Blame src/sortedcache.c

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#include "sortedcache.h"
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int git_sortedcache_new(
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	git_sortedcache **out,
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	size_t item_path_offset,
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	git_sortedcache_free_item_fn free_item,
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	void *free_item_payload,
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	git_vector_cmp item_cmp,
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	const char *path)
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{
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	git_sortedcache *sc;
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	size_t pathlen, alloclen;
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	pathlen = path ? strlen(path) : 0;
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	GITERR_CHECK_ALLOC_ADD(&alloclen, sizeof(git_sortedcache), pathlen);
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	GITERR_CHECK_ALLOC_ADD(&alloclen, alloclen, 1);
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	sc = git__calloc(1, alloclen);
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	GITERR_CHECK_ALLOC(sc);
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	git_pool_init(&sc->pool, 1);
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	if (git_vector_init(&sc->items, 4, item_cmp) < 0 ||
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		git_strmap_alloc(&sc->map) < 0)
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		goto fail;
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	if (git_rwlock_init(&sc->lock)) {
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		giterr_set(GITERR_OS, "failed to initialize lock");
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		goto fail;
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	}
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	sc->item_path_offset  = item_path_offset;
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	sc->free_item         = free_item;
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	sc->free_item_payload = free_item_payload;
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	GIT_REFCOUNT_INC(sc);
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	if (pathlen)
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		memcpy(sc->path, path, pathlen);
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	*out = sc;
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	return 0;
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fail:
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	git_strmap_free(sc->map);
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	git_vector_free(&sc->items);
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	git_pool_clear(&sc->pool);
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	git__free(sc);
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	return -1;
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}
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void git_sortedcache_incref(git_sortedcache *sc)
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{
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	GIT_REFCOUNT_INC(sc);
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}
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const char *git_sortedcache_path(git_sortedcache *sc)
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{
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	return sc->path;
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}
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static void sortedcache_clear(git_sortedcache *sc)
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{
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	git_strmap_clear(sc->map);
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	if (sc->free_item) {
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		size_t i;
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		void *item;
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		git_vector_foreach(&sc->items, i, item) {
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			sc->free_item(sc->free_item_payload, item);
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		}
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	}
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	git_vector_clear(&sc->items);
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	git_pool_clear(&sc->pool);
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}
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static void sortedcache_free(git_sortedcache *sc)
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{
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	/* acquire write lock to make sure everyone else is done */
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	if (git_sortedcache_wlock(sc) < 0)
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		return;
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	sortedcache_clear(sc);
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	git_vector_free(&sc->items);
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	git_strmap_free(sc->map);
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	git_sortedcache_wunlock(sc);
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	git_rwlock_free(&sc->lock);
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	git__free(sc);
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}
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void git_sortedcache_free(git_sortedcache *sc)
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{
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	if (!sc)
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		return;
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	GIT_REFCOUNT_DEC(sc, sortedcache_free);
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}
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static int sortedcache_copy_item(void *payload, void *tgt_item, void *src_item)
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{
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	git_sortedcache *sc = payload;
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	/* path will already have been copied by upsert */
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	memcpy(tgt_item, src_item, sc->item_path_offset);
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	return 0;
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}
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/* copy a sorted cache */
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int git_sortedcache_copy(
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	git_sortedcache **out,
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	git_sortedcache *src,
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	bool lock,
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	int (*copy_item)(void *payload, void *tgt_item, void *src_item),
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	void *payload)
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{
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	int error = 0;
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	git_sortedcache *tgt;
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	size_t i;
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	void *src_item, *tgt_item;
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	/* just use memcpy if no special copy fn is passed in */
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	if (!copy_item) {
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		copy_item = sortedcache_copy_item;
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		payload   = src;
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	}
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	if ((error = git_sortedcache_new(
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			&tgt, src->item_path_offset,
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			src->free_item, src->free_item_payload,
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			src->items._cmp, src->path)) < 0)
