3f685e8824
Instead of embedding a lock bit in rtree leaf elements, we associate extents with a small set of mutexes. This gets us two things: - We can use the system mutexes. This (hypothetically) protects us from priority inversion, and lets us stop doing a backoff/sleep loop, instead opting for precise wakeups from the mutex. - Cuts down on the number of mutex acquisitions we have to do (from 4 in the worst case to two). We end up simplifying most of the rtree code (which no longer has to deal with locking or concurrency at all), at the cost of additional complexity in the extent code: since the mutex protecting the rtree leaf elements is determined by reading the extent out of those elements, the initial read is racy, so that we may acquire an out of date mutex. We re-check the extent in the leaf after acquiring the mutex to protect us from this race.
46 lines
1.6 KiB
C
46 lines
1.6 KiB
C
#ifndef JEMALLOC_INTERNAL_RTREE_EXTERNS_H
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#define JEMALLOC_INTERNAL_RTREE_EXTERNS_H
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/*
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* Split the bits into one to three partitions depending on number of
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* significant bits. It the number of bits does not divide evenly into the
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* number of levels, place one remainder bit per level starting at the leaf
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* level.
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*/
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static const rtree_level_t rtree_levels[] = {
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#if RTREE_HEIGHT == 1
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{RTREE_NSB, RTREE_NHIB + RTREE_NSB}
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#elif RTREE_HEIGHT == 2
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{RTREE_NSB/2, RTREE_NHIB + RTREE_NSB/2},
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{RTREE_NSB/2 + RTREE_NSB%2, RTREE_NHIB + RTREE_NSB}
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#elif RTREE_HEIGHT == 3
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{RTREE_NSB/3, RTREE_NHIB + RTREE_NSB/3},
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{RTREE_NSB/3 + RTREE_NSB%3/2,
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RTREE_NHIB + RTREE_NSB/3*2 + RTREE_NSB%3/2},
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{RTREE_NSB/3 + RTREE_NSB%3 - RTREE_NSB%3/2, RTREE_NHIB + RTREE_NSB}
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#else
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# error Unsupported rtree height
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#endif
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};
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bool rtree_new(rtree_t *rtree, bool zeroed);
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typedef rtree_node_elm_t *(rtree_node_alloc_t)(tsdn_t *, rtree_t *, size_t);
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extern rtree_node_alloc_t *JET_MUTABLE rtree_node_alloc;
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typedef rtree_leaf_elm_t *(rtree_leaf_alloc_t)(tsdn_t *, rtree_t *, size_t);
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extern rtree_leaf_alloc_t *JET_MUTABLE rtree_leaf_alloc;
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typedef void (rtree_node_dalloc_t)(tsdn_t *, rtree_t *, rtree_node_elm_t *);
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extern rtree_node_dalloc_t *JET_MUTABLE rtree_node_dalloc;
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typedef void (rtree_leaf_dalloc_t)(tsdn_t *, rtree_t *, rtree_leaf_elm_t *);
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extern rtree_leaf_dalloc_t *JET_MUTABLE rtree_leaf_dalloc;
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#ifdef JEMALLOC_JET
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void rtree_delete(tsdn_t *tsdn, rtree_t *rtree);
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#endif
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rtree_leaf_elm_t *rtree_leaf_elm_lookup_hard(tsdn_t *tsdn, rtree_t *rtree,
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rtree_ctx_t *rtree_ctx, uintptr_t key, bool dependent, bool init_missing);
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#endif /* JEMALLOC_INTERNAL_RTREE_EXTERNS_H */
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