findbypath for MongoFile

dbtests/mmaptests.cpp

@@ -52,6 +52,13 @@ namespace MMapTests {
                     char *w = (char *) f.view_write();
                     strcpy(w + 6, "world");
                 }
+                MongoFileFinder ff;
+                ASSERT( ff.findByPath(fn) );
+                ASSERT( ff.findByPath("asdf") == 0 );
+            }
+            {
+                MongoFileFinder ff;
+                ASSERT( ff.findByPath(fn) == 0 );
             }
 
             int N = 10000;

dbtests/test.vcxproj

@@ -583,6 +583,7 @@
     <ClCompile Include="..\util\concurrency\task.cpp" />
     <ClCompile Include="..\util\concurrency\thread_pool.cpp" />
     <ClCompile Include="..\util\concurrency\vars.cpp" />
+    <ClCompile Include="..\util\file_allocator.cpp" />
     <ClCompile Include="..\util\log.cpp" />
     <ClCompile Include="..\util\logfile.cpp" />
     <ClCompile Include="..\util\mmap_win.cpp" />

dbtests/test.vcxproj.filters

@@ -764,6 +764,9 @@
     <ClCompile Include="..\db\security_key.cpp">
       <Filter>db\cpp</Filter>
     </ClCompile>
+    <ClCompile Include="..\util\file_allocator.cpp">
+      <Filter>util\cpp</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <None Include="..\SConstruct">

util/file_allocator.cpp

@@ -15,7 +15,7 @@
  *    limitations under the License.
  */
 
-#include "../pch.h"
+#include "pch.h"
 #include <fcntl.h>
 #include <errno.h>
 

util/mmap.cpp

@@ -23,6 +23,7 @@
 namespace mongo {
 
     set<MongoFile*> MongoFile::mmfiles;
+    map<string,MongoFile*> MongoFile::pathToFile;
 
     /* Create. Must not exist. 
     @param zero fill file with zeros when true
@@ -77,6 +78,7 @@ namespace mongo {
     void MongoFile::destroyed() {
         rwlock lk( mmmutex , true );
         mmfiles.erase(this);
+        pathToFile.erase( filename() );
     }
 
     /*static*/
@@ -166,6 +168,15 @@ namespace mongo {
         rwlock lk( mmmutex , true );
         mmfiles.insert(this);
     }
+    
+    void MongoFile::setFilename(string fn) { 
+        rwlock( mmmutex, true );
+        assert( _filename.empty() );
+        _filename = fn;
+        MongoFile *&ptf = pathToFile[fn];
+        massert(10000, "MongoFile : multiple opens of same filename", ptf == 0);
+        ptf = this;
+    }
 
 #if defined(_DEBUG) && !defined(_TESTINTENT)
 

util/mmap.h

@@ -44,6 +44,7 @@ namespace mongo {
         template < class F >
         static void forEach( F fun );
 
+        /** note: you need to be in mmmutex when using this. forEach (above) handles that for you automatically. */
         static set<MongoFile*>& getAllFiles()  { return mmfiles; }
 
         // callbacks if you need them
@@ -62,7 +63,11 @@ namespace mongo {
 
         virtual bool isMongoMMF() { return false; }
 
+        string filename() const { return _filename; }
+        void setFilename(string fn);
+
     private:
+        string _filename;
         static int _flushAll( bool sync ); // returns n flushed
     protected:
         virtual void close() = 0;
@@ -83,6 +88,8 @@ namespace mongo {
         virtual void _unlock() {}
 
         static set<MongoFile*> mmfiles;
+    public:
+        static map<string,MongoFile*> pathToFile;
         static RWLock mmmutex;
     };
 
@@ -92,6 +99,28 @@ namespace mongo {
     inline void MongoFile::unmarkAllWritable() {}
 #endif
 
