osd: replace vectors_equal() with operator==(vector<>, vector<>)

src/include/mempool.h

@@ -431,7 +431,40 @@ DEFINE_MEMORY_POOLS_HELPER(P)
 
 };
 
-
+// the elements allocated by mempool is in the same memory space as the ones
+// allocated by the default allocator. so compare them in an efficient way:
+// libstdc++'s std::equal is specialized to use memcmp if T is integer or
+// pointer. this is good enough for our usecase. use
+// std::is_trivially_copyable<T> to expand the support to more types if
+// nececssary.
+template<typename T, mempool::pool_index_t pool_index>
+bool operator==(const std::vector<T, std::allocator<T>>& lhs,
+		const std::vector<T, mempool::pool_allocator<pool_index, T>>& rhs)
+{
+  return (lhs.size() == rhs.size() &&
+	  std::equal(lhs.begin(), lhs.end(), rhs.begin()));
+}
+
+template<typename T, mempool::pool_index_t pool_index>
+bool operator!=(const std::vector<T, std::allocator<T>>& lhs,
+		const std::vector<T, mempool::pool_allocator<pool_index, T>>& rhs)
+{
+  return !(lhs == rhs);
+}
+
+template<typename T, mempool::pool_index_t pool_index>
+bool operator==(const std::vector<T, mempool::pool_allocator<pool_index, T>>& lhs,
+		const std::vector<T, std::allocator<T>>& rhs)
+{
+  return rhs == lhs;
+}
+
+template<typename T, mempool::pool_index_t pool_index>
+bool operator!=(const std::vector<T, mempool::pool_allocator<pool_index, T>>& lhs,
+		const std::vector<T, std::allocator<T>>& rhs)
+{
+  return !(lhs == rhs);
+}
 
 // Use this for any type that is contained by a container (unless it
 // is a class you defined; see below).

src/mon/OSDMonitor.cc

@@ -2690,7 +2690,7 @@ bool OSDMonitor::preprocess_pgtemp(MonOpRequestRef op)
     //        an existing pg_primary field to imply a change
     if (p->second.size() &&
 	(osdmap.pg_temp->count(p->first) == 0 ||
-	 !vectors_equal(osdmap.pg_temp->get(p->first), p->second) ||
+	 osdmap.pg_temp->get(p->first) != p->second ||
 	 osdmap.primary_temp->count(p->first)))
       return false;
   }

src/osd/OSDMap.cc

@@ -1527,7 +1527,7 @@ void OSDMap::clean_temps(CephContext *cct,
     vector<int> raw_up;
     int primary;
     tmpmap.pg_to_raw_up(pg.first, &raw_up, &primary);
-    if (vectors_equal(raw_up, pg.second)) {
+    if (raw_up == pg.second) {
       ldout(cct, 10) << __func__ << "  removing pg_temp " << pg.first << " "
 		     << pg.second << " that matches raw_up mapping" << dendl;
       if (osdmap.pg_temp->count(pg.first))
@@ -3712,7 +3712,7 @@ int OSDMap::clean_pg_upmaps(
     vector<int> raw;
     int primary;
     pg_to_raw_osds(p.first, &raw, &primary);
-    if (vectors_equal(raw, p.second)) {
+    if (raw == p.second) {
       ldout(cct, 10) << " removing redundant pg_upmap " << p.first << " "
 		     << p.second << dendl;
       pending_inc->old_pg_upmap.insert(p.first);

src/osd/OSDMap.h

@@ -43,18 +43,6 @@ class CephContext;
 class CrushWrapper;
 class health_check_map_t;
 
-// FIXME C++11 does not have std::equal for two differently-typed containers.
-// use this until we move to c++14
-template<typename A, typename B>
-bool vectors_equal(A a, B b)
-{
-  return
-    a.size() == b.size() &&
-    (a.empty() ||
-     memcmp((char*)&a[0], (char*)&b[0], sizeof(a[0]) * a.size()) == 0);
-}
-
-
 /*
  * we track up to two intervals during which the osd was alive and
  * healthy.  the most recent is [up_from,up_thru), where up_thru is