@ -30,11 +30,29 @@
* routines ( e . g . , open ( 2 ) and fopen ( 3 ) ) themselves . Otherwise , we
* may find ourselves short of real file descriptors anyway .
*
* This file used to contain a bunch of stuff to support RAID levels 0
* ( jbod ) , 1 ( duplex ) and 5 ( xor parity ) . That stuff is all gone
* because the parallel query processing code that called it is all
* gone . If you really need it you could get it from the original
* POSTGRES source .
* INTERFACE ROUTINES
*
* PathNameOpenFile and OpenTemporaryFile are used to open virtual files .
* A File opened with OpenTemporaryFile is automatically deleted when the
* File is closed , either explicitly or implicitly at end of transaction or
* process exit . PathNameOpenFile is intended for files that are held open
* for a long time , like relation files . It is the caller ' s responsibility
* to close them , there is no automatic mechanism in fd . c for that .
*
* AllocateFile , AllocateDir and OpenTransientFile are wrappers around
* fopen ( 3 ) , opendir ( 3 ) , and open ( 2 ) , respectively . They behave like the
* corresponding native functions , except that the handle is registered with
* the current subtransaction , and will be automatically closed at abort .
* These are intended for short operations like reading a configuration file .
* and there is a fixed limit on the number files that can be open using these
* functions at any one time .
*
* Finally , BasicOpenFile is a just thin wrapper around open ( ) that can
* release file descriptors in use by the virtual file descriptors if
* necessary . There is no automatic cleanup of file descriptors returned by
* BasicOpenFile , it is solely the caller ' s responsibility to close the file
* descriptor by calling close ( 2 ) .
*
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/
@ -94,11 +112,11 @@ int max_files_per_process = 1000;
/*
* Maximum number of file descriptors to open for either VFD entries or
* AllocateFile / AllocateDir operations . This is initialized to a conservative
* value , and remains that way indefinitely in bootstrap or standalone - backend
* cases . In normal postmaster operation , the postmaster calls
* set_max_safe_fds ( ) late in initialization to update the value , and that
* value is then inherited by forked subprocesses .
* AllocateFile / AllocateDir / OpenTransientFile operations . This is initialized
* to a conservative value , and remains that way indefinitely in bootstrap or
* standalone - backend cases . In normal postmaster operation , the postmaster
* calls set_max_safe_fds ( ) late in initialization to update the value , and
* that value is then inherited by forked subprocesses .
*
* Note : the value of max_files_per_process is taken into account while
* setting this variable , and so need not be tested separately .
@ -171,10 +189,10 @@ static bool have_xact_temporary_files = false;
static uint64 temporary_files_size = 0 ;
/*
* List of stdio FILEs and < dirent . h > DIRs opened with AllocateFile
* and AllocateDir .
* List of OS handles opened with AllocateFile , AllocateDir and
* OpenTransientFile .
*
* Since we don ' t want to encourage heavy use of AllocateFile or AllocateDir ,
* Since we don ' t want to encourage heavy use of those functions ,
* it seems OK to put a pretty small maximum limit on the number of
* simultaneously allocated descs .
*/
@ -183,7 +201,8 @@ static uint64 temporary_files_size = 0;
typedef enum
{
AllocateDescFile ,
AllocateDescDir
AllocateDescDir ,
AllocateDescRawFD
} AllocateDescKind ;
typedef struct
@ -193,6 +212,7 @@ typedef struct
{
FILE * file ;
DIR * dir ;
int fd ;
} desc ;
SubTransactionId create_subid ;
} AllocateDesc ;
@ -1523,8 +1543,49 @@ TryAgain:
return NULL ;
}
/*
* Like AllocateFile , but returns an unbuffered fd like open ( 2 )
*/
int
OpenTransientFile ( FileName fileName , int fileFlags , int fileMode )
{
int fd ;
DO_DB ( elog ( LOG , " OpenTransientFile: Allocated %d (%s) " ,
numAllocatedDescs , fileName ) ) ;
/*
* The test against MAX_ALLOCATED_DESCS prevents us from overflowing
* allocatedFiles [ ] ; the test against max_safe_fds prevents BasicOpenFile
* from hogging every one of the available FDs , which ' d lead to infinite
* looping .
*/
if ( numAllocatedDescs > = MAX_ALLOCATED_DESCS | |
numAllocatedDescs > = max_safe_fds - 1 )
elog ( ERROR , " exceeded MAX_ALLOCATED_DESCS while trying to open file \" %s \" " ,
fileName ) ;
fd = BasicOpenFile ( fileName , fileFlags , fileMode ) ;
if ( fd > = 0 )
{
AllocateDesc * desc = & allocatedDescs [ numAllocatedDescs ] ;
desc - > kind = AllocateDescRawFD ;
desc - > desc . fd = fd ;
desc - > create_subid = GetCurrentSubTransactionId ( ) ;
numAllocatedDescs + + ;
return fd ;
}
return - 1 ; /* failure */
}
/*
* Free an AllocateDesc of either type .
* Free an AllocateDesc of any type .
*
* The argument * must * point into the allocatedDescs [ ] array .
*/
@ -1542,6 +1603,9 @@ FreeDesc(AllocateDesc *desc)
case AllocateDescDir :
result = closedir ( desc - > desc . dir ) ;
break ;
case AllocateDescRawFD :
result = close ( desc - > desc . fd ) ;
break ;
default :
elog ( ERROR , " AllocateDesc kind not recognized " ) ;
result = 0 ; /* keep compiler quiet */
@ -1583,6 +1647,33 @@ FreeFile(FILE *file)
return fclose ( file ) ;
}
/*
* Close a file returned by OpenTransientFile .
*
* Note we do not check close ' s return value - - - it is up to the caller
* to handle close errors .
*/
int
CloseTransientFile ( int fd )
{
int i ;
DO_DB ( elog ( LOG , " CloseTransientFile: Allocated %d " , numAllocatedDescs ) ) ;
/* Remove fd from list of allocated files, if it's present */
for ( i = numAllocatedDescs ; - - i > = 0 ; )
{
AllocateDesc * desc = & allocatedDescs [ i ] ;
if ( desc - > kind = = AllocateDescRawFD & & desc - > desc . fd = = fd )
return FreeDesc ( desc ) ;
}
/* Only get here if someone passes us a file not in allocatedDescs */
elog ( WARNING , " fd passed to CloseTransientFile was not obtained from OpenTransientFile " ) ;
return close ( fd ) ;
}
/*
* Routines that want to use < dirent . h > ( ie , DIR * ) should use AllocateDir
@ -1874,7 +1965,7 @@ AtProcExit_Files(int code, Datum arg)
* exiting . If that ' s the case , we should remove all temporary files ; if
* that ' s not the case , we are being called for transaction commit / abort
* and should only remove transaction - local temp files . In either case ,
* also clean up " allocated " stdio files and dir s .
* also clean up " allocated " stdio files , dirs and f ds.
*/
static void
CleanupTempFiles ( bool isProcExit )
@ -1916,7 +2007,7 @@ CleanupTempFiles(bool isProcExit)
have_xact_temporary_files = false ;
}
/* Clean up "allocated" stdio files and dir s. */
/* Clean up "allocated" stdio files, dirs and f ds. */
while ( numAllocatedDescs > 0 )
FreeDesc ( & allocatedDescs [ 0 ] ) ;
}
Heikki Linnakangas
13 years ago