+    /** look up a MMF by filename. scoped mutex locking convention.  
+        example:
+          MMFFinderByName finder;
+          MongoMMF *a = finder.find("file_name_a");
+          MongoMMF *b = finder.find("file_name_b");
+    */
+    class MongoFileFinder : boost::noncopyable {
+    public:
+        MongoFileFinder() : _lk(MongoFile::mmmutex,false) { }
+
+        /** @return The MongoFile object associated with the specified file name.  If no file is open 
+                    with the specified name, returns null.
+        */
+        MongoFile* findByPath(string path) { 
+            map<string,MongoFile*>::iterator i = MongoFile::pathToFile.find(path);
+            return  i == MongoFile::pathToFile.end() ? 0 : i->second;
+        }
+
+    private:
+        rwlock _lk;
+    };
+
     struct MongoFileAllowWrites {
         MongoFileAllowWrites(){
             MongoFile::markAllWritable();
@@ -132,7 +161,6 @@ namespace mongo {
 
         long shortLength() const          { return (long) len; }
         unsigned long long length() const { return len; }
-        string filename() const           { return _filename; }
 
         /** create a new view with the specified properties. 
             automatically cleaned up upon close/destruction of the MemoryMappedFile object. 
@@ -147,7 +175,6 @@ namespace mongo {
         HANDLE maphandle;
         vector<void *> views;
         unsigned long long len;
-        string _filename;
 
 #ifdef _WIN32
         boost::shared_ptr<mutex> _flushMutex;

util/mmap_win.cpp

@@ -23,7 +23,7 @@
 namespace mongo {
 
     MemoryMappedFile::MemoryMappedFile()
-        : _flushMutex(new mutex("flushMutex")), _filename("??")
+        : _flushMutex(new mutex("flushMutex"))
     {
         fd = 0;
         maphandle = 0;
@@ -64,7 +64,7 @@ namespace mongo {
         void *p = MapViewOfFile(maphandle, FILE_MAP_COPY, /*f ofs hi*/0, /*f ofs lo*/ 0, /*dwNumberOfBytesToMap 0 means to eof*/0);
         if ( p == 0 ) {
             DWORD e = GetLastError();
-            log() << "FILE_MAP_COPY MapViewOfFile failed " << _filename << " " << errnoWithDescription(e) << endl;
+            log() << "FILE_MAP_COPY MapViewOfFile failed " << filename() << " " << errnoWithDescription(e) << endl;
         }
         else { 
             views.push_back(p);
@@ -77,7 +77,7 @@ namespace mongo {
         void *p = MapViewOfFile(maphandle, FILE_MAP_READ, /*f ofs hi*/0, /*f ofs lo*/ 0, /*dwNumberOfBytesToMap 0 means to eof*/0);
         if ( p == 0 ) {
             DWORD e = GetLastError();
-            log() << "FILE_MAP_READ MapViewOfFile failed " << _filename << " " << errnoWithDescription(e) << endl;
+            log() << "FILE_MAP_READ MapViewOfFile failed " << filename() << " " << errnoWithDescription(e) << endl;
         }
         else { 
             views.push_back(p);
@@ -86,7 +86,7 @@ namespace mongo {
     }
 
     void* MemoryMappedFile::map(const char *filenameIn, unsigned long long &length, int options) {
-        _filename = filenameIn;
+        setFilename(filenameIn);
         /* big hack here: Babble uses db names with colons.  doesn't seem to work on windows.  temporary perhaps. */
         char filename[256];
         strncpy(filename, filenameIn, 255);
@@ -209,13 +209,13 @@ namespace mongo {
     void MemoryMappedFile::flush(bool sync) {
         uassert(13056, "Async flushing not supported on windows", sync);
         if( !views.empty() ) {
-            WindowsFlushable f( views[0] , fd , _filename , _flushMutex);
+            WindowsFlushable f( views[0] , fd , filename() , _flushMutex);
             f.flush();
         }
     }
 
     MemoryMappedFile::Flushable * MemoryMappedFile::prepareFlush() {
-        return new WindowsFlushable( views.empty() ? 0 : views[0] , fd , _filename , _flushMutex );
+        return new WindowsFlushable( views.empty() ? 0 : views[0] , fd , filename() , _flushMutex );
     }
     void MemoryMappedFile::_lock() {}
     void MemoryMappedFile::_unlock() {}