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// Much of the documentation comments in this module are copied from the descriptions on
// https://7687.org, with minor modifications.
//
// Original copyright and license information for these descriptions:
// Copyright © 2002-2020 Neo4j, Inc.
// CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/)
//
// The aforementioned documentation comments are thus licensed under CC BY-SA 4.0.
use std::{collections::VecDeque, io};
use bytes::*;
use futures_util::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
use bolt_client_macros::*;
use bolt_proto::{
error::Error as ProtocolError, message::*, version::*, Message, ServerState, ServerState::*,
Value,
};
use crate::{
error::{CommunicationError, CommunicationResult, ConnectionError, ConnectionResult},
Metadata, Params, RoutingContext,
};
mod v1;
mod v2;
mod v3;
mod v4;
mod v4_1;
mod v4_2;
mod v4_3;
const PREAMBLE: [u8; 4] = [0x60, 0x60, 0xB0, 0x17];
/// Return whether a version is compatible with version specifier.
fn is_compatible(version: u32, specifier: u32) -> bool {
let (major, minor) = (version & 0xff, version >> 8 & 0xff);
let (specified_major, specified_minor, range) = (
specifier & 0xff,
specifier >> 8 & 0xff,
specifier >> 16 & 0xff,
);
major == specified_major
&& (specified_minor.saturating_sub(range)..=specified_minor).contains(&minor)
}
/// An asynchronous client for Bolt servers.
#[derive(Debug)]
pub struct Client<S: AsyncRead + AsyncWrite + Unpin> {
stream: S,
version: u32,
server_state: ServerState,
sent_queue: VecDeque<Message>,
open_tx_streams: usize,
}
impl<S: AsyncRead + AsyncWrite + Unpin> Client<S> {
/// Attempt to create a new client from an asynchronous stream. A handshake will be performed
/// with the provided protocol version specifiers, and, if this succeeds, a Client will be
/// returned.
pub async fn new(mut stream: S, version_specifiers: &[u32; 4]) -> ConnectionResult<Self> {
let mut version_specifiers_bytes = BytesMut::with_capacity(16);
version_specifiers
.iter()
.for_each(|&v| version_specifiers_bytes.put_u32(v));
stream.write_all(&PREAMBLE).await?;
stream.write_all(&version_specifiers_bytes).await?;
stream.flush().await?;
let mut u32_bytes = [0, 0, 0, 0];
stream.read_exact(&mut u32_bytes).await?;
let version = u32::from_be_bytes(u32_bytes);
if version > 0 {
for &specifier in version_specifiers {
if is_compatible(version, specifier) {
return Ok(Self {
stream,
version,
server_state: Connected,
sent_queue: VecDeque::default(),
open_tx_streams: 0,
});
}
}
}
Err(ConnectionError::HandshakeFailed(*version_specifiers))
}
/// Get the current version of this client.
pub fn version(&self) -> u32 {
self.version
}
/// Get the current server state for this client.
pub fn server_state(&self) -> ServerState {
self.server_state
}
pub(crate) async fn read_message(&mut self) -> CommunicationResult<Message> {
let message = Message::from_stream(&mut self.stream)
.await
.map_err(ProtocolError::from)?;
#[cfg(test)]
println!("<<< {:?}\n", message);
match (self.server_state, self.sent_queue.pop_front(), message) {
// CONNECTED
(Connected, Some(Message::Init(_)), Message::Success(success)) => {
self.server_state = Ready;
Ok(Message::Success(success))
}
(Connected, Some(Message::Init(_)), Message::Failure(failure)) => {
self.server_state = Defunct;
Ok(Message::Failure(failure))
}
(Connected, Some(Message::Hello(_)), Message::Success(success)) => {
self.server_state = Ready;
Ok(Message::Success(success))
}
(Connected, Some(Message::Hello(_)), Message::Failure(failure)) => {
self.server_state = Defunct;
Ok(Message::Failure(failure))
}
// READY
(Ready, Some(Message::Run(_)), Message::Success(success)) => {
self.server_state = Streaming;
Ok(Message::Success(success))
}
(Ready, Some(Message::Run(_)), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
(Ready, Some(Message::RunWithMetadata(_)), Message::Success(success)) => {
self.server_state = Streaming;
Ok(Message::Success(success))
}
(Ready, Some(Message::RunWithMetadata(_)), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
(Ready, Some(Message::Begin(_)), Message::Success(success)) => {
self.server_state = TxReady;
Ok(Message::Success(success))
}
(Ready, Some(Message::Begin(_)), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
(Ready, Some(Message::Route(_)), Message::Success(success)) => {
self.server_state = Ready;
Ok(Message::Success(success))
}
// STREAMING
(Streaming, Some(Message::PullAll), Message::Success(success)) => {
self.server_state = Ready;
Ok(Message::Success(success))
}
(Streaming, Some(Message::PullAll), Message::Record(record)) => {
self.server_state = Streaming;
// Put the PULL_ALL message back so we can keep consuming records
self.sent_queue.push_front(Message::PullAll);
Ok(Message::Record(record))
}
(Streaming, Some(Message::PullAll), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
