From 37a08ea222cf9c4fd58ef5488ed90c8cae3bf590 Mon Sep 17 00:00:00 2001
From: erickson <erickson@9efc2488-bf62-4759-914b-345cdb29e865>
Date: Mon, 22 Nov 2010 22:21:35 +0000
Subject: [PATCH] in the rare case the select() is interrupted while waiting on
 child statuses, exit early to prevent read()'s on invalid file handles and
 allow the calling code to loop back around and try again

git-svn-id: svn://svn.open-ils.org/OpenSRF/trunk@2101 9efc2488-bf62-4759-914b-345cdb29e865
---
 src/libopensrf/osrf_prefork.c | 33 ++++++++++++++++++---------------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/src/libopensrf/osrf_prefork.c b/src/libopensrf/osrf_prefork.c
index 92e8288..c5a2f27 100644
--- a/src/libopensrf/osrf_prefork.c
+++ b/src/libopensrf/osrf_prefork.c
@@ -92,7 +92,7 @@ static void prefork_run( prefork_simple* forker );
 static void add_prefork_child( prefork_simple* forker, prefork_child* child );
 
 static void del_prefork_child( prefork_simple* forker, pid_t pid );
-static void check_children( prefork_simple* forker, int forever );
+static int check_children( prefork_simple* forker, int forever );
 static int  prefork_child_process_request( prefork_child*, char* data );
 static int prefork_child_init_hook( prefork_child* );
 static prefork_child* prefork_child_init( prefork_simple* forker,
@@ -718,9 +718,12 @@ static void prefork_run( prefork_simple* forker ) {
 
 		while( ! honored ) {
 
-			if( !no_recheck )
-				check_children( forker, 0 );
-			no_recheck = 0;
+            if( !no_recheck ) {
+                if(check_children( forker, 0 ) < 0) {
+                    continue; // check failed, try again
+                }
+            }
+            no_recheck = 0;
 
 			osrfLogDebug( OSRF_LOG_MARK, "Server received inbound data" );
 
@@ -800,9 +803,10 @@ static void prefork_run( prefork_simple* forker ) {
 
 			if( !honored ) {
 				osrfLogWarning( OSRF_LOG_MARK, "No children available, waiting..." );
-				check_children( forker, 1 );
-				// Tell the loop not to call check_children again, since we're calling it now
-				no_recheck = 1;
+				if( check_children( forker, 1 ) >= 0 ) {
+				    // Tell the loop not to call check_children again, since we just successfully called it
+				    no_recheck = 1;
+                }
 			}
 
 			if( child_dead )
@@ -816,14 +820,11 @@ static void prefork_run( prefork_simple* forker ) {
 }
 
 
-/* XXX Add a flag which tells select() to wait forever on children
-	in the best case, this will be faster than calling usleep(x), and
-	in the worst case it won't be slower and will do less logging...
-*/
 /**
 	@brief See if any children have become available.
 	@param forker Pointer to the prefork_simple that owns the children.
 	@param forever Boolean: true if we should wait indefinitely.
+    @return 0 or greater if successful, -1 on select error/interrupt
 
 	Call select() for all the children in the active list.  Read each active file
 	descriptor and move the corresponding child to the idle list.
@@ -831,7 +832,7 @@ static void prefork_run( prefork_simple* forker ) {
 	If @a forever is true, wait indefinitely for input.  Otherwise return immediately if
 	there are no active file descriptors.
 */
-static void check_children( prefork_simple* forker, int forever ) {
+static int check_children( prefork_simple* forker, int forever ) {
 
 	if( child_dead )
 		reap_children( forker );
@@ -842,7 +843,7 @@ static void check_children( prefork_simple* forker, int forever ) {
 		// If forever is false, then the children may all be idle, and that's okay.
 		if( forever )
 			osrfLogError( OSRF_LOG_MARK, "No active child processes to check" );
-		return;
+		return 0;
 	}
 
 	int select_ret;
@@ -885,8 +886,8 @@ static void check_children( prefork_simple* forker, int forever ) {
 		}
 	}
 
-	if( select_ret == 0 )
-		return;
+    if( select_ret <= 0 ) // we're done here
+        return select_ret;
 
 	// Check each child in the active list.
 	// If it has responded, move it to the idle list.
@@ -930,6 +931,8 @@ static void check_children( prefork_simple* forker, int forever ) {
 		}
 		cur_child = next_child;
 	} while( forker->first_child && forker->first_child != next_child );
+
+    return select_ret;
 }
 
 /**
-- 
2.43.2