зеркало из https://github.com/microsoft/git.git
Add treap implementation
Provide macros to generate a type-specific treap implementation and various functions to operate on it. It uses obj_pool.h to store memory nodes in a treap. Previously committed nodes are never removed from the pool; after any *_commit operation, it is assumed (correctly, in the case of svn-fast-export) that someone else must care about them. Treaps provide a memory-efficient binary search tree structure. Insertion/deletion/search are about as about as fast in the average case as red-black trees and the chances of worst-case behavior are vanishingly small, thanks to (pseudo-)randomness. The bad worst-case behavior is a small price to pay, given that treaps are much simpler to implement. >From http://www.canonware.com/download/trp/trp_hash/trp.h [db: Altered to reference nodes by offset from a common base pointer] [db: Bob Jenkins' hashing implementation dropped for Knuth's] [db: Methods unnecessary for search and insert dropped] [rr: Squelched compiler warnings] [db: Added support for immutable treap nodes] [jn: Reintroduced treap_nsearch(); with tests] Signed-off-by: David Barr <david.barr@cordelta.com> Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jason Evans
Junio C Hamano
Родитель
4709455db3
Коммит
951f316470
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@ -173,6 +173,7 @@
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/test-run-command
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/test-sha1
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/test-sigchain
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/test-treap
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/common-cmds.h
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*.tar.gz
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*.dsc
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3
Makefile
3
Makefile
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@ -415,6 +415,7 @@ TEST_PROGRAMS_NEED_X += test-path-utils
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TEST_PROGRAMS_NEED_X += test-run-command
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TEST_PROGRAMS_NEED_X += test-sha1
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TEST_PROGRAMS_NEED_X += test-sigchain
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TEST_PROGRAMS_NEED_X += test-treap
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TEST_PROGRAMS_NEED_X += test-index-version
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TEST_PROGRAMS = $(patsubst %,%$X,$(TEST_PROGRAMS_NEED_X))
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@ -1866,7 +1867,7 @@ xdiff-interface.o $(XDIFF_OBJS): \
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xdiff/xutils.h xdiff/xprepare.h xdiff/xdiffi.h xdiff/xemit.h
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$(VCSSVN_OBJS): \
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vcs-svn/obj_pool.h
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vcs-svn/obj_pool.h vcs-svn/trp.h
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endif
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exec_cmd.s exec_cmd.o: EXTRA_CPPFLAGS = \
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@ -76,4 +76,26 @@ test_expect_success 'obj pool: high-water mark' '
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test_cmp expected actual
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'
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test_expect_success 'treap sort' '
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cat <<-\EOF >unsorted &&
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68
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12
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13
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13
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68
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13
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13
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21
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10
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11
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12
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13
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13
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EOF
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sort unsorted >expected &&
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test-treap <unsorted >actual &&
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test_cmp expected actual
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'
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test_done
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@ -0,0 +1,65 @@
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/*
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* test-treap.c: code to exercise the svn importer's treap structure
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*/
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#include "cache.h"
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#include "vcs-svn/obj_pool.h"
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#include "vcs-svn/trp.h"
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struct int_node {
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uintmax_t n;
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struct trp_node children;
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};
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obj_pool_gen(node, struct int_node, 3)
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static int node_cmp(struct int_node *a, struct int_node *b)
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{
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return (a->n > b->n) - (a->n < b->n);
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}
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trp_gen(static, treap_, struct int_node, children, node, node_cmp)
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static void strtonode(struct int_node *item, const char *s)
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{
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char *end;
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item->n = strtoumax(s, &end, 10);
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if (*s == '\0' || (*end != '\n' && *end != '\0'))
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die("invalid integer: %s", s);
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}
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int main(int argc, char *argv[])
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{
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struct strbuf sb = STRBUF_INIT;
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struct trp_root root = { ~0 };
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uint32_t item;
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if (argc != 1)
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usage("test-treap < ints");
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while (strbuf_getline(&sb, stdin, '\n') != EOF) {
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item = node_alloc(1);
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strtonode(node_pointer(item), sb.buf);
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treap_insert(&root, node_pointer(item));
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}
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item = node_offset(treap_first(&root));
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while (~item) {
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uint32_t next;
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struct int_node *tmp = node_pointer(node_alloc(1));
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tmp->n = node_pointer(item)->n;
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next = node_offset(treap_next(&root, node_pointer(item)));
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treap_remove(&root, node_pointer(item));
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item = node_offset(treap_nsearch(&root, tmp));
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if (item != next && (!~item || node_pointer(item)->n != tmp->n))
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die("found %"PRIuMAX" in place of %"PRIuMAX"",
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~item ? node_pointer(item)->n : ~(uintmax_t) 0,
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~next ? node_pointer(next)->n : ~(uintmax_t) 0);
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printf("%"PRIuMAX"\n", tmp->n);
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}
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node_reset();
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return 0;
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}
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@ -1,6 +1,9 @@
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Copyright (C) 2010 David Barr <david.barr@cordelta.com>.
