pack-objects: merge read_lock and lock in packing_data struct
authorPatrick Hogg <phogg@novamoon.net>
Fri, 25 Jan 2019 00:22:05 +0000 (19:22 -0500)
committerJunio C Hamano <gitster@pobox.com>
Mon, 28 Jan 2019 19:22:12 +0000 (11:22 -0800)
Rename the packing_data lock to obd_lock and upgrade it to a recursive
mutex to make it suitable for current read_lock usages. Additionally
remove the superfluous #ifndef NO_PTHREADS guard around mutex
initialization in prepare_packing_data as the mutex functions
themselves are already protected.

Signed-off-by: Patrick Hogg <phogg@novamoon.net>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
builtin/pack-objects.c
pack-objects.c
pack-objects.h

index 506061b..cfef482 100644 (file)
@@ -1953,10 +1953,6 @@ static int delta_cacheable(unsigned long src_size, unsigned long trg_size,
        return 0;
 }
 
-/* Protect access to object database */
-#define read_lock()            packing_data_read_lock(&to_pack)
-#define read_unlock()          packing_data_read_unlock(&to_pack)
-
 /* Protect delta_cache_size */
 static pthread_mutex_t cache_mutex;
 #define cache_lock()           pthread_mutex_lock(&cache_mutex)
@@ -1992,11 +1988,11 @@ unsigned long oe_get_size_slow(struct packing_data *pack,
        unsigned long used, avail, size;
 
        if (e->type_ != OBJ_OFS_DELTA && e->type_ != OBJ_REF_DELTA) {
-               read_lock();
+               packing_data_lock(&to_pack);
                if (oid_object_info(the_repository, &e->idx.oid, &size) < 0)
                        die(_("unable to get size of %s"),
                            oid_to_hex(&e->idx.oid));
-               read_unlock();
+               packing_data_unlock(&to_pack);
                return size;
        }
 
@@ -2004,7 +2000,7 @@ unsigned long oe_get_size_slow(struct packing_data *pack,
        if (!p)
                BUG("when e->type is a delta, it must belong to a pack");
 
-       read_lock();
+       packing_data_lock(&to_pack);
        w_curs = NULL;
        buf = use_pack(p, &w_curs, e->in_pack_offset, &avail);
        used = unpack_object_header_buffer(buf, avail, &type, &size);
@@ -2013,7 +2009,7 @@ unsigned long oe_get_size_slow(struct packing_data *pack,
                    oid_to_hex(&e->idx.oid));
 
        unuse_pack(&w_curs);
-       read_unlock();
+       packing_data_unlock(&to_pack);
        return size;
 }
 
@@ -2075,9 +2071,9 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
 
        /* Load data if not already done */
        if (!trg->data) {
-               read_lock();
+               packing_data_lock(&to_pack);
                trg->data = read_object_file(&trg_entry->idx.oid, &type, &sz);
-               read_unlock();
+               packing_data_unlock(&to_pack);
                if (!trg->data)
                        die(_("object %s cannot be read"),
                            oid_to_hex(&trg_entry->idx.oid));
@@ -2088,9 +2084,9 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
                *mem_usage += sz;
        }
        if (!src->data) {
-               read_lock();
+               packing_data_lock(&to_pack);
                src->data = read_object_file(&src_entry->idx.oid, &type, &sz);
-               read_unlock();
+               packing_data_unlock(&to_pack);
                if (!src->data) {
                        if (src_entry->preferred_base) {
                                static int warned = 0;
@@ -2336,9 +2332,9 @@ static void find_deltas(struct object_entry **list, unsigned *list_size,
 
 static void try_to_free_from_threads(size_t size)
 {
-       read_lock();
+       packing_data_lock(&to_pack);
        release_pack_memory(size);
-       read_unlock();
+       packing_data_unlock(&to_pack);
 }
 
 static try_to_free_t old_try_to_free_routine;
index 3554c43..a1dc5eb 100644 (file)
@@ -148,10 +148,7 @@ void prepare_packing_data(struct packing_data *pdata)
                                             1U << OE_SIZE_BITS);
        pdata->oe_delta_size_limit = git_env_ulong("GIT_TEST_OE_DELTA_SIZE",
                                                   1UL << OE_DELTA_SIZE_BITS);
-#ifndef NO_PTHREADS
-       pthread_mutex_init(&pdata->lock, NULL);
-       init_recursive_mutex(&pdata->read_lock);
-#endif
+       init_recursive_mutex(&pdata->odb_lock);
 }
 
 struct object_entry *packlist_alloc(struct packing_data *pdata,
index 0a038e3..1667cba 100644 (file)
@@ -145,8 +145,11 @@ struct packing_data {
        struct packed_git **in_pack_by_idx;
        struct packed_git **in_pack;
 
-       pthread_mutex_t lock;
-       pthread_mutex_t read_lock;
+       /*
+        * During packing with multiple threads, protect the in-core
+        * object database from concurrent accesses.
+        */
+       pthread_mutex_t odb_lock;
 
        /*
         * This list contains entries for bases which we know the other side
@@ -166,22 +169,14 @@ struct packing_data {
 
 void prepare_packing_data(struct packing_data *pdata);
 
+/* Protect access to object database */
 static inline void packing_data_lock(struct packing_data *pdata)
 {
-       pthread_mutex_lock(&pdata->lock);
+       pthread_mutex_lock(&pdata->odb_lock);
 }
 static inline void packing_data_unlock(struct packing_data *pdata)
 {
-       pthread_mutex_unlock(&pdata->lock);
-}
-
-static inline void packing_data_read_lock(struct packing_data *pdata)
-{
-       pthread_mutex_lock(&pdata->read_lock);
-}
-static inline void packing_data_read_unlock(struct packing_data *pdata)
-{
-       pthread_mutex_unlock(&pdata->read_lock);
+       pthread_mutex_unlock(&pdata->odb_lock);
 }
 
 struct object_entry *packlist_alloc(struct packing_data *pdata,