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-rw-r--r--name-hash.c731
1 files changed, 731 insertions, 0 deletions
diff --git a/name-hash.c b/name-hash.c
new file mode 100644
index 0000000..5d3c7b1
--- /dev/null
+++ b/name-hash.c
@@ -0,0 +1,731 @@
+/*
+ * name-hash.c
+ *
+ * Hashing names in the index state
+ *
+ * Copyright (C) 2008 Linus Torvalds
+ */
+#include "cache.h"
+#include "thread-utils.h"
+
+struct dir_entry {
+ struct hashmap_entry ent;
+ struct dir_entry *parent;
+ int nr;
+ unsigned int namelen;
+ char name[FLEX_ARRAY];
+};
+
+static int dir_entry_cmp(const void *unused_cmp_data,
+ const struct hashmap_entry *eptr,
+ const struct hashmap_entry *entry_or_key,
+ const void *keydata)
+{
+ const struct dir_entry *e1, *e2;
+ const char *name = keydata;
+
+ e1 = container_of(eptr, const struct dir_entry, ent);
+ e2 = container_of(entry_or_key, const struct dir_entry, ent);
+
+ return e1->namelen != e2->namelen || strncasecmp(e1->name,
+ name ? name : e2->name, e1->namelen);
+}
+
+static struct dir_entry *find_dir_entry__hash(struct index_state *istate,
+ const char *name, unsigned int namelen, unsigned int hash)
+{
+ struct dir_entry key;
+ hashmap_entry_init(&key.ent, hash);
+ key.namelen = namelen;
+ return hashmap_get_entry(&istate->dir_hash, &key, ent, name);
+}
+
+static struct dir_entry *find_dir_entry(struct index_state *istate,
+ const char *name, unsigned int namelen)
+{
+ return find_dir_entry__hash(istate, name, namelen, memihash(name, namelen));
+}
+
+static struct dir_entry *hash_dir_entry(struct index_state *istate,
+ struct cache_entry *ce, int namelen)
+{
+ /*
+ * Throw each directory component in the hash for quick lookup
+ * during a git status. Directory components are stored without their
+ * closing slash. Despite submodules being a directory, they never
+ * reach this point, because they are stored
+ * in index_state.name_hash (as ordinary cache_entries).
+ */
+ struct dir_entry *dir;
+
+ /* get length of parent directory */
+ while (namelen > 0 && !is_dir_sep(ce->name[namelen - 1]))
+ namelen--;
+ if (namelen <= 0)
+ return NULL;
+ namelen--;
+
+ /* lookup existing entry for that directory */
+ dir = find_dir_entry(istate, ce->name, namelen);
+ if (!dir) {
+ /* not found, create it and add to hash table */
+ FLEX_ALLOC_MEM(dir, name, ce->name, namelen);
+ hashmap_entry_init(&dir->ent, memihash(ce->name, namelen));
+ dir->namelen = namelen;
+ hashmap_add(&istate->dir_hash, &dir->ent);
+
+ /* recursively add missing parent directories */
+ dir->parent = hash_dir_entry(istate, ce, namelen);
+ }
+ return dir;
+}
+
+static void add_dir_entry(struct index_state *istate, struct cache_entry *ce)
+{
+ /* Add reference to the directory entry (and parents if 0). */
+ struct dir_entry *dir = hash_dir_entry(istate, ce, ce_namelen(ce));
+ while (dir && !(dir->nr++))
+ dir = dir->parent;
+}
+
+static void remove_dir_entry(struct index_state *istate, struct cache_entry *ce)
+{
+ /*
+ * Release reference to the directory entry. If 0, remove and continue
+ * with parent directory.
