    indexing
    	description: "[
    		Facilities for tuning up the garbage collection mechanism.
    		This class may be used as ancestor by classes needing its facilities.
    	]"
    	legal: "See notice at end of class."
    	status: "See notice at end of class."
    	date: "$Date: 2006-08-25 18:03:36 -0700 (Fri, 25 Aug 2006) $"
    	revision: "$Revision: 62989 $"

    class interface
    	MEMORY

    create
    	default_create
    			-- Process instances of classes with no creation clause.
    			-- (Default: do nothing.)
    			-- (from ANY)

    feature -- Access

    	c_memory: INTEGER_32 is 2
    			-- Code for the C memory managed
    			-- by the garbage collector
    			-- (from MEM_CONST)

    	eiffel_memory: INTEGER_32 is 1
    			-- Code for the Eiffel memory managed
    			-- by the garbage collector
    			-- (from MEM_CONST)

    	full_collector: INTEGER_32 is 0
    			-- Statistics for full collections
    			-- (from MEM_CONST)

    	generating_type: STRING_8
    			-- Name of current object's generating type
    			-- (type of which it is a direct instance)
    			-- (from ANY)

    	generator: STRING_8
    			-- Name of current object's generating class
    			-- (base class of the type of which it is a direct instance)
    			-- (from ANY)

    	incremental_collector: INTEGER_32 is 1
    			-- Statistics for incremental collections
    			-- (from MEM_CONST)

    	total_memory: INTEGER_32 is 0
    			-- Code for all the memory managed
    			-- by the garbage collector
    			-- (from MEM_CONST)

    feature -- Measurement

    	gc_statistics (collector_type: INTEGER_32): GC_INFO
    			-- Garbage collection information for `collector_type'.
    		require
    			type_ok: collector_type = full_collector or collector_type = incremental_collector

    	memory_statistics (memory_type: INTEGER_32): MEM_INFO
    			-- Memory usage information for `memory_type'
    		require
    			type_ok: memory_type = total_memory or memory_type = eiffel_memory or memory_type = c_memory

    feature -- Comparison

    	frozen deep_equal (some: ANY; other: like arg #1): BOOLEAN
    			-- Are `some' and `other' either both void
    			-- or attached to isomorphic object structures?
    			-- (from ANY)
    		ensure -- from ANY
    			shallow_implies_deep: standard_equal (some, other) implies Result
    			both_or_none_void: (some = Void) implies (Result = (other = Void))
    			same_type: (Result and (some /= Void)) implies some.same_type (other)
    			symmetric: Result implies deep_equal (other, some)

    	frozen equal (some: ANY; other: like arg #1): BOOLEAN
    			-- Are `some' and `other' either both void or attached
    			-- to objects considered equal?
    			-- (from ANY)
    		ensure -- from ANY
    			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.is_equal (other))

    	is_equal (other: like Current): BOOLEAN
    			-- Is `other' attached to an object considered
    			-- equal to current object?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			symmetric: Result implies other.is_equal (Current)
    			consistent: standard_is_equal (other) implies Result

    	frozen standard_equal (some: ANY; other: like arg #1): BOOLEAN
    			-- Are `some' and `other' either both void or attached to
    			-- field-by-field identical objects of the same type?
    			-- Always uses default object comparison criterion.
    			-- (from ANY)
    		ensure -- from ANY
    			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.standard_is_equal (other))

    	frozen standard_is_equal (other: like Current): BOOLEAN
    			-- Is `other' attached to an object of the same type
    			-- as current object, and field-by-field identical to it?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			same_type: Result implies same_type (other)
    			symmetric: Result implies other.standard_is_equal (Current)

    feature -- Status report

    	chunk_size: INTEGER_32
    			-- Minimal size of a memory chunk. The run-time always
    			-- allocates a multiple of this size.
    			-- If the environment variable EIF_MEMORY_CHUNK
    			-- is defined, it is set to the closest reasonable
    			-- value from it.

    	coalesce_period: INTEGER_32
    			-- Period of full coalesce (in number of collections)
    			-- If the environment variable EIF_FULL_COALESCE_PERIOD
    			-- is defined, it is set to the closest reasonable
    			-- value from it.
    			-- If null, no full coalescing is launched.

