/*
* Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
* University Research and Technology
* Corporation. All rights reserved.
* Copyright (c) 2004-2006 The University of Tennessee and The University
* of Tennessee Research Foundation. All rights
* reserved.
* Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
* University of Stuttgart. All rights reserved.
* Copyright (c) 2004-2005 The Regents of the University of California.
* All rights reserved.
* Copyright (c) 2007 Voltaire All rights reserved.
* $COPYRIGHT$
*
* Additional copyrights may follow
*
* $HEADER$
*/
/**
* @file
*
* The opal_list_t interface is used to provide a generic
* doubly-linked list container for Open MPI. It was inspired by (but
* is slightly different than) the Stantard Template Library (STL)
* std::list class. One notable difference from std::list is that
* when an opal_list_t is destroyed, all of the opal_list_item_t
* objects that it contains are orphaned -- they are \em not
* destroyed.
*
* The general idea is that opal_list_item_t objects can be put on an
* opal_list_t. Hence, you create a new type that derives from
* opal_list_item_t; this new type can then be used with opal_list_t
* containers.
*
* NOTE: opal_list_item_t instances can only be on \em one list at a
* time. Specifically, if you add an opal_list_item_t to one list,
* and then add it to another list (without first removing it from the
* first list), you will effectively be hosing the first list. You
* have been warned.
*
* If OMPI_ENABLE_DEBUG is true, a bunch of checks occur, including
* some spot checks for a debugging reference count in an attempt to
* ensure that an opal_list_item_t is only one *one* list at a time.
* Given the highly concurrent nature of this class, these spot checks
* cannot guarantee that an item is only one list at a time.
* Specifically, since it is a desirable attribute of this class to
* not use locks for normal operations, it is possible that two
* threads may [erroneously] modify an opal_list_item_t concurrently.
*
* The only way to guarantee that a debugging reference count is valid
* for the duration of an operation is to lock the item_t during the
* operation. But this fundamentally changes the desirable attribute
* of this class (i.e., no locks). So all we can do is spot-check the
* reference count in a bunch of places and check that it is still the
* value that we think it should be. But this doesn't mean that you
* can run into "unlucky" cases where two threads are concurrently
* modifying an item_t, but all the spot checks still return the
* "right" values. All we can do is hope that we have enough spot
* checks to statistically drive down the possibility of the unlucky
* cases happening.
*/
#ifndef OPAL_LIST_H
#define OPAL_LIST_H
#include <stdio.h>
#include <stdlib.h>
#include "opal/class/opal_object.h"
#if OMPI_ENABLE_DEBUG
/* Need atomics for debugging (reference counting) */
#include "opal/sys/atomic.h"
#include "opal/threads/mutex.h"
#endif
#if defined(c_plusplus) || defined(__cplusplus)
extern "C" {
#endif
/**
* \internal
*
* The class for the list container.
*/
OPAL_DECLSPEC OBJ_CLASS_DECLARATION(opal_list_t);
/**
* \internal
*
* Base class for items that are put in list (opal_list_t) containers.
*/
OPAL_DECLSPEC OBJ_CLASS_DECLARATION(opal_list_item_t);
/**
* \internal
*
* Struct of an opal_list_item_t
*/
struct opal_list_item_t
{
opal_object_t super;
/**< Generic parent class for all Open MPI objects */
volatile struct opal_list_item_t *opal_list_next;
/**< Pointer to next list item */
volatile struct opal_list_item_t *opal_list_prev;
/**< Pointer to previous list item */
int32_t item_free;
#if OMPI_ENABLE_DEBUG
/** Atomic reference count for debugging */
volatile int32_t opal_list_item_refcount;
/** The list this item belong to */
volatile struct opal_list_t* opal_list_item_belong_to;
#endif
};
/**
* Base type for items that are put in a list (opal_list_t) containers.
*/
typedef struct opal_list_item_t opal_list_item_t;
/**
* Get the next item in a list.
*
* @param item A list item.
