module Core_gc:sig
..end
add_finalizer b f
ensures that f
runs after b
becomes unreachable. The
OCaml runtime only supports finalizers on heap blocks, hence add_finalizer
requires
b : _ Heap_block.t
. The runtime essentially maintains a set of finalizer pairs:
'a Heap_block.t * ('a Heap_block.t -> unit)
Each call to add_finalizer
adds a new pair to the set. It is allowed for many
pairs to have the same heap block, the same function, or both. Each pair is a
distinct element of the set.
After a garbage collection determines that a heap block b
is unreachable, it removes
from the set of finalizers all finalizer pairs (b, f)
whose block is b
, and then
and runs f b
for all such pairs. Thus, a finalizer registered with add_finalizer
will run at most once.
The GC will call the finalisation functions in the order of deallocation. When
several values become unreachable at the same time (i.e. during the same GC cycle),
the finalisation functions will be called in the reverse order of the corresponding
calls to add_finalizer
. If add_finalizer
is called in the same order as the
values are allocated, that means each value is finalised before the values it depends
upon. Of course, this becomes false if additional dependencies are introduced by
assignments.
In a finalizer pair (b, f)
, it is a mistake for the closure of f
to reference
(directly or indirectly) b
-- f
should only access b
via its argument.
Referring to b
in any other way will cause b
to be kept alive forever, since f
itself is a root of garbage collection, and can itself only be collected after the
pair (b, f)
is removed from the set of finalizers.
The f
function can use all features of O'Caml, including assignments that make the
value reachable again. It can also loop forever (in this case, the other finalisation
functions will be called during the execution of f). It can call add_finalizer
on
v
or other values to register other functions or even itself. It can raise an
exception; in this case the exception will interrupt whatever the program was doing
when the function was called.
add_finalizer_exn b f
is like add_finalizer
, but will raise if b
is not a
heap block.
include Gc
val add_finalizer : 'a Core_kernel.Std.Heap_block.t ->
('a Core_kernel.Std.Heap_block.t -> unit) -> unit
add_finalizer b f
ensures that f
runs after b
becomes unreachable. The
OCaml runtime only supports finalizers on heap blocks, hence add_finalizer
requires
b : _ Heap_block.t
. The runtime essentially maintains a set of finalizer pairs:
'a Heap_block.t * ('a Heap_block.t -> unit)
Each call to add_finalizer
adds a new pair to the set. It is allowed for many
pairs to have the same heap block, the same function, or both. Each pair is a
distinct element of the set.
After a garbage collection determines that a heap block b
is unreachable, it removes
from the set of finalizers all finalizer pairs (b, f)
whose block is b
, and then
and runs f b
for all such pairs. Thus, a finalizer registered with add_finalizer
will run at most once.
The GC will call the finalisation functions in the order of deallocation. When
several values become unreachable at the same time (i.e. during the same GC cycle),
the finalisation functions will be called in the reverse order of the corresponding
calls to add_finalizer
. If add_finalizer
is called in the same order as the
values are allocated, that means each value is finalised before the values it depends
upon. Of course, this becomes false if additional dependencies are introduced by
assignments.
In a finalizer pair (b, f)
, it is a mistake for the closure of f
to reference
(directly or indirectly) b
-- f
should only access b
via its argument.
Referring to b
in any other way will cause b
to be kept alive forever, since f
itself is a root of garbage collection, and can itself only be collected after the
pair (b, f)
is removed from the set of finalizers.
The f
function can use all features of O'Caml, including assignments that make the
value reachable again. It can also loop forever (in this case, the other finalisation
functions will be called during the execution of f). It can call add_finalizer
on
v
or other values to register other functions or even itself. It can raise an
exception; in this case the exception will interrupt whatever the program was doing
when the function was called.
add_finalizer_exn b f
is like add_finalizer
, but will raise if b
is not a
heap block.
val add_finalizer_exn : 'a -> ('a -> unit) -> unit
val finalise_release : unit -> unit
finalise_release
to tell the
GC that it can launch the next finalisation function without waiting
for the current one to return.