From: Han-Wen Nienhuys <hanwen@xxxxxxxxxx> The reftable format includes support for an (OID => ref) map. This map can speed up visibility and reachability checks. In particular, various operations along the fetch/push path within Gerrit have ben sped up by using this structure. The map is constructed with help of a binary tree. Object IDs are hashes, so they are uniformly distributed. Hence, the tree does not attempt forced rebalancing. Signed-off-by: Han-Wen Nienhuys <hanwen@xxxxxxxxxx> --- Makefile | 4 ++- reftable/tree.c | 63 ++++++++++++++++++++++++++++++++++++++++ reftable/tree.h | 34 ++++++++++++++++++++++ reftable/tree_test.c | 61 ++++++++++++++++++++++++++++++++++++++ t/helper/test-reftable.c | 1 + 5 files changed, 162 insertions(+), 1 deletion(-) create mode 100644 reftable/tree.c create mode 100644 reftable/tree.h create mode 100644 reftable/tree_test.c diff --git a/Makefile b/Makefile index 89f998a9a5f2..5ac204eb211c 100644 --- a/Makefile +++ b/Makefile @@ -2406,12 +2406,14 @@ REFTABLE_OBJS += reftable/block.o REFTABLE_OBJS += reftable/blocksource.o REFTABLE_OBJS += reftable/publicbasics.o REFTABLE_OBJS += reftable/record.o +REFTABLE_OBJS += reftable/tree.o REFTABLE_OBJS += reftable/zlib-compat.o +REFTABLE_TEST_OBJS += reftable/basics_test.o REFTABLE_TEST_OBJS += reftable/block_test.o REFTABLE_TEST_OBJS += reftable/record_test.o REFTABLE_TEST_OBJS += reftable/test_framework.o -REFTABLE_TEST_OBJS += reftable/basics_test.o +REFTABLE_TEST_OBJS += reftable/tree_test.o TEST_OBJS := $(patsubst %$X,%.o,$(TEST_PROGRAMS)) $(patsubst %,t/helper/%,$(TEST_BUILTINS_OBJS)) diff --git a/reftable/tree.c b/reftable/tree.c new file mode 100644 index 000000000000..0061d14e306c --- /dev/null +++ b/reftable/tree.c @@ -0,0 +1,63 @@ +/* +Copyright 2020 Google LLC + +Use of this source code is governed by a BSD-style +license that can be found in the LICENSE file or at +https://developers.google.com/open-source/licenses/bsd +*/ + +#include "tree.h" + +#include "basics.h" +#include "system.h" + +struct tree_node *tree_search(void *key, struct tree_node **rootp, + int (*compare)(const void *, const void *), + int insert) +{ + int res; + if (*rootp == NULL) { + if (!insert) { + return NULL; + } else { + struct tree_node *n = + reftable_calloc(sizeof(struct tree_node)); + n->key = key; + *rootp = n; + return *rootp; + } + } + + res = compare(key, (*rootp)->key); + if (res < 0) + return tree_search(key, &(*rootp)->left, compare, insert); + else if (res > 0) + return tree_search(key, &(*rootp)->right, compare, insert); + return *rootp; +} + +void infix_walk(struct tree_node *t, void (*action)(void *arg, void *key), + void *arg) +{ + if (t->left != NULL) { + infix_walk(t->left, action, arg); + } + action(arg, t->key); + if (t->right != NULL) { + infix_walk(t->right, action, arg); + } +} + +void tree_free(struct tree_node *t) +{ + if (t == NULL) { + return; + } + if (t->left != NULL) { + tree_free(t->left); + } + if (t->right != NULL) { + tree_free(t->right); + } + reftable_free(t); +} diff --git a/reftable/tree.h b/reftable/tree.h new file mode 100644 index 000000000000..fbdd002e23af --- /dev/null +++ b/reftable/tree.h @@ -0,0 +1,34 @@ +/* +Copyright 2020 Google LLC + +Use of this source code is governed by a BSD-style +license that can be found in the LICENSE file or at +https://developers.google.com/open-source/licenses/bsd +*/ + +#ifndef TREE_H +#define TREE_H + +/* tree_node is a generic binary search tree. */ +struct tree_node { + void *key; + struct tree_node *left, *right; +}; + +/* looks for `key` in `rootp` using `compare` as comparison function. If insert + * is set, insert the key if it's not found. Else, return NULL. + */ +struct tree_node *tree_search(void *key, struct tree_node **rootp, + int (*compare)(const void *, const void *), + int insert); + +/* performs an infix walk of the tree. */ +void infix_walk(struct tree_node *t, void (*action)(void *arg, void *key), + void *arg); + +/* + * deallocates the tree nodes recursively. Keys should be deallocated separately + * by walking over the tree. */ +void tree_free(struct tree_node *t); + +#endif diff --git a/reftable/tree_test.c b/reftable/tree_test.c new file mode 100644 index 000000000000..26d1e694252e --- /dev/null +++ b/reftable/tree_test.c @@ -0,0 +1,61 @@ +/* +Copyright 2020 Google LLC + +Use of this source code is governed by a BSD-style +license that can be found in the LICENSE file or at +https://developers.google.com/open-source/licenses/bsd +*/ + +#include "tree.h" + +#include "basics.h" +#include "record.h" +#include "test_framework.h" +#include "reftable-tests.h" + +static int test_compare(const void *a, const void *b) +{ + return (char *)a - (char *)b; +} + +struct curry { + void *last; +}; + +static void check_increasing(void *arg, void *key) +{ + struct curry *c = (struct curry *)arg; + if (c->last != NULL) { + assert(test_compare(c->last, key) < 0); + } + c->last = key; +} + +static void test_tree(void) +{ + struct tree_node *root = NULL; + + void *values[11] = { NULL }; + struct tree_node *nodes[11] = { NULL }; + int i = 1; + struct curry c = { NULL }; + do { + nodes[i] = tree_search(values + i, &root, &test_compare, 1); + i = (i * 7) % 11; + } while (i != 1); + + for (i = 1; i < ARRAY_SIZE(nodes); i++) { + assert(values + i == nodes[i]->key); + assert(nodes[i] == + tree_search(values + i, &root, &test_compare, 0)); + } + + infix_walk(root, check_increasing, &c); + tree_free(root); +} + +int tree_test_main(int argc, const char *argv[]) +{ + RUN_TEST(test_tree); + return 0; +} diff --git a/t/helper/test-reftable.c b/t/helper/test-reftable.c index c9deeaf08c7a..050551fa6985 100644 --- a/t/helper/test-reftable.c +++ b/t/helper/test-reftable.c @@ -6,5 +6,6 @@ int cmd__reftable(int argc, const char **argv) basics_test_main(argc, argv); block_test_main(argc, argv); record_test_main(argc, argv); + tree_test_main(argc, argv); return 0; } -- gitgitgadget