(Streaming, Some(Message::Pull(_)), Message::Success(success)) => {
self.server_state = match success.metadata().get("has_more") {
Some(&Value::Boolean(true)) => Streaming,
_ => Ready,
};
Ok(Message::Success(success))
}
(Streaming, Some(Message::Pull(pull)), Message::Record(record)) => {
self.server_state = Streaming;
// Put the PULL message back so we can keep consuming records
self.sent_queue.push_front(Message::Pull(pull));
Ok(Message::Record(record))
}
(Streaming, Some(Message::Pull(_)), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
(Streaming, Some(Message::DiscardAll), Message::Success(success)) => {
self.server_state = Ready;
Ok(Message::Success(success))
}
(Streaming, Some(Message::DiscardAll), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
(Streaming, Some(Message::Discard(_)), Message::Success(success)) => {
self.server_state = match success.metadata().get("has_more") {
Some(&Value::Boolean(true)) => Streaming,
_ => Ready,
};
Ok(Message::Success(success))
}
(Streaming, Some(Message::Discard(_)), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
// TX_READY
(TxReady, Some(Message::RunWithMetadata(_)), Message::Success(success)) => {
self.open_tx_streams += 1;
self.server_state = TxStreaming;
Ok(Message::Success(success))
}
(TxReady, Some(Message::RunWithMetadata(_)), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
(TxReady, Some(Message::Commit), Message::Success(success)) => {
self.server_state = Ready;
Ok(Message::Success(success))
}
(TxReady, Some(Message::Commit), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
(TxReady, Some(Message::Rollback), Message::Success(success)) => {
self.server_state = Ready;
Ok(Message::Success(success))
}
(TxReady, Some(Message::Rollback), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
// TX_STREAMING
(TxStreaming, Some(Message::RunWithMetadata(_)), Message::Success(success)) => {
self.open_tx_streams += 1;
self.server_state = TxStreaming;
Ok(Message::Success(success))
}
(TxStreaming, Some(Message::RunWithMetadata(_)), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
(TxStreaming, Some(Message::PullAll), Message::Success(success)) => {
self.open_tx_streams -= 1;
self.server_state = TxReady;
Ok(Message::Success(success))
}
(TxStreaming, Some(Message::PullAll), Message::Record(record)) => {
self.server_state = TxStreaming;
// Put the PULL_ALL message back so we can keep consuming records
self.sent_queue.push_front(Message::PullAll);
Ok(Message::Record(record))
}
(TxStreaming, Some(Message::PullAll), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
(TxStreaming, Some(Message::Pull(_)), Message::Success(success)) => {
self.server_state = match success.metadata().get("has_more") {
Some(&Value::Boolean(true)) => TxStreaming,
_ => {
self.open_tx_streams -= 1;
if self.open_tx_streams > 0 {
TxStreaming
} else {
TxReady
}
}
};
Ok(Message::Success(success))
}
(TxStreaming, Some(Message::Pull(pull)), Message::Record(record)) => {
self.server_state = TxStreaming;
// Put the PULL message back so we can keep consuming records
self.sent_queue.push_front(Message::Pull(pull));
Ok(Message::Record(record))
}
(TxStreaming, Some(Message::Pull(_)), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
(TxStreaming, Some(Message::DiscardAll), Message::Success(success)) => {
self.open_tx_streams -= 1;
self.server_state = TxReady;
Ok(Message::Success(success))
}
(TxStreaming, Some(Message::DiscardAll), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
(TxStreaming, Some(Message::Discard(_)), Message::Success(success)) => {
self.server_state = match success.metadata().get("has_more") {
Some(&Value::Boolean(true)) => TxStreaming,
_ => {
self.open_tx_streams -= 1;
if self.open_tx_streams > 0 {
TxStreaming
} else {
TxReady
}
}
};
Ok(Message::Success(success))
}
(TxStreaming, Some(Message::Discard(_)), Message::Failure(failure)) => {
self.server_state = Failed;
Ok(Message::Failure(failure))
}
// FAILED
(Failed, Some(Message::Run(_)), Message::Ignored) => {
self.server_state = Failed;
Ok(Message::Ignored)
}
(Failed, Some(Message::RunWithMetadata(_)), Message::Ignored) => {
self.server_state = Failed;
Ok(Message::Ignored)
}
(Failed, Some(Message::PullAll), Message::Ignored) => {
self.server_state = Failed;
Ok(Message::Ignored)
}
(Failed, Some(Message::Pull(_)), Message::Ignored) => {
self.server_state = Failed;
Ok(Message::Ignored)
}
(Failed, Some(Message::DiscardAll), Message::Ignored) => {
self.server_state = Failed;
Ok(Message::Ignored)
}
(Failed, Some(Message::Discard(_)), Message::Ignored) => {
self.server_state = Failed;
Ok(Message::Ignored)
}
(Failed, Some(Message::AckFailure), Message::Success(success)) => {
self.server_state = Ready;
Ok(Message::Success(success))
}
(Failed, Some(Message::AckFailure), Message::Failure(failure)) => {
self.server_state = Defunct;
