Fix memory leak in chrom_calc. (bmad-sim#1730)

Author: DavidSagan

bmad/code/chrom_calc.f90

@@ -6,6 +6,9 @@
 ! This will handle open geometry lattices. In this case, dbeta/dpz and dalpha/dpz are are
 ! taken to be what is set in the beginning element.
 !
+! Note: If chrom_calc is to be repeatedly called, supplying low_E_lat, high_E_lat, low_E_orb, and/or high_E_orb will save time
+! since memory will not have to be repeatedly allocated.
+!
 ! Input:
 !   lat           -- lat_struct: Lat
 !   delta_e       -- real(rp): +/- Delta energy used for the calculation. Notice that the energy difference
@@ -35,7 +38,7 @@ subroutine chrom_calc (lat, delta_e, chrom_a, chrom_b, err_flag, &
 
 type (lat_struct), target :: lat
 type (lat_struct), optional, target :: low_E_lat, high_E_lat
-type (lat_struct), target :: this_lat
+type (lat_struct), target :: temp_lat
 type (lat_struct), pointer :: lat2
 type (coord_struct), allocatable, optional, target :: low_E_orb(:), high_E_orb(:)
 type (coord_struct), optional :: orb0
@@ -53,7 +56,7 @@ subroutine chrom_calc (lat, delta_e, chrom_a, chrom_b, err_flag, &
 integer nt, nm, stat, ix_br, ie, i0, ix_fix
 
 logical, optional, intent(out) :: err_flag
-logical err, used_this_lat
+logical err
 
 character(*), parameter :: r_name = 'chrom_calc'
 
@@ -78,14 +81,12 @@ subroutine chrom_calc (lat, delta_e, chrom_a, chrom_b, err_flag, &
 nt = branch%n_ele_track
 nm = branch%n_ele_max
 
-! lower energy tune
+! Low energy calc.
 
 if (present(low_E_lat)) then
   lat2 => low_E_lat
-  used_this_lat = .false.
 else
-  lat2 => this_lat
-  used_this_lat = .true.
+  lat2 => temp_lat
 endif
 
 lat2 = lat
@@ -171,20 +172,17 @@ subroutine chrom_calc (lat, delta_e, chrom_a, chrom_b, err_flag, &
 branch%ele(i0:nm)%y%detap_dpz = branch2%ele(i0:nm)%y%etap
 branch%ele(i0:nm)%z%detap_dpz = branch2%ele(i0:nm)%z%etap
 
-! higher energy tune
+! Higher energy lattice
 
 if (present(high_E_lat)) then
   lat2 => high_E_lat
-  used_this_lat = .false.
 else
-  lat2 => this_lat
+  lat2 => temp_lat
 endif
 
-if (.not. used_this_lat) then
-  lat2 = lat
-  branch2 => lat2%branch(ix_br)
-  call set_on_off (rfcavity$, lat2, off$, ix_branch = ix_br)
-endif
+lat2 = lat
+branch2 => lat2%branch(ix_br)
+call set_on_off (rfcavity$, lat2, off$, ix_branch = ix_br)
 
 if (present(high_E_orb)) then
   call reallocate_coord (high_E_orb, branch%n_ele_max)
@@ -268,5 +266,6 @@ subroutine chrom_calc (lat, delta_e, chrom_a, chrom_b, err_flag, &
 branch%ele(i0:nm)%z%detap_dpz = (branch2%ele(i0:nm)%z%etap - branch%ele(i0:nm)%z%detap_dpz) / dE
 
 if (present(err_flag)) err_flag = .false.
+if (.not. present(low_E_lat) .or. .not. present(high_E_lat)) call deallocate_lat_pointers(temp_lat)
 
 end subroutine

bmad/doc/lat-struct.tex

@@ -69,7 +69,7 @@ \section{Initializing}
 
 
 %----------------------------------------------------------------------------
-\section{Pointers}
+\section{Pointers: Allocation and Deallocation}
 \label{s:lat:point}
 \index{lat_struct!pointers}
 
@@ -86,8 +86,8 @@ \section{Pointers}
 place but the pointers in \vn{lattice1} will point to different locations in physical memory so that
 changes to one lattice will not affect the other.
 
-\Hyperref{r:deallocate.lat.pointers}{deallocate_lat_pointers} Initial allocation of the pointers in
-a \vn{lat_struct} variable is generally handled by the \Hyperref{r:bmad.parser}{bmad_parser} and
+Initial allocation of the pointers in
+a \vn{lat_struct} instance is generally handled by the \Hyperref{r:bmad.parser}{bmad_parser} and
 \Hyperref{r:lat.equal.lat}{lat_equal_lat} routines.  Once allocated, local \vn{lat_struct} variables
 must have the save attribute or the pointers within must be appropriately deallocated before leaving
 the routine.

bmad/low_level/deallocate_lat_pointers.f90

@@ -1,7 +1,8 @@
 !+
 ! Subroutine deallocate_lat_pointers (lat)
 !
-! Subroutine to deallocate the pointers in a lat.
+! Routine to deallocate the pointers in a lat.
+! This routine must be called before a lat_struct instance goes out-of-scope. 
 !
 ! Input:
 !   lat -- lat_struct: Lat with pointers.