    	collecting: BOOLEAN
    			-- Is garbage collection enabled?

    	collection_period: INTEGER_32
    			-- Period of full collection.
    			-- If the environment variable EIF_FULL_COLLECTION_PERIOD
    			-- is defined, it is set to the closest reasonable
    			-- value from it.
    			-- If null, no full collection is launched.

    	conforms_to (other: ANY): BOOLEAN
    			-- Does type of current object conform to type
    			-- of `other' (as per Eiffel: The Language, chapter 13)?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void

    	generation_object_limit: INTEGER_32
    			-- Maximum size of object in generational scavenge zone.
    			-- If the environment variable EIF_GS_LIMIT
    			-- is defined, it is set to the closest reasonable
    			-- value from it.

    	largest_coalesced_block: INTEGER_32
    			-- Size of largest coalesced block since last call to
    			-- `largest_coalesced'; 0 if none.

    	max_mem: INTEGER_32
    			-- Maximum amount of bytes the run-time can allocate.

    	memory_count_map: HASH_TABLE [INTEGER_32, INTEGER_32]
    			-- Number of instances per dynamic type present in system.
    			-- Same as memory_map except that no references on the objects themselves
    			-- is kept.

    	memory_map: HASH_TABLE [ARRAYED_LIST [ANY], INTEGER_32]
    			-- Retrieves all object in system as a table indexed by dynamic type
    			-- where elements are all instances of a given data type.

    	memory_threshold: INTEGER_32
    			-- Minimum amount of bytes to be allocated before
    			-- starting an automatic garbage collection.

    	objects_instance_of (an_object: ANY): SPECIAL [ANY]
    			-- Objects that have same dynamic type as `an_object'.

    	referers (an_object: ANY): SPECIAL [ANY]
    			-- Objects that refer to `an_object'.

    	same_type (other: ANY): BOOLEAN
    			-- Is type of current object identical to type of `other'?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			definition: Result = (conforms_to (other) and other.conforms_to (Current))

    	scavenge_zone_size: INTEGER_32
    			-- Size of generational scavenge zone.
    			-- If the environment variable EIF_MEMORY_SCAVENGE
    			-- is defined, it is set to the closest reasonable
    			-- value from it.

    	tenure: INTEGER_32
    			-- Maximum age of object before being considered
    			-- as old (old objects are not scanned during
    			-- partial collection).
    			-- If the environment variable EIF_TENURE_MAX
    			-- is defined, it is set to the closest reasonable
    			-- value from it.

    feature -- Status setting

    	allocate_compact
    			-- Enter ``memory'' mode: will try to compact memory
    			-- before requesting more from the operating system.

    	allocate_fast
    			-- Enter ``speed'' mode: will optimize speed of memory
    			-- allocation rather than memory usage.

    	allocate_tiny
    			-- Enter ``tiny'' mode: will enter ``memory'' mode
    			-- after having freed as much memory as possible.

    	collection_off
    			-- Disable garbage collection.

    	collection_on
    			-- Enable garbage collection.

    	disable_time_accounting
    			-- Disable GC time accounting (default).

    	enable_time_accounting
    			-- Enable GC time accouting, accessible in gc_statistics.

    	set_coalesce_period (value: INTEGER_32)
    			-- Set coalesce_period. Every `value' collection,
    			-- the Garbage Collector will coalesce
    			-- the whole memory.
    		require
    			positive_value: value >= 0

    	set_collection_period (value: INTEGER_32)
    			-- Set collection_period. Every `value' collection,
    			-- the Garbage collector will perform a collection
    			-- on the whole memory (full collection), otherwise
    			-- a simple partial collection is done.
    		require
    			positive_value: value >= 0

    	set_max_mem (value: INTEGER_32)
    			-- Set the maximum amount of memory the run-time can allocate.
    		require
    			positive_value: value > 0

    	set_memory_threshold (value: INTEGER_32)
    			-- Set a new memory_threshold in bytes. Whenever the memory
    			-- allocated for Eiffel reaches this value, an automatic
    			-- collection is performed.
    		require
    			positive_value: value > 0

    feature -- Removal

    	collect
    			-- Force a partial collection cycle if garbage
    			-- collection is enabled; do nothing otherwise.