Ok(Message::Failure(failure))
}
// INTERRUPTED
(Interrupted, Some(Message::Run(_)), _) => {
self.server_state = Interrupted;
Ok(Message::Ignored)
}
(Interrupted, Some(Message::RunWithMetadata(_)), _) => {
self.server_state = Interrupted;
Ok(Message::Ignored)
}
(Interrupted, Some(Message::PullAll), Message::Record(_)) => {
self.server_state = Interrupted;
// Put the PULL_ALL message back so we can keep consuming records
self.sent_queue.push_front(Message::PullAll);
Ok(Message::Ignored)
}
(Interrupted, Some(Message::PullAll), _) => {
self.server_state = Interrupted;
Ok(Message::Ignored)
}
(Interrupted, Some(Message::Pull(pull)), Message::Record(_)) => {
self.server_state = Interrupted;
// Put the PULL message back so we can keep consuming records
self.sent_queue.push_front(Message::Pull(pull));
Ok(Message::Ignored)
}
(Interrupted, Some(Message::Pull(_)), _) => {
self.server_state = Interrupted;
Ok(Message::Ignored)
}
(Interrupted, Some(Message::DiscardAll), _) => {
self.server_state = Interrupted;
Ok(Message::Ignored)
}
(Interrupted, Some(Message::Discard(_)), _) => {
self.server_state = Interrupted;
Ok(Message::Ignored)
}
(Interrupted, Some(Message::Begin(_)), _) => {
self.server_state = Interrupted;
Ok(Message::Ignored)
}
(Interrupted, Some(Message::Commit), _) => {
self.server_state = Interrupted;
Ok(Message::Ignored)
}
(Interrupted, Some(Message::Rollback), _) => {
self.server_state = Interrupted;
Ok(Message::Ignored)
}
(Interrupted, Some(Message::AckFailure), _) => {
self.server_state = Interrupted;
Ok(Message::Ignored)
}
(Interrupted, Some(Message::Reset), Message::Success(success)) => {
self.open_tx_streams = 0;
self.server_state = Ready;
Ok(Message::Success(success))
}
(Interrupted, Some(Message::Reset), Message::Failure(failure)) => {
self.server_state = Defunct;
Ok(Message::Failure(failure))
}
(state, request, response) => {
self.server_state = Defunct;
Err(CommunicationError::InvalidResponse {
state,
request,
response,
})
}
}
}
pub(crate) async fn send_message(&mut self, message: Message) -> CommunicationResult<()> {
match (self.server_state, &message) {
(Connected, Message::Init(_)) => {}
(Connected, Message::Hello(_)) => {}
(Ready, Message::Run(_)) => {}
(Ready, Message::RunWithMetadata(_)) => {}
(Ready, Message::Begin(_)) => {}
(Ready, Message::Route(_)) => {}
(Ready, Message::Reset) => {}
(Ready, Message::Goodbye) => {}
(Streaming, Message::PullAll) => {}
(Streaming, Message::Pull(_)) => {}
(Streaming, Message::DiscardAll) => {}
(Streaming, Message::Discard(_)) => {}
(Streaming, Message::Reset) => {}
(Streaming, Message::Goodbye) => {}
(TxReady, Message::RunWithMetadata(_)) => {}
(TxReady, Message::Commit) => {}
(TxReady, Message::Rollback) => {}
(TxReady, Message::Reset) => {}
(TxReady, Message::Goodbye) => {}
(TxStreaming, Message::RunWithMetadata(_)) => {}
(TxStreaming, Message::PullAll) => {}
(TxStreaming, Message::Pull(_)) => {}
(TxStreaming, Message::DiscardAll) => {}
(TxStreaming, Message::Discard(_)) => {}
(TxStreaming, Message::Reset) => {}
(TxStreaming, Message::Goodbye) => {}
(Failed, Message::Run(_)) => {}
(Failed, Message::RunWithMetadata(_)) => {}
(Failed, Message::PullAll) => {}
(Failed, Message::Pull(_)) => {}
(Failed, Message::DiscardAll) => {}
(Failed, Message::Discard(_)) => {}
(Failed, Message::AckFailure) => {}
(Failed, Message::Reset) => {}
(Failed, Message::Goodbye) => {}
(Interrupted, Message::Run(_)) => {}
(Interrupted, Message::RunWithMetadata(_)) => {}
(Interrupted, Message::PullAll) => {}
(Interrupted, Message::Pull(_)) => {}
(Interrupted, Message::DiscardAll) => {}
(Interrupted, Message::Discard(_)) => {}
(Interrupted, Message::AckFailure) => {}
(Interrupted, Message::Begin(_)) => {}
(Interrupted, Message::Commit) => {}
(Interrupted, Message::Rollback) => {}
(Interrupted, Message::Reset) => {}
(Interrupted, Message::Goodbye) => {}
(state, message) => {
self.server_state = Defunct;
return Err(CommunicationError::InvalidState {
state,
message: message.clone(),
});
}
}
#[cfg(test)]
println!(">>> {:?}", message);
let chunks = message.clone().into_chunks().map_err(ProtocolError::from)?;
for chunk in chunks {
self.stream.write_all(&chunk).await?;
}
self.stream.flush().await?;
// Immediate state changes
match message {
Message::Reset => self.server_state = Interrupted,
Message::Goodbye => self.server_state = Disconnected,
_ => {}
}
self.sent_queue.push_back(message);
Ok(())
}
/// Send a [`HELLO`](Message::Hello) (or [`INIT`](Message::Init)) message to the server.
/// _(Sends `INIT` for Bolt v1 - v2, and `HELLO` for Bolt v3+.)_
///
/// # Description
/// The `HELLO` message requests the connection to be authorized for use with the remote
/// database. Clients should send a `HELLO` message to the server immediately after connection
/// and process the response before using that connection in any other way.