+ */
+ struct dir_entry *dir = hash_dir_entry(istate, ce, ce_namelen(ce));
+ while (dir && !(--dir->nr)) {
+ struct dir_entry *parent = dir->parent;
+ hashmap_remove(&istate->dir_hash, &dir->ent, NULL);
+ free(dir);
+ dir = parent;
+ }
+}
+
+static void hash_index_entry(struct index_state *istate, struct cache_entry *ce)
+{
+ if (ce->ce_flags & CE_HASHED)
+ return;
+ ce->ce_flags |= CE_HASHED;
+ hashmap_entry_init(&ce->ent, memihash(ce->name, ce_namelen(ce)));
+ hashmap_add(&istate->name_hash, &ce->ent);
+
+ if (ignore_case)
+ add_dir_entry(istate, ce);
+}
+
+static int cache_entry_cmp(const void *unused_cmp_data,
+ const struct hashmap_entry *eptr,
+ const struct hashmap_entry *entry_or_key,
+ const void *remove)
+{
+ const struct cache_entry *ce1, *ce2;
+
+ ce1 = container_of(eptr, const struct cache_entry, ent);
+ ce2 = container_of(entry_or_key, const struct cache_entry, ent);
+
+ /*
+ * For remove_name_hash, find the exact entry (pointer equality); for
+ * index_file_exists, find all entries with matching hash code and
+ * decide whether the entry matches in same_name.
+ */
+ return remove ? !(ce1 == ce2) : 0;
+}
+
+static int lazy_try_threaded = 1;
+static int lazy_nr_dir_threads;
+
+/*
+ * Set a minimum number of cache_entries that we will handle per
+ * thread and use that to decide how many threads to run (up to
+ * the number on the system).
+ *
+ * For guidance setting the lower per-thread bound, see:
+ * t/helper/test-lazy-init-name-hash --analyze
+ */
+#define LAZY_THREAD_COST (2000)
+
+/*
+ * We use n mutexes to guard n partitions of the "istate->dir_hash"
+ * hashtable. Since "find" and "insert" operations will hash to a
+ * particular bucket and modify/search a single chain, we can say
+ * that "all chains mod n" are guarded by the same mutex -- rather
+ * than having a single mutex to guard the entire table. (This does
+ * require that we disable "rehashing" on the hashtable.)
+ *
+ * So, a larger value here decreases the probability of a collision
+ * and the time that each thread must wait for the mutex.
+ */
+#define LAZY_MAX_MUTEX (32)
+
+static pthread_mutex_t *lazy_dir_mutex_array;
+
+/*
+ * An array of lazy_entry items is used by the n threads in
+ * the directory parse (first) phase to (lock-free) store the
+ * intermediate results. These values are then referenced by
+ * the 2 threads in the second phase.
+ */
+struct lazy_entry {
+ struct dir_entry *dir;
+ unsigned int hash_dir;
+ unsigned int hash_name;
+};
+
+/*
+ * Decide if we want to use threads (if available) to load
+ * the hash tables. We set "lazy_nr_dir_threads" to zero when
+ * it is not worth it.
+ */
+static int lookup_lazy_params(struct index_state *istate)
+{
+ int nr_cpus;
+
+ lazy_nr_dir_threads = 0;
+
+ if (!lazy_try_threaded)
+ return 0;
+
+ /*
+ * If we are respecting case, just use the original
+ * code to build the "istate->name_hash". We don't
+ * need the complexity here.
+ */
+ if (!ignore_case)
+ return 0;
+
+ nr_cpus = online_cpus();
+ if (nr_cpus < 2)
+ return 0;
+
+ if (istate->cache_nr < 2 * LAZY_THREAD_COST)
+ return 0;
+
+ if (istate->cache_nr < nr_cpus * LAZY_THREAD_COST)
+ nr_cpus = istate->cache_nr / LAZY_THREAD_COST;
+ lazy_nr_dir_threads = nr_cpus;
+ return lazy_nr_dir_threads;
+}
+
+/*
+ * Initialize n mutexes for use when searching and inserting
+ * into "istate->dir_hash". All "dir" threads are trying
+ * to insert partial pathnames into the hash as they iterate
+ * over their portions of the index, so lock contention is
+ * high.
+ *
+ * However, the hashmap is going to put items into bucket
+ * chains based on their hash values. Use that to create n
+ * mutexes and lock on mutex[bucket(hash) % n]. This will
+ * decrease the collision rate by (hopefully) a factor of n.
