server-skynet-source-3rd-je.../include/jemalloc/internal/rtree.h
2016-06-03 12:27:41 -07:00

497 lines
14 KiB
C

/*
* This radix tree implementation is tailored to the singular purpose of
* associating metadata with chunks that are currently owned by jemalloc.
*
*******************************************************************************
*/
#ifdef JEMALLOC_H_TYPES
typedef struct rtree_elm_s rtree_elm_t;
typedef struct rtree_elm_witness_s rtree_elm_witness_t;
typedef struct rtree_elm_witness_tsd_s rtree_elm_witness_tsd_t;
typedef struct rtree_level_s rtree_level_t;
typedef struct rtree_s rtree_t;
/*
* RTREE_BITS_PER_LEVEL must be a power of two that is no larger than the
* machine address width.
*/
#define LG_RTREE_BITS_PER_LEVEL 4
#define RTREE_BITS_PER_LEVEL (1U << LG_RTREE_BITS_PER_LEVEL)
/* Maximum rtree height. */
#define RTREE_HEIGHT_MAX \
((1U << (LG_SIZEOF_PTR+3)) / RTREE_BITS_PER_LEVEL)
/* Used for two-stage lock-free node initialization. */
#define RTREE_NODE_INITIALIZING ((rtree_elm_t *)0x1)
/*
* Maximum number of concurrently acquired elements per thread. This controls
* how many witness_t structures are embedded in tsd. Ideally rtree_elm_t would
* have a witness_t directly embedded, but that would dramatically bloat the
* tree. This must contain enough entries to e.g. coalesce two extents.
*/
#define RTREE_ELM_ACQUIRE_MAX 4
/* Initializers for rtree_elm_witness_tsd_t. */
#define RTREE_ELM_WITNESS_INITIALIZER { \
NULL, \
WITNESS_INITIALIZER("rtree_elm", WITNESS_RANK_RTREE_ELM) \
}
#define RTREE_ELM_WITNESS_TSD_INITIALIZER { \
{ \
RTREE_ELM_WITNESS_INITIALIZER, \
RTREE_ELM_WITNESS_INITIALIZER, \
RTREE_ELM_WITNESS_INITIALIZER, \
RTREE_ELM_WITNESS_INITIALIZER \
} \
}
#endif /* JEMALLOC_H_TYPES */
/******************************************************************************/
#ifdef JEMALLOC_H_STRUCTS
struct rtree_elm_s {
union {
void *pun;
rtree_elm_t *child;
extent_t *extent;
};
};
struct rtree_elm_witness_s {
const rtree_elm_t *elm;
witness_t witness;
};
struct rtree_elm_witness_tsd_s {
rtree_elm_witness_t witnesses[RTREE_ELM_ACQUIRE_MAX];
};
struct rtree_level_s {
/*
* A non-NULL subtree points to a subtree rooted along the hypothetical
* path to the leaf node corresponding to key 0. Depending on what keys
* have been used to store to the tree, an arbitrary combination of
* subtree pointers may remain NULL.
*
* Suppose keys comprise 48 bits, and LG_RTREE_BITS_PER_LEVEL is 4.
* This results in a 3-level tree, and the leftmost leaf can be directly
* accessed via subtrees[2], the subtree prefixed by 0x0000 (excluding
* 0x00000000) can be accessed via subtrees[1], and the remainder of the
* tree can be accessed via subtrees[0].
*
* levels[0] : [<unused> | 0x0001******** | 0x0002******** | ...]
*
* levels[1] : [<unused> | 0x00000001**** | 0x00000002**** | ... ]
*
* levels[2] : [extent(0x000000000000) | extent(0x000000000001) | ...]
*
* This has practical implications on x64, which currently uses only the
* lower 47 bits of virtual address space in userland, thus leaving
* subtrees[0] unused and avoiding a level of tree traversal.