///
/// The server must be in the [`Connected`](bolt_proto::ServerState::Connected) state to be
/// able to process a `HELLO` message. For any other states, receipt of a `HELLO` message is
/// considered a protocol violation and leads to connection closure.
///
/// If authentication fails, the server will respond with a [`FAILURE`](Message::Failure)
/// message and immediately close the connection. Clients wishing to retry initialization
/// should establish a new connection.
///
/// # Fields
/// `metadata` should contain at least two entries:
/// - `user_agent`, which should conform to the format `"Name/Version"`, for example
/// `"Example/1.0.0"` (see
/// [here](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/User-Agent)).
/// - `scheme` is the authentication scheme. Predefined schemes are `"none"`, `"basic"`, or
/// `"kerberos"`.
///
/// If using Bolt v4.3 or later, the following additional `metadata` entries can be specified:
/// - `routing`, a map which should contain routing context information as well as an `address`
/// field indicating to which address the client should initially connect. Leaving this
/// unspecified indicates that the server should not carry out any routing.
/// _(Bolt v4.3+ only.)_
///
/// Further entries in `metadata` are passed to the implementation of the chosen
/// authentication scheme. Their names, types, and defaults depend on that choice. For
/// example, the scheme `"basic"` requires `metadata` to contain the username and password in
/// the form `{"principal": "<username>", "credentials": "<password>"}`.
///
/// # Response
/// - [`Message::Success`] - initialization has completed successfully and the server has
/// entered the [`Ready`](bolt_proto::ServerState::Ready) state. The server may include
/// metadata that describes details of the server environment and/or the connection. The
/// following fields are defined for inclusion in the `SUCCESS` metadata:
/// - `server`, the server agent string (e.g. `"Neo4j/4.3.0"`)
/// - `connection_id`, a unique identifier for the connection (e.g. `"bolt-61"`)
/// _(Bolt v3+ only.)_
/// - `hints`, a map of configuration hints (e.g. `{"connection.recv_timeout_seconds": 120}`)
/// These hints may be interpreted or ignored by drivers at their own discretion in order
/// to augment operations where applicable. Hints remain valid throughout the lifetime of a
/// given connection and cannot be changed. As such, newly established connections may
/// observe different hints as the server configuration is adjusted.
/// _(Bolt v4.3+ only.)_
/// - [`Message::Failure`] - initialization has failed and the server has entered the
/// [`Defunct`](bolt_proto::ServerState::Defunct) state. The server may choose to include
/// metadata describing the nature of the failure but will immediately close the connection
/// after the failure has been sent.
#[bolt_version(1, 2, 3, 4, 4.1, 4.2, 4.3)]
pub async fn hello(&mut self, mut metadata: Metadata) -> CommunicationResult<Message> {
let message = match self.version() {
V1_0 | V2_0 => {
let user_agent: String = metadata
.value
.remove("user_agent")
.ok_or_else(|| {
io::Error::new(io::ErrorKind::InvalidInput, "missing user_agent")
})?
.try_into()
.map_err(|_| {
io::Error::new(io::ErrorKind::InvalidInput, "user_agent must be a string")
})?;
let auth_token = metadata.value;
Message::Init(Init::new(user_agent, auth_token))
}
_ => Message::Hello(Hello::new(metadata.value)),
};
self.send_message(message).await?;
self.read_message().await
}
/// Send a [`ROUTE`](Message::Route) message to the server.
/// _(Bolt v4.3+ only.)_
///
/// # Description
/// The `ROUTE` message instructs the server to return the current routing table.
///
/// The server must be in the [`Ready`](bolt_proto::ServerState::Ready) state to be able to
/// successfully process a `ROUTE` request. If the server is in the
/// [`Failed`](bolt_proto::ServerState::Failed) or
/// [`Interrupted`](bolt_proto::ServerState::Interrupted) state, the response will be
/// [`IGNORED`](Message::Ignored). For any other states, receipt of a `ROUTE` request will be
/// considered a protocol violation and will lead to connection closure.
///
/// # Fields
/// - `context`, which should contain routing context information as well as an `address`
/// field indicating to which address the client should initially connect.
/// - `bookmarks`, a list of strings containing some kind of bookmark identification, e.g
/// `["bkmk-transaction:1", "bkmk-transaction:2"]`. Default is `[]`.
/// - `database`, a string containing the name of the database for which this command should be
/// run. `""` denotes the server-side configured default database.
///
/// # Response
/// - [`Message::Success`] - the routing table has been successfully retrieved and the server
/// has entered the [`Ready`](bolt_proto::ServerState::Ready) state. The server sends the
/// following metadata fields in the response:
/// - `rt`, a map with the following fields:
/// - `ttl`, an integer denoting the number of seconds this routing table should be
/// considered valid
/// - `servers`, a list of maps representing roles for one or more addresses. Each element
/// will have the following fields:
/// - `role`, a server role. Possible values are `"READ"`, `"WRITE"`, and `"ROUTE"`.
/// - `addresses`, a list of strings representing the servers with the specified role
/// - [`Message::Ignored`] - the server is in the [`Failed`](bolt_proto::ServerState::Failed)
/// or [`Interrupted`](bolt_proto::ServerState::Interrupted) state, and the request was
/// discarded without being processed. No server state change has occurred.
