diff options
Diffstat (limited to 'src/bftw.c')
| -rw-r--r-- | src/bftw.c | 136 |
1 files changed, 94 insertions, 42 deletions
@@ -7,6 +7,8 @@ * - struct bftw_file: A file that has been encountered during the traversal. * They have reference-counted links to their parents in the directory tree. * + * - struct bftw_list: A linked list of bftw_file's. + * * - struct bftw_cache: An LRU list of bftw_file's with open file descriptors, * used for openat() to minimize the amount of path re-traversals. * @@ -39,11 +41,14 @@ struct bftw_file { struct bftw_file *parent; /** The root under which this file was found. */ struct bftw_file *root; + /** The next file in the queue, if any. */ + struct bftw_file *next; - /** Queue link. */ - struct slink link; - /** LRU link. */ - struct link lru; + /** LRU list links. */ + struct { + struct bftw_file *prev; + struct bftw_file *next; + } lru; /** This file's depth in the walk. */ size_t depth; @@ -68,36 +73,42 @@ struct bftw_file { char name[]; }; -/** Move from a list entry to a bftw_file. */ -#define BFTW_FILE(...) \ - LIST_ITEM(struct bftw_file, __VA_ARGS__) +/** + * A linked list of bftw_file's. + */ +struct bftw_list { + struct bftw_file *head; + struct bftw_file **tail; +}; /** * A cache of open directories. */ struct bftw_cache { - /** The LRU list. */ - struct list list; + /** The head of the LRU list. */ + struct bftw_file *head; + /** The tail of the LRU list. */ + struct bftw_file *tail; /** The insertion target for the LRU list. */ - struct link *target; + struct bftw_file *target; /** The remaining capacity of the LRU list. */ size_t capacity; }; /** Initialize a cache. */ static void bftw_cache_init(struct bftw_cache *cache, size_t capacity) { - list_init(&cache->list); + LIST_INIT(cache); cache->target = NULL; cache->capacity = capacity; } /** Remove a bftw_file from the cache. */ static void bftw_cache_remove(struct bftw_cache *cache, struct bftw_file *file) { - if (cache->target == &file->lru) { - cache->target = cache->target->prev; + if (cache->target == file) { + cache->target = file->lru.prev; } - list_remove(&cache->list, &file->lru); + LIST_REMOVE(cache, file, lru); ++cache->capacity; } @@ -106,7 +117,7 @@ static void bftw_cache_remove(struct bftw_cache *cache, struct bftw_file *file) static void bftw_file_close(struct bftw_cache *cache, struct bftw_file *file) { assert(file->fd >= 0); - if (list_attached(&cache->list, &file->lru)) { + if (LIST_ATTACHED(cache, file, lru)) { bftw_cache_remove(cache, file); } @@ -116,11 +127,11 @@ static void bftw_file_close(struct bftw_cache *cache, struct bftw_file *file) { /** Pop the least recently used directory from the cache. */ static int bftw_cache_pop(struct bftw_cache *cache) { - if (list_is_empty(&cache->list)) { + struct bftw_file *file = cache->tail; + if (!file) { return -1; } - struct bftw_file *file = BFTW_FILE(cache->list.tail, lru); bftw_file_close(cache, file); return 0; } @@ -138,11 +149,11 @@ static int bftw_cache_add(struct bftw_cache *cache, struct bftw_file *file) { assert(cache->capacity > 0); --cache->capacity; - list_insert_after(&cache->list, cache->target, &file->lru); + LIST_INSERT(cache, cache->target, file, lru); // Prefer to keep the root paths open by keeping them at the head of the list if (file->depth == 0) { - cache->target = &file->lru; + cache->target = file; } return 0; @@ -159,8 +170,9 @@ static size_t bftw_child_nameoff(const struct bftw_file *parent) { /** Destroy a cache. */ static void bftw_cache_destroy(struct bftw_cache *cache) { + assert(!cache->head); + assert(!cache->tail); assert(!cache->target); - assert(list_is_empty(&cache->list)); } /** Create a new bftw_file. */ @@ -186,8 +198,8 @@ static struct bftw_file *bftw_file_new(struct bftw_file *parent, const char *nam file->nameoff = 0; } - slink_init(&file->link); - link_init(&file->lru); + file->next = NULL; + file->lru.prev = file->lru.next = NULL; file->refcount = 1; file->fd = -1; @@ -280,16 +292,19 @@ static int