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All rights reserved.
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Copyright (C) 2008 Jason Evans <jasone@canonware.com>.
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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@ -0,0 +1,236 @@
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/*
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* C macro implementation of treaps.
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*
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* Usage:
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* #include <stdint.h>
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* #include "trp.h"
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* trp_gen(...)
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*
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* Licensed under a two-clause BSD-style license.
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* See LICENSE for details.
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*/
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#ifndef TRP_H_
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#define TRP_H_
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#define MAYBE_UNUSED __attribute__((__unused__))
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/* Node structure. */
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struct trp_node {
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uint32_t trpn_left;
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uint32_t trpn_right;
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};
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/* Root structure. */
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struct trp_root {
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uint32_t trp_root;
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};
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/* Pointer/Offset conversion. */
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#define trpn_pointer(a_base, a_offset) (a_base##_pointer(a_offset))
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#define trpn_offset(a_base, a_pointer) (a_base##_offset(a_pointer))
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#define trpn_modify(a_base, a_offset) \
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do { \
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if ((a_offset) < a_base##_pool.committed) { \
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uint32_t old_offset = (a_offset);\
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(a_offset) = a_base##_alloc(1); \
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*trpn_pointer(a_base, a_offset) = \
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*trpn_pointer(a_base, old_offset); \
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} \
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} while (0);
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/* Left accessors. */
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#define trp_left_get(a_base, a_field, a_node) \
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(trpn_pointer(a_base, a_node)->a_field.trpn_left)
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#define trp_left_set(a_base, a_field, a_node, a_left) \
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do { \
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trpn_modify(a_base, a_node); \
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trp_left_get(a_base, a_field, a_node) = (a_left); \
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} while(0)
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/* Right accessors. */
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#define trp_right_get(a_base, a_field, a_node) \
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(trpn_pointer(a_base, a_node)->a_field.trpn_right)
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#define trp_right_set(a_base, a_field, a_node, a_right) \
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do { \
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trpn_modify(a_base, a_node); \
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trp_right_get(a_base, a_field, a_node) = (a_right); \
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} while(0)
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/*
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* Fibonacci hash function.
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* The multiplier is the nearest prime to (2^32 times (√5 - 1)/2).
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* See Knuth §6.4: volume 3, 3rd ed, p518.
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*/
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#define trpn_hash(a_node) (uint32_t) (2654435761u * (a_node))
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/* Priority accessors. */
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#define trp_prio_get(a_node) trpn_hash(a_node)
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/* Node initializer. */
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#define trp_node_new(a_base, a_field, a_node) \
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do { \
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trp_left_set(a_base, a_field, (a_node), ~0); \
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trp_right_set(a_base, a_field, (a_node), ~0); \
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} while(0)
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/* Internal utility macros. */
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#define trpn_first(a_base, a_field, a_root, r_node) \
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do { \
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(r_node) = (a_root); \
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if ((r_node) == ~0) \
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return NULL; \
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while (~trp_left_get(a_base, a_field, (r_node))) \
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(r_node) = trp_left_get(a_base, a_field, (r_node)); \
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} while (0)
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#define trpn_rotate_left(a_base, a_field, a_node, r_node) \
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do { \
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(r_node) = trp_right_get(a_base, a_field, (a_node)); \
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trp_right_set(a_base, a_field, (a_node), \
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trp_left_get(a_base, a_field, (r_node))); \
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trp_left_set(a_base, a_field, (r_node), (a_node)); \
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} while(0)
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#define trpn_rotate_right(a_base, a_field, a_node, r_node) \
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do { \
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(r_node) = trp_left_get(a_base, a_field, (a_node)); \
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trp_left_set(a_base, a_field, (a_node), \
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trp_right_get(a_base, a_field, (r_node))); \
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trp_right_set(a_base, a_field, (r_node), (a_node)); \
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} while(0)
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#define trp_gen(a_attr, a_pre, a_type, a_field, a_base, a_cmp) \
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a_attr a_type MAYBE_UNUSED *a_pre##first(struct trp_root *treap) \
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{ \
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uint32_t ret; \
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trpn_first(a_base, a_field, treap->trp_root, ret); \
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return trpn_pointer(a_base, ret); \
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} \
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a_attr a_type MAYBE_UNUSED *a_pre##next(struct trp_root *treap, a_type *node) \
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{ \
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uint32_t ret; \
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uint32_t offset = trpn_offset(a_base, node); \
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if (~trp_right_get(a_base, a_field, offset)) { \
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trpn_first(a_base, a_field, \
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trp_right_get(a_base, a_field, offset), ret); \
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} else { \
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uint32_t tnode = treap->trp_root; \
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ret = ~0; \
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while (1) { \
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int cmp = (a_cmp)(trpn_pointer(a_base, offset), \
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trpn_pointer(a_base, tnode)); \
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if (cmp < 0) { \
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ret = tnode; \
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tnode = trp_left_get(a_base, a_field, tnode); \
