From: Austin Clements <amdragon@mit.edu>
Date: Mon, 15 Aug 2011 18:11:22 +0000 (-0400)
Subject: Only commit log to disk if something was written in to it.
X-Git-Url: https://git.devinivas.org/?a=commitdiff_plain;h=843eecfcd0c23f2b9466e5c3289c1819950ccb47;p=cs3210-lab0.git

Only commit log to disk if something was written in to it.

Without this, every write to the console results in log writes.
---

diff --git a/log.c b/log.c
index e9a16c5..6b5c329 100644
--- a/log.c
+++ b/log.c
@@ -143,11 +143,13 @@ begin_trans(void)
 void
 commit_trans(void)
 {
-  write_head();        // This causes all blocks till log.head to be commited
-  install_trans();     // Install all the transactions till head
-  log.lh.n = 0; 
-  write_head();        // Reclaim log
-
+  if (log.lh.n > 0) {
+    write_head();        // This causes all blocks till log.head to be commited
+    install_trans();     // Install all the transactions till head
+    log.lh.n = 0; 
+    write_head();        // Reclaim log
+  }
+  
   acquire(&log.lock);
   log.intrans = 0;
   wakeup(&log);