bftw_file_open(struct bftw_cache *cache, struct bftw_file *file, cons } // Handle ENAMETOOLONG by manually traversing the path component-by-component - struct slist parents; - slist_init(&parents); - for (struct bftw_file *cur = file; cur != base; cur = cur->parent) { - slist_prepend(&parents, &cur->link); + struct bftw_list parents; + SLIST_INIT(&parents); + + struct bftw_file *cur; + for (cur = file; cur != base; cur = cur->parent) { + SLIST_PREPEND(&parents, cur); } - LIST_DRAIN(&parents, struct bftw_file, cur) { + while ((cur = parents.head)) { if (!cur->parent || cur->parent->fd >= 0) { bftw_file_openat(cache, cur, cur->parent, cur->name); } + SLIST_POP(&parents); } return file->fd; @@ -348,9 +363,9 @@ struct bftw_state { /** The cache of open directories. */ struct bftw_cache cache; /** The queue of files left to explore. */ - struct slist queue; + struct bftw_list queue; /** A batch of files to enqueue. */ - struct slist batch; + struct bftw_list batch; /** The current path. */ char *path; @@ -396,8 +411,8 @@ static int bftw_state_init(struct bftw_state *state, const struct bftw_args *arg bftw_cache_init(&state->cache, args->nopenfd); - slist_init(&state->queue); - slist_init(&state->batch); + SLIST_INIT(&state->queue); + SLIST_INIT(&state->batch); state->file = NULL; state->previous = NULL; @@ -757,7 +772,7 @@ static int bftw_push(struct bftw_state *state, const char *name, bool fill_id) { bftw_fill_id(file, &state->ftwbuf); } - slist_append(&state->batch, &file->link); + SLIST_APPEND(&state->batch, file); return 0; } @@ -800,11 +815,12 @@ static int bftw_build_path(struct bftw_state *state) { * Pop the next file from the queue. */ static int bftw_pop(struct bftw_state *state) { - if (!state->queue.head) { + state->file = state->queue.head; + if (!state->file) { return 0; } - state->file = BFTW_FILE(slist_pop(&state->queue)); + SLIST_POP(&state->queue); if (bftw_build_path(state) != 0) { return -1; @@ -940,8 +956,10 @@ static enum bftw_action bftw_gc_file(struct bftw_state *state, enum bftw_gc_flag * Drain all the files from the queue. */ static void bftw_drain_queue(struct bftw_state *state) { - LIST_DRAIN(&state->queue, struct bftw_file, file) { - state->file = file; + while (state->queue.head) { + state->file = state->queue.head; + SLIST_POP(&state->queue); + bftw_gc_file(state, BFTW_VISIT_NONE); } } @@ -966,21 +984,55 @@ static int bftw_state_destroy(struct bftw_state *state) { return state->error ? -1 : 0; } -/** Comparison function for BFTW_SORT. */ -static bool bftw_file_cmp(struct slink *left, struct slink *right, const void *ptr) { - return strcoll(BFTW_FILE(left)->name, BFTW_FILE(right)->name) <= 0; +/** Sort a bftw_list by filename. */ +static void bftw_list_sort(struct bftw_list *queue) { + if (!queue->head || !queue->head->next) { + return; + } + + struct bftw_list left, right; + SLIST_INIT(&left); + SLIST_INIT(&right); + + // Split + for (struct bftw_file *hare = queue->head; hare && (hare = hare->next); hare = hare->next) { + struct bftw_file *tortoise = queue->head; + SLIST_POP(queue); + SLIST_APPEND(&left, tortoise); + } + SLIST_EXTEND(&right, queue); + + // Recurse + bftw_list_sort(&left); + bftw_list_sort(&right); + + // Merge + while (left.head && right.head) { + struct bftw_file *lf = left.head; + struct bftw_file *rf = right.head; + + if (strcoll(lf->name, rf->name) <= 0) { + SLIST_POP(&left); + SLIST_APPEND(queue, lf); + } else { + SLIST_POP(&right); + SLIST_APPEND(queue, rf); + } + } + SLIST_EXTEND(queue, &left); + SLIST_EXTEND(queue, &right); } /** Finish adding a batch of files. */ static void bftw_batch_finish(struct bftw_state *state) { if (state->flags & BFTW_SORT) { - slist_sort(&state->batch, bftw_file_cmp, NULL); + bftw_list_sort(&state->batch); } if (state->strategy == BFTW_DFS) { - slist_extend(&state->batch, &state->queue); + SLIST_EXTEND(&state->batch, &state->queue); } - slist_extend(&state->queue, &state->batch); + SLIST_EXTEND(&state->queue, &state->batch); } /** |