*/
union {
void *subtree_pun;
rtree_elm_t *subtree;
};
/* Number of key bits distinguished by this level. */
unsigned bits;
/*
* Cumulative number of key bits distinguished by traversing to
* corresponding tree level.
*/
unsigned cumbits;
};
struct rtree_s {
unsigned height;
/*
* Precomputed table used to convert from the number of leading 0 key
* bits to which subtree level to start at.
*/
unsigned start_level[RTREE_HEIGHT_MAX];
rtree_level_t levels[RTREE_HEIGHT_MAX];
};
#endif /* JEMALLOC_H_STRUCTS */
/******************************************************************************/
#ifdef JEMALLOC_H_EXTERNS
bool rtree_new(rtree_t *rtree, unsigned bits);
#ifdef JEMALLOC_JET
typedef rtree_elm_t *(rtree_node_alloc_t)(tsdn_t *, rtree_t *, size_t);
extern rtree_node_alloc_t *rtree_node_alloc;
typedef void (rtree_node_dalloc_t)(tsdn_t *, rtree_t *, rtree_elm_t *);
extern rtree_node_dalloc_t *rtree_node_dalloc;
void rtree_delete(tsdn_t *tsdn, rtree_t *rtree);
#endif
rtree_elm_t *rtree_subtree_read_hard(tsdn_t *tsdn, rtree_t *rtree,
unsigned level);
rtree_elm_t *rtree_child_read_hard(tsdn_t *tsdn, rtree_t *rtree,
rtree_elm_t *elm, unsigned level);
void rtree_elm_witness_acquire(tsdn_t *tsdn, const rtree_t *rtree,
uintptr_t key, const rtree_elm_t *elm);
void rtree_elm_witness_access(tsdn_t *tsdn, const rtree_t *rtree,
const rtree_elm_t *elm);
void rtree_elm_witness_release(tsdn_t *tsdn, const rtree_t *rtree,
const rtree_elm_t *elm);
void rtree_elm_witnesses_cleanup(tsd_t *tsd);
#endif /* JEMALLOC_H_EXTERNS */
/******************************************************************************/
#ifdef JEMALLOC_H_INLINES
#ifndef JEMALLOC_ENABLE_INLINE
unsigned rtree_start_level(rtree_t *rtree, uintptr_t key);
uintptr_t rtree_subkey(rtree_t *rtree, uintptr_t key, unsigned level);
bool rtree_node_valid(rtree_elm_t *node);
rtree_elm_t *rtree_child_tryread(rtree_elm_t *elm, bool dependent);
rtree_elm_t *rtree_child_read(tsdn_t *tsdn, rtree_t *rtree, rtree_elm_t *elm,
unsigned level, bool dependent);
extent_t *rtree_elm_read(rtree_elm_t *elm, bool dependent);
void rtree_elm_write(rtree_elm_t *elm, const extent_t *extent);
rtree_elm_t *rtree_subtree_tryread(rtree_t *rtree, unsigned level,
bool dependent);
rtree_elm_t *rtree_subtree_read(tsdn_t *tsdn, rtree_t *rtree,
unsigned level, bool dependent);
rtree_elm_t *rtree_elm_lookup(tsdn_t *tsdn, rtree_t *rtree, uintptr_t key,
bool dependent, bool init_missing);
bool rtree_write(tsdn_t *tsdn, rtree_t *rtree, uintptr_t key,
const extent_t *extent);
