Re: java1.4.2 "rws" mode fix: LogToFile.java diff

[Suresh Thalamati]

Joseph Grace wrote:
Dear derby-dev:
Apologies for any faux-pas.  I'm not sure what diff to use, so I used 
diff -c2 to make the following patch.

I made this change to get derby running under java 1.4.2 on Mac OSX 
10.3.5 (i.e., the latest and greatest version).  I believe the patch 
fixes a bug where the database gets created twice unnecessarily.  This 
bug was causing the simple instructions example ("connect 
'jdbc:derby:test;create=true';") to choke with a file already exists 
error.  Apparently, this situation crops up whenever "rws" mode was 
available, and would not occur prior to 1.4.1 (since apparently "rws" 
was too buggy to use until 1.4.2 and, so, was avoided).  Anyway, 
here's what I believe is a fix for that issue and, at least, got the 
database to initialize per instructions on my system.

Hi Joe ,
  I am trying to understand the problem you described above.  What is 
the error you are seeing when you try to create 
  the database  in the  Mac environment. Are u seeing this problem  
with JDK1.4.2 on  any other OS ?
  Could  you please explain  more on  how  database can be  created 
twice ? 
   From the changes described  here, what I find  is  you are trying to 
avoid  open/create
   of  log file in "rw" mode first and  then  in  "rws" mode  by making 
 it  a single  privRandomAccess File call:

 >> StorageRandomAccessFile theLog = privRandomAccessFile( logFile, 
isWriteSynced? "rws": "rw");

 


*** LogToFile.java.org  Thu Aug 26 12:07:32 2004
--- LogToFile.java      Tue Aug 31 22:19:16 2004
***************
*** 889,902 ****
                                                lastFlush   = 
endPosition;


  I think  the following part of the  changes might increase database 
creation time when write sync is enabled..
  Please correct me if  my observation is  not right . I think  the 
Reason behind opening files in "RW" mode first 
  and then reopen in "RWS"  might have been  to make preallocation of 
the log file  finish  faster.
.  Preallocation of  the log file  by doing writes  to a file opened in 
"rws"  mode   will be much  slower than 
  doing writes to file opened in "rw" mode  .


***************
*** 3004,3008 ****
                                        // don't need to try to delete 
it, we know it isn't there
!                     StorageRandomAccessFile theLog = 
privRandomAccessFile(logFile, "rw");

                                        if (!initLogFile(theLog, 
logFileNumber, LogCounter.INVALID_LOG_INSTANT))
--- 3004,3008 ----

                                        // don't need to try to delete 
it, we know it isn't there
!                     StorageRandomAccessFile theLog = 
privRandomAccessFile( logFile, isWriteSynced? "rws": "rw");

                                        if (!initLogFile(theLog, 
logFileNumber, LogCounter.INVALID_LOG_INSTANT))
***************
*** 3015,3028 ****
                                        lastFlush = 
theLog.getFilePointer();

!                     //if write sync is true , prellocate the log file
!                     //and reopen the file in rws mode.
!                     if(isWriteSynced)
                      {
!                         //extend the file by wring zeros to it
!                         preAllocateNewLogFile(theLog);
!                         theLog.close();
!                         theLog=  privRandomAccessFile(logFile, "rws");
!                         //postion the log at the current log end 
postion
!                         theLog.seek(endPosition);
                      }
                                        logOut = new 
LogAccessFile(theLog, logBufferSize);
--- 3015,3026 ----
                                        lastFlush = 
theLog.getFilePointer();

!                     //  if write sync is true , preallocate the log 
file
!                     //  and reposition cursor.
!                     if( isWriteSynced)
                      {
!                         //  extend the file by writing zeros to it
!                         preAllocateNewLogFile( theLog);
!                         //  position the log at the current log end 
position
!                         theLog.seek( endPosition);
                      }
                                        logOut = new 
LogAccessFile(theLog, logBufferSize);


Thanks
-suresh