[PATCH 4/9] Add treap implementation
- From
Jonathan Nieder <jrnieder@gmail.com>
- Date
- Jul 16, 2010, 10:23 UTC
- Message-ID
- <20100716102313.GC14374@burratino>
- In-Reply-To
- <20100716101352.GA14374@burratino>
From: Jason Evans <jasone@canonware.com>
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]
Signed-off-by: David Barr <david.barr@cordelta.com> Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> --- Tweaked treap_search() to always return the node after a missing node, like it is documented to. For vcs-svn this doesn’t matter but the predictable semantics should make debugging easier.
The rest of the patches are almost identical to the versions Ram sent; see the aforementioned git tree if you are interested in trying them out. Testing would be quite welcome.
.gitignore | 1 + Makefile | 3 +- t/t0080-vcs-svn.sh | 22 +++++ test-treap.c | 65 +++++++++++++++ vcs-svn/LICENSE | 3 + vcs-svn/trp.h | 223 ++++++++++++++++++++++++++++++++++++++++++++++++++++ vcs-svn/trp.txt | 98 +++++++++++++++++++++++ 7 files changed, 414 insertions(+), 1 deletions(-) create mode 100644 test-treap.c create mode 100644 vcs-svn/trp.h create mode 100644 vcs-svn/trp.txt
diff --git a/.gitignore b/.gitignore index 1e64a6a..af47653 100644 --- a/.gitignore +++ b/.gitignore @@ -173,6 +173,7 @@ /test-run-command /test-sha1 /test-sigchain +/test-treap /common-cmds.h *.tar.gz *.dsc diff --git a/Makefile b/Makefile index 3b873cd..71d77c4 100644 --- a/Makefile +++ b/Makefile @@ -415,6 +415,7 @@ TEST_PROGRAMS_NEED_X += test-path-utils TEST_PROGRAMS_NEED_X += test-run-command TEST_PROGRAMS_NEED_X += test-sha1 TEST_PROGRAMS_NEED_X += test-sigchain +TEST_PROGRAMS_NEED_X += test-treap TEST_PROGRAMS_NEED_X += test-index-version TEST_PROGRAMS = $(patsubst %,%$X,$(TEST_PROGRAMS_NEED_X)) @@ -1865,7 +1866,7 @@ xdiff-interface.o $(XDIFF_OBJS): \ xdiff/xutils.h xdiff/xprepare.h xdiff/xdiffi.h xdiff/xemit.h $(VCSSVN_OBJS): \ - vcs-svn/obj_pool.h + vcs-svn/obj_pool.h vcs-svn/trp.h endif exec_cmd.s exec_cmd.o: EXTRA_CPPFLAGS = \ diff --git a/t/t0080-vcs-svn.sh b/t/t0080-vcs-svn.sh index 3f29496..dd5bab8 100755 --- a/t/t0080-vcs-svn.sh +++ b/t/t0080-vcs-svn.sh @@ -76,4 +76,26 @@ test_expect_success 'obj pool: high-water mark' ' test_cmp expected actual ' +test_expect_success 'treap sort' ' + cat <<-\EOF >unsorted && + 58 + 2 + 3 + 3 + 58 + 3 + 3 + 11 + 0 + 1 + 2 + 3 + 3 + EOF + sort -n unsorted >expected && + + test-treap <unsorted >actual && + test_cmp expected actual +' + test_done diff --git a/test-treap.c b/test-treap.c new file mode 100644 index 0000000..eae7324 --- /dev/null +++ b/test-treap.c @@ -0,0 +1,65 @@ +/* + * test-treap.c: code to exercise the svn importer's treap structure + */ + +#include "cache.h" +#include "vcs-svn/obj_pool.h" +#include "vcs-svn/trp.h" + +struct int_node { + uintmax_t n; + struct trp_node children; +}; + +obj_pool_gen(node, struct int_node, 3) + +static int node_cmp(struct int_node *a, struct int_node *b) +{ + return (a->n > b->n) - (a->n < b->n); +} + +trp_gen(static, treap_, struct int_node, children, node, node_cmp) + +static void strtonode(struct int_node *item, const char *s) +{ + char *end; + item->n = strtoumax(s, &end, 10); + if (*s == '\0' || (*end != '\n' && *end != '\0')) + die("invalid integer: %s", s); +} + +int main(int argc, char *argv[]) +{ + struct strbuf sb = STRBUF_INIT; + struct trp_root root = { ~0 }; + uint32_t item; + + if (argc != 1) + usage("test-treap < ints"); + + while (strbuf_getline(&sb, stdin, '\n') != EOF) { + item = node_alloc(1); + strtonode(node_pointer(item), sb.buf); + treap_insert(&root, node_pointer(item)); + } + + item = node_offset(treap_first(&root)); + while (~item) { + uint32_t next; + struct int_node *tmp = node_pointer(node_alloc(1)); + + tmp->n = node_pointer(item)->n; + next = node_offset(treap_next(&root, node_pointer(item))); + + treap_remove(&root, node_pointer(item)); + item = node_offset(treap_search(&root, tmp)); + + if (item != next && (!~item || node_pointer(item)->n != tmp->n)) + die("found %"PRIuMAX" in place of %"PRIuMAX"", + ~item ? node_pointer(item)->n : ~(uintmax_t) 0, + ~next ? node_pointer(next)->n : ~(uintmax_t) 0); + printf("%"PRIuMAX"\n", tmp->n); + } + node_reset(); + return 0; +} diff --git a/vcs-svn/LICENSE b/vcs-svn/LICENSE index 6e52372..a3d384c 100644 --- a/vcs-svn/LICENSE +++ b/vcs-svn/LICENSE @@ -1,6 +1,9 @@ Copyright (C) 2010 David Barr <david.barr@cordelta.com>. All rights reserved. +Copyright (C) 2008 Jason Evans <jasone@canonware.com>. +All rights reserved. + Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: diff --git a/vcs-svn/trp.h b/vcs-svn/trp.h new file mode 100644 index 0000000..49940cf --- /dev/null +++ b/vcs-svn/trp.h @@ -0,0 +1,223 @@ +/* + * C macro implementation of treaps. + * + * Usage: + * #include <stdint.h> + * #include "trp.h" + * trp_gen(...) + * + * Licensed under a two-clause BSD-style license. + * See LICENSE for details. + */ + +#ifndef TRP_H_ +#define TRP_H_ + +#define MAYBE_UNUSED __attribute__((__unused__)) + +/* Node structure. */ +struct trp_node { + uint32_t trpn_left; + uint32_t trpn_right; +}; + +/* Root structure. */ +struct trp_root { + uint32_t trp_root; +}; + +/* Pointer/Offset conversion. */ +#define trpn_pointer(a_base, a_offset) (a_base##_pointer(a_offset)) +#define trpn_offset(a_base, a_pointer) (a_base##_offset(a_pointer)) +#define trpn_modify(a_base, a_offset) \ + do { \ + if ((a_offset) < a_base##_pool.committed) { \ + uint32_t old_offset = (a_offset);\ + (a_offset) = a_base##_alloc(1); \ + *trpn_pointer(a_base, a_offset) = \ + *trpn_pointer(a_base, old_offset); \ + } \ + } while (0); + +/* Left accessors. */ +#define trp_left_get(a_base, a_field, a_node) \ + (trpn_pointer(a_base, a_node)->a_field.trpn_left) +#define trp_left_set(a_base, a_field, a_node, a_left) \ + do { \ + trpn_modify(a_base, a_node); \ + trp_left_get(a_base, a_field, a_node) = (a_left); \ + } while(0) + +/* Right accessors. */ +#define trp_right_get(a_base, a_field, a_node) \ + (trpn_pointer(a_base, a_node)->a_field.trpn_right) +#define trp_right_set(a_base, a_field, a_node, a_right) \ + do { \ + trpn_modify(a_base, a_node); \ + trp_right_get(a_base, a_field, a_node) = (a_right); \ + } while(0) + +/* + * Fibonacci hash