diff options
| -rw-r--r-- | src/bftw.c | 132 |
1 files changed, 100 insertions, 32 deletions
@@ -51,11 +51,15 @@ struct bftw_file { /** This file's depth in the walk. */ size_t depth; - /** Reference count. */ + /** Reference count (for ->parent). */ size_t refcount; + /** Pin count (for ->fd). */ + size_t pincount; /** An open descriptor to this file, or -1. */ int fd; + /** An open directory for this file, if any. */ + struct bfs_dir *dir; /** This file's type, if known. */ enum bfs_type type; @@ -101,27 +105,58 @@ static void bftw_cache_init(struct bftw_cache *cache, size_t capacity) { cache->capacity = capacity; } -/** Remove a bftw_file from the cache. */ -static void bftw_cache_remove(struct bftw_cache *cache, struct bftw_file *file) { +/** Remove a bftw_file from the LRU list. */ +static void bftw_lru_remove(struct bftw_cache *cache, struct bftw_file *file) { if (cache->target == file) { cache->target = file->lru.prev; } LIST_REMOVE(cache, file, lru); +} +/** Remove a bftw_file from the cache. */ +static void bftw_cache_remove(struct bftw_cache *cache, struct bftw_file *file) { + bftw_lru_remove(cache, file); ++cache->capacity; } /** Close a bftw_file. */ static void bftw_file_close(struct bftw_cache *cache, struct bftw_file *file) { bfs_assert(file->fd >= 0); + bfs_assert(file->pincount == 0); - if (LIST_ATTACHED(cache, file, lru)) { - bftw_cache_remove(cache, file); + if (file->dir) { + bfs_assert(file->fd == bfs_dirfd(file->dir)); + bfs_closedir(file->dir); + file->dir = NULL; + } else { + xclose(file->fd); } - xclose(file->fd); file->fd = -1; + bftw_cache_remove(cache, file); +} + +/** Free an open directory. */ +static void bftw_file_freedir(struct bftw_cache *cache, struct bftw_file *file) { + if (!file->dir) { + return; + } + + // Try to keep an open fd if any children exist + bool reffed = file->refcount > 1; + // Keep the fd the same if it's pinned + bool pinned = file->pincount > 0; + + if (reffed || pinned) { + int fd = bfs_freedir(file->dir, pinned); + if (fd >= 0) { + file->fd = fd; + file->dir = NULL; + } + } else { + bftw_file_close(cache, file); + } } /** Pop the least recently used directory from the cache. */ @@ -135,6 +170,18 @@ static int bftw_cache_pop(struct bftw_cache *cache) { return 0; } +/** Add a bftw_file to the LRU list. */ +static void bftw_lru_add(struct bftw_cache *cache, struct bftw_file *file) { + bfs_assert(file->fd >= 0); + + 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; + } +} + /** Add a bftw_file to the cache. */ static int bftw_cache_add(struct bftw_cache *cache, struct bftw_file *file) { bfs_assert(file->fd >= 0); @@ -148,14 +195,28 @@ static int bftw_cache_add(struct bftw_cache *cache, struct bftw_file *file) { bfs_assert(cache->capacity > 0); --cache->capacity; - LIST_INSERT(cache, cache->target, file, lru); + bftw_lru_add(cache, file); + return 0; +} - // Prefer to keep the root paths open by keeping them at the head of the list - if (file->depth == 0) { - cache->target = file; +/** Pin a cache entry so it won't be closed. */ +static void bftw_cache_pin(struct bftw_cache *cache, struct bftw_file *file) { + bfs_assert(file->fd >= 0); + + if (file->pincount++ == 0) { + bftw_lru_remove(cache, file); } +} - return 0; +/** Unpin a cache entry. */ +static void bftw_cache_unpin(struct bftw_cache *cache, struct bftw_file *file) { + bfs_assert(file->fd >= 0); + bfs_assert(file->pincount > 0); + + if (--file->pincount == 0) { + bftw_lru_add(cache, file); + bftw_file_freedir(cache, file); + } } /** Compute the name offset of a child path. */ @@ -201,7 +262,9 @@ static struct bftw_file *bftw_file_new(struct bftw_file *parent, const char *nam file->lru.prev = file->lru.next = NULL; file->refcount = 1; + file->pincount = 0; file->fd = -1; + file->dir = NULL; file->type = BFS_UNKNOWN; file->dev = -1; @@ -234,8 +297,7 @@ static int bftw_file_openat(struct bftw_cache *cache, struct bftw_file *file, st int at_fd = AT_FDCWD; if (base) { - // Remove base from the cache temporarily so it stays open - bftw_cache_remove(cache, base); + bftw_cache_pin(cache, base); at_fd = base->fd; } @@ -250,7 +312,7 @@ static int bftw_file_openat(struct bftw_cache *cache, struct bftw_file *file, st } if (base) { - bftw_cache_add(cache, base); + bftw_cache_unpin(cache, base); } if (fd >= 0) { @@ -309,6 +371,19 @@ static int bftw_file_open(struct bftw_cache *cache, struct bftw_file *file, cons } /** + * Associate an open directory with a bftw_file. + */ +static void bftw_file_set_dir(struct bftw_cache *cache, struct bftw_file *file, struct bfs_dir *dir) { + bfs_assert(!file->dir); + file->dir = dir; + + if (file->fd < 0) { + file->fd = bfs_dirfd(dir); + bftw_cache_add(cache, file); + } +} + +/** * Open a bftw_file as a directory. * * @param cache @@ -326,7 +401,11 @@ static struct bfs_dir *bftw_file_opendir(struct bftw_cache *cache, struct bftw_f return NULL; } - return bfs_opendir(fd, NULL); + struct bfs_dir *dir = bfs_opendir(fd, NULL); + if (dir) { + bftw_file_set_dir(cache, file, dir); + } + return dir; } /** Free a bftw_file. */ @@ -798,7 +877,9 @@ static int bftw_opendir(struct bftw_state *state) { } state->dir = bftw_file_opendir(&state->cache, state->file, state->path); - if (!state->dir) { + if (state->dir) { + bftw_cache_pin(&state->cache, state->file); + } else { state->direrror = errno; } return 0; @@ -848,22 +929,9 @@ static int bftw_gc(struct bftw_state *state, enum bftw_gc_flags flags) { int ret = 0; if (state->dir) { - struct bftw_file *file = state->file; - bfs_assert(file && file->fd >= 0); - - if (file->refcount > 1) { - // Keep the fd around if any subdirectories exist - file->fd = bfs_freedir(state->dir, false); - } else { - file->fd = -1; - } - - if (file->fd < 0) { - bfs_closedir(state->dir); - bftw_cache_remove(&state->cache, file); - } + bftw_cache_unpin(&state->cache, state->file); + bftw_file_freedir(&state->cache, state->file); } - state->dir = NULL; state->de = NULL; @@ -876,8 +944,8 @@ static int bftw_gc(struct bftw_state *state, enum bftw_gc_flags flags) { } else { state->error = state->direrror; } - state->direrror = 0; } + state->direrror = 0; enum bftw_gc_flags visit = BFTW_VISIT_FILE; while (state->file) { |