*
* @returns The next item in the list
*/
#define opal_list_get_next(item) \
((item) ? ((opal_list_item_t*) ((opal_list_item_t*)(item))->opal_list_next) : NULL)
/**
* Get the next item in a list.
*
* @param item A list item.
*
* @returns The next item in the list
*/
#define opal_list_get_prev(item) \
((item) ? ((opal_list_item_t*) ((opal_list_item_t*)(item))->opal_list_prev) : NULL)
/**
* \internal
*
* Struct of an opal_list_t
*/
struct opal_list_t
{
opal_object_t super;
/**< Generic parent class for all Open MPI objects */
opal_list_item_t opal_list_sentinel;
/**< Head and tail item of the list */
volatile size_t opal_list_length;
/**< Quick reference to the number of items in the list */
};
/**
* List container type.
*/
typedef struct opal_list_t opal_list_t;
/**
* Check for empty list
*
* @param list The list container
*
* @returns true if list's size is 0, false otherwise
*
* This is an O(1) operation.
*
* This is an inlined function in compilers that support inlining,
* so it's usually a cheap operation.
*/
static inline bool opal_list_is_empty(opal_list_t* list)
{
return (list->opal_list_sentinel.opal_list_next ==
&(list->opal_list_sentinel) ? true : false);
}
/**
* Return the first item on the list (does not remove it).
*
* @param list The list container
*
* @returns A pointer to the first item on the list
*
* This is an O(1) operation to return the first item on the list. It
* should be compared against the returned value from
* opal_list_get_end() to ensure that the list is not empty.
*
* This is an inlined function in compilers that support inlining, so
* it's usually a cheap operation.
*/
static inline opal_list_item_t* opal_list_get_first(opal_list_t* list)
{
opal_list_item_t* item = (opal_list_item_t*)list->opal_list_sentinel.opal_list_next;
#if OMPI_ENABLE_DEBUG
/* Spot check: ensure that the first item is only on one list */
assert(1 == item->opal_list_item_refcount);
assert( list == item->opal_list_item_belong_to );
#endif
return item;
}
/**
* Return the last item on the list (does not remove it).
*
* @param list The list container
*
* @returns A pointer to the last item on the list
*
* This is an O(1) operation to return the last item on the list. It
* should be compared against the returned value from
* opal_list_get_begin() to ensure that the list is not empty.
*
* This is an inlined function in compilers that support inlining, so
* it's usually a cheap operation.
*/
static inline opal_list_item_t* opal_list_get_last(opal_list_t* list)
{
opal_list_item_t* item = (opal_list_item_t *)list->opal_list_sentinel.opal_list_prev;
#if OMPI_ENABLE_DEBUG
/* Spot check: ensure that the last item is only on one list */
assert( 1 == item->opal_list_item_refcount );
assert( list == item->opal_list_item_belong_to );
#endif
return item;
}
/**
* Return the beginning of the list; an invalid list entry suitable
* for comparison only.
*
* @param list The list container
*
* @returns A pointer to the beginning of the list.
*
* This is an O(1) operation to return the beginning of the list.
* Similar to the STL, this is a special invalid list item -- it
* should \em not be used for storage. It is only suitable for
* comparison to other items in the list to see if they are valid or
* not; it's ususally used when iterating through the items in a list.
*
* This is an inlined function in compilers that support inlining, so
* it's usually a cheap operation.
*/
static inline opal_list_item_t* opal_list_get_begin(opal_list_t* list)
{
return &(list->opal_list_sentinel);
}
/**
* Return the end of the list; an invalid list entry suitable for
* comparison only.
*
* @param list The list container
*
* @returns A pointer to the end of the list.
*
* This is an O(1) operation to return the end of the list.
* Similar to the STL, this is a special invalid list item -- it
* should \em not be used for storage. It is only suitable for
* comparison to other items in the list to see if they are valid or
* not; it's ususally used when iterating through the items in a list.
*
* This is an inlined function in compilers that support inlining, so
* it's usually a cheap operation.
*/
static inline opal_list_item_t* opal_list_get_end(opal_list_t* list)
{
return &(list->opal_list_sentinel);
}
/**
* Return the number of items in a list
*
* @param list The list container
*
* @returns The size of the list (size_t)
*
* This is an O(1) lookup to return the size of the list.
