SERVER-2612 -- support logRotate under windows

Add code to support the "logRotate" server command (e.g. "db.runCommand({logRotate:1})").
Windows does not support the "kill -SIGUSR1 <pid>" alternative that is available in
Linux.

1 files changed, 41 insertions, 25 deletions

diff --git a/util/log.cpp b/util/log.cpp
index 51f59be239b..0dc75eddf6e 100644
--- a/util/log.cpp
+++ b/util/log.cpp
@@ -25,12 +25,16 @@ using namespace std;
 
 #ifdef _WIN32
 # include <io.h>
+# include <fcntl.h>
 #else
 # include <cxxabi.h>
 # include <sys/file.h>
 #endif
 
-//#include "../db/jsobj.h"
+#ifdef _WIN32
+# define dup2   _dup2       // Microsoft headers use ISO C names
+# define fileno _fileno
+#endif
 
 namespace mongo {
 
@@ -85,60 +89,72 @@ namespace mongo {
             }
 
             if ( _file ) {
-#ifdef _WIN32
-                cout << "log rotation net yet supported on windows" << endl;
-                return;
-#else
 
 #ifdef POSIX_FADV_DONTNEED
                 posix_fadvise(fileno(_file), 0, 0, POSIX_FADV_DONTNEED);
 #endif
 
-                struct tm t;
-                localtime_r( &_opened , &t );
-
+                // Rename the (open) existing log file to a timestamped name
                 stringstream ss;
-                ss << _path << "." << terseCurrentTime(false);
+                ss << _path << "." << terseCurrentTime( false );
                 string s = ss.str();
                 rename( _path.c_str() , s.c_str() );
-#endif
             }
 
-
-            FILE* tmp = freopen(_path.c_str(), (_append ? "a" : "w"), stdout);
-            if (!tmp) {
+            FILE* tmp = 0;  // The new file using the original logpath name
+
+#if _WIN32
+            // We rename an open log file (above, on next rotation) and the trick to getting Windows to do that is
+            // to open the file with FILE_SHARE_DELETE.  So, we can't use the freopen() call that non-Windows
+            // versions use because it would open the file without the FILE_SHARE_DELETE flag we need.
+            //
+            HANDLE newFileHandle = CreateFileA(
+                    _path.c_str(),
+                    GENERIC_WRITE,
+                    FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+                    NULL,
+                    OPEN_ALWAYS,
+                    FILE_ATTRIBUTE_NORMAL,
+                    NULL
+            );
+            if ( INVALID_HANDLE_VALUE != newFileHandle ) {
+                int newFileDescriptor = _open_osfhandle( reinterpret_cast<intptr_t>(newFileHandle), _O_APPEND );
+                tmp = _fdopen( newFileDescriptor, _append ? "a" : "w" );
+            }
+#else
+            tmp = freopen(_path.c_str(), _append ? "a" : "w", stdout);
+#endif
+            if ( !tmp ) {
                 cerr << "can't open: " << _path.c_str() << " for log file" << endl;
                 dbexit( EXIT_BADOPTIONS );
-                assert(0);
+                assert( 0 );
             }
 
-#ifdef _WIN32 // windows has these functions it just gives them a funny name
-# define dup2 _dup2
-# define fileno _fileno
-#endif
-            // redirect stderr to log file
-            dup2(fileno(tmp), 2);
+            // redirect stdout and stderr to log file
+            dup2( fileno( tmp ), 1 );   // stdout
+            dup2( fileno( tmp ), 2 );   // stderr
 
             Logstream::setLogFile(tmp); // after this point no thread will be using old file
 
+#if _WIN32
+            if ( _file )
+                fclose( _file );  // In Windows, we still have the old file open, close it now
+#endif
+
 #if 0 // enable to test redirection
             cout << "written to cout" << endl;
             cerr << "written to cerr" << endl;
             log() << "written to log()" << endl;
 #endif
 
-            _file = tmp;
-            _opened = time(0);
+            _file = tmp;    // Save new file for next rotation
         }
 
     private:
-
         bool _enabled;
         string _path;
         bool _append;
-
         FILE * _file;
-        time_t _opened;
 
     } loggingManager;