From 5d4ccd4e85930aea4d212e2c2276a6879fbd050a Mon Sep 17 00:00:00 2001
From: Donald Sharp <sharpd@cumulusnetworks.com>
Date: Fri, 4 Mar 2016 03:52:12 +0000
Subject: [PATCH] lib: Refactore thread_process_fd

thread_process_fd is looping over the read and write
fd's separately.  There is no need to do this individually.
loop over both the read and write fdset's at the same time.
This will improve select processing performance, especially
for large data sets.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
---
 lib/thread.c | 59 ++++++++++++++++++++++++++++++++--------------------
 1 file changed, 37 insertions(+), 22 deletions(-)

diff --git a/lib/thread.c b/lib/thread.c
index b2c321c6d1..9c009ead1b 100644
--- a/lib/thread.c
+++ b/lib/thread.c
@@ -1070,25 +1070,45 @@ thread_run (struct thread_master *m, struct thread *thread,
 }
 
 static int
-thread_process_fd (struct thread **thread_array, thread_fd_set *fdset,
-		   thread_fd_set *mfdset, int num, int fd_limit)
+thread_process_fds_helper (struct thread_master *m, struct thread *thread, thread_fd_set *fdset)
+{
+  thread_fd_set *mfdset = NULL;
+  struct thread **thread_array;
+
+  if (!thread)
+    return 0;
+
+  if (thread->type == THREAD_READ)
+    {
+      mfdset = &m->readfd;
+      thread_array = m->read;
+    }
+  else
+    {
+      mfdset = &m->writefd;
+      thread_array = m->write;
+    }
+
+  if (fd_is_set (THREAD_FD (thread), fdset))
+    {
+      fd_clear_read_write (THREAD_FD (thread), mfdset);
+      thread_delete_fd (thread_array, thread);
+      thread_list_add (&m->ready, thread);
+      thread->type = THREAD_READY;
+      return 1;
+    }
+  return 0;
+}
+
+static int
+thread_process_fds (struct thread_master *m, thread_fd_set *rset, thread_fd_set *wset, int num)
 {
-  struct thread *thread;
   int ready = 0, index;
 
-  assert (thread_array);
-  
-  for (index = 0; index < fd_limit && ready < num; ++index)
+  for (index = 0; index < m->fd_limit && ready < num; ++index)
     {
-      thread = thread_array[index];
-      if (thread && fd_is_set (THREAD_FD (thread), fdset))
-        {
-          assert (fd_clear_read_write (THREAD_FD (thread), mfdset));
-          thread_delete_fd (thread_array, thread);
-          thread_list_add (&thread->master->ready, thread);
-          thread->type = THREAD_READY;
-          ready++;
-        }
+      ready += thread_process_fds_helper (m, m->read[index], rset);
+      ready += thread_process_fds_helper (m, m->write[index], wset);
     }
   return num - ready;
 }
@@ -1217,7 +1237,7 @@ thread_fetch (struct thread_master *m, struct thread *fetch)
           if (errno == EINTR)
             continue; /* signal received - process it */
           zlog_warn ("select() error: %s", safe_strerror (errno));
-            return NULL;
+          return NULL;
         }
 
 #if defined HAVE_SNMP && defined SNMP_AGENTX
@@ -1242,12 +1262,7 @@ thread_fetch (struct thread_master *m, struct thread *fetch)
       
       /* Got IO, process it */
       if (num > 0)
-        {
-          /* Normal priority read thread. */
-          num = thread_process_fd (m->read, &readfd, &m->readfd, num, m->fd_limit);
-          /* Write thread. */
-          num = thread_process_fd (m->write, &writefd, &m->writefd, num, m->fd_limit);
-        }
+        thread_process_fds (m, &readfd, &writefd, num);
 
 #if 0
       /* If any threads were made ready above (I/O or foreground timer),
-- 
2.39.5