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} else if (cmp > 0) { \
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tnode = trp_right_get(a_base, a_field, tnode); \
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} else { \
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break; \
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} \
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} \
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} \
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return trpn_pointer(a_base, ret); \
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} \
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a_attr a_type MAYBE_UNUSED *a_pre##search(struct trp_root *treap, a_type *key) \
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{ \
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int cmp; \
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uint32_t ret = treap->trp_root; \
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while (~ret && (cmp = (a_cmp)(key, trpn_pointer(a_base,ret)))) { \
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if (cmp < 0) { \
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ret = trp_left_get(a_base, a_field, ret); \
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} else { \
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ret = trp_right_get(a_base, a_field, ret); \
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} \
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} \
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return trpn_pointer(a_base, ret); \
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} \
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a_attr a_type MAYBE_UNUSED *a_pre##nsearch(struct trp_root *treap, a_type *key) \
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{ \
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int cmp; \
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uint32_t ret = treap->trp_root; \
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while (~ret && (cmp = (a_cmp)(key, trpn_pointer(a_base,ret)))) { \
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if (cmp < 0) { \
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if (!~trp_left_get(a_base, a_field, ret)) \
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break; \
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ret = trp_left_get(a_base, a_field, ret); \
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} else { \
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ret = trp_right_get(a_base, a_field, ret); \
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} \
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} \
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return trpn_pointer(a_base, ret); \
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} \
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a_attr uint32_t MAYBE_UNUSED a_pre##insert_recurse(uint32_t cur_node, uint32_t ins_node) \
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{ \
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if (cur_node == ~0) { \
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return (ins_node); \
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} else { \
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uint32_t ret; \
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int cmp = (a_cmp)(trpn_pointer(a_base, ins_node), \
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trpn_pointer(a_base, cur_node)); \
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if (cmp < 0) { \
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uint32_t left = a_pre##insert_recurse( \
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trp_left_get(a_base, a_field, cur_node), ins_node); \
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trp_left_set(a_base, a_field, cur_node, left); \
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if (trp_prio_get(left) < trp_prio_get(cur_node)) \
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trpn_rotate_right(a_base, a_field, cur_node, ret); \
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else \
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ret = cur_node; \
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} else { \
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uint32_t right = a_pre##insert_recurse( \
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trp_right_get(a_base, a_field, cur_node), ins_node); \
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trp_right_set(a_base, a_field, cur_node, right); \
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if (trp_prio_get(right) < trp_prio_get(cur_node)) \
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trpn_rotate_left(a_base, a_field, cur_node, ret); \
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else \
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ret = cur_node; \
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} \
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return (ret); \
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} \
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} \
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a_attr void MAYBE_UNUSED a_pre##insert(struct trp_root *treap, a_type *node) \
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{ \
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uint32_t offset = trpn_offset(a_base, node); \
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trp_node_new(a_base, a_field, offset); \
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treap->trp_root = a_pre##insert_recurse(treap->trp_root, offset); \
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} \
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a_attr uint32_t MAYBE_UNUSED a_pre##remove_recurse(uint32_t cur_node, uint32_t rem_node) \
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{ \
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int cmp = a_cmp(trpn_pointer(a_base, rem_node), \
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trpn_pointer(a_base, cur_node)); \
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if (cmp == 0) { \
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uint32_t ret; \
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uint32_t left = trp_left_get(a_base, a_field, cur_node); \
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uint32_t right = trp_right_get(a_base, a_field, cur_node); \
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if (left == ~0) { \
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if (right == ~0) \
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return (~0); \
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} else if (right == ~0 || trp_prio_get(left) < trp_prio_get(right)) { \
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trpn_rotate_right(a_base, a_field, cur_node, ret); \
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right = a_pre##remove_recurse(cur_node, rem_node); \
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trp_right_set(a_base, a_field, ret, right); \
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return (ret); \
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} \
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trpn_rotate_left(a_base, a_field, cur_node, ret); \
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left = a_pre##remove_recurse(cur_node, rem_node); \
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trp_left_set(a_base, a_field, ret, left); \
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return (ret); \
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} else if (cmp < 0) { \
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uint32_t left = a_pre##remove_recurse( \
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trp_left_get(a_base, a_field, cur_node), rem_node); \
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trp_left_set(a_base, a_field, cur_node, left); \
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return (cur_node); \
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} else { \
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uint32_t right = a_pre##remove_recurse( \
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trp_right_get(a_base, a_field, cur_node), rem_node); \
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trp_right_set(a_base, a_field, cur_node, right); \
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return (cur_node); \
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} \
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} \
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a_attr void MAYBE_UNUSED a_pre##remove(struct trp_root *treap, a_type *node) \
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{ \
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treap->trp_root = a_pre##remove_recurse(treap->trp_root, \
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trpn_offset(a_base, node)); \
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} \
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#endif
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@ -0,0 +1,103 @@
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Motivation
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==========
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Treaps provide a memory-efficient binary search tree structure.