*
* This is an inlined function in compilers that support inlining, so
* it's usually a cheap operation.
*
* \warning The size of the list is cached as part of the list. In
* the future, calling \c opal_list_splice or \c opal_list_join may
* result in this function recomputing the list size, which would be
* an O(N) operation. If \c opal_list_splice or \c opal_list_join is
* never called on the specified list, this function will always be
* O(1).
*/
static inline size_t opal_list_get_size(opal_list_t* list)
{
#if OMPI_ENABLE_DEBUG && 0
/* not sure if we really want this running in devel, as it does
* slow things down. Wanted for development of splice / join to
* make sure length was reset properly
*/
size_t check_len = 0;
opal_list_item_t *item;
for (item = opal_list_get_first(list) ;
item != opal_list_get_end(list) ;
item = opal_list_get_next(item)) {
check_len++;
}
if (check_len != list->opal_list_length) {
fprintf(stderr," Error :: opal_list_get_size - opal_list_length does not match actual list length\n");
fflush(stderr);
abort();
}
#endif
return list->opal_list_length;
}
/**
* Remove an item from a list.
*
* @param list The list container
* @param item The item to remove
*
* @returns A pointer to the item on the list previous to the one
* that was removed.
*
* This is an O(1) operation to remove an item from the list. The
* forward / reverse pointers in the list are updated and the item is
* removed. The list item that is returned is now "owned" by the
* caller -- they are responsible for OBJ_RELEASE()'ing it.
*
* If debugging is enabled (specifically, if --enable-debug was used
* to configure Open MPI), this is an O(N) operation because it checks
* to see if the item is actually in the list first.
*
* This is an inlined function in compilers that support inlining, so
* it's usually a cheap operation.
*/
static inline opal_list_item_t *opal_list_remove_item
(opal_list_t *list, opal_list_item_t *item)
{
#if OMPI_ENABLE_DEBUG
opal_list_item_t *item_ptr;
bool found = false;
/* check to see that the item is in the list */
for (item_ptr = opal_list_get_first(list);
item_ptr != opal_list_get_end(list);
item_ptr = (opal_list_item_t *)(item_ptr->opal_list_next)) {
if (item_ptr == (opal_list_item_t *) item) {
found = true;
break;
}
}
if (!found) {
fprintf(stderr," Warning :: opal_list_remove_item - the item %p is not on the list %p \n",(void*) item, (void*) list);
fflush(stderr);
return (opal_list_item_t *)NULL;
}
assert( list == item->opal_list_item_belong_to );
#endif
/* reset next pointer of previous element */
item->opal_list_prev->opal_list_next=item->opal_list_next;
/* reset previous pointer of next element */
item->opal_list_next->opal_list_prev=item->opal_list_prev;
list->opal_list_length--;
#if OMPI_ENABLE_DEBUG
/* Spot check: ensure that this item is still only on one list */
OPAL_THREAD_ADD32( &(item->opal_list_item_refcount), -1 );
assert(0 == item->opal_list_item_refcount);
item->opal_list_item_belong_to = NULL;
#endif
return (opal_list_item_t *)item->opal_list_prev;
}
/**
* Append an item to the end of the list.
*
* @param list The list container
* @param item The item to append
*
* This is an O(1) operation to append an item to the end of a list.
* The opal_list_item_t is not OBJ_RETAIN()'ed; it is assumed that
* "ownership" of the item is passed from the caller to the list.
*
* This is an inlined function in compilers that support inlining, so
* it's usually a cheap operation.