/// - [`Message::Failure`] - the request could not be processed successfully and the server has
/// entered the [`Failed`](bolt_proto::ServerState::Failed) state. The server may attach
/// metadata to the message to provide more detail on the nature of the failure.
#[bolt_version(4.3)]
pub async fn route(
&mut self,
context: RoutingContext,
bookmarks: impl Into<Vec<String>>,
database: impl Into<String>,
) -> CommunicationResult<Message> {
let route_msg = Route::new(context.value, bookmarks.into(), database.into());
self.send_message(Message::Route(route_msg)).await?;
self.read_message().await
}
/// Send a [`RUN`](Message::Run) message to the server.
/// _(Bolt v1+. For Bolt v1 - v2, the `metadata` parameter is ignored.)_
///
/// # Description
/// A `RUN` message submits a new query for execution, the result of which will be consumed by
/// a subsequent message, such as [`PULL`](Message::Pull).
///
/// The server must be in either the [`Ready`](bolt_proto::ServerState::Ready) state, the
/// [`TxReady`](bolt_proto::ServerState::TxReady) state (Bolt v3+), or the
/// [`TxStreaming`](bolt_proto::ServerState::TxStreaming) state (Bolt v4+) to be able to
/// successfully process a `RUN` request. If the server is in the
/// [`Failed`](bolt_proto::ServerState::Failed) or
/// [`Interrupted`](bolt_proto::ServerState::Interrupted) state, the response will be
/// [`IGNORED`](Message::Ignored). For any other states, receipt of a `RUN` request will be
/// considered a protocol violation and will lead to connection closure.
///
/// # Fields
/// - `query` contains a database query or remote procedure call.
/// - `parameters` contains variable fields for `query`.
///
/// If using Bolt v3 or later, the following `metadata` entries can be specified:
/// - `bookmarks`, a list of strings containing some kind of bookmark identification, e.g
/// `["bkmk-transaction:1", "bkmk-transaction:2"]`. Default is `[]`.
/// - `tx_timeout`, an integer specifying a transaction timeout in milliseconds. Default is the
/// server-side configured timeout.
/// - `tx_metadata`, a map containing some metadata information, mainly used for logging.
/// - `mode`, a string which specifies what kind of server should be used for this
/// transaction. For write access, use `"w"` and for read access use `"r"`. Default is `"w"`.
/// - `db`, a string containing the name of the database where the transaction should take
/// place. [`null`](bolt_proto::Value::Null) and `""` denote the server-side configured
/// default database. Default is `null`. _(Bolt v4+ only.)_
///
/// # Response
/// - [`Message::Success`] - the request has been successfully received and the server has
/// entered the [`Streaming`](bolt_proto::ServerState::Streaming) state. Clients should not
/// consider a `SUCCESS` response to indicate completion of the execution of the query,
/// merely acceptance of it. The server may attach metadata to the message to provide header
/// detail for the results that follow. The following fields are defined for inclusion in the
/// metadata:
/// - `fields`, the fields included in the result (e.g. `["name", "age"]`)
/// - `result_available_after`, the time in milliseconds after which the first record in the
/// result stream is available. _(Bolt v1 - v2 only.)_
/// - `t_first`, supercedes `result_available_after`. _(Bolt v3+ only.)_
/// - `qid`, an integer that specifies the server-assigned query ID. This is sent for
/// queries submitted within an explicit transaction. _(Bolt v4+ only.)_
/// - [`Message::Ignored`] - the server is in the [`Failed`](bolt_proto::ServerState::Failed)
/// or [`Interrupted`](bolt_proto::ServerState::Interrupted) state, and the request was
/// discarded without being processed. No server state change has occurred.
/// - [`Message::Failure`] - the request could not be processed successfully or is invalid, and
/// the server has entered the [`Failed`](bolt_proto::ServerState::Failed) state. The server
/// may attach metadata to the message to provide more detail on the nature of the failure.
#[bolt_version(1, 2, 3, 4, 4.1, 4.2, 4.3)]
pub async fn run(
&mut self,
query: impl Into<String>,
parameters: Option<Params>,
metadata: Option<Metadata>,
) -> CommunicationResult<Message> {
let message = match self.version() {
V1_0 | V2_0 => {
Message::Run(Run::new(query.into(), parameters.unwrap_or_default().value))
}
_ => Message::RunWithMetadata(RunWithMetadata::new(
query.into(),
parameters.unwrap_or_default().value,
metadata.unwrap_or_default().value,
)),
};
self.send_message(message).await?;
self.read_message().await
}
/// Send a [`PULL`](Message::Pull) (or [`PULL_ALL`](Message::PullAll)) message to the server.
/// _(Sends `PULL_ALL` for Bolt v1 - v3, and `PULL` for Bolt v4+. For Bolt v1 - v3, the
/// `metadata` parameter is ignored.)_
///
/// # Description
/// The `PULL` message issues a request to stream outstanding results back to the client,
/// before returning to the [`Ready`](bolt_proto::ServerState::Ready) state.
///
/// Result details consist of zero or more [`RECORD`](Message::Record) messages and a summary
/// message. Each record carries with it a list of values which form the data content of the
/// record. The order of the values within that list should be meaningful to the client,
/// perhaps based on a requested ordering for that result, but no guarantees are made around
/// the order of records within the result. A record should only be considered valid if
/// accompanied by a [`SUCCESS`](Message::Success) summary message.
