addFinalizer: Register a finalizer to garbage collect allocated memory

In omegahat/Rffi: Interface to libffi to dynamically invoke arbitrary compiled routines at run-time without compiled bindings

Register a finalizer to garbage collect allocated memory

Description

This function and its methods allow us to arrange a C routine to be called to garbage collect native memory associated with an R object. We use it in this package to free memory allocated for native objects.

Usage

addFinalizer(obj, finalizer, default = character(),...)

Arguments

obj	the external pointer for which to register the finalizer
finalizer	the finalizer routine. This can be a string giving the name of the routine to be dynamically resolved by searching all DSOs/DLLs, or a NativeSymbolInfo or NativeSymbol object which are already resolved references to a native routine.
default	from RAutoGenRunTime package
...	additional arguments for methods

Value

NULL. This is used for its side-effect of registering a finalizer.

Author(s)

Duncan Temple Lang

See Also

alloc

There are two routines in the Rffi package that can be used as finalizers for R external pointer objects: R_free and R_verbose_free. The latter can be used to see when the finalizer is being invoked and for what address in the external pointer object.

Examples

  # call a routine that explicitly allocates its return value
  # so we arrange to free it when we no longer need it.

  myStruct.type = structType(list(s = sint16Type, i = sint32Type, d = doubleType, str = stringType))  
  cif = CIF(pointerType)

  ans = callCIF(cif, "getStructP")
  getStructValue(ans, myStruct.type)
  free(ans)

  ans = callCIF(cif, "getStructP")
  addFinalizer(ans, "R_verbose_free")
  getStructValue(ans, myStruct.type)
  rm(ans)
  gc()

omegahat/Rffi documentation built on Nov. 29, 2023, 12:48 a.m.