extent_t *rtree_read(tsdn_t *tsdn, rtree_t *rtree, uintptr_t key,
bool dependent);
rtree_elm_t *rtree_elm_acquire(tsdn_t *tsdn, rtree_t *rtree, uintptr_t key,
bool dependent, bool init_missing);
extent_t *rtree_elm_read_acquired(tsdn_t *tsdn, const rtree_t *rtree,
rtree_elm_t *elm);
void rtree_elm_write_acquired(tsdn_t *tsdn, const rtree_t *rtree,
rtree_elm_t *elm, const extent_t *extent);
void rtree_elm_release(tsdn_t *tsdn, const rtree_t *rtree, rtree_elm_t *elm);
void rtree_clear(tsdn_t *tsdn, rtree_t *rtree, uintptr_t key);
#endif
#if (defined(JEMALLOC_ENABLE_INLINE) || defined(JEMALLOC_RTREE_C_))
JEMALLOC_ALWAYS_INLINE unsigned
rtree_start_level(rtree_t *rtree, uintptr_t key)
{
unsigned start_level;
if (unlikely(key == 0))
return (rtree->height - 1);
start_level = rtree->start_level[lg_floor(key) >>
LG_RTREE_BITS_PER_LEVEL];
assert(start_level < rtree->height);
return (start_level);
}
JEMALLOC_ALWAYS_INLINE uintptr_t
rtree_subkey(rtree_t *rtree, uintptr_t key, unsigned level)
{
return ((key >> ((ZU(1) << (LG_SIZEOF_PTR+3)) -
rtree->levels[level].cumbits)) & ((ZU(1) <<
rtree->levels[level].bits) - 1));
}
JEMALLOC_ALWAYS_INLINE bool
rtree_node_valid(rtree_elm_t *node)
{
return ((uintptr_t)node > (uintptr_t)RTREE_NODE_INITIALIZING);
}
JEMALLOC_ALWAYS_INLINE rtree_elm_t *
rtree_child_tryread(rtree_elm_t *elm, bool dependent)
{
rtree_elm_t *child;
/* Double-checked read (first read may be stale). */
child = elm->child;
if (!dependent && !rtree_node_valid(child))
child = atomic_read_p(&elm->pun);
assert(!dependent || child != NULL);
return (child);
}
JEMALLOC_ALWAYS_INLINE rtree_elm_t *
rtree_child_read(tsdn_t *tsdn, rtree_t *rtree, rtree_elm_t *elm, unsigned level,
bool dependent)
{
rtree_elm_t *child;
child = rtree_child_tryread(elm, dependent);
if (!dependent && unlikely(!rtree_node_valid(child)))
child = rtree_child_read_hard(tsdn, rtree, elm, level);
assert(!dependent || child != NULL);
return (child);
}
JEMALLOC_ALWAYS_INLINE extent_t *
rtree_elm_read(rtree_elm_t *elm, bool dependent)
{
extent_t *extent;
if (dependent) {
/*
* Reading a value on behalf of a pointer to a valid allocation
* is guaranteed to be a clean read even without
* synchronization, because the rtree update became visible in
* memory before the pointer came into existence.
*/
extent = elm->extent;
} else {
/*
* An arbitrary read, e.g. on behalf of ivsalloc(), may not be
* dependent on a previous rtree write, which means a stale read
* could result if synchronization were omitted here.
