[ovs-dev] [PATCH v2 2/9] ovsdb: storage: Allow setting the name for the unbacked storage.

[Mark Gray]

On 12/06/2021 03:00, Ilya Maximets wrote:
> ovsdb_create() requires schema or storage to be nonnull, but in
> practice it requires to have schema name or a storage name to
> use it as a database name.  Only clustered storage has a name.
> This means that only clustered database can be created without
> schema,  Changing that by allowing unbacked storage to have a
> name.  This way we can create database with unbacked storage
> without schema.  Will be used in next commits to create database
> for ovsdb 'relay' service model.
> 
> Signed-off-by: Ilya Maximets <i.maximets at ovn.org>
> ---
>  ovsdb/file.c         |  2 +-
>  ovsdb/ovsdb-server.c |  2 +-
>  ovsdb/storage.c      | 13 ++++++++++---
>  ovsdb/storage.h      |  2 +-
>  tests/test-ovsdb.c   |  6 +++---
>  5 files changed, 16 insertions(+), 9 deletions(-)
> 
> diff --git a/ovsdb/file.c b/ovsdb/file.c
> index 0b8bdfe37..59220824f 100644
> --- a/ovsdb/file.c
> +++ b/ovsdb/file.c
> @@ -318,7 +318,7 @@ ovsdb_convert(const struct ovsdb *src, const struct ovsdb_schema *new_schema,
>                struct ovsdb **dstp)
>  {
>      struct ovsdb *dst = ovsdb_create(ovsdb_schema_clone(new_schema),
> -                                     ovsdb_storage_create_unbacked());
> +                                     ovsdb_storage_create_unbacked(NULL));
>      struct ovsdb_txn *txn = ovsdb_txn_create(dst);
>      struct ovsdb_error *error = NULL;
>  
> diff --git a/ovsdb/ovsdb-server.c b/ovsdb/ovsdb-server.c
> index b09232c65..23bd226a3 100644
> --- a/ovsdb/ovsdb-server.c
> +++ b/ovsdb/ovsdb-server.c
> @@ -738,7 +738,7 @@ add_server_db(struct server_config *config)
>      /* We don't need txn_history for server_db. */
>  
>      db->filename = xstrdup("<internal>");
> -    db->db = ovsdb_create(schema, ovsdb_storage_create_unbacked());
> +    db->db = ovsdb_create(schema, ovsdb_storage_create_unbacked(NULL));
>      bool ok OVS_UNUSED = ovsdb_jsonrpc_server_add_db(config->jsonrpc, db->db);
>      ovs_assert(ok);
>      add_db(config, db);
> diff --git a/ovsdb/storage.c b/ovsdb/storage.c
> index 40415fcf6..d727b1eac 100644
> --- a/ovsdb/storage.c
> +++ b/ovsdb/storage.c
> @@ -45,6 +45,8 @@ struct ovsdb_storage {
>      struct ovsdb_log *log;
>      struct raft *raft;
>  
> +    char *unbacked_name; /* Name of the unbacked storage. */
> +

Bit of a nit but should this be a "const char *" type?

>      /* All kinds of storage. */
>      struct ovsdb_error *error;  /* If nonnull, a permanent error. */
>      long long next_snapshot_min; /* Earliest time to take next snapshot. */
> @@ -121,12 +123,14 @@ ovsdb_storage_open_standalone(const char *filename, bool rw)
>  }
>  
>  /* Creates and returns new storage without any backing.  Nothing will be read
> - * from the storage, and writes are discarded. */
> + * from the storage, and writes are discarded.  If 'name' is nonnull, it will
> + * be used as a storage name. */
>  struct ovsdb_storage *
> -ovsdb_storage_create_unbacked(void)
> +ovsdb_storage_create_unbacked(const char *name)
>  {
>      struct ovsdb_storage *storage = xzalloc(sizeof *storage);
>      schedule_next_snapshot(storage, false);
> +    storage->unbacked_name = nullable_xstrdup(name);
>      return storage;
>  }
>  
> @@ -137,6 +141,7 @@ ovsdb_storage_close(struct ovsdb_storage *storage)
>          ovsdb_log_close(storage->log);
>          raft_close(storage->raft);
>          ovsdb_error_destroy(storage->error);
> +        free(storage->unbacked_name);

Can this ^ not be NULL?

