4a346f5593
Rework rtree_ctx_t to encapsulate an rtree leaf LRU lookup cache rather than a single-path element lookup cache. The replacement is logically much simpler, as well as slightly faster in the fast path case and less prone to degraded performance during non-trivial sequences of lookups.
81 lines
2.1 KiB
C
81 lines
2.1 KiB
C
#ifndef JEMALLOC_INTERNAL_RTREE_STRUCTS_H
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#define JEMALLOC_INTERNAL_RTREE_STRUCTS_H
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struct rtree_elm_s {
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union {
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void *pun;
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rtree_elm_t *child;
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extent_t *extent;
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};
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};
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struct rtree_elm_witness_s {
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const rtree_elm_t *elm;
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witness_t witness;
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};
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struct rtree_elm_witness_tsd_s {
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rtree_elm_witness_t witnesses[RTREE_ELM_ACQUIRE_MAX];
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};
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struct rtree_level_s {
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/*
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* A non-NULL subtree points to a subtree rooted along the hypothetical
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* path to the leaf node corresponding to key 0. Depending on what keys
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* have been used to store to the tree, an arbitrary combination of
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* subtree pointers may remain NULL.
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*
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* Suppose keys comprise 48 bits, and LG_RTREE_BITS_PER_LEVEL is 4.
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* This results in a 3-level tree, and the leftmost leaf can be directly
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* accessed via levels[2], the subtree prefixed by 0x0000 (excluding
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* 0x00000000) can be accessed via levels[1], and the remainder of the
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* tree can be accessed via levels[0].
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*
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* levels[0] : [<unused> | 0x0001******** | 0x0002******** | ...]
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*
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* levels[1] : [<unused> | 0x00000001**** | 0x00000002**** | ... ]
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*
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* levels[2] : [extent(0x000000000000) | extent(0x000000000001) | ...]
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*
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* This has practical implications on x64, which currently uses only the
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* lower 47 bits of virtual address space in userland, thus leaving
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* levels[0] unused and avoiding a level of tree traversal.
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*/
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union {
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void *subtree_pun;
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rtree_elm_t *subtree;
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};
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/* Number of key bits distinguished by this level. */
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unsigned bits;
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/*
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* Cumulative number of key bits distinguished by traversing to
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* corresponding tree level.
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*/
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unsigned cumbits;
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};
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struct rtree_ctx_cache_elm_s {
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uintptr_t leafkey;
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rtree_elm_t *leaf;
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};
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struct rtree_ctx_s {
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#ifndef _MSC_VER
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JEMALLOC_ALIGNED(CACHELINE)
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#endif
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rtree_ctx_cache_elm_t cache[RTREE_CTX_NCACHE];
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};
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struct rtree_s {
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unsigned height;
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/*
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* Precomputed table used to convert from the number of leading 0 key
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* bits to which subtree level to start at.
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*/
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unsigned start_level[RTREE_HEIGHT_MAX + 1];
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rtree_level_t levels[RTREE_HEIGHT_MAX];
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malloc_mutex_t init_lock;
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};
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#endif /* JEMALLOC_INTERNAL_RTREE_STRUCTS_H */
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