+ */
+static void init_dir_mutex(void)
+{
+ int j;
+
+ lazy_dir_mutex_array = xcalloc(LAZY_MAX_MUTEX, sizeof(pthread_mutex_t));
+
+ for (j = 0; j < LAZY_MAX_MUTEX; j++)
+ init_recursive_mutex(&lazy_dir_mutex_array[j]);
+}
+
+static void cleanup_dir_mutex(void)
+{
+ int j;
+
+ for (j = 0; j < LAZY_MAX_MUTEX; j++)
+ pthread_mutex_destroy(&lazy_dir_mutex_array[j]);
+
+ free(lazy_dir_mutex_array);
+}
+
+static void lock_dir_mutex(int j)
+{
+ pthread_mutex_lock(&lazy_dir_mutex_array[j]);
+}
+
+static void unlock_dir_mutex(int j)
+{
+ pthread_mutex_unlock(&lazy_dir_mutex_array[j]);
+}
+
+static inline int compute_dir_lock_nr(
+ const struct hashmap *map,
+ unsigned int hash)
+{
+ return hashmap_bucket(map, hash) % LAZY_MAX_MUTEX;
+}
+
+static struct dir_entry *hash_dir_entry_with_parent_and_prefix(
+ struct index_state *istate,
+ struct dir_entry *parent,
+ struct strbuf *prefix)
+{
+ struct dir_entry *dir;
+ unsigned int hash;
+ int lock_nr;
+
+ /*
+ * Either we have a parent directory and path with slash(es)
+ * or the directory is an immediate child of the root directory.
+ */
+ assert((parent != NULL) ^ (strchr(prefix->buf, '/') == NULL));
+
+ if (parent)
+ hash = memihash_cont(parent->ent.hash,
+ prefix->buf + parent->namelen,
+ prefix->len - parent->namelen);
+ else
+ hash = memihash(prefix->buf, prefix->len);
+
+ lock_nr = compute_dir_lock_nr(&istate->dir_hash, hash);
+ lock_dir_mutex(lock_nr);
+
+ dir = find_dir_entry__hash(istate, prefix->buf, prefix->len, hash);
+ if (!dir) {
+ FLEX_ALLOC_MEM(dir, name, prefix->buf, prefix->len);
+ hashmap_entry_init(&dir->ent, hash);
+ dir->namelen = prefix->len;
+ dir->parent = parent;
+ hashmap_add(&istate->dir_hash, &dir->ent);
+
+ if (parent) {
+ unlock_dir_mutex(lock_nr);
+
+ /* All I really need here is an InterlockedIncrement(&(parent->nr)) */
+ lock_nr = compute_dir_lock_nr(&istate->dir_hash, parent->ent.hash);
+ lock_dir_mutex(lock_nr);
+ parent->nr++;
+ }
+ }
+
+ unlock_dir_mutex(lock_nr);
+
+ return dir;
+}
+
+/*
+ * handle_range_1() and handle_range_dir() are derived from
+ * clear_ce_flags_1() and clear_ce_flags_dir() in unpack-trees.c
+ * and handle the iteration over the entire array of index entries.
+ * They use recursion for adjacent entries in the same parent
+ * directory.
+ */
+static int handle_range_1(
+ struct index_state *istate,
+ int k_start,
+ int k_end,
+ struct dir_entry *parent,
+ struct strbuf *prefix,
+ struct lazy_entry *lazy_entries);
+
+static int handle_range_dir(
+ struct index_state *istate,
+ int k_start,
+ int k_end,
+ struct dir_entry *parent,
+ struct strbuf *prefix,
+ struct lazy_entry *lazy_entries,
+ struct dir_entry **dir_new_out)
+{
+ int rc, k;
+ int input_prefix_len = prefix->len;
+ struct dir_entry *dir_new;
+
+ dir_new = hash_dir_entry_with_parent_and_prefix(istate, parent, prefix);
+
+ strbuf_addch(prefix, '/');
+
+ /*
+ * Scan forward in the index array for index entries having the same
+ * path prefix (that are also in this directory).
+ */
+ if (k_start + 1 >= k_end)
+ k = k_end;
+ else if (strncmp(istate->cache[k_start + 1]->name, prefix->buf, prefix->len) > 0)
+ k = k_start + 1;
+ else if (strncmp(istate->cache[k_end - 1]->name, prefix->buf, prefix->len) == 0)
+ k = k_end;
+ else {
+ int begin = k_start;
+ int end = k_end;
+ assert(begin >= 0);
+ while (begin < end) {
+ int mid = begin + ((end - begin) >> 1);
+ int cmp = strncmp(istate->cache[mid]->name, prefix->buf, prefix->len);
+ if (cmp == 0) /* mid has same prefix; look in second part */
+ begin = mid + 1;
+ else if (cmp > 0) /* mid is past group; look in first part */
+ end = mid;
+ else
+ die("cache entry out of order");
+ }
+ k = begin;
+ }
+
+ /*
+ * Recurse and process what we can of this subset [k_start, k).
