tdb: use tdb_nest_lock() for transaction lock.

[ccan] / ccan / tdb / lock.c

diff --git a/ccan/tdb/lock.c b/ccan/tdb/lock.c
index 66cfcbdeea6eab9cd943f7b18a9dd8f66e4c9f8e..870601126bdb82d72163f3aba5b0f76f66c5c86e 100644 (file)
--- a/ccan/tdb/lock.c
+++ b/ccan/tdb/lock.c
@@ -224,12 +224,24 @@ static tdb_off_t lock_offset(int list)
        return FREELIST_TOP + 4*list;
 }
 
+static struct tdb_lock_type *find_nestlock(struct tdb_context *tdb,
+                                          tdb_off_t offset)
+{
+       unsigned int i;
+
+       for (i=0; i<tdb->num_lockrecs; i++) {
+               if (tdb->lockrecs[i].off == offset) {
+                       return &tdb->lockrecs[i];
+               }
+       }
+       return NULL;
+}
+
 /* lock an offset in the database. */
 int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
                  enum tdb_lock_flags flags)
 {
        struct tdb_lock_type *new_lck;
-       int i;
 
        if (offset >= lock_offset(tdb->header.hash_size)) {
                tdb->ecode = TDB_ERR_LOCK;
@@ -240,24 +252,14 @@ int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
        if (tdb->flags & TDB_NOLOCK)
                return 0;
 
-       for (i=0; i<tdb->num_lockrecs; i++) {
-               if (tdb->lockrecs[i].off == offset) {
-                       if (tdb->lockrecs[i].count == 0) {
-                               /*
-                                * Can't happen, see tdb_unlock(). It should
-                                * be an assert.
-                                */
-                               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock: "
-                                        "lck->count == 0 for offset %u",
-                                        offset));
-                       }
-                       /*
-                        * Just increment the in-memory struct, posix locks
-                        * don't stack.
-                        */
-                       tdb->lockrecs[i].count++;
-                       return 0;
-               }
+       new_lck = find_nestlock(tdb, offset);
+       if (new_lck) {
+               /*
+                * Just increment the in-memory struct, posix locks
+                * don't stack.
+                */
+               new_lck->count++;
+               return 0;
        }
 
        new_lck = (struct tdb_lock_type *)realloc(
@@ -332,8 +334,7 @@ int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype,
                    bool mark_lock)
 {
        int ret = -1;
-       int i;
-       struct tdb_lock_type *lck = NULL;
+       struct tdb_lock_type *lck;
 
        if (tdb->flags & TDB_NOLOCK)
                return 0;
@@ -344,13 +345,7 @@ int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype,
                return ret;
        }
 
-       for (i=0; i<tdb->num_lockrecs; i++) {
-               if (tdb->lockrecs[i].off == offset) {
-                       lck = &tdb->lockrecs[i];
-                       break;
-               }
-       }
-
+       lck = find_nestlock(tdb, offset);
        if ((lck == NULL) || (lck->count == 0)) {
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: count is 0\n"));
                return -1;
@@ -420,18 +415,7 @@ int tdb_unlock(struct tdb_context *tdb, int list, int ltype)
  */
 int tdb_transaction_lock(struct tdb_context *tdb, int ltype)
 {
-       if (tdb->transaction_lock_count > 0) {
-               tdb->transaction_lock_count++;
-               return 0;
-       }
-
-       if (tdb->methods->brlock(tdb, ltype, TRANSACTION_LOCK, 1, TDB_LOCK_WAIT) == -1) {
-               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_lock: failed to get transaction lock\n"));
-               tdb->ecode = TDB_ERR_LOCK;
-               return -1;
-       }
-       tdb->transaction_lock_count++;
-       return 0;
+       return tdb_nest_lock(tdb, TRANSACTION_LOCK, ltype, TDB_LOCK_WAIT);
 }
 
 /*
@@ -439,16 +423,7 @@ int tdb_transaction_lock(struct tdb_context *tdb, int ltype)
  */
 int tdb_transaction_unlock(struct tdb_context *tdb, int ltype)
 {
-       int ret;
-       if (tdb->transaction_lock_count > 1) {
-               tdb->transaction_lock_count--;
-               return 0;
-       }
-       ret = tdb->methods->brunlock(tdb, ltype, TRANSACTION_LOCK, 1);
-       if (ret == 0) {
-               tdb->transaction_lock_count = 0;
-       }
-       return ret;
+       return tdb_nest_unlock(tdb, TRANSACTION_LOCK, ltype, false);
 }
 
 
@@ -474,8 +449,8 @@ static int _tdb_lockall(struct tdb_context *tdb, int ltype,
                tdb->ecode = TDB_ERR_LOCK;
                return -1;
        }
-       
-       if (tdb->num_locks != 0) {
+
+       if (tdb_have_extra_locks(tdb)) {
                /* can't combine global and chain locks */
                tdb->ecode = TDB_ERR_LOCK;
                return -1;
@@ -691,3 +666,46 @@ int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off)
                        count++;
        return (count == 1 ? tdb->methods->brunlock(tdb, F_RDLCK, off, 1) : 0);
 }
+
+bool tdb_have_extra_locks(struct tdb_context *tdb)
+{
+       unsigned int extra = tdb->num_lockrecs;
+
+       if (tdb->allrecord_lock.count) {
+               return true;
+       }
+
+       /* In a transaction, we expect to hold the transaction lock */
+       if (tdb->transaction && find_nestlock(tdb, TRANSACTION_LOCK)) {
+               extra--;
+       }
+
+       return extra;
+}
+
+/* The transaction code uses this to remove all locks. */
+void tdb_release_extra_locks(struct tdb_context *tdb)
+{
+       unsigned int i, extra = 0;
+
+       if (tdb->allrecord_lock.count != 0) {
+               tdb_brunlock(tdb, tdb->allrecord_lock.ltype,
+                            FREELIST_TOP, 4*tdb->header.hash_size);
+               tdb->allrecord_lock.count = 0;
+       }
+
+       for (i=0;i<tdb->num_lockrecs;i++) {
+               struct tdb_lock_type *lck = &tdb->lockrecs[i];
+
+               if (tdb->transaction && lck->off == TRANSACTION_LOCK) {
+                       tdb->lockrecs[extra++] = *lck;
+               } else {
+                       tdb_brunlock(tdb, lck->ltype, lck->off, 1);
+               }
+       }
+       tdb->num_locks = extra;
+       tdb->num_lockrecs = extra;
+       if (tdb->num_lockrecs == 0) {
+               SAFE_FREE(tdb->lockrecs);
+       }
+}