Currently, when clients connect to SQL server, we inform them of any
errors opening the database via an asynchronous IPC. But we already know
about these errors before returning from the connect() IPC, so this
roundabout propagation is a bit unnecessary. Now if we fail to open the
database, we will simply not send back a valid connection ID.
Disconnect has a similar story. Rather than disconnecting and invoking
an asynchronous IPC to inform the client of the disconnect, make the
disconnect() IPC synchronous (because all it does is remove the database
from the map of open databases). Further, the only user of this command
is the SQL REPL when it wants to connect to a different database, so it
makes sense to block it. This did require moving a bit of logic around
in the REPL to accommodate this change.
When storing IDs and sending values over IPC, this changes SQLServer to:
1. Stop using -1 as a nominal "bad" ID. Store the IDs as unsigned, and
use Optional in the one place that the IPC needs to indicate an ID
was not allocated.
2. Let LibIPC encode/decode enumerations (SQLErrorCode) on our behalf.
3. Use size_t for array sizes.
One of the benefits of prepared statements is that the SQL string is
parsed just once and re-used. This updates SQLStatement to do just that
and store the parsed result.
We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
Database::get_schema currently either returns a RefPtr to an existing
schema, a nullptr if the schema doesn't exist, or an Error if some
internal error occured. Change this to return a NonnullRefPtr to an
exisiting schema, or a SQL::Result with any error, including if the
schema was not found. Callers can then handle that specific error code
if they want.
Returning a NonnullRefPtr will enable some further cleanup. This had
some fallout of needing to change some other methods' return types from
AK::ErrorOr to SQL::Result so that TRY may continue to be used.
Rename sql_statement to prepare_statement and statement_execute to
execute_statement. The former aligns more with other database libraries
(e.g. Java's JDBC prepareStatement). The latter reads less awkwardly.
The handling of filesystem level errors was basically non-existing or
consisting of `VERIFY_NOT_REACHED` assertions. Addressed this by
* Adding `open` methods to `Heap` and `Database` which return errors.
* Changing the interface of methods of these classes and clients
downstream to propagate these errors.
The constructors of `Heap` and `Database` don't open the underlying
filesystem file anymore.
The SQL statement handlers return an `SQLErrorCode::InternalError`
error code if an error comes back from the lower levels. Note that some
of these errors are things like duplicate index entry errors that should
be caught before the SQL layer attempts to actually update the database.
Added tests to catch attempts to open weird or non-existent files as
databases.
Finally, in between me writing this patch and submitting the PR the
AK::Result<Foo, Bar> template got deprecated in favour of ErrorOr<Foo>.
This resulted in more busywork.
The database the sql client connected to was 'hardcoded' to the login
name of the calling user.
- Extended the IPC API to be more expressive when connecting, by
returning the name of the database the client connected to in the
'connected' callback.
- Gave the sql client a command line argument (-d/--database) allowing
an alternative database name to be specified
A subsequent commit will have a dot command allowing the user to
connect to different databases from the same sql session.
If you capture a stack variable by reference in a lamdba definition,
and this lambda outlives the scope of the stack variable, this reference
may point to garbage when the lambda is executed. Therefore capture as
little as possible (typically only ``this``), and what is captured is
captured by value
Only one place used this argument and it was to hold on to a strong ref
for the object. Since we already do that now, there's no need to keep
this argument around since this can be easily captured.
This commit contains no changes.
In the DatabaseConnection constructor, there's a deferred_invoke
callback that references the client_id. But depending on when the
callback occurs, the reference of the client_id can change. This created
a problem when connecting to SQLServer using the SQL utility because
depending on when the callback was invoked, the client_id could change.
m_client_id is set in the constructor and that reference will not change
depending on when the callback is invoked.
This patch introduces the SQLServer system server. This service is
supposed to be the only process/application talking to database storage.
This makes things like locking and caching more reliable, easier to
implement, and more efficient.
In LibSQL we added a client component that does the ugly IPC nitty-
gritty for you. All that's needed is setting a number of event handler
lambdas and you can connect to databases and execute statements on them.
Applications that wish to use this SQLClient class obviously need to
link LibSQL and LibIPC.