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		return error;
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	if (lock && git_sortedcache_rlock(src) < 0) {
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		git_sortedcache_free(tgt);
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		return -1;
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	}
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	git_vector_foreach(&src->items, i, src_item) {
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		char *path = ((char *)src_item) + src->item_path_offset;
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		if ((error = git_sortedcache_upsert(&tgt_item, tgt, path)) < 0 ||
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			(error = copy_item(payload, tgt_item, src_item)) < 0)
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			break;
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	}
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	if (lock)
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		git_sortedcache_runlock(src);
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	if (error)
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		git_sortedcache_free(tgt);
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	*out = !error ? tgt : NULL;
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	return error;
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}
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/* lock sortedcache while making modifications */
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int git_sortedcache_wlock(git_sortedcache *sc)
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{
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	GIT_UNUSED(sc); /* prevent warning when compiled w/o threads */
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	if (git_rwlock_wrlock(&sc->lock) < 0) {
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		giterr_set(GITERR_OS, "unable to acquire write lock on cache");
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		return -1;
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	}
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	return 0;
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}
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/* unlock sorted cache when done with modifications */
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void git_sortedcache_wunlock(git_sortedcache *sc)
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{
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	git_vector_sort(&sc->items);
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	git_rwlock_wrunlock(&sc->lock);
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}
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/* lock sortedcache for read */
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int git_sortedcache_rlock(git_sortedcache *sc)
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{
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	GIT_UNUSED(sc); /* prevent warning when compiled w/o threads */
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	if (git_rwlock_rdlock(&sc->lock) < 0) {
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		giterr_set(GITERR_OS, "unable to acquire read lock on cache");
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		return -1;
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	}
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	return 0;
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}
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/* unlock sorted cache when done reading */
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void git_sortedcache_runlock(git_sortedcache *sc)
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{
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	GIT_UNUSED(sc); /* prevent warning when compiled w/o threads */
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	git_rwlock_rdunlock(&sc->lock);
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}
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/* if the file has changed, lock cache and load file contents into buf;
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 * returns <0 on error, >0 if file has not changed
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 */
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int git_sortedcache_lockandload(git_sortedcache *sc, git_buf *buf)
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{
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	int error, fd;
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	struct stat st;
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	if ((error = git_sortedcache_wlock(sc)) < 0)
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		return error;
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	if ((error = git_futils_filestamp_check(&sc->stamp, sc->path)) <= 0)
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		goto unlock;
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	if ((fd = git_futils_open_ro(sc->path)) < 0) {
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		error = fd;
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		goto unlock;
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	}
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	if (p_fstat(fd, &st) < 0) {
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		giterr_set(GITERR_OS, "failed to stat file");
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		error = -1;
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		(void)p_close(fd);
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		goto unlock;
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	}
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	if (!git__is_sizet(st.st_size)) {
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		giterr_set(GITERR_INVALID, "unable to load file larger than size_t");
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		error = -1;
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		(void)p_close(fd);
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		goto unlock;
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	}
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	if (buf)
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		error = git_futils_readbuffer_fd(buf, fd, (size_t)st.st_size);
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	(void)p_close(fd);
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	if (error < 0)
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		goto unlock;
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	return 1; /* return 1 -> file needs reload and was successfully loaded */
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unlock:
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	git_sortedcache_wunlock(sc);
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	return error;
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}
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void git_sortedcache_updated(git_sortedcache *sc)
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{
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	/* update filestamp to latest value */
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	git_futils_filestamp_check(&sc->stamp, sc->path);
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}
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/* release all items in sorted cache */
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int git_sortedcache_clear(git_sortedcache *sc, bool wlock)
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{
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	if (wlock && git_sortedcache_wlock(sc) < 0)
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		return -1;
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	sortedcache_clear(sc);
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	if (wlock)
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		git_sortedcache_wunlock(sc);
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	return 0;
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}
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/* find and/or insert item, returning pointer to item data */
