+	char *ret_buf = *buf;
 
-	memcpy(&rec, dbuf.dptr, sizeof(rec));
+	*buf = NULL;
+	*len = 0;
+
+	if (total_len - (ret_buf - msgs_buf) < sizeof(rec))
+		return False;
+
+	memcpy(&rec, ret_buf, sizeof(rec));
+	ret_buf += sizeof(rec);
 
 	if (rec.msg_version != MESSAGE_VERSION) {
 		DEBUG(0,("message version %d received (expected %d)\n", rec.msg_version, MESSAGE_VERSION));
-		goto failed;
+		return False;
 	}
 
 	if (rec.len > 0) {
-		(*buf) = (void *)malloc(rec.len);
-		if (!(*buf))
-			goto failed;
-
-		memcpy(*buf, dbuf.dptr+sizeof(rec), rec.len);
-	} else {
-		*buf = NULL;
+		if (total_len - (ret_buf - msgs_buf) < rec.len)
+			return False;
 	}
 
 	*len = rec.len;
 	*msg_type = rec.msg_type;
 	*src = rec.src;
+	*buf = ret_buf;
 
-	if (dbuf.dsize - (sizeof(rec)+rec.len) > 0)
-		memmove(dbuf.dptr, dbuf.dptr+sizeof(rec)+rec.len, dbuf.dsize - (sizeof(rec)+rec.len));
-	dbuf.dsize -= sizeof(rec)+rec.len;
-
-	if (dbuf.dsize == 0)
-		tdb_delete(tdb, kbuf);
-	else
-		tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
-
-	SAFE_FREE(dbuf.dptr);
-	tdb_chainunlock(tdb, kbuf);
 	return True;
-
- failed:
-	tdb_chainunlock(tdb, kbuf);
-	SAFE_FREE(dbuf.dptr);
-	return False;
 }
 
 /****************************************************************************
  Receive and dispatch any messages pending for this process.
  Notice that all dispatch handlers for a particular msg_type get called,
  so you can register multiple handlers for a message.
+ *NOTE*: Dispatch functions must be able to cope with incoming
+ messages on an *odd* byte boundary.
 ****************************************************************************/
 
 void message_dispatch(void)
 {
 	int msg_type;
 	pid_t src;
-	void *buf;
-	size_t len;
+	char *buf;
+	char *msgs_buf;
+	size_t len, total_len;
 	struct dispatch_fns *dfn;
 	int n_handled;
 
-	if (!received_signal) return;
+	if (!received_signal)
+		return;
 
 	DEBUG(10,("message_dispatch: received_signal = %d\n", received_signal));
 
 	received_signal = 0;
 
-	while (message_recv(&msg_type, &src, &buf, &len)) {
-		DEBUG(10,("message_dispatch: received msg_type=%d src_pid=%d\n",
-			  msg_type, (int) src));
+	if (!retrieve_all_messages(&msgs_buf, &total_len))
+		return;
+
+	for (buf = msgs_buf; message_recv(msgs_buf, total_len, &msg_type, &src, &buf, &len); buf += len) {
+		DEBUG(10,("message_dispatch: received msg_type=%d src_pid=%u\n",
+			  msg_type, (unsigned int) src));
 		n_handled = 0;
 		for (dfn = dispatch_fns; dfn; dfn = dfn->next) {
 			if (dfn->msg_type == msg_type) {
 				DEBUG(10,("message_dispatch: processing message of type %d.\n", msg_type));
-				dfn->fn(msg_type, src, buf, len);
+				dfn->fn(msg_type, src, len ? (void *)buf : NULL, len);
 				n_handled++;
 			}
 		}
 		if (!n_handled) {
-			DEBUG(5,("message_dispatch: warning: no handlers registered for "
-				 "msg_type %d in pid %d\n",
-				 msg_type, sys_getpid()));
+			DEBUG(5,("message_dispatch: warning: no handlers registed for "
+				 "msg_type %d in pid %u\n",
+				 msg_type, (unsigned int)sys_getpid()));
 		}
-		SAFE_FREE(buf);
 	}
+	SAFE_FREE(msgs_buf);
 }
 
 /****************************************************************************
  Register a dispatch function for a particular message type.
+ *NOTE*: Dispatch functions must be able to cope with incoming
+ messages on an *odd* byte boundary.
 ****************************************************************************/
 
 void message_register(int msg_type,