+ */
+ rc = handle_range_1(istate, k_start, k, dir_new, prefix, lazy_entries);
+
+ strbuf_setlen(prefix, input_prefix_len);
+
+ *dir_new_out = dir_new;
+ return rc;
+}
+
+static int handle_range_1(
+ struct index_state *istate,
+ int k_start,
+ int k_end,
+ struct dir_entry *parent,
+ struct strbuf *prefix,
+ struct lazy_entry *lazy_entries)
+{
+ int input_prefix_len = prefix->len;
+ int k = k_start;
+
+ while (k < k_end) {
+ struct cache_entry *ce_k = istate->cache[k];
+ const char *name, *slash;
+
+ if (prefix->len && strncmp(ce_k->name, prefix->buf, prefix->len))
+ break;
+
+ name = ce_k->name + prefix->len;
+ slash = strchr(name, '/');
+
+ if (slash) {
+ int len = slash - name;
+ int processed;
+ struct dir_entry *dir_new;
+
+ strbuf_add(prefix, name, len);
+ processed = handle_range_dir(istate, k, k_end, parent, prefix, lazy_entries, &dir_new);
+ if (processed) {
+ k += processed;
+ strbuf_setlen(prefix, input_prefix_len);
+ continue;
+ }
+
+ strbuf_addch(prefix, '/');
+ processed = handle_range_1(istate, k, k_end, dir_new, prefix, lazy_entries);
+ k += processed;
+ strbuf_setlen(prefix, input_prefix_len);
+ continue;
+ }
+
+ /*
+ * It is too expensive to take a lock to insert "ce_k"
+ * into "istate->name_hash" and increment the ref-count
+ * on the "parent" dir. So we defer actually updating
+ * permanent data structures until phase 2 (where we
+ * can change the locking requirements) and simply
+ * accumulate our current results into the lazy_entries
+ * data array).
+ *
+ * We do not need to lock the lazy_entries array because
+ * we have exclusive access to the cells in the range
+ * [k_start,k_end) that this thread was given.
+ */
+ lazy_entries[k].dir = parent;
+ if (parent) {
+ lazy_entries[k].hash_name = memihash_cont(
+ parent->ent.hash,
+ ce_k->name + parent->namelen,
+ ce_namelen(ce_k) - parent->namelen);
+ lazy_entries[k].hash_dir = parent->ent.hash;
+ } else {
+ lazy_entries[k].hash_name = memihash(ce_k->name, ce_namelen(ce_k));
+ }
+
+ k++;
+ }
+
+ return k - k_start;
+}
+
+struct lazy_dir_thread_data {
+ pthread_t pthread;
+ struct index_state *istate;
+ struct lazy_entry *lazy_entries;
+ int k_start;
+ int k_end;
+};
+
+static void *lazy_dir_thread_proc(void *_data)
+{
+ struct lazy_dir_thread_data *d = _data;
+ struct strbuf prefix = STRBUF_INIT;
+ handle_range_1(d->istate, d->k_start, d->k_end, NULL, &prefix, d->lazy_entries);
+ strbuf_release(&prefix);
+ return NULL;
+}
+
+struct lazy_name_thread_data {
+ pthread_t pthread;
+ struct index_state *istate;
+ struct lazy_entry *lazy_entries;
+};
+
+static void *lazy_name_thread_proc(void *_data)
+{
+ struct lazy_name_thread_data *d = _data;
+ int k;
+
+ for (k = 0; k < d->istate->cache_nr; k++) {
+ struct cache_entry *ce_k = d->istate->cache[k];
+ ce_k->ce_flags |= CE_HASHED;
+ hashmap_entry_init(&ce_k->ent, d->lazy_entries[k].hash_name);
+ hashmap_add(&d->istate->name_hash, &ce_k->ent);
+ }
+
+ return NULL;
+}
+
+static inline void lazy_update_dir_ref_counts(