*/
extent = (extent_t *)atomic_read_p(&elm->pun);
}
/* Mask the lock bit. */
extent = (extent_t *)((uintptr_t)extent & ~((uintptr_t)0x1));
return (extent);
}
JEMALLOC_INLINE void
rtree_elm_write(rtree_elm_t *elm, const extent_t *extent)
{
atomic_write_p(&elm->pun, extent);
}
JEMALLOC_ALWAYS_INLINE rtree_elm_t *
rtree_subtree_tryread(rtree_t *rtree, unsigned level, bool dependent)
{
rtree_elm_t *subtree;
/* Double-checked read (first read may be stale). */
subtree = rtree->levels[level].subtree;
if (!dependent && unlikely(!rtree_node_valid(subtree)))
subtree = atomic_read_p(&rtree->levels[level].subtree_pun);
assert(!dependent || subtree != NULL);
return (subtree);
}
JEMALLOC_ALWAYS_INLINE rtree_elm_t *
rtree_subtree_read(tsdn_t *tsdn, rtree_t *rtree, unsigned level, bool dependent)
{
rtree_elm_t *subtree;
subtree = rtree_subtree_tryread(rtree, level, dependent);
if (!dependent && unlikely(!rtree_node_valid(subtree)))
subtree = rtree_subtree_read_hard(tsdn, rtree, level);
assert(!dependent || subtree != NULL);
return (subtree);
}
JEMALLOC_ALWAYS_INLINE rtree_elm_t *
rtree_elm_lookup(tsdn_t *tsdn, rtree_t *rtree, uintptr_t key, bool dependent,
bool init_missing)
{
uintptr_t subkey;
unsigned start_level;
rtree_elm_t *node;
assert(!dependent || !init_missing);
start_level = rtree_start_level(rtree, key);
node = init_missing ? rtree_subtree_read(tsdn, rtree, start_level,
dependent) : rtree_subtree_tryread(rtree, start_level, dependent);
#define RTREE_GET_BIAS (RTREE_HEIGHT_MAX - rtree->height)
switch (start_level + RTREE_GET_BIAS) {
#define RTREE_GET_SUBTREE(level) \
case level: \
assert(level < (RTREE_HEIGHT_MAX-1)); \
if (!dependent && unlikely(!rtree_node_valid(node))) \
return (NULL); \
subkey = rtree_subkey(rtree, key, level - \
RTREE_GET_BIAS); \
node = init_missing ? rtree_child_read(tsdn, rtree, \
&node[subkey], level - RTREE_GET_BIAS, dependent) : \
rtree_child_tryread(&node[subkey], dependent); \
/* Fall through. */
#define RTREE_GET_LEAF(level) \
case level: \
assert(level == (RTREE_HEIGHT_MAX-1)); \
if (!dependent && unlikely(!rtree_node_valid(node))) \
return (NULL); \
subkey = rtree_subkey(rtree, key, level - \
RTREE_GET_BIAS); \
/* \
* node is a leaf, so it contains values rather than \
* child pointers. \
*/ \
return (&node[subkey]);
#if RTREE_HEIGHT_MAX > 1
RTREE_GET_SUBTREE(0)
#endif
#if RTREE_HEIGHT_MAX > 2
RTREE_GET_SUBTREE(1)
#endif
#if RTREE_HEIGHT_MAX > 3
RTREE_GET_SUBTREE(2)
#endif
#if RTREE_HEIGHT_MAX > 4
RTREE_GET_SUBTREE(3)
#endif
#if RTREE_HEIGHT_MAX > 5
RTREE_GET_SUBTREE(4)
#endif
#if RTREE_HEIGHT_MAX > 6
RTREE_GET_SUBTREE(5)
#endif
#if RTREE_HEIGHT_MAX > 7
RTREE_GET_SUBTREE(6)
#endif
#if RTREE_HEIGHT_MAX > 8
RTREE_GET_SUBTREE(7)
#endif
#if RTREE_HEIGHT_MAX > 9
RTREE_GET_SUBTREE(8)
#endif
#if RTREE_HEIGHT_MAX > 10
RTREE_GET_SUBTREE(9)
#endif
#if RTREE_HEIGHT_MAX > 11
RTREE_GET_SUBTREE(10)
#endif
#if RTREE_HEIGHT_MAX > 12
RTREE_GET_SUBTREE(11)
#endif
#if RTREE_HEIGHT_MAX > 13
RTREE_GET_SUBTREE(12)
#endif
#if RTREE_HEIGHT_MAX > 14
