concurrency work

SConstruct

@@ -388,7 +388,7 @@ if has_option( "asio" ):
     coreServerFiles += [ "util/net/message_server_asio.cpp" ]
 
 # mongod files - also files used in tools. present in dbtests, but not in mongos and not in client libs.
-serverOnlyFiles = Split( "util/compress.cpp db/key.cpp db/btreebuilder.cpp util/logfile.cpp util/alignedbuilder.cpp db/mongommf.cpp db/dur.cpp db/durop.cpp db/dur_writetodatafiles.cpp db/dur_preplogbuffer.cpp db/dur_commitjob.cpp db/dur_recover.cpp db/dur_journal.cpp db/introspect.cpp db/btree.cpp db/clientcursor.cpp db/tests.cpp db/repl.cpp db/repl/rs.cpp db/repl/consensus.cpp db/repl/rs_initiate.cpp db/repl/replset_commands.cpp db/repl/manager.cpp db/repl/health.cpp db/repl/heartbeat.cpp db/repl/rs_config.cpp db/repl/rs_rollback.cpp db/repl/rs_sync.cpp db/repl/rs_initialsync.cpp db/oplog.cpp db/repl_block.cpp db/btreecursor.cpp db/cloner.cpp db/namespace.cpp db/cap.cpp db/matcher_covered.cpp db/dbeval.cpp db/restapi.cpp db/dbhelpers.cpp db/instance.cpp db/client.cpp db/database.cpp db/pdfile.cpp db/record.cpp db/cursor.cpp db/security.cpp db/queryoptimizer.cpp db/queryoptimizercursor.cpp db/extsort.cpp db/cmdline.cpp" )
+serverOnlyFiles = Split( "util/compress.cpp db/d_concurrency.cpp db/key.cpp db/btreebuilder.cpp util/logfile.cpp util/alignedbuilder.cpp db/mongommf.cpp db/dur.cpp db/durop.cpp db/dur_writetodatafiles.cpp db/dur_preplogbuffer.cpp db/dur_commitjob.cpp db/dur_recover.cpp db/dur_journal.cpp db/introspect.cpp db/btree.cpp db/clientcursor.cpp db/tests.cpp db/repl.cpp db/repl/rs.cpp db/repl/consensus.cpp db/repl/rs_initiate.cpp db/repl/replset_commands.cpp db/repl/manager.cpp db/repl/health.cpp db/repl/heartbeat.cpp db/repl/rs_config.cpp db/repl/rs_rollback.cpp db/repl/rs_sync.cpp db/repl/rs_initialsync.cpp db/oplog.cpp db/repl_block.cpp db/btreecursor.cpp db/cloner.cpp db/namespace.cpp db/cap.cpp db/matcher_covered.cpp db/dbeval.cpp db/restapi.cpp db/dbhelpers.cpp db/instance.cpp db/client.cpp db/database.cpp db/pdfile.cpp db/record.cpp db/cursor.cpp db/security.cpp db/queryoptimizer.cpp db/queryoptimizercursor.cpp db/extsort.cpp db/cmdline.cpp" )
 
 serverOnlyFiles += [ "db/index.cpp" , "db/scanandorder.cpp" ] + Glob( "db/geo/*.cpp" ) + Glob( "db/ops/*.cpp" )
 

db/client.h

@@ -141,8 +141,6 @@ namespace mongo {
             */
         bool sometimes(unsigned howOften) { return ++_sometimes % howOften == 0; }
 
-    public:
-
         /* set _god=true temporarily, safely */
         class GodScope {
             bool _prev;
@@ -221,9 +219,14 @@ namespace mongo {
 
             string _ns;
             Database * _db;
-
         }; // class Client::Context
 
+        struct LockStatus { 
+            LockStatus() : db(), coll() { }
+            int db;
+            int coll;
+        } lockStatus;
+
     }; // class Client
 
     /** get the Client object for this thread. */

db/d_concurrency.cpp

@@ -0,0 +1,17 @@
+#include "../pch.h"
+#include "database.h"
+#include "d_concurrency.h"
+#include "../util/concurrency/threadlocal.h"
+#include "../util/concurrency/rwlock.h"
+#include "client.h"
+
+using namespace std;
+
+namespace mongo {
+
+    LockCollectionForReading::LockCollectionForReading(const char *ns)
+    {
+//...
+    }
+
+}

db/d_concurrency.h

@@ -0,0 +1,38 @@
+// @file d_concurrency.h
+
+#pragma once
+
+//#include "mongomutex.h"
+
+namespace mongo {
+
+    /* these may be used recursively as long as you do not
+       try to go from sharable to exclusive
+    */
+
+    //void assertDbLocked();
+    //void assertCollectionLocked();
+
+    /*class LockDatabaseExclusively : boost::noncopyable { 
+    public:
+        LockDatabaseExclusively(const char *db);
+    };*/
+
+    /*class LockCollectionUpgradably : boost::noncopyable { 
+    public:
+        LockCollectionUpgradably(const char *ns);
+    };*/
+
+    class LockCollectionForReading : boost::noncopyable { 
+        Database *db;
+    public:
+        LockCollectionForReading(const char *ns);
+        ~LockCollectionForReading();
+    };
+
+    class LockCollectionExclusively : boost::noncopyable { 
+    public:
+        LockCollectionExclusively(const char *ns);
+    };
+
+}

db/database.h

@@ -19,9 +19,12 @@
 #pragma once
 
 #include "cmdline.h"
+#include "namespace.h"
 
 namespace mongo {
 
+    class Extent;
+    class MongoDataFile;
     class ClientCursor;
     struct ByLocKey;
     typedef map<ByLocKey, ClientCursor*> CCByLoc;
@@ -126,6 +129,8 @@ namespace mongo {
         const string profileName; // "alleyinsider.system.profile"
         CCByLoc ccByLoc;
         int magic; // used for making sure the object is still loaded in memory
+
+        RWLockBase dbLock; // d_concurrency.h
     };
 
 } // namespace mongo

db/instance.cpp

@@ -41,6 +41,7 @@
 #include "ops/update.h"
 #include "ops/delete.h"
 #include "ops/query.h"
+#include "d_concurrency.h"
 
 namespace mongo {
 
@@ -473,7 +474,8 @@ namespace mongo {
 
         writelock lk;
 
-        // writelock is used to synchronize stepdowns w/ writes
+        // void ReplSetImpl::relinquish() uses big write lock so 
+        // this is thus synchronized given our lock above.
         uassert( 10054 ,  "not master", isMasterNs( ns ) );
         
         // if this ever moves to outside of lock, need to adjust check Client::Context::_finishInit
@@ -666,7 +668,9 @@ namespace mongo {
         }
 
         writelock lk(ns);
+        //LockCollectionExclusively lk(ns);
 
+        // CONCURRENCY TODO: is being read locked in big log sufficient here?
         // writelock is used to synchronize stepdowns w/ writes
         uassert( 10058 , "not master", isMasterNs(ns) );
 

dbtests/test.vcxproj.filters

@@ -893,6 +893,9 @@
     <ClCompile Include="..\db\commands\cloud.cpp">
       <Filter>db\cpp</Filter>
     </ClCompile>
+    <ClCompile Include="..\db\d_concurrency.cpp">
+      <Filter>db\cpp</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <None Include="..\SConstruct">