///
/// The server must be in the [`Streaming`](bolt_proto::ServerState::Streaming) or
/// [`TxStreaming`](bolt_proto::ServerState::TxStreaming) state to be able to successfully
/// process a `PULL` request. If the server is in the
/// [`Failed`](bolt_proto::ServerState::Failed) state or
/// [`Interrupted`](bolt_proto::ServerState::Interrupted) state, the response will be
/// [`IGNORED`](Message::Ignored). For any other states, receipt of a `PULL` request will
/// be considered a protocol violation and will lead to connection closure.
///
/// # Fields
/// For Bolt v4+, additional metadata is passed along with this message:
/// - `n` is an integer specifying how many records to fetch. `-1` will fetch all records. `n`
/// has no default and must be present.
/// - `qid` is an integer that specifies for which statement the `PULL` operation should be
/// carried out within an explicit transaction. `-1` is the default, which denotes the last
/// executed statement.
///
/// # Response
/// - `(_, `[`Message::Success`]`)` - results have been successfully pulled and the server has
/// entered the [`Ready`](bolt_proto::ServerState::Ready) state. The server may attach
/// metadata to the `SUCCESS` message to provide footer detail for the results. The
/// following fields are defined for inclusion in the metadata:
/// - `type`, the type of query: read-only (`"r"`), write-only (`"w"`), read-write (`"rw"`),
/// or schema (`"s"`)
/// - `result_consumed_after`, the time in milliseconds after which the last record in the
/// result stream is consumed. _(Bolt v1 - v2 only.)_
/// - `t_last`, supercedes `result_consumed_after`. _(Bolt v3+ only.)_
/// - `bookmark` (e.g. `"bookmark:1234"`). _(Bolt v3+ only.)_
/// - `stats`, a map containing counter information, such as DB hits, etc. _(Bolt v3+ only.)_
/// - `plan`, a map containing the query plan result. _(Bolt v3+ only.)_
/// - `profile`, a map containing the query profile result. _(Bolt v3+ only.)_
/// - `notifications`: a map containing any notifications generated during execution of the
/// query. _(Bolt v3+ only.)_
/// - `db`, a string containing the name of the database where the query was executed.
/// _(Bolt v4+ only.)_
/// - `has_more`, a boolean indicating whether there are still records left in the result
/// stream. Default is `false`. _(Bolt v4+ only.)_
/// - `(_, `[`Message::Ignored`]`)` - the server is in the
/// [`Failed`](bolt_proto::ServerState::Failed) or
/// [`Interrupted`](bolt_proto::ServerState::Interrupted) state, and the request was
/// discarded without being processed. No server state change has occurred.
/// - `(_, `[`Message::Failure`]`)` - the request could not be processed
/// successfully and the server has entered the [`Failed`](bolt_proto::ServerState::Failed)
/// state. The server may attach metadata to the message to provide more detail on the
/// nature of the failure. Failure may occur at any time during result streaming, so any
/// records returned in the response should be considered invalid.
#[bolt_version(1, 2, 3, 4, 4.1, 4.2, 4.3)]
pub async fn pull(
&mut self,
metadata: Option<Metadata>,
) -> CommunicationResult<(Vec<Record>, Message)> {
match self.version() {
V1_0 | V2_0 | V3_0 => self.send_message(Message::PullAll).await?,
_ => {
self.send_message(Message::Pull(Pull::new(metadata.unwrap_or_default().value)))
.await?
}
}
let mut records = vec![];
loop {
match self.read_message().await? {
Message::Record(record) => records.push(record),
Message::Success(success) => return Ok((records, Message::Success(success))),
Message::Failure(failure) => return Ok((records, Message::Failure(failure))),
Message::Ignored => return Ok((vec![], Message::Ignored)),
_ => unreachable!(),
}
}
}
/// Send a [`DISCARD`](Message::Discard) (or [`DISCARD_ALL`](Message::DiscardAll)) message to
/// the server.
/// _(Sends a `DISCARD_ALL` for Bolt v1 - v3, and `DISCARD` for Bold v4+. For Bolt v1 - v3,
/// the `metadata` parameter is ignored.)_
///
/// # Description
/// The `DISCARD` message issues a request to discard the outstanding result and return to the
/// [`Ready`](bolt_proto::ServerState::Ready) state. A receiving server will not abort the
/// request but continue to process it without streaming any detail messages to the client.
///
/// The server must be in the [`Streaming`](bolt_proto::ServerState::Streaming) or
/// [`TxStreaming`](bolt_proto::ServerState::TxStreaming) state to be able to successfully
/// process a `DISCARD` request. If the server is in the
/// [`Failed`](bolt_proto::ServerState::Failed) state or
/// [`Interrupted`](bolt_proto::ServerState::Interrupted) state, the response will be
/// [`IGNORED`](Message::Ignored). For any other states, receipt of a `DISCARD` request
/// will be considered a protocol violation and will lead to connection closure.
///
/// # Fields
/// For Bolt v4+, additional metadata is passed along with this message:
/// - `n` is an integer specifying how many records to discard. `-1` will discard all records.
/// `n` has no default and must be present.
/// - `qid` is an integer that specifies for which statement the `DISCARD` operation should be
/// carried out within an explicit transaction. `-1` is the default, which denotes the last
/// executed statement.
///
/// # Response
/// - [`Message::Success`] - results have been successfully discarded and the server has
/// entered the [`Ready`](bolt_proto::ServerState::Ready) state. The server may attach
/// metadata to the message to provide footer detail for the discarded results.