>          free(storage);
>      }
>  }
> @@ -230,7 +235,9 @@ ovsdb_storage_wait(struct ovsdb_storage *storage)
>  const char *
>  ovsdb_storage_get_name(const struct ovsdb_storage *storage)
>  {
> -    return storage->raft ? raft_get_name(storage->raft) : NULL;
> +    return storage->unbacked_name ? storage->unbacked_name
> +           : storage->raft ? raft_get_name(storage->raft)
> +           : NULL;
>  }
>  
>  /* Attempts to read a log record from 'storage'.
> diff --git a/ovsdb/storage.h b/ovsdb/storage.h
> index 02b6e7e6c..e120094d7 100644
> --- a/ovsdb/storage.h
> +++ b/ovsdb/storage.h
> @@ -29,7 +29,7 @@ struct uuid;
>  struct ovsdb_error *ovsdb_storage_open(const char *filename, bool rw,
>                                         struct ovsdb_storage **)
>      OVS_WARN_UNUSED_RESULT;
> -struct ovsdb_storage *ovsdb_storage_create_unbacked(void);
> +struct ovsdb_storage *ovsdb_storage_create_unbacked(const char *name);
>  void ovsdb_storage_close(struct ovsdb_storage *);
>  
>  const char *ovsdb_storage_get_model(const struct ovsdb_storage *);
> diff --git a/tests/test-ovsdb.c b/tests/test-ovsdb.c
> index a886f971e..fb6b3acca 100644
> --- a/tests/test-ovsdb.c
> +++ b/tests/test-ovsdb.c
> @@ -1485,7 +1485,7 @@ do_execute__(struct ovs_cmdl_context *ctx, bool ro)
>      json = parse_json(ctx->argv[1]);
>      check_ovsdb_error(ovsdb_schema_from_json(json, &schema));
>      json_destroy(json);
> -    db = ovsdb_create(schema, ovsdb_storage_create_unbacked());
> +    db = ovsdb_create(schema, ovsdb_storage_create_unbacked(NULL));
>  
>      for (i = 2; i < ctx->argc; i++) {
>          struct json *params, *result;
> @@ -1551,7 +1551,7 @@ do_trigger(struct ovs_cmdl_context *ctx)
>      json = parse_json(ctx->argv[1]);
>      check_ovsdb_error(ovsdb_schema_from_json(json, &schema));
>      json_destroy(json);
> -    db = ovsdb_create(schema, ovsdb_storage_create_unbacked());
> +    db = ovsdb_create(schema, ovsdb_storage_create_unbacked(NULL));

I think destroying the ovsdb_storage object will trigger a segfault.
Maybe you should add a call to ovsdb_storage_close(struct ovsdb_storage
*storage) in order to test that path.
>  
>      ovsdb_server_init(&server);
>      ovsdb_server_add_db(&server, db);
> @@ -1781,7 +1781,7 @@ do_transact(struct ovs_cmdl_context *ctx)
>                        "       \"j\": {\"type\": \"integer\"}}}}}");
>      check_ovsdb_error(ovsdb_schema_from_json(json, &schema));
>      json_destroy(json);
> -    do_transact_db = ovsdb_create(schema, ovsdb_storage_create_unbacked());
> +    do_transact_db = ovsdb_create(schema, ovsdb_storage_create_unbacked(NULL));
>      do_transact_table = ovsdb_get_table(do_transact_db, "mytable");
>      ovs_assert(do_transact_table != NULL);
>  
>