*/
#if OMPI_ENABLE_DEBUG
#define opal_list_append(l,i) \
_opal_list_append(l,i,__FILE__,__LINE__)
#else
#define opal_list_append(l,i) \
_opal_list_append(l,i)
#endif /* OMPI_ENABLE_DEBUG */
static inline void _opal_list_append(opal_list_t *list, opal_list_item_t *item
#if OMPI_ENABLE_DEBUG
, const char* FILE_NAME, int LINENO
#endif /* OMPI_ENABLE_DEBUG */
)
{
opal_list_item_t* sentinel = &(list->opal_list_sentinel);
#if OMPI_ENABLE_DEBUG
/* Spot check: ensure that this item is previously on no lists */
assert(0 == item->opal_list_item_refcount);
assert( NULL == item->opal_list_item_belong_to );
item->super.cls_init_file_name = FILE_NAME;
item->super.cls_init_lineno = LINENO;
#endif
/* set new element's previous pointer */
item->opal_list_prev = sentinel->opal_list_prev;
/* reset previous pointer on current last element */
sentinel->opal_list_prev->opal_list_next = item;
/* reset new element's next pointer */
item->opal_list_next = sentinel;
/* reset the list's tail element previous pointer */
sentinel->opal_list_prev = item;
/* increment list element counter */
list->opal_list_length++;
#if OMPI_ENABLE_DEBUG
/* Spot check: ensure this item is only on the list that we just
appended it to */
OPAL_THREAD_ADD32( &(item->opal_list_item_refcount), 1 );
assert(1 == item->opal_list_item_refcount);
item->opal_list_item_belong_to = list;
#endif
}
/**
* Prepend an item to the beginning of the list.
*
* @param list The list container
* @param item The item to prepend
*
* This is an O(1) operation to prepend an item to the beginning of a
* list. The opal_list_item_t is not OBJ_RETAIN()'ed; it is assumed
* that "ownership" of the item is passed from the caller to the list.
*
* This is an inlined function in compilers that support inlining, so
* it's usually a cheap operation.
*/
static inline void opal_list_prepend(opal_list_t *list,
opal_list_item_t *item)
{
opal_list_item_t* sentinel = &(list->opal_list_sentinel);
#if OMPI_ENABLE_DEBUG
/* Spot check: ensure that this item is previously on no lists */
assert(0 == item->opal_list_item_refcount);
assert( NULL == item->opal_list_item_belong_to );
#endif
/* reset item's next pointer */
item->opal_list_next = sentinel->opal_list_next;
/* reset item's previous pointer */
item->opal_list_prev = sentinel;
/* reset previous first element's previous poiner */
sentinel->opal_list_next->opal_list_prev = item;
/* reset head's next pointer */
sentinel->opal_list_next = item;
/* increment list element counter */
list->opal_list_length++;
#if OMPI_ENABLE_DEBUG
/* Spot check: ensure this item is only on the list that we just
prepended it to */
OPAL_THREAD_ADD32( &(item->opal_list_item_refcount), 1 );
assert(1 == item->opal_list_item_refcount);
item->opal_list_item_belong_to = list;
#endif
}
/**
* Remove the first item from the list and return it.
*
* @param list The list container
*
* @returns The first item on the list. If the list is empty,
* NULL will be returned
*
* This is an O(1) operation to return the first item on the list. If
* the list is not empty, a pointer to the first item in the list will
* be returned. Ownership of the item is transferred from the list to
* the caller; no calls to OBJ_RETAIN() or OBJ_RELEASE() are invoked.
*
* This is an inlined function in compilers that support inlining, so
* it's usually a cheap operation.
*/
static inline opal_list_item_t *opal_list_remove_first(opal_list_t *list)
{
/* Removes and returns first item on list.
Caller now owns the item and should release the item
when caller is done with it.
*/
volatile opal_list_item_t *item;
if ( 0 == list->opal_list_length ) {
return (opal_list_item_t *)NULL;
}
#if OMPI_ENABLE_DEBUG
/* Spot check: ensure that the first item is only on this list */
assert(1 == list->opal_list_sentinel.opal_list_next->opal_list_item_refcount);
#endif
/* reset list length counter */
list->opal_list_length--;
/* get pointer to first element on the list */
item = list->opal_list_sentinel.opal_list_next;
/* reset previous pointer of next item on the list */
item->opal_list_next->opal_list_prev = item->opal_list_prev;
/* reset the head next pointer */
list->opal_list_sentinel.opal_list_next = item->opal_list_next;
#if OMPI_ENABLE_DEBUG
assert( list == item->opal_list_item_belong_to );
item->opal_list_item_belong_to = NULL;
item->opal_list_prev=(opal_list_item_t *)NULL;
item->opal_list_next=(opal_list_item_t *)NULL;
/* Spot check: ensure that the item we're returning is now on no
lists */
OPAL_THREAD_ADD32( &(item->opal_list_item_refcount), -1 );
assert(0 == item->opal_list_item_refcount);
#endif
return (opal_list_item_t *) item;
}
/**
* Remove the last item from the list and return it.