+ struct index_state *istate,
+ struct lazy_entry *lazy_entries)
+{
+ int k;
+
+ for (k = 0; k < istate->cache_nr; k++) {
+ if (lazy_entries[k].dir)
+ lazy_entries[k].dir->nr++;
+ }
+}
+
+static void threaded_lazy_init_name_hash(
+ struct index_state *istate)
+{
+ int err;
+ int nr_each;
+ int k_start;
+ int t;
+ struct lazy_entry *lazy_entries;
+ struct lazy_dir_thread_data *td_dir;
+ struct lazy_name_thread_data *td_name;
+
+ if (!HAVE_THREADS)
+ return;
+
+ k_start = 0;
+ nr_each = DIV_ROUND_UP(istate->cache_nr, lazy_nr_dir_threads);
+
+ lazy_entries = xcalloc(istate->cache_nr, sizeof(struct lazy_entry));
+ td_dir = xcalloc(lazy_nr_dir_threads, sizeof(struct lazy_dir_thread_data));
+ td_name = xcalloc(1, sizeof(struct lazy_name_thread_data));
+
+ init_dir_mutex();
+
+ /*
+ * Phase 1:
+ * Build "istate->dir_hash" using n "dir" threads (and a read-only index).
+ */
+ for (t = 0; t < lazy_nr_dir_threads; t++) {
+ struct lazy_dir_thread_data *td_dir_t = td_dir + t;
+ td_dir_t->istate = istate;
+ td_dir_t->lazy_entries = lazy_entries;
+ td_dir_t->k_start = k_start;
+ k_start += nr_each;
+ if (k_start > istate->cache_nr)
+ k_start = istate->cache_nr;
+ td_dir_t->k_end = k_start;
+ err = pthread_create(&td_dir_t->pthread, NULL, lazy_dir_thread_proc, td_dir_t);
+ if (err)
+ die(_("unable to create lazy_dir thread: %s"), strerror(err));
+ }
+ for (t = 0; t < lazy_nr_dir_threads; t++) {
+ struct lazy_dir_thread_data *td_dir_t = td_dir + t;
+ if (pthread_join(td_dir_t->pthread, NULL))
+ die("unable to join lazy_dir_thread");
+ }
+
+ /*
+ * Phase 2:
+ * Iterate over all index entries and add them to the "istate->name_hash"
+ * using a single "name" background thread.
+ * (Testing showed it wasn't worth running more than 1 thread for this.)
+ *
+ * Meanwhile, finish updating the parent directory ref-counts for each
+ * index entry using the current thread. (This step is very fast and
+ * doesn't need threading.)
+ */
+ td_name->istate = istate;
+ td_name->lazy_entries = lazy_entries;
+ err = pthread_create(&td_name->pthread, NULL, lazy_name_thread_proc, td_name);
+ if (err)
+ die(_("unable to create lazy_name thread: %s"), strerror(err));
+
+ lazy_update_dir_ref_counts(istate, lazy_entries);
+
+ err = pthread_join(td_name->pthread, NULL);
+ if (err)
+ die(_("unable to join lazy_name thread: %s"), strerror(err));
+
+ cleanup_dir_mutex();
+
+ free(td_name);
+ free(td_dir);
+ free(lazy_entries);
+}
+
+static void lazy_init_name_hash(struct index_state *istate)
+{
+
+ if (istate->name_hash_initialized)
+ return;
+ trace_performance_enter();
+ hashmap_init(&istate->name_hash, cache_entry_cmp, NULL, istate->cache_nr);
+ hashmap_init(&istate->dir_hash, dir_entry_cmp, NULL, istate->cache_nr);
+
+ if (lookup_lazy_params(istate)) {
+ /*
+ * Disable item counting and automatic rehashing because
+ * we do per-chain (mod n) locking rather than whole hashmap
+ * locking and we need to prevent the table-size from changing
+ * and bucket items from being redistributed.
