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psblas3/base/modules/psb_hash_mod.f90

381 lines
11 KiB
Fortran

!!$
!!$ Parallel Sparse BLAS version 3.0
!!$ (C) Copyright 2006, 2007, 2008, 2009, 2010
!!$ Salvatore Filippone University of Rome Tor Vergata
!!$ Alfredo Buttari CNRS-IRIT, Toulouse
!!$
!!$ Redistribution and use in source and binary forms, with or without
!!$ modification, are permitted provided that the following conditions
!!$ are met:
!!$ 1. Redistributions of source code must retain the above copyright
!!$ notice, this list of conditions and the following disclaimer.
!!$ 2. Redistributions in binary form must reproduce the above copyright
!!$ notice, this list of conditions, and the following disclaimer in the
!!$ documentation and/or other materials provided with the distribution.
!!$ 3. The name of the PSBLAS group or the names of its contributors may
!!$ not be used to endorse or promote products derived from this
!!$ software without specific written permission.
!!$
!!$ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
!!$ ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
!!$ TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
!!$ PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PSBLAS GROUP OR ITS CONTRIBUTORS
!!$ BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
!!$ CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
!!$ SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
!!$ INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
!!$ CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
!!$ ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
!!$ POSSIBILITY OF SUCH DAMAGE.
!!$
!!$
!
! package: psb_hash_mod
!
! This module implements a very simple minded hash table.
! The hash is based on the idea of open addressing with double hashing;
! the primary hash function h1(K) is simply the remainder modulo 2^N, while
! the secondary hash function is 1 if H1(k) == 0, otherwise IOR((2^N-H1(k)),1)
! (See Knuth: TAOCP, Vol. 3, sec. 6.4)
! These hash functions are not very smart; however they are very simple and fast.
! The intended usage of this hash table is to store indices of halo points, which
! are supposed to be few compared to the internal indices (which are stored elsewhere).
! Therefore, either the table has a very low occupancy, and this scheme will work,
! or we have lots more to worry about in parallel performance than the efficiency
! of this hashing scheme.
!
!
!
module psb_hash_mod
use psb_const_mod
!
! For us a hash is a Nx2 table.
! Note: we are assuming that the keys are positive numbers.
! Allocatable scalars would be a nice solution...
!
type psb_hash_type
integer(psb_ipk_) :: nbits, hsize, hmask, nk
integer(psb_ipk_), allocatable :: table(:,:)
integer(psb_long_int_k_) :: nsrch, nacc
end type psb_hash_type
integer(psb_ipk_), parameter :: HashDuplicate = 123, HashOK=0, HashOutOfMemory=-512,&
& HashFreeEntry = -1, HashNotFound = -256
interface psb_hash_init
module procedure psb_hash_init_v, psb_hash_init_n
end interface
interface psb_sizeof
module procedure psb_sizeof_hash_type
end interface
interface psb_move_alloc
module procedure HashTransfer
end interface
interface psb_hash_copy
module procedure HashCopy
end interface
interface psb_free
module procedure HashFree
end interface
contains
!
! This is based on the djb2 hashing algorithm
! see e.g. http://www.cse.yorku.ca/~oz/hash.html
!
function hashval(key) result(val)
integer(psb_ipk_), intent(in) :: key
integer(psb_ipk_), parameter :: ival=5381, mask=huge(ival)
integer(psb_ipk_) :: key_, val, i
key_ = key
val = ival
do i=1, psb_sizeof_int
val = val * 33 + iand(key_,255)
key_ = ishft(key_,-8)
end do
val = val + ishft(val,-5)
val = iand(val,mask)
end function hashval
function psb_Sizeof_hash_type(hash) result(val)
type(psb_hash_type) :: hash
integer(psb_long_int_k_) :: val
val = 4*psb_sizeof_int + 2*psb_sizeof_long_int
if (allocated(hash%table)) &
& val = val + psb_sizeof_int * size(hash%table)
end function psb_Sizeof_hash_type
function psb_hash_avg_acc(hash)
type(psb_hash_type), intent(in) :: hash
real(psb_dpk_) :: psb_hash_avg_acc
psb_hash_avg_acc = dble(hash%nacc)/dble(hash%nsrch)
end function psb_hash_avg_acc
subroutine HashFree(hashin,info)
use psb_realloc_mod
type(psb_hash_type) :: hashin
info = psb_success_
if (allocated(hashin%table)) then
deallocate(hashin%table,stat=info)
end if
hashin%nbits = 0
hashin%hsize = 0
hashin%hmask = 0
hashin%nk = 0
end subroutine HashFree
subroutine HashTransfer(hashin,hashout,info)
use psb_realloc_mod
type(psb_hash_type) :: hashin
type(psb_hash_type) :: hashout
integer(psb_ipk_), intent(out) :: info
info = HashOk
hashout%nbits = hashin%nbits
hashout%hsize = hashin%hsize
hashout%hmask = hashin%hmask
hashout%nk = hashin%nk
hashout%nsrch = hashin%nsrch
hashout%nacc = hashin%nacc
call psb_move_alloc(hashin%table, hashout%table,info)
end subroutine HashTransfer
subroutine HashCopy(hashin,hashout,info)
use psb_realloc_mod
type(psb_hash_type) :: hashin
type(psb_hash_type) :: hashout
integer(psb_ipk_), intent(out) :: info
info = HashOk
hashout%nbits = hashin%nbits
hashout%hsize = hashin%hsize
hashout%hmask = hashin%hmask
hashout%nk = hashin%nk
hashout%nsrch = hashin%nsrch
hashout%nacc = hashin%nacc
call psb_safe_ab_cpy(hashin%table, hashout%table,info)
end subroutine HashCopy
subroutine CloneHashTable(hashin,hashout,info)
type(psb_hash_type), pointer :: hashin
type(psb_hash_type), pointer :: hashout
integer(psb_ipk_), intent(out) :: info
if (associated(hashout)) then
deallocate(hashout,stat=info)
!if (info /= psb_success_) return
end if
if (associated(hashin)) then
allocate(hashout,stat=info)
if (info /= psb_success_) return
call HashCopy(hashin,hashout,info)
end if
end subroutine CloneHashTable
subroutine psb_hash_init_V(v,hash,info)
integer(psb_ipk_), intent(in) :: v(:)
type(psb_hash_type), intent(out) :: hash
integer(psb_ipk_), intent(out) :: info
integer(psb_ipk_) :: i,j,nbits, nv
info = psb_success_
nv = size(v)
call psb_hash_init(nv,hash,info)
if (info /= psb_success_) return
do i=1,nv
call psb_hash_searchinskey(v(i),j,i,hash,info)
if ((j /= i).or.(info /= HashOK)) then
write(psb_err_unit,*) 'Error from hash_ins',i,v(i),j,info
info = HashNotFound
return
end if
end do
end subroutine psb_hash_init_V
subroutine psb_hash_init_n(nv,hash,info)
integer(psb_ipk_), intent(in) :: nv
type(psb_hash_type), intent(out) :: hash
integer(psb_ipk_), intent(out) :: info
integer(psb_ipk_) :: hsize,nbits
info = psb_success_
nbits = 12
hsize = 2**nbits
!