/// The following fields are defined for inclusion in the metadata:
/// - `type`, the type of query: read-only (`"r"`), write-only (`"w"`), read-write (`"rw"`),
/// or schema (`"s"`)
/// - `result_consumed_after`, the time in milliseconds after which the last record in the
/// result stream is consumed. _(Bolt v1 - v2 only.)_
/// - `t_last`, supercedes `result_consumed_after`. _(Bolt v3+ only.)_
/// - `bookmark` (e.g. `"bookmark:1234"`). _(Bolt v3+ only.)_
/// - `db`, a string containing the name of the database where the query was executed.
/// _(Bolt v4+ only.)_
/// - `has_more`, a boolean indicating whether there are still records left in the result
/// stream. Default is `false`. _(Bolt v4+ only.)_
/// - [`Message::Ignored`] - the server is in the [`Failed`](bolt_proto::ServerState::Failed)
/// or [`Interrupted`](bolt_proto::ServerState::Interrupted) state, and the request was
/// discarded without being processed. No server state change has occurred.
/// - [`Message::Failure`] - the request could not be processed successfully and the server has
/// entered the [`Failed`](bolt_proto::ServerState::Failed) state. The server may attach
/// metadata to the message to provide more detail on the nature of the failure.
#[bolt_version(1, 2, 3, 4, 4.1, 4.2, 4.3)]
pub async fn discard(&mut self, metadata: Option<Metadata>) -> CommunicationResult<Message> {
let message = match self.version() {
V1_0 | V2_0 | V3_0 => Message::DiscardAll,
_ => Message::Discard(Discard::new(metadata.unwrap_or_default().value)),
};
self.send_message(message).await?;
self.read_message().await
}
/// Send a [`BEGIN`](Message::Begin) message to the server.
/// _(Bolt v3+ only.)_
///
/// # Description
/// The `BEGIN` message starts a new explicit transaction and transitions the server to the
/// [`TxReady`](bolt_proto::ServerState::TxReady) state. The explicit transaction is closed
/// with either the [`COMMIT`](Message::Commit) message or [`ROLLBACK`](Message::Rollback)
/// message.
///
/// The server must be in the [`Ready`](bolt_proto::ServerState::Ready) state to be able to
/// successfully process a `BEGIN` request. If the server is in the
/// [`Failed`](bolt_proto::ServerState::Failed) or
/// [`Interrupted`](bolt_proto::ServerState::Interrupted) state, the response will be
/// [`IGNORED`](Message::Ignored). For any other states, receipt of a `BEGIN` request will be
/// considered a protocol violation and will lead to connection closure.
///
/// # Fields
/// `metadata` may contain the following optional fields:
/// - `bookmarks`, a list of strings containing some kind of bookmark identification, e.g
/// `["bkmk-transaction:1", "bkmk-transaction:2"]`. Default is `[]`.
/// - `tx_timeout`, an integer specifying a transaction timeout in milliseconds. Default is the
/// server-side configured timeout.
/// - `tx_metadata`, a map containing some metadata information, mainly used for logging.
/// - `mode`, a string which specifies what kind of server should be used for this
/// transaction. For write access, use `"w"` and for read access use `"r"`. Default is `"w"`.
/// - `db`, a string containing the name of the database where the transaction should take
/// place. [`null`](bolt_proto::Value::Null) and `""` denote the server-side configured
/// default database. Default is `null`. _(Bolt v4+ only.)_
///
/// # Response
/// - [`Message::Success`] - the transaction has been successfully started and the server has
/// entered the [`TxReady`](bolt_proto::ServerState::Ready) state.
/// - [`Message::Ignored`] - the server is in the [`Failed`](bolt_proto::ServerState::Failed)
/// or [`Interrupted`](bolt_proto::ServerState::Interrupted) state, and the request was
/// discarded without being processed. No server state change has occurred.
/// - [`Message::Failure`] - the request could not be processed successfully and the server has
/// entered the [`Failed`](bolt_proto::ServerState::Failed) state. The server may attach
/// metadata to the message to provide more detail on the nature of the failure.
#[bolt_version(3, 4, 4.1, 4.2, 4.3)]
pub async fn begin(&mut self, metadata: Option<Metadata>) -> CommunicationResult<Message> {
let begin_msg = Begin::new(metadata.unwrap_or_default().value);
self.send_message(Message::Begin(begin_msg)).await?;
self.read_message().await
}
/// Send a [`COMMIT`](Message::Commit) message to the server.
/// _(Bolt v3+ only.)_
///
/// # Description
/// The `COMMIT` message requests to commit the results of an explicit transaction and
/// transition the server back to the [`Ready`](bolt_proto::ServerState::Ready) state.
///
/// The server must be in the [`TxReady`](bolt_proto::ServerState::TxReady) state to be able to
/// successfully process a `COMMIT` request, which means that any outstanding results in the
/// result stream must be consumed via [`Client::pull`]. If the server is in the
/// [`Failed`](bolt_proto::ServerState::Failed) or
/// [`Interrupted`](bolt_proto::ServerState::Interrupted) state, the response will be
/// [`IGNORED`](Message::Ignored). For any other states, receipt of a `COMMIT` request will be
/// considered a protocol violation and will lead to connection closure.
