better checkShardVersion

3 files changed, 28 insertions, 5 deletions

diff --git a/s/shard.cpp b/s/shard.cpp
index 9e293c360b1..91f6dc544fb 100644
--- a/s/shard.cpp
+++ b/s/shard.cpp
@@ -150,6 +150,8 @@ namespace mongo {
     
     // -------  ShardManager --------
 
+    unsigned long long ShardManager::NextSequenceNumber = 1;
+
     ShardManager::ShardManager( DBConfig * config , string ns , ShardKeyPattern pattern ) : _config( config ) , _ns( ns ) , _key( pattern ){
         Shard temp(0);
         
@@ -173,9 +175,11 @@ namespace mongo {
             s->_markModified();
             
             _shards.push_back( s );
-
+            
             log() << "no shards for:" << ns << " so creating first: " << s->toString() << endl;
         }
+
+        _sequenceNumber = ++NextSequenceNumber;
     }
     
     ShardManager::~ShardManager(){
@@ -231,6 +235,7 @@ namespace mongo {
             if ( ! s->_modified )
                 continue;
             s->save( true );
+            _sequenceNumber = ++NextSequenceNumber;
         }
 
         massert( "how did version get smalled" , getVersion() >= a );
diff --git a/s/shard.h b/s/shard.h
index 482203188d1..98ca2ee37e8 100644
--- a/s/shard.h
+++ b/s/shard.h
@@ -138,16 +138,26 @@ namespace mongo {
 
         ServerShardVersion getVersion( const string& server ) const;
         ServerShardVersion getVersion() const;
+
+        /**
+         * this is just an increasing number of how many shard managers we have so we know if something has been updated
+         */
+        unsigned long long getSequenceNumber(){
+            return _sequenceNumber;
+        }
+        
     private:
         DBConfig * _config;
         string _ns;
         ShardKeyPattern _key;
         
         vector<Shard*> _shards;
-
+        
         mutex _lock;
-
+        unsigned long long _sequenceNumber;
+        
         friend class Shard;
+        static unsigned long long NextSequenceNumber;
     };
 
 } // namespace mongo
diff --git a/s/strategy.cpp b/s/strategy.cpp
index 68cdf71f8ab..dc644cb86e7 100644
--- a/s/strategy.cpp
+++ b/s/strategy.cpp
@@ -50,6 +50,8 @@ namespace mongo {
         dbcon.done();
     }
 
+    map<DBClientBase*,unsigned long long> checkShardVersionLastSequence;
+
     void checkShardVersion( DBClientBase& conn , const string& ns , bool authoritative ){
         // TODO: cache, optimize, etc...
         
@@ -62,11 +64,17 @@ namespace mongo {
         
         
         ShardManager * manager = conf->getShardManager( ns , authoritative );
-        
-        ServerShardVersion version = manager->getVersion( conn.getServerAddress() );
+
+        unsigned long long & sequenceNumber = checkShardVersionLastSequence[ &conn ];        
+        if ( manager->getSequenceNumber() == sequenceNumber )
+            return;
+
+        ServerShardVersion version = manager->getVersion( conn.getServerAddress() ); 
 
         BSONObj result;
         if ( setShardVersion( conn , ns , version , authoritative , result ) ){
+            // success!
+            sequenceNumber = manager->getSequenceNumber();
             return;
         }