*
* @param list The list container
*
* @returns The last item on the list. If the list is empty,
* NULL will be returned
*
* This is an O(1) operation to return the last item on the list. If
* the list is not empty, a pointer to the last item in the list will
* be returned. Ownership of the item is transferred from the list to
* the caller; no calls to OBJ_RETAIN() or OBJ_RELEASE() are invoked.
*
* This is an inlined function in compilers that support inlining, so
* it's usually a cheap operation.
*/
static inline opal_list_item_t *opal_list_remove_last(opal_list_t *list)
{
/* Removes, releases and returns last item on list.
Caller now owns the item and should release the item
when caller is done with it.
*/
volatile opal_list_item_t *item;
if ( 0 == list->opal_list_length ) {
return (opal_list_item_t *)NULL;
}
#if OMPI_ENABLE_DEBUG
/* Spot check: ensure that the first item is only on this list */
assert(1 == list->opal_list_sentinel.opal_list_prev->opal_list_item_refcount);
#endif
/* reset list length counter */
list->opal_list_length--;
/* get item */
item = list->opal_list_sentinel.opal_list_prev;
/* reset previous pointer on next to last pointer */
item->opal_list_prev->opal_list_next = item->opal_list_next;
/* reset tail's previous pointer */
list->opal_list_sentinel.opal_list_prev = item->opal_list_prev;
#if OMPI_ENABLE_DEBUG
assert( list == item->opal_list_item_belong_to );
item->opal_list_next = item->opal_list_prev = (opal_list_item_t *)NULL;
/* Spot check: ensure that the item we're returning is now on no
lists */
OPAL_THREAD_ADD32( &(item->opal_list_item_refcount), -1 );
assert(0 == item->opal_list_item_refcount);
item->opal_list_item_belong_to = NULL;
#endif
return (opal_list_item_t *) item;
}
/**
* Add an item to the list before a given element
*
* @param list The list container
* @param pos List element to insert \c item before
* @param item The item to insert
*
* Inserts \c item before \c pos. This is an O(1) operation.
*/
static inline void opal_list_insert_pos(opal_list_t *list, opal_list_item_t *pos,
opal_list_item_t *item)
{
#if OMPI_ENABLE_DEBUG
/* Spot check: ensure that the item we're insertting is currently
not on any list */
assert(0 == item->opal_list_item_refcount);
assert( NULL == item->opal_list_item_belong_to );
#endif
/* point item at the existing elements */
item->opal_list_next = pos;
item->opal_list_prev = pos->opal_list_prev;
/* splice into the list */
pos->opal_list_prev->opal_list_next = item;
pos->opal_list_prev = item;
/* reset list length counter */
list->opal_list_length++;
#if OMPI_ENABLE_DEBUG
/* Spot check: double check that this item is only on the list
that we just added it to */
OPAL_THREAD_ADD32( &(item->opal_list_item_refcount), 1 );
assert(1 == item->opal_list_item_refcount);
item->opal_list_item_belong_to = list;
#endif
}
/**
* Add an item to the list at a specific index location in the list.
*
* @param list The list container
* @param item The item to insert
* @param index Location to add the item
*
* @returns true if insertion succeeded; otherwise false
*
* This is potentially an O(N) operation to traverse down to the
* correct location in the list and add an item.
*
* Example: if idx = 2 and list = item1->item2->item3->item4, then
* after insert, list = item1->item2->item->item3->item4.
