From: Sage Weil <sage@redhat.com>
Date: Sat, 28 Oct 2017 20:37:03 +0000 (-0500)
Subject: include/interval_set: tolerate maps that invalidate iterator on change
X-Git-Tag: v12.2.5~17^2~9
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=4b5103d4282db537c75b58a797a1b66db6563d1d;p=ceph.git

include/interval_set: tolerate maps that invalidate iterator on change

These changes picked out of the diff between the original
btree_interval_set.h and interval_set.h (sadly I had it rolled into the
initial commit so it was tedious to identify these).

Signed-off-by: Sage Weil <sage@redhat.com>
(cherry picked from commit 87aed2026a8f689540a92eeeea6b4054b6c69acd)
---

diff --git a/src/include/interval_set.h b/src/include/interval_set.h
index 9092b3b3ceb1..fd48c2a2be7c 100644
--- a/src/include/interval_set.h
+++ b/src/include/interval_set.h
@@ -22,6 +22,14 @@
 
 #include "encoding.h"
 
+/*
+ * *** NOTE ***
+ *
+ * This class is written to work with a variety of map-like containers,
+ * *include* ones that invalidate iterators when they are modified (e.g.,
+ * flat_map and btree_map).
+ */
+
 #ifndef MIN
 # define MIN(a,b)  ((a)<=(b) ? (a):(b))
 #endif
@@ -461,30 +469,34 @@ class interval_set {
         
         typename Map::iterator n = p;
         n++;
+	if (pstart)
+	  *pstart = p->first;
         if (n != m.end() && 
             start+len == n->first) {   // combine with next, too!
           p->second += n->second;
+	  if (plen)
+	    *plen = p->second;
           m.erase(n);
-        }
-	if (pstart)
-	  *pstart = p->first;
-	if (plen)
-	  *plen = p->second;
+        } else {
+	  if (plen)
+	    *plen = p->second;
+	}
       } else {
         if (start+len == p->first) {
-          m[start] = len + p->second;  // append to front 
 	  if (pstart)
 	    *pstart = start;
 	  if (plen)
 	    *plen = len + p->second;
+	  T psecond = p->second;
           m.erase(p);
+          m[start] = len + psecond;  // append to front
         } else {
           assert(p->first > start+len);
-          m[start] = len;              // new interval
 	  if (pstart)
 	    *pstart = start;
 	  if (plen)
 	    *plen = len;
+          m[start] = len;              // new interval
         }
       }
     }