///
/// To instead cancel pending changes, send a [`ROLLBACK`](Message::Rollback) message.
///
/// # Response
/// - [`Message::Success`] - the transaction has been successfully committed and the server has
/// entered the [`Ready`](bolt_proto::ServerState::Ready) state. The server sends the
/// following metadata fields in the response:
/// - `bookmark` (e.g. `"bookmark:1234"`)
/// - [`Message::Ignored`] - the server is in the [`Failed`](bolt_proto::ServerState::Failed)
/// or [`Interrupted`](bolt_proto::ServerState::Interrupted) state, and the request was
/// discarded without being processed. No server state change has occurred.
/// - [`Message::Failure`] - the request could not be processed successfully and the server has
/// entered the [`Failed`](bolt_proto::ServerState::Failed) state. The server may attach
/// metadata to the message to provide more detail on the nature of the failure.
#[bolt_version(3, 4, 4.1, 4.2, 4.3)]
pub async fn commit(&mut self) -> CommunicationResult<Message> {
self.send_message(Message::Commit).await?;
self.read_message().await
}
/// Send a [`ROLLBACK`](Message::Rollback) message to the server.
/// _(Bolt v3+ only.)_
///
/// # Description
/// The `ROLLBACK` message requests to cancel a transaction and transition the server back to
/// the [`Ready`](bolt_proto::ServerState::Ready) state. Any changes made since the transaction
/// was started will be undone.
///
/// The server must be in the [`TxReady`](bolt_proto::ServerState::TxReady) state to be able to
/// successfully process a `ROLLBACK` request, which means that any outstanding results in the
/// result stream must be consumed via [`Client::pull`]. If the server is in the
/// [`Failed`](bolt_proto::ServerState::Failed) or
/// [`Interrupted`](bolt_proto::ServerState::Interrupted) state, the response will be
/// [`IGNORED`](Message::Ignored). For any other states, receipt of a `ROLLBACK` request will
/// be considered a protocol violation and will lead to connection closure.
///
/// To instead persist pending changes, send a [`COMMIT`](Message::Commit) message.
///
/// # Response
/// - [`Message::Success`] - the transaction has been successfully reverted and the server has
/// entered the [`Ready`](bolt_proto::ServerState::Ready) state.
/// - [`Message::Ignored`] - the server is in the [`Failed`](bolt_proto::ServerState::Failed)
/// or [`Interrupted`](bolt_proto::ServerState::Interrupted) state, and the request was
/// discarded without being processed. No server state change has occurred.
/// - [`Message::Failure`] - the request could not be processed successfully and the server has
/// entered the [`Failed`](bolt_proto::ServerState::Failed) state. The server may attach
/// metadata to the message to provide more detail on the nature of the failure.
#[bolt_version(3, 4, 4.1, 4.2, 4.3)]
pub async fn rollback(&mut self) -> CommunicationResult<Message> {
self.send_message(Message::Rollback).await?;
self.read_message().await
}
/// Send an [`ACK_FAILURE`](Message::AckFailure) message to the server.
/// _(Bolt v1 - v2 only. For Bolt v3+, see [`Client::reset`].)_
///
/// # Description
/// `ACK_FAILURE` signals to the server that the client has acknowledged a previous failure and
/// should return to the [`Ready`](bolt_proto::ServerState::Ready) state.
///
/// The server must be in the [`Failed`](bolt_proto::ServerState::Failed) state to be able to
/// successfully process an `ACK_FAILURE` request. For any other states, receipt of an
/// `ACK_FAILURE` request will be considered a protocol violation and will lead to connection
/// closure.
///
/// # Response
/// - [`Message::Success`] - failure has been successfully acknowledged and the server has
/// entered the [`Ready`](bolt_proto::ServerState::Ready) state. The server may attach
/// metadata to the `SUCCESS` message.
/// - [`Message::Failure`] - the request could not be processed successfully and the server has
/// entered the [`Defunct`](bolt_proto::ServerState::Defunct) state. The server may choose to
/// include metadata describing the nature of the failure but will immediately close the
/// connection after the failure has been sent.
#[bolt_version(1, 2)]
pub async fn ack_failure(&mut self) -> CommunicationResult<Message> {
self.send_message(Message::AckFailure).await?;
self.read_message().await
}
/// Send a [`RESET`](Message::Reset) message to the server.
/// _(Bolt v1+. For Bolt v1 - v2, see [`Client::ack_failure`] for just clearing the
/// [`Failed`](bolt_proto::ServerState::Failed) state.)_
///
/// # Description
/// The `RESET` message requests that the connection be set back to its initial state, as if
/// initialization had just been successfully completed. The `RESET` message is unique in that
/// it on arrival at the server, it jumps ahead in the message queue, stopping any unit of work
/// that happens to be executing. All the queued messages originally in front of the `RESET`
/// message will then be [`IGNORED`](Message::Ignored) until the `RESET` position is reached,
/// at which point the server will be ready for a new session.
///
/// Specifically, `RESET` will:
/// - force any currently processing message to abort with [`IGNORED`](Message::Ignored)
/// - force any pending messages that have not yet started processing to be
/// [`IGNORED`](Message::Ignored)
/// - clear any outstanding [`Failed`](bolt_proto::ServerState::Failed) state
/// - dispose of any outstanding result records
/// - cancel the current transaction, if any
///
/// # Response
/// - [