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Insertion/deletion/search are about as about as fast in the average
|
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case as red-black trees and the chances of worst-case behavior are
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vanishingly small, thanks to (pseudo-)randomness. The bad worst-case
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behavior is a small price to pay, given that treaps are much simpler
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to implement.
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API
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===
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||||
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||||
The trp API generates a data structure and functions to handle a
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large growing set of objects stored in a pool.
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The caller:
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||||
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. Specifies parameters for the generated functions with the
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trp_gen(static, foo_, ...) macro.
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. Allocates a `struct trp_root` variable and sets it to {~0}.
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. Adds new nodes to the set using `foo_insert`.
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. Can find a specific item in the set using `foo_search`.
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. Can iterate over items in the set using `foo_first` and `foo_next`.
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||||
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. Can remove an item from the set using `foo_remove`.
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Example:
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||||
|
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----
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||||
struct ex_node {
|
||||
const char *s;
|
||||
struct trp_node ex_link;
|
||||
};
|
||||
static struct trp_root ex_base = {~0};
|
||||
obj_pool_gen(ex, struct ex_node, 4096);
|
||||
trp_gen(static, ex_, struct ex_node, ex_link, ex, strcmp)
|
||||
struct ex_node *item;
|
||||
|
||||
item = ex_pointer(ex_alloc(1));
|
||||
item->s = "hello";
|
||||
ex_insert(&ex_base, item);
|
||||
item = ex_pointer(ex_alloc(1));
|
||||
item->s = "goodbye";
|
||||
ex_insert(&ex_base, item);
|
||||
for (item = ex_first(&ex_base); item; item = ex_next(&ex_base, item))
|
||||
printf("%s\n", item->s);
|
||||
----
|
||||
|
||||
Functions
|
||||
---------
|
||||
|
||||
trp_gen(attr, foo_, node_type, link_field, pool, cmp)::
|
||||
|
||||
Generate a type-specific treap implementation.
|
||||
+
|
||||
. The storage class for generated functions will be 'attr' (e.g., `static`).
|
||||
. Generated function names are prefixed with 'foo_' (e.g., `treap_`).
|
||||
. Treap nodes will be of type 'node_type' (e.g., `struct treap_node`).
|
||||
This type must be a struct with at least one `struct trp_node` field
|
||||
to point to its children.
|
||||
. The field used to access child nodes will be 'link_field'.
|
||||
. All treap nodes must lie in the 'pool' object pool.
|
||||
. Treap nodes must be totally ordered by the 'cmp' relation, with the
|
||||
following prototype:
|
||||
+
|
||||
int (*cmp)(node_type \*a, node_type \*b)
|
||||
+
|
||||
and returning a value less than, equal to, or greater than zero
|
||||
according to the result of comparison.
|
||||
|
||||
void foo_insert(struct trp_root *treap, node_type \*node)::
|
||||
|
||||
Insert node into treap. If inserted multiple times,
|
||||
a node will appear in the treap multiple times.
|
||||
|
||||
void foo_remove(struct trp_root *treap, node_type \*node)::
|
||||
|
||||
Remove node from treap. Caller must ensure node is
|
||||
present in treap before using this function.
|
||||
|
||||
node_type *foo_search(struct trp_root \*treap, node_type \*key)::
|
||||
|
||||
Search for a node that matches key. If no match is found,
|
||||
result is NULL.
|
||||
|
||||
node_type *foo_nsearch(struct trp_root \*treap, node_type \*key)::
|
||||
|
||||
Like `foo_search`, but if if the key is missing return what
|
||||
would be key's successor, were key in treap (NULL if no
|
||||
successor).
|
||||
|
||||
node_type *foo_first(struct trp_root \*treap)::
|
||||
|
||||
Find the first item from the treap, in sorted order.
|
||||
|
||||
node_type *foo_next(struct trp_root \*treap, node_type \*node)::
|
||||
|
||||
Find the next item.
|
||||
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