function. + * The multiplier is the nearest prime to (2^32 times (√5 - 1)/2). + * See Knuth §6.4: volume 3, 3rd ed, p518. + */ +#define trpn_hash(a_node) (uint32_t) (2654435761u * (a_node)) + +/* Priority accessors. */ +#define trp_prio_get(a_node) trpn_hash(a_node) + +/* Node initializer. */ +#define trp_node_new(a_base, a_field, a_node) \ + do { \ + trp_left_set(a_base, a_field, (a_node), ~0); \ + trp_right_set(a_base, a_field, (a_node), ~0); \ + } while(0) + +/* Internal utility macros. */ +#define trpn_first(a_base, a_field, a_root, r_node) \ + do { \ + (r_node) = (a_root); \ + if ((r_node) == ~0) \ + return NULL; \ + while (~trp_left_get(a_base, a_field, (r_node))) \ + (r_node) = trp_left_get(a_base, a_field, (r_node)); \ + } while (0) + +#define trpn_rotate_left(a_base, a_field, a_node, r_node) \ + do { \ + (r_node) = trp_right_get(a_base, a_field, (a_node)); \ + trp_right_set(a_base, a_field, (a_node), \ + trp_left_get(a_base, a_field, (r_node))); \ + trp_left_set(a_base, a_field, (r_node), (a_node)); \ + } while(0) + +#define trpn_rotate_right(a_base, a_field, a_node, r_node) \ + do { \ + (r_node) = trp_left_get(a_base, a_field, (a_node)); \ + trp_left_set(a_base, a_field, (a_node), \ + trp_right_get(a_base, a_field, (r_node))); \ + trp_right_set(a_base, a_field, (r_node), (a_node)); \ + } while(0) + +#define trp_gen(a_attr, a_pre, a_type, a_field, a_base, a_cmp) \ +a_attr a_type MAYBE_UNUSED *a_pre##first(struct trp_root *treap) \ +{ \ + uint32_t ret; \ + trpn_first(a_base, a_field, treap->trp_root, ret); \ + return trpn_pointer(a_base, ret); \ +} \ +a_attr a_type MAYBE_UNUSED *a_pre##next(struct trp_root *treap, a_type *node) \ +{ \ + uint32_t ret; \ + uint32_t offset = trpn_offset(a_base, node); \ + if (~trp_right_get(a_base, a_field, offset)) { \ + trpn_first(a_base, a_field, \ + trp_right_get(a_base, a_field, offset), ret); \ + } else { \ + uint32_t tnode = treap->trp_root; \ + ret = ~0; \ + while (1) { \ + int cmp = (a_cmp)(trpn_pointer(a_base, offset), \ + trpn_pointer(a_base, tnode)); \ + if (cmp < 0) { \ + ret = tnode; \ + tnode = trp_left_get(a_base, a_field, tnode); \ + } else if (cmp > 0) { \ + tnode = trp_right_get(a_base, a_field, tnode); \ + } else { \ + break; \ + } \ + } \ + } \ + return trpn_pointer(a_base, ret); \ +} \ +a_attr a_type MAYBE_UNUSED *a_pre##search(struct trp_root *treap, a_type *key) \ +{ \ + int cmp; \ + uint32_t ret = treap->trp_root; \ + while (~ret && (cmp = (a_cmp)(key, trpn_pointer(a_base,ret)))) { \ + if (cmp < 0) { \ + if (!~trp_left_get(a_base, a_field, ret)) \ + break; \ + ret = trp_left_get(a_base, a_field, ret); \ + } else { \ + ret = trp_right_get(a_base, a_field, ret); \ + } \ + } \ + return trpn_pointer(a_base, ret); \ +} \ +a_attr uint32_t MAYBE_UNUSED a_pre##insert_recurse(uint32_t cur_node, uint32_t ins_node) \ +{ \ + if (cur_node == ~0) { \ + return (ins_node); \ + } else { \ + uint32_t ret; \ + int cmp = (a_cmp)(trpn_pointer(a_base, ins_node), \ + trpn_pointer(a_base, cur_node)); \ + if (cmp < 0) { \ + uint32_t left = a_pre##insert_recurse( \ + trp_left_get(a_base, a_field, cur_node), ins_node); \ + trp_left_set(a_base, a_field, cur_node, left); \ + if (trp_prio_get(left) < trp_prio_get(cur_node)) \ + trpn_rotate_right(a_base, a_field, cur_node, ret); \ + else \ + ret = cur_node; \ + } else { \ + uint32_t right = a_pre##insert_recurse( \ + trp_right_get(a_base, a_field, cur_node), ins_node); \ + trp_right_set(a_base, a_field, cur_node, right); \ + if (trp_prio_get(right) < trp_prio_get(cur_node)) \ + trpn_rotate_left(a_base, a_field, cur_node, ret); \ + else \ + ret = cur_node; \ + } \ + return (ret); \ + } \ +} \ +a_attr void MAYBE_UNUSED a_pre##insert(struct trp_root *treap, a_type *node) \ +{ \ + uint32_t offset = trpn_offset(a_base, node); \ + trp_node_new(a_base, a_field, offset); \ + treap->trp_root = a_pre##insert_recurse(treap->trp_root, offset); \ +} \ +a_attr uint32_t MAYBE_UNUSED a_pre##remove_recurse(uint32_t cur_node, uint32_t rem_node) \ +{ \ + int cmp = a_cmp(trpn_pointer(a_base, rem_node), \ + trpn_pointer(a_base, cur_node)); \ + if (cmp == 0) { \ + uint32_t ret; \ + uint32_t left = trp_left_get(a_base, a_field, cur_node); \ + uint32_t right = trp_right_get(a_base, a_field, cur_node); \ + if (left == ~0) { \ + if (right == ~0) \ + return (~0); \ + } else if (right == ~0 || trp_prio_get(left) < trp_prio_get(right)) { \ + trpn_rotate_right(a_base, a_field, cur_node, ret); \ + right = a_pre##remove_recurse(cur_node, rem_node); \ + trp_right_set(a_base, a_field, ret, right); \ + return (ret); \ + } \ + trpn_rotate_left(a_base, a_field, cur_node, ret); \ + left = a_pre##remove_recurse(cur_node, rem_node); \ + trp_left_set(a_base, a_field, ret, left); \ + return (ret); \ + } else if (cmp < 0) { \ + uint32_t left = a_pre##remove_recurse( \ + trp_left_get(a_base, a_field, cur_node), rem_node); \ + trp_left_set(a_base, a_field, cur_node, left); \ + return (cur_node); \ + } else { \ + uint32_t right = a_pre##remove_recurse( \ + trp_right_get(a_base, a_field, cur_node), rem_node); \ + trp_right_set(a_base, a_field, cur_node, right); \ + return (cur_node); \ + } \ +} \ +a_attr void MAYBE_UNUSED a_pre##remove(struct trp_root *treap, a_type *node) \ +{ \ + treap->trp_root = a_pre##remove_recurse(treap->trp_root, \ + trpn_offset(a_base, node)); \ +} \ + +#endif diff --git a/vcs-svn/trp.txt b/vcs-svn/trp.txt new file mode 100644 index 0000000..9247eba --- /dev/null +++ b/vcs-svn/trp.txt @@ -0,0 +1,98 @@ +Motivation +========== + +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. + +API +=== + +The trp API generates a data structure and functions to handle a +large growing set of objects stored in a pool. + +The caller: + +. Specifies parameters for the generated functions with the + trp_gen(static, foo_, ...) macro. + +. Allocates a `struct trp_root` variable and sets it to {~0}. + +. Adds new nodes to the set using `foo_insert`. + +. Can find a specific item in the set using `foo_search`. + +. Can iterate over items in the set using `foo_first` and `foo_next`. + +. Can remove an item from the set using `foo_remove`. + +Example: + +---- +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, + 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.
-- 1.7.2.rc2