    	dispose
    			-- Action to be executed just before garbage collection
    			-- reclaims an object.
    			-- Default version does nothing; redefine in descendants
    			-- to perform specific dispose actions. Those actions
    			-- should only take care of freeing external resources;
    			-- they should not perform remote calls on other objects
    			-- since these may also be dead and reclaimed.

    	free (object: ANY)
    			-- Free `object', by-passing garbage collection.
    			-- Erratic behavior will result if the object is still
    			-- referenced.

    	full_coalesce
    			-- Coalesce the whole memory: merge adjacent free
    			-- blocks to reduce fragmentation. Useful, when
    			-- a lot of memory is allocated with garbage collector off.

    	full_collect
    			-- Force a full collection cycle if garbage
    			-- collection is enabled; do nothing otherwise.

    	mem_free (addr: POINTER)
    			-- Free memory of object at `addr'.
    			-- (Preferred interface is free.)

    feature -- Duplication

    	copy (other: like Current)
    			-- Update current object using fields of object attached
    			-- to `other', so as to yield equal objects.
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    			type_identity: same_type (other)
    		ensure -- from ANY
    			is_equal: is_equal (other)

    	frozen deep_copy (other: like Current)
    			-- Effect equivalent to that of:
    			--		copy (`other' . deep_twin)
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			deep_equal: deep_equal (Current, other)

    	frozen deep_twin: like Current
    			-- New object structure recursively duplicated from Current.
    			-- (from ANY)
    		ensure -- from ANY
    			deep_equal: deep_equal (Current, Result)

    	frozen standard_copy (other: like Current)
    			-- Copy every field of `other' onto corresponding field
    			-- of current object.
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    			type_identity: same_type (other)
    		ensure -- from ANY
    			is_standard_equal: standard_is_equal (other)

    	frozen standard_twin: like Current
    			-- New object field-by-field identical to `other'.
    			-- Always uses default copying semantics.
    			-- (from ANY)
    		ensure -- from ANY
    			standard_twin_not_void: Result /= Void
    			equal: standard_equal (Result, Current)

    	frozen twin: like Current
    			-- New object equal to `Current'
    			-- twin calls copy; to change copying/twining semantics, redefine copy.
    			-- (from ANY)
    		ensure -- from ANY
    			twin_not_void: Result /= Void
    			is_equal: Result.is_equal (Current)

    feature -- Basic operations

    	frozen default: like Current
    			-- Default value of object's type
    			-- (from ANY)

    	frozen default_pointer: POINTER
    			-- Default value of type `POINTER'
    			-- (Avoid the need to write `p'.default for
    			-- some `p' of type `POINTER'.)
    			-- (from ANY)

    	default_rescue
    			-- Process exception for routines with no Rescue clause.
    			-- (Default: do nothing.)
    			-- (from ANY)

    	frozen do_nothing
    			-- Execute a null action.
    			-- (from ANY)

    feature -- Output

    	io: STD_FILES
    			-- Handle to standard file setup
    			-- (from ANY)

    	out: STRING_8
    			-- New string containing terse printable representation
    			-- of current object
    			-- Was declared in ANY as synonym of tagged_out.
    			-- (from ANY)

    	print (some: ANY)
    			-- Write terse external representation of `some'
    			-- on standard output.
    			-- (from ANY)

    	frozen tagged_out: STRING_8
    			-- New string containing terse printable representation
    			-- of current object
    			-- Was declared in ANY as synonym of out.
    			-- (from ANY)

    feature -- Platform

    	operating_environment: OPERATING_ENVIRONMENT
    			-- Objects available from the operating system
    			-- (from ANY)

    invariant
    		-- from ANY
    	reflexive_equality: standard_is_equal (Current)
    	reflexive_conformance: conforms_to (Current)

    indexing
    	library: "EiffelBase: Library of reusable components for Eiffel."
    	copyright: "Copyright (c) 1984-2006, Eiffel Software and others"
    	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
    	source: "[
    		Eiffel Software
    		356 Storke Road, Goleta, CA 93117 USA
    		Telephone 805-685-1006, Fax 805-685-6869
    		Website http://www.eiffel.com
    		Customer support http://support.eiffel.com
    	]"

    end -- class MEMORY