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int git_sortedcache_upsert(void **out, git_sortedcache *sc, const char *key)
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{
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	int error = 0;
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	khiter_t pos;
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	void *item;
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	size_t keylen, itemlen;
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	char *item_key;
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	pos = git_strmap_lookup_index(sc->map, key);
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	if (git_strmap_valid_index(sc->map, pos)) {
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		item = git_strmap_value_at(sc->map, pos);
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		goto done;
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	}
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	keylen  = strlen(key);
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	itemlen = sc->item_path_offset + keylen + 1;
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	itemlen = (itemlen + 7) & ~7;
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	if ((item = git_pool_mallocz(&sc->pool, (uint32_t)itemlen)) == NULL) {
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		/* don't use GITERR_CHECK_ALLOC b/c of lock */
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		error = -1;
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		goto done;
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	}
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	/* one strange thing is that even if the vector or hash table insert
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	 * fail, there is no way to free the pool item so we just abandon it
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	 */
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	item_key = ((char *)item) + sc->item_path_offset;
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	memcpy(item_key, key, keylen);
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	pos = git_strmap_put(sc->map, item_key, &error);
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	if (error < 0)
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		goto done;
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	if (!error)
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		git_strmap_set_key_at(sc->map, pos, item_key);
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	git_strmap_set_value_at(sc->map, pos, item);
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	error = git_vector_insert(&sc->items, item);
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	if (error < 0)
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		git_strmap_delete_at(sc->map, pos);
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done:
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	if (out)
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		*out = !error ? item : NULL;
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	return error;
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}
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/* lookup item by key */
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void *git_sortedcache_lookup(const git_sortedcache *sc, const char *key)
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{
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	khiter_t pos = git_strmap_lookup_index(sc->map, key);
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	if (git_strmap_valid_index(sc->map, pos))
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		return git_strmap_value_at(sc->map, pos);
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	return NULL;
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}
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/* find out how many items are in the cache */
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size_t git_sortedcache_entrycount(const git_sortedcache *sc)
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{
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	return git_vector_length(&sc->items);
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}
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/* lookup item by index */
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void *git_sortedcache_entry(git_sortedcache *sc, size_t pos)
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{
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	/* make sure the items are sorted so this gets the correct item */
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	if (!git_vector_is_sorted(&sc->items))
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		git_vector_sort(&sc->items);
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	return git_vector_get(&sc->items, pos);
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}
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/* helper struct so bsearch callback can know offset + key value for cmp */
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struct sortedcache_magic_key {
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	size_t offset;
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	const char *key;
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};
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static int sortedcache_magic_cmp(const void *key, const void *value)
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{
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	const struct sortedcache_magic_key *magic = key;
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	const char *value_key = ((const char *)value) + magic->offset;
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	return strcmp(magic->key, value_key);
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}
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/* lookup index of item by key */
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int git_sortedcache_lookup_index(
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	size_t *out, git_sortedcache *sc, const char *key)
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{
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	struct sortedcache_magic_key magic;
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	magic.offset = sc->item_path_offset;
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	magic.key    = key;
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	return git_vector_bsearch2(out, &sc->items, sortedcache_magic_cmp, &magic);
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}
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/* remove entry from cache */
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int git_sortedcache_remove(git_sortedcache *sc, size_t pos)
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{
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	char *item;
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	khiter_t mappos;
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	/* because of pool allocation, this can't actually remove the item,
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	 * but we can remove it from the items vector and the hash table.
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	 */
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	if ((item = git_vector_get(&sc->items, pos)) == NULL) {
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		giterr_set(GITERR_INVALID, "removing item out of range");
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		return GIT_ENOTFOUND;
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	}
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	(void)git_vector_remove(&sc->items, pos);
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	mappos = git_strmap_lookup_index(sc->map, item + sc->item_path_offset);
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	git_strmap_delete_at(sc->map, mappos);
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	if (sc->free_item)
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		sc->free_item(sc->free_item_payload, item);
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	return 0;
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}
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