3 files changed, 45 insertions, 0 deletions
diff --git a/src/mongo/bson/oid.cpp b/src/mongo/bson/oid.cpp
index fb7d6ead891..4f25fef6085 100644
--- a/src/mongo/bson/oid.cpp
+++ b/src/mongo/bson/oid.cpp
@@ -19,6 +19,7 @@
 
 #include <boost/functional/hash.hpp>
 
+#include "mongo/platform/atomic_uint64.h"
 #include "mongo/bson/bsonobjbuilder.h"
 #include "mongo/bson/oid.h"
 #include "mongo/bson/util/atomic_int.h"
@@ -135,6 +136,27 @@ namespace mongo {
         }
     }
 
+    void OID::initSequential() {
+        static AtomicUInt64 sequence;
+
+        {
+            unsigned t = (unsigned) time(0);
+            unsigned char *T = (unsigned char *) &t;
+            _time[0] = T[3]; // big endian order because we use memcmp() to compare OID's
+            _time[1] = T[2];
+            _time[2] = T[1];
+            _time[3] = T[0];
+        }
+        
+        {
+            unsigned long long nextNumber = sequence.fetchAndAdd();
+            unsigned char* numberData = reinterpret_cast<unsigned char*>(&nextNumber);
+            for ( int i=0; i<8; i++ ) {
+                data[4+i] = numberData[7-i];
+            }
+        }
+    }
+
     void OID::init( string s ) {
         verify( s.size() == 24 );
         const char *p = s.c_str();
diff --git a/src/mongo/bson/oid.h b/src/mongo/bson/oid.h
index e803a290481..bd527f084ed 100644
--- a/src/mongo/bson/oid.h
+++ b/src/mongo/bson/oid.h
@@ -66,6 +66,13 @@ namespace mongo {
         /** sets the contents to a new oid / randomized value */
         void init();
 
+        /** sets the contents to a new oid
+         * guaranteed to be sequential
+         * NOT guaranteed to be globally unique
+         *     only unique for this process
+         * */
+        void initSequential();
+
         /** init from a 24 char hex string */
         void init( std::string s );
 
diff --git a/src/mongo/dbtests/jsobjtests.cpp b/src/mongo/dbtests/jsobjtests.cpp
index 8cb06099dca..b156f004621 100644
--- a/src/mongo/dbtests/jsobjtests.cpp
+++ b/src/mongo/dbtests/jsobjtests.cpp
@@ -1271,6 +1271,21 @@ namespace JsobjTests {
                 ASSERT( BSON("" << max).woCompare( BSON("" << oid)  )> 0  );
             }
         };
+
+        class Seq {
+        public:
+            void run() {
+                for ( int i=0; i<10000; i++ ) {
+                    OID a;
+                    OID b;
+                    
+                    a.initSequential();
+                    b.initSequential();
+
+                    ASSERT( a < b );
+                }
+            }
+        };
     } // namespace OIDTests
 
 
@@ -2293,6 +2308,7 @@ namespace JsobjTests {
             add< OIDTests::increasing >();
             add< OIDTests::ToDate >();
             add< OIDTests::FromDate >();
+            add< OIDTests::Seq >();
             add< ValueStreamTests::LabelBasic >();
             add< ValueStreamTests::LabelShares >();
             add< ValueStreamTests::LabelDouble >();