Erl_Interface

Reference Manual

Version 3.13.1

Table of Contents

erl_malloc

C Library

erl_malloc

Library Summary

Memory allocation functions.

Description

Note

The support for VxWorks is deprecated as of OTP 22, and will be removed in OTP 23.

Note

The old legacy erl_interface library (functions with prefix erl_) is deprecated as of OTP 22, and will be removed in OTP 23. This does not apply to the ei library. Reasonably new gcc compilers will issue deprecation warnings. In order to disable these warnings, define the macro EI_NO_DEPR_WARN.

This module provides functions for allocating and deallocating memory.

Exports

ETERM *erl_alloc_eterm(
etype)

Types

unsigned char etype;

Allocates an (ETERM) structure.

Specify etype as one of the following constants:

  • ERL_INTEGER
  • ERL_U_INTEGER (unsigned integer)
  • ERL_ATOM
  • ERL_PID (Erlang process identifier)
  • ERL_PORT
  • ERL_REF (Erlang reference)
  • ERL_LIST
  • ERL_EMPTY_LIST
  • ERL_TUPLE
  • ERL_BINARY
  • ERL_FLOAT
  • ERL_VARIABLE
  • ERL_SMALL_BIG (bignum)
  • ERL_U_SMALL_BIG (bignum)

ERL_SMALL_BIG and ERL_U_SMALL_BIG are for creating Erlang bignums, which can contain integers of any size. The size of an integer in Erlang is machine-dependent, but any integer > 2^28 requires a bignum.

void erl_eterm_release(void)

Clears the freelist, where blocks are placed when they are released by erl_free_term() and erl_free_compound().

void erl_eterm_statistics(
allocated,
freed)

Types

long *allocated;
long *freed;

Reports term allocation statistics.

allocated and freed are initialized to contain information about the fix-allocator used to allocate ETERM components.

  • allocated is the number of blocks currently allocated to ETERM objects.

  • freed is the length of the freelist, where blocks are placed when they are released by erl_free_term() and erl_free_compound().

void erl_free(
ptr)

Types

void *ptr;

Calls the standard free() function.

void erl_free_array(
array,
size)

Types

ETERM **array;
int size;

Frees an array of Erlang terms.

  • array is an array of ETERM* objects.
  • size is the number of terms in the array.

void erl_free_compound(
t)

Types

ETERM *t;

Normally it is the programmer's responsibility to free each Erlang term that has been returned from any of the Erl_Interface functions. However, as many of the functions that build new Erlang terms in fact share objects with other existing terms, it can be difficult for the programmer to maintain pointers to all such terms to free them individually.

erl_free_compound() recursively frees all of the subterms associated with a specified Erlang term, regardless of whether we are still holding pointers to the subterms.

For an example, see section Building Terms and Patterns in the User's Guide.

void erl_free_term(
t)

Types

ETERM *t;

Frees an Erlang term.

void erl_malloc(
size)

Types

long size;

Calls the standard malloc() function.