@ -170,12 +170,12 @@ struct TIDBitmap
} ;
/*
* When iterating over a bitmap in sorted order , a TBMIterator is used to
* track our progress . There can be several iterators scanning the same
* bitmap concurrently . Note that the bitmap becomes read - only as soon as
* any iterator is created .
* When iterating over a backend - local b itmap in sorted order , a
* TBMPrivateIterator is used to track our progress . There can be several
* iterators scanning the same bitmap concurrently . Note that the bitmap
* becomes read - only as soon as any iterator is created .
*/
struct TBMIterator
struct TBMPrivate Iterator
{
TIDBitmap * tbm ; /* TIDBitmap we're iterating over */
int spageptr ; /* next spages index */
@ -213,8 +213,8 @@ typedef struct PTIterationArray
} PTIterationArray ;
/*
* same as TBMIterator , but it is used for joint iteration , therefore this
* also holds a reference to the shared state .
* same as TBMPrivate Iterator , but it is used for joint iteration , therefore
* this also holds a reference to the shared state .
*/
struct TBMSharedIterator
{
@ -673,31 +673,32 @@ tbm_is_empty(const TIDBitmap *tbm)
}
/*
* tbm_begin_iterate - prepare to iterate through a TIDBitmap
* tbm_begin_private_ iterate - prepare to iterate through a TIDBitmap
*
* The TBMIterator struct is created in the caller ' s memory context .
* For a clean shutdown of the iteration , call tbm_end_iterate ; but it ' s
* okay to just allow the memory context to be released , too . It is caller ' s
* responsibility not to touch the TBMIterator anymore once the TIDBitmap
* is freed .
* The TBMPrivate Iterator struct is created in the caller ' s memory context .
* For a clean shutdown of the iteration , call tbm_end_private_ iterate ; but
* it ' s okay to just allow the memory context to be released , too . It is
* caller ' s responsibility not to touch the TBMPrivateIterator anymore once
* the TIDBitmap is freed .
*
* NB : after this is called , it is no longer allowed to modify the contents
* of the bitmap . However , you can call this multiple times to scan the
* contents repeatedly , including parallel scans .
*/
TBMIterator *
tbm_begin_iterate ( TIDBitmap * tbm )
TBMPrivate Iterator *
tbm_begin_private_ iterate ( TIDBitmap * tbm )
{
TBMIterator * iterator ;
TBMPrivate Iterator * iterator ;
Assert ( tbm - > iterating ! = TBM_ITERATING_SHARED ) ;
/*
* Create the TBMIterator struct , with enough trailing space to serve the
* needs of the TBMIterateResult sub - struct .
* Create the TBMPrivate Iterator struct , with enough trailing space to
* serve the needs of the TBMIterateResult sub - struct .
*/
iterator = ( TBMIterator * ) palloc ( sizeof ( TBMIterator ) +
MAX_TUPLES_PER_PAGE * sizeof ( OffsetNumber ) ) ;
iterator = ( TBMPrivateIterator * ) palloc ( sizeof ( TBMPrivateIterator ) +
MAX_TUPLES_PER_PAGE *
sizeof ( OffsetNumber ) ) ;
iterator - > tbm = tbm ;
/*
@ -878,7 +879,7 @@ tbm_prepare_shared_iterate(TIDBitmap *tbm)
ptchunks = dsa_get_address ( tbm - > dsa , tbm - > ptchunks ) ;
/*
* For every shared iterator , referring to pagetable and iterator array ,
* For every shared iterator referring to pagetable and iterator array ,
* increase the refcount by 1 so that while freeing the shared iterator we
* don ' t free pagetable and iterator array until its refcount becomes 0.
*/
@ -956,7 +957,7 @@ tbm_advance_schunkbit(PagetableEntry *chunk, int *schunkbitp)
}
/*
* tbm_iterate - scan through next page of a TIDBitmap
* tbm_private_ iterate - scan through next page of a TIDBitmap
*
* Returns a TBMIterateResult representing one page , or NULL if there are
* no more pages to scan . Pages are guaranteed to be delivered in numerical
@ -968,7 +969,7 @@ tbm_advance_schunkbit(PagetableEntry *chunk, int *schunkbitp)
* testing , recheck is always set true when ntuples < 0. )
*/
TBMIterateResult *
tbm_iterate ( TBMIterator * iterator )
tbm_private_ iterate ( TBMPrivate Iterator * iterator )
{
TIDBitmap * tbm = iterator - > tbm ;
TBMIterateResult * output = & ( iterator - > output ) ;
@ -1136,14 +1137,14 @@ tbm_shared_iterate(TBMSharedIterator *iterator)
}
/*
* tbm_end_iterate - finish an iteration over a TIDBitmap
* tbm_end_private_ iterate - finish an iteration over a TIDBitmap
*
* Currently this is just a pfree , but it might do more someday . ( For
* instance , it could be useful to count open iterators and allow the
* bitmap to return to read / write status when there are no more iterators . )
*/
void
tbm_end_iterate ( TBMIterator * iterator )
tbm_end_private_ iterate ( TBMPrivate Iterator * iterator )
{
pfree ( iterator ) ;
}
@ -1556,3 +1557,66 @@ tbm_calculate_entries(double maxbytes)
return nbuckets ;
}
/*
* Create a shared or private bitmap iterator and start iteration .
*
* ` tbm ` is only used to create the private iterator and dsa and dsp are only
* used to create the shared iterator .
*
* Before invoking tbm_begin_iterate ( ) to create a shared iterator , one
* process must already have invoked tbm_prepare_shared_iterate ( ) to create
* and set up the TBMSharedIteratorState .
*/
TBMIterator
tbm_begin_iterate ( TIDBitmap * tbm , dsa_area * dsa , dsa_pointer dsp )
{
TBMIterator iterator = { 0 } ;
/* Allocate a private iterator and attach the shared state to it */
if ( DsaPointerIsValid ( dsp ) )
{
iterator . shared = true ;
iterator . i . shared_iterator = tbm_attach_shared_iterate ( dsa , dsp ) ;
}
else
{
iterator . shared = false ;
iterator . i . private_iterator = tbm_begin_private_iterate ( tbm ) ;
}
return iterator ;
}
/*
* Clean up shared or private bitmap iterator .
*/
void
tbm_end_iterate ( TBMIterator * iterator )
{
Assert ( iterator ) ;
if ( iterator - > shared )
tbm_end_shared_iterate ( iterator - > i . shared_iterator ) ;
else
tbm_end_private_iterate ( iterator - > i . private_iterator ) ;
* iterator = ( TBMIterator )
{
0
} ;
}
/*
* Get the next TBMIterateResult from the shared or private bitmap iterator .
*/
TBMIterateResult *
tbm_iterate ( TBMIterator * iterator )
{
Assert ( iterator ) ;
if ( iterator - > shared )
return tbm_shared_iterate ( iterator - > i . shared_iterator ) ;
else
return tbm_private_iterate ( iterator - > i . private_iterator ) ;
}
Melanie Plageman
9 months ago