! Figure out the smallest power of 2 bigger than NV
! Note: in our intended usage NV will be the size of the
! local index space, NOT the global index space.
!
do
if (hsize < 0) then
write(psb_err_unit,*) 'Error: hash size overflow ',hsize,nbits
info = -2
return
end if
if (hsize > nv) exit
nbits = nbits + 1
hsize = hsize * 2
end do
hash%nbits = nbits
hash%hsize = hsize
hash%hmask = hsize-1
hash%nsrch = 0
hash%nacc = 0
allocate(hash%table(0:hsize-1,2),stat=info)
if (info /= psb_success_) then
write(psb_err_unit,*) 'Error: memory allocation failure ',hsize
info = HashOutOfMemory
return
end if
hash%table = HashFreeEntry
hash%nk = 0
end subroutine psb_hash_init_n
subroutine psb_hash_realloc(hash,info)
type(psb_hash_type), intent(inout) :: hash
integer(psb_ipk_), intent(out) :: info
type(psb_hash_type) :: nhash
integer(psb_ipk_) :: key, val, nextval,i
info = HashOk
call psb_hash_init((hash%hsize+1),nhash,info)
if (info /= HashOk) then
info = HashOutOfMemory
return
endif
do i=0, hash%hsize-1
key = hash%table(i,1)
nextval = hash%table(i,2)
if (key /= HashFreeEntry) then
call psb_hash_searchinskey(key,val,nextval,nhash,info)
if (info /= psb_success_) then
info = HashOutOfMemory
return
end if
end if
end do
call HashTransfer(nhash,hash,info)
end subroutine psb_hash_realloc
recursive subroutine psb_hash_searchinskey(key,val,nextval,hash,info)
integer(psb_ipk_), intent(in) :: key,nextval
type(psb_hash_type) :: hash
integer(psb_ipk_), intent(out) :: val, info
integer(psb_ipk_) :: hsize,hmask, hk, hd
info = HashOK
hsize = hash%hsize
hmask = hash%hmask
hk = iand(hashval(key),hmask)
if (hk == 0) then
hd = 1
else
hd = hsize - hk
hd = ior(hd,1)
end if
hash%nsrch = hash%nsrch + 1
do
hash%nacc = hash%nacc + 1
if (hash%table(hk,1) == key) then
val = hash%table(hk,2)
info = HashDuplicate
return
end if
if (hash%table(hk,1) == HashFreeEntry) then
if (hash%nk == hash%hsize -1) then
!
! Note: because of the way we allocate things at CDALL
! time this is really unlikely; if we get here, we
! have at least as many halo indices as internals, which
! means we're already in trouble. But we try to keep going.
!
call psb_hash_realloc(hash,info)
if (info /= HashOk) then
info = HashOutOfMemory
return
else
call psb_hash_searchinskey(key,val,nextval,hash,info)
return
end if
else
hash%nk = hash%nk + 1
hash%table(hk,1) = key
hash%table(hk,2) = nextval
val = nextval
return
end if
end if
hk = hk - hd
if (hk < 0) hk = hk + hsize
end do
end subroutine psb_hash_searchinskey
subroutine psb_hash_searchkey(key,val,hash,info)
integer(psb_ipk_), intent(in) :: key
type(psb_hash_type) :: hash
integer(psb_ipk_), intent(out) :: val, info
integer(psb_ipk_) :: hsize,hmask, hk, hd
info = HashOK
if (.not.allocated(hash%table) ) then
val = HashFreeEntry
return
end if
hsize = hash%hsize
hmask = hash%hmask
hk = iand(hashval(key),hmask)
if (hk == 0) then
hd = 1
else
hd = hsize - hk
hd = ior(hd,1)
end if
hash%nsrch = hash%nsrch + 1
do
hash%nacc = hash%nacc + 1
if (hash%table(hk,1) == key) then
val = hash%table(hk,2)
return
end if
if (hash%table(hk,1) == HashFreeEntry) then
val = HashFreeEntry
!!$ info = HashNotFound
return
end if
hk = hk - hd
if (hk < 0) hk = hk + hsize
end do
end subroutine psb_hash_searchkey
end module psb_hash_mod