*
* If index is greater than the length of the list, no action is
* performed and false is returned.
*/
OPAL_DECLSPEC bool opal_list_insert(opal_list_t *list, opal_list_item_t *item,
long long idx);
/**
* Join a list into another list
*
* @param thislist List container for list being operated on
* @param pos List item in \c thislist marking the position before
* which items are inserted
* @param xlist List container for list being spliced from
*
* Join a list into another list. All of the elements of \c xlist
* are inserted before \c pos and removed from \c xlist.
*
* This operation is an O(1) operation. Both \c thislist and \c
* xlist must be valid list containsers. \c xlist will be empty
* but valid after the call. All pointers to \c opal_list_item_t
* containers remain valid, including those that point to elements
* in \c xlist.
*/
OPAL_DECLSPEC void opal_list_join(opal_list_t *thislist, opal_list_item_t *pos,
opal_list_t *xlist);
/**
* Splice a list into another list
*
* @param thislist List container for list being operated on
* @param pos List item in \c thislist marking the position before
* which items are inserted
* @param xlist List container for list being spliced from
* @param first List item in \c xlist marking the start of elements
* to be copied into \c thislist
* @param last List item in \c xlist marking the end of elements
* to be copied into \c thislist
*
* Splice a subset of a list into another list. The \c [first,
* last) elements of \c xlist are moved into \c thislist,
* inserting them before \c pos. \c pos must be a valid iterator
* in \c thislist and \c [first, last) must be a valid range in \c
* xlist. \c postition must not be in the range \c [first, last).
* It is, however, valid for \c xlist and \c thislist to be the
* same list.
*
* This is an O(N) operation because the length of both lists must
* be recomputed.
*/
OPAL_DECLSPEC void opal_list_splice(opal_list_t *thislist, opal_list_item_t *pos,
opal_list_t *xlist, opal_list_item_t *first,
opal_list_item_t *last);
/**
* Comparison function for opal_list_sort(), below.
*
* @param a Pointer to a pointer to an opal_list_item_t.
* Explanation below.
* @param b Pointer to a pointer to an opal_list_item_t.
* Explanation below.
* @retval 1 if \em a is greater than \em b
* @retval 0 if \em a is equal to \em b
* @retval 11 if \em a is less than \em b
*
* This function is invoked by qsort(3) from within
* opal_list_sort(). It is important to understand what
* opal_list_sort() does before invoking qsort, so go read that
* documentation first.
*
* The important thing to realize here is that a and b will be \em
* double pointers to the items that you need to compare. Here's
* a sample compare function to illustrate this point:
*
* \verb
* static int compare(opal_list_item_t **a, opal_list_item_t **b)
* {
* orte_pls_base_cmp_t *aa = *((orte_pls_base_cmp_t **) a);
* orte_pls_base_cmp_t *bb = *((orte_pls_base_cmp_t **) b);
*
* if (bb->priority > aa->priority) {
* return 1;
* } else if (bb->priority == aa->priority) {
* return 0;
* } else {
* return -1;
* }
* }
* \endverb
*/
typedef int (*opal_list_item_compare_fn_t)(opal_list_item_t **a,
opal_list_item_t **b);
/**
* Sort a list with a provided compare function.
*
* @param list The list to sort
* @param compare Compare function
*
* Put crassly, this function's complexity is O(N) + O(log(N)).
* Its algorithm is:
*
* - remove every item from the list and put the corresponding
* (opal_list_item_t*)'s in an array
* - call qsort(3) with that array and your compare function
* - re-add every element of the now-sorted array to the list
*
* The resulting list is now ordered. Note, however, that since
* an array of pointers is sorted, the comparison function must do
* a double de-reference to get to the actual opal_list_item_t (or
* whatever the underlying type is). See the documentation of
* opal_list_item_compare_fn_t for an example).
*/
OPAL_DECLSPEC int opal_list_sort(opal_list_t* list, opal_list_item_compare_fn_t compare);
#if defined(c_plusplus) || defined(__cplusplus)
}
#endif
#endif /* OPAL_LIST_H */