RTREE_GET_SUBTREE(13)
#endif
#if RTREE_HEIGHT_MAX > 15
RTREE_GET_SUBTREE(14)
#endif
#if RTREE_HEIGHT_MAX > 16
# error Unsupported RTREE_HEIGHT_MAX
#endif
RTREE_GET_LEAF(RTREE_HEIGHT_MAX-1)
#undef RTREE_GET_SUBTREE
#undef RTREE_GET_LEAF
default: not_reached();
}
#undef RTREE_GET_BIAS
not_reached();
}
JEMALLOC_INLINE bool
rtree_write(tsdn_t *tsdn, rtree_t *rtree, uintptr_t key, const extent_t *extent)
{
rtree_elm_t *elm;
assert(extent != NULL); /* Use rtree_clear() for this case. */
assert(((uintptr_t)extent & (uintptr_t)0x1) == (uintptr_t)0x0);
elm = rtree_elm_lookup(tsdn, rtree, key, false, true);
if (elm == NULL)
return (true);
assert(rtree_elm_read(elm, false) == NULL);
rtree_elm_write(elm, extent);
return (false);
}
JEMALLOC_ALWAYS_INLINE extent_t *
rtree_read(tsdn_t *tsdn, rtree_t *rtree, uintptr_t key, bool dependent)
{
rtree_elm_t *elm;
elm = rtree_elm_lookup(tsdn, rtree, key, dependent, false);
if (elm == NULL)
return (NULL);
return (rtree_elm_read(elm, dependent));
}
JEMALLOC_INLINE rtree_elm_t *
rtree_elm_acquire(tsdn_t *tsdn, rtree_t *rtree, uintptr_t key, bool dependent,
bool init_missing)
{
rtree_elm_t *elm;
elm = rtree_elm_lookup(tsdn, rtree, key, dependent, init_missing);
if (!dependent && elm == NULL)
return (NULL);
{
extent_t *extent;
void *s;
do {
extent = rtree_elm_read(elm, false);
/* The least significant bit serves as a lock. */
s = (void *)((uintptr_t)extent | (uintptr_t)0x1);
} while (atomic_cas_p(&elm->pun, (void *)extent, s));
}
if (config_debug)
rtree_elm_witness_acquire(tsdn, rtree, key, elm);
return (elm);
}
JEMALLOC_INLINE extent_t *
rtree_elm_read_acquired(tsdn_t *tsdn, const rtree_t *rtree, rtree_elm_t *elm)
{
extent_t *extent;
assert(((uintptr_t)elm->pun & (uintptr_t)0x1) == (uintptr_t)0x1);
extent = (extent_t *)((uintptr_t)elm->pun & ~((uintptr_t)0x1));
assert(((uintptr_t)extent & (uintptr_t)0x1) == (uintptr_t)0x0);
if (config_debug)
rtree_elm_witness_access(tsdn, rtree, elm);
return (extent);
}
JEMALLOC_INLINE void
rtree_elm_write_acquired(tsdn_t *tsdn, const rtree_t *rtree, rtree_elm_t *elm,
const extent_t *extent)
{
assert(((uintptr_t)extent & (uintptr_t)0x1) == (uintptr_t)0x0);
assert(((uintptr_t)elm->pun & (uintptr_t)0x1) == (uintptr_t)0x1);
if (config_debug)
rtree_elm_witness_access(tsdn, rtree, elm);
elm->pun = (void *)((uintptr_t)extent | (uintptr_t)0x1);
assert(rtree_elm_read_acquired(tsdn, rtree, elm) == extent);
}
JEMALLOC_INLINE void
rtree_elm_release(tsdn_t *tsdn, const rtree_t *rtree, rtree_elm_t *elm)
{
rtree_elm_write(elm, rtree_elm_read_acquired(tsdn, rtree, elm));
if (config_debug)
rtree_elm_witness_release(tsdn, rtree, elm);
}
JEMALLOC_INLINE void
rtree_clear(tsdn_t *tsdn, rtree_t *rtree, uintptr_t key)
{
rtree_elm_t *elm;
elm = rtree_elm_acquire(tsdn, rtree, key, true, false);
rtree_elm_write_acquired(tsdn, rtree, elm, NULL);
rtree_elm_release(tsdn, rtree, elm);
}
#endif
#endif /* JEMALLOC_H_INLINES */
/******************************************************************************/