From 1b194a97c571b0c901ed0ca9d8935d0565000f59 Mon Sep 17 00:00:00 2001
From: Eliot Horowitz <eliot@10gen.com>
Date: Mon, 2 Aug 2010 11:02:16 -0400
Subject: [PATCH] fix cursor generation in mongos and clean up killCursor
 logging

---
 db/instance.cpp |  2 +-
 s/cursors.cpp   | 68 ++++++++++++++++++++++++++++++++++++++++---------
 s/cursors.h     |  8 ++++--
 3 files changed, 63 insertions(+), 15 deletions(-)

diff --git a/db/instance.cpp b/db/instance.cpp
index ab18d21f4af..ec3b793291c 100644
--- a/db/instance.cpp
+++ b/db/instance.cpp
@@ -380,7 +380,7 @@ namespace mongo {
         int n = *x++;
         uassert( 13004 , "sent 0 cursors to kill" , n >= 1 );
         if ( n > 2000 ) {
-            problem() << "Assertion failure, receivedKillCursors, n=" << n << endl;
+            log( n < 30000 ? LL_WARNING : LL_ERROR ) << "receivedKillCursors, n=" << n << endl;
             assert( n < 30000 );
         }
         killCursors(n, (long long *) x);
diff --git a/s/cursors.cpp b/s/cursors.cpp
index dd7da1c2544..eca6b78c8a6 100644
--- a/s/cursors.cpp
+++ b/s/cursors.cpp
@@ -36,11 +36,7 @@ namespace mongo {
         _totalSent = 0;
         _done = false;
 
-        do {
-            // TODO: only create _id when needed
-            _id = security.getNonce();
-        } while ( _id == 0 );
-
+        _id = 0;
     }
 
     ShardedClientCursor::~ShardedClientCursor(){
@@ -49,6 +45,14 @@ namespace mongo {
         _cursor = 0;
     }
 
+    long long ShardedClientCursor::getId(){
+        if ( _id <= 0 ){
+            _id = cursorCache.genId();
+            assert( _id >= 0 );
+        }
+        return _id;
+    }
+
     bool ShardedClientCursor::sendNextBatch( Request& r , int ntoreturn ){
         uassert( 10191 ,  "cursor already done" , ! _done );
                 
@@ -81,12 +85,17 @@ namespace mongo {
                 sendMore = false;
                 break;
             }
+
+            if ( ntoreturn == 0 && _totalSent == 0 && num > 100 ){
+                // first batch should be max 100 unless batch size specified
+                break;
+            }
         }
 
         bool hasMore = sendMore && _cursor->more();
-        log(6) << "\t hasMore:" << hasMore << " wouldSendMoreIfHad: " << sendMore << " id:" << _id << " totalSent: " << _totalSent << endl;
+        log(6) << "\t hasMore:" << hasMore << " wouldSendMoreIfHad: " << sendMore << " id:" << getId() << " totalSent: " << _totalSent << endl;
         
-        replyToQuery( 0 , r.p() , r.m() , b.buf() , b.len() , num , _totalSent , hasMore ? _id : 0 );
+        replyToQuery( 0 , r.p() , r.m() , b.buf() , b.len() , num , _totalSent , hasMore ? getId() : 0 );
         _totalSent += num;
         _done = ! hasMore;
         
@@ -95,7 +104,7 @@ namespace mongo {
     
 
     CursorCache::CursorCache()
-        :_mutex( "CursorCache" ){
+        :_mutex( "CursorCache" ), _shardedTotal(0){
     }
 
     CursorCache::~CursorCache(){
@@ -120,31 +129,65 @@ namespace mongo {
     }
     
     void CursorCache::store( ShardedClientCursorPtr cursor ){
+        assert( cursor->getId() );
         scoped_lock lk( _mutex );
         _cursors[cursor->getId()] = cursor;
+        _shardedTotal++;
     }
     void CursorCache::remove( long long id ){
+        assert( id );
         scoped_lock lk( _mutex );
         _cursors.erase( id );
     }
 
     void CursorCache::storeRef( const string& server , long long id ){
+        assert( id );
         scoped_lock lk( _mutex );
         _refs[id] = server;
     }
     
+    long long CursorCache::genId(){
+        while ( true ){
+            long long x = security.getNonce();
+            if ( x == 0 )
+                continue;
+            if ( x < 0 )
+                x *= -1;
+            
+            scoped_lock lk( _mutex );
+            MapSharded::iterator i = _cursors.find( x );
+            if ( i != _cursors.end() )
+                continue;
+            
+            MapNormal::iterator j = _refs.find( x );
+            if ( j != _refs.end() )
+                continue;
+            
+            return x;
+        }
+    }
+
     void CursorCache::gotKillCursors(Message& m ){
         int *x = (int *) m.singleData()->_data;
         x++; // reserved
         int n = *x++;
-        
+
+        if ( n > 2000 ){
+            log( n < 30000 ? LL_WARNING : LL_ERROR ) << "receivedKillCursors, n=" << n << endl;
+        }
+
+
         uassert( 13286 , "sent 0 cursors to kill" , n >= 1 );
-        uassert( 13287 , "too many cursors to kill" , n < 10000 );
+        uassert( 13287 , "too many cursors to kill" , n < 30000 );
         
         long long * cursors = (long long *)x;
         for ( int i=0; i<n; i++ ){
             long long id = cursors[i];
-
+            if ( ! id ){
+                log( LL_WARNING ) << " got cursor id of 0 to kill" << endl;
+                continue;
+            }
+            
             string server;            
             {
                 scoped_lock lk( _mutex );
@@ -157,7 +200,7 @@ namespace mongo {
                 
                 MapNormal::iterator j = _refs.find( id );
                 if ( j == _refs.end() ){
-                    log() << "can't find cursor: " << id << endl;
+                    log( LL_WARNING ) << "can't find cursor: " << id << endl;
                     continue;
                 }
                 server = j->second;
@@ -174,6 +217,7 @@ namespace mongo {
     void CursorCache::appendInfo( BSONObjBuilder& result ){
         scoped_lock lk( _mutex );
         result.append( "sharded" , (int)_cursors.size() );
+        result.appendNumber( "shardedEver" , _shardedTotal );
         result.append( "refs" , (int)_refs.size() );
         result.append( "totalOpen" , (int)(_cursors.size() + _refs.size() ) );
     }
diff --git a/s/cursors.h b/s/cursors.h
index 80c32f8708e..7eb8591d947 100644
--- a/s/cursors.h
+++ b/s/cursors.h
@@ -29,12 +29,12 @@
 
 namespace mongo {
 
-    class ShardedClientCursor {
+    class ShardedClientCursor : boost::noncopyable {
     public:
         ShardedClientCursor( QueryMessage& q , ClusteredCursor * cursor );
         virtual ~ShardedClientCursor();
 
-        long long getId(){ return _id; }
+        long long getId();
         
         /**
          * @return whether there is more data left
@@ -76,10 +76,14 @@ namespace mongo {
         
         void appendInfo( BSONObjBuilder& result );
 
+        long long genId();
     private:
         mutex _mutex;
+
         MapSharded _cursors;
         MapNormal _refs;
+        
+        long long _shardedTotal;
     };
     
     extern CursorCache cursorCache;