+ */
+ hashmap_disable_item_counting(&istate->dir_hash);
+ threaded_lazy_init_name_hash(istate);
+ hashmap_enable_item_counting(&istate->dir_hash);
+ } else {
+ int nr;
+ for (nr = 0; nr < istate->cache_nr; nr++)
+ hash_index_entry(istate, istate->cache[nr]);
+ }
+
+ istate->name_hash_initialized = 1;
+ trace_performance_leave("initialize name hash");
+}
+
+/*
+ * A test routine for t/helper/ sources.
+ *
+ * Returns the number of threads used or 0 when
+ * the non-threaded code path was used.
+ *
+ * Requesting threading WILL NOT override guards
+ * in lookup_lazy_params().
+ */
+int test_lazy_init_name_hash(struct index_state *istate, int try_threaded)
+{
+ lazy_nr_dir_threads = 0;
+ lazy_try_threaded = try_threaded;
+
+ lazy_init_name_hash(istate);
+
+ return lazy_nr_dir_threads;
+}
+
+void add_name_hash(struct index_state *istate, struct cache_entry *ce)
+{
+ if (istate->name_hash_initialized)
+ hash_index_entry(istate, ce);
+}
+
+void remove_name_hash(struct index_state *istate, struct cache_entry *ce)
+{
+ if (!istate->name_hash_initialized || !(ce->ce_flags & CE_HASHED))
+ return;
+ ce->ce_flags &= ~CE_HASHED;
+ hashmap_remove(&istate->name_hash, &ce->ent, ce);
+
+ if (ignore_case)
+ remove_dir_entry(istate, ce);
+}
+
+static int slow_same_name(const char *name1, int len1, const char *name2, int len2)
+{
+ if (len1 != len2)
+ return 0;
+
+ while (len1) {
+ unsigned char c1 = *name1++;
+ unsigned char c2 = *name2++;
+ len1--;
+ if (c1 != c2) {
+ c1 = toupper(c1);
+ c2 = toupper(c2);
+ if (c1 != c2)
+ return 0;
+ }
+ }
+ return 1;
+}
+
+static int same_name(const struct cache_entry *ce, const char *name, int namelen, int icase)
+{
+ int len = ce_namelen(ce);
+
+ /*
+ * Always do exact compare, even if we want a case-ignoring comparison;
+ * we do the quick exact one first, because it will be the common case.
+ */
+ if (len == namelen && !memcmp(name, ce->name, len))
+ return 1;
+
+ if (!icase)
+ return 0;
+
+ return slow_same_name(name, namelen, ce->name, len);
+}
+
+int index_dir_exists(struct index_state *istate, const char *name, int namelen)
+{
+ struct dir_entry *dir;
+
+ lazy_init_name_hash(istate);
+ dir = find_dir_entry(istate, name, namelen);
+ return dir && dir->nr;
+}
+
+void adjust_dirname_case(struct index_state *istate, char *name)
+{
+ const char *startPtr = name;
+ const char *ptr = startPtr;
+
+ lazy_init_name_hash(istate);
+ while (*ptr) {
+ while (*ptr && *ptr != '/')
+ ptr++;
+
+ if (*ptr == '/') {
+ struct dir_entry *dir;
+
+ dir = find_dir_entry(istate, name, ptr - name);
+ if (dir) {
+ memcpy((void *)startPtr, dir->name + (startPtr - name), ptr - startPtr);
+ startPtr = ptr + 1;
+ }
+ ptr++;
+ }
+ }
+}
+
+struct cache_entry *index_file_exists(struct index_state *istate, const char *name, int namelen, int icase)
+{
+ struct cache_entry *ce;
+ unsigned int hash = memihash(name, namelen);
+
+ lazy_init_name_hash(istate);
+
+ ce = hashmap_get_entry_from_hash(&istate->name_hash, hash, NULL,
+ struct cache_entry, ent);
+ hashmap_for_each_entry_from(&istate->name_hash, ce, ent) {
+ if (same_name(ce, name, namelen, icase))
+ return ce;
+ }
+ return NULL;
+}
+
+void free_name_hash(struct index_state *istate)
+{
+ if (!istate->name_hash_initialized)
+ return;
+ istate->name_hash_initialized = 0;
+
+ hashmap_clear(&istate->name_hash);
+ hashmap_clear_and_free(&istate->dir_hash, struct dir_entry, ent);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-17 01:04:00 +0000