tdb2: implement tdb_chainlock_read/tdb_chainunlock_read.

[ccan] / ccan / tdb2 / tdb2.h

diff --git a/ccan/tdb2/tdb2.h b/ccan/tdb2/tdb2.h
index fa5787c3779acd424e7f3cbde6a4c5e6746eb45d..802bcdbe10e02d7b52fc51fb90a9cec968a2f527 100644 (file)
--- a/ccan/tdb2/tdb2.h
+++ b/ccan/tdb2/tdb2.h
@@ -311,7 +311,7 @@ enum TDB_ERROR tdb_transaction_prepare_commit(struct tdb_context *tdb);
  * a negative enum TDB_ERROR value.
  */
 #define tdb_traverse(tdb, fn, p)                                       \
-       tdb_traverse_(tdb, typesafe_cb_preargs(int, (fn), (p),          \
+       tdb_traverse_(tdb, typesafe_cb_preargs(int, void *, (fn), (p),  \
                                               struct tdb_context *,    \
                                               TDB_DATA, TDB_DATA), (p))
 
@@ -334,7 +334,8 @@ int64_t tdb_traverse_(struct tdb_context *tdb,
  */
 #define tdb_parse_record(tdb, key, parse, p)                           \
        tdb_parse_record_((tdb), (key),                                 \
-                         typesafe_cb_preargs(enum TDB_ERROR, (parse), (p), \
+                         typesafe_cb_preargs(enum TDB_ERROR, void *,   \
+                                             (parse), (p),             \
                                              TDB_DATA, TDB_DATA), (p))
 
 enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb,
@@ -394,7 +395,7 @@ enum TDB_ERROR tdb_nextkey(struct tdb_context *tdb, struct tdb_data *key);
  * @tdb: the tdb context returned from tdb_open()
  * @key: the key to lock.
  *
- * This prevents any changes from occurring to a group of keys including @key,
+ * This prevents any access occurring to a group of keys including @key,
  * even if @key does not exist.  This allows primitive atomic updates of
  * records without using transactions.
  *
@@ -411,8 +412,70 @@ enum TDB_ERROR tdb_chainlock(struct tdb_context *tdb, TDB_DATA key);
  * tdb_chainunlock - unlock a record in the TDB
  * @tdb: the tdb context returned from tdb_open()
  * @key: the key to unlock.
+ *
+ * The key must have previously been locked by tdb_chainlock().
+ */
+void tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key);
+
+/**
+ * tdb_chainlock_read - lock a record in the TDB, for reading
+ * @tdb: the tdb context returned from tdb_open()
+ * @key: the key to lock.
+ *
+ * This prevents any changes from occurring to a group of keys including @key,
+ * even if @key does not exist.  This allows primitive atomic updates of
+ * records without using transactions.
+ *
+ * You cannot begin a transaction while holding a tdb_chainlock_read(), nor can
+ * you do any operations on any other keys in the database.  This also means
+ * that you cannot hold more than one tdb_chainlock()/read() at a time.
+ *
+ * See Also:
+ *     tdb_chainlock()
+ */
+enum TDB_ERROR tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key);
+
+/**
+ * tdb_chainunlock_read - unlock a record in the TDB for reading
+ * @tdb: the tdb context returned from tdb_open()
+ * @key: the key to unlock.
+ *
+ * The key must have previously been locked by tdb_chainlock_read().
+ */
+void tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key);
+
+/**
+ * tdb_lockall - lock the entire TDB
+ * @tdb: the tdb context returned from tdb_open()
+ *
+ * You cannot hold a tdb_chainlock while calling this.  It nests, so you
+ * must call tdb_unlockall as many times as you call tdb_lockall.
+ */
+enum TDB_ERROR tdb_lockall(struct tdb_context *tdb);
+
+/**
+ * tdb_unlockall - unlock the entire TDB
+ * @tdb: the tdb context returned from tdb_open()
+ */
+void tdb_unlockall(struct tdb_context *tdb);
+
+/**
+ * tdb_lockall_read - lock the entire TDB for reading
+ * @tdb: the tdb context returned from tdb_open()
+ *
+ * This prevents others writing to the database, eg. tdb_delete, tdb_store,
+ * tdb_append, but not tdb_fetch.
+ *
+ * You cannot hold a tdb_chainlock while calling this.  It nests, so you
+ * must call tdb_unlockall_read as many times as you call tdb_lockall_read.
+ */
+enum TDB_ERROR tdb_lockall_read(struct tdb_context *tdb);
+
+/**
+ * tdb_unlockall_read - unlock the entire TDB for reading
+ * @tdb: the tdb context returned from tdb_open()
  */
-enum TDB_ERROR tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key);
+void tdb_unlockall_read(struct tdb_context *tdb);
 
 /**
  * tdb_wipe_all - wipe the database clean
@@ -427,7 +490,7 @@ enum TDB_ERROR tdb_wipe_all(struct tdb_context *tdb);
  * tdb_check - check a TDB for consistency
  * @tdb: the tdb context returned from tdb_open()
  * @check: function to check each key/data pair (or NULL)
- * @private: argument for @check, must match type.
+ * @private_data: argument for @check, must match type.
  *
  * This performs a consistency check of the open database, optionally calling
  * a check() function on each record so you can do your own data consistency
@@ -436,18 +499,18 @@ enum TDB_ERROR tdb_wipe_all(struct tdb_context *tdb);
  *
  * Returns TDB_SUCCESS or an error.
  */
-#define tdb_check(tdb, check, private)                                 \
-       tdb_check_((tdb), typesafe_cb_preargs(enum TDB_ERROR,           \
-                                             (check), (private),       \
+#define tdb_check(tdb, check, private_data)                            \
+       tdb_check_((tdb), typesafe_cb_preargs(enum TDB_ERROR, void *,   \
+                                             (check), (private_data),  \
                                              struct tdb_data,          \
                                              struct tdb_data),         \
-                  (private))
+                  (private_data))
 
 enum TDB_ERROR tdb_check_(struct tdb_context *tdb,
                          enum TDB_ERROR (*check)(struct tdb_data key,
                                                  struct tdb_data data,
-                                                 void *private),
-                         void *private);
+                                                 void *private_data),
+                         void *private_data);
 
 /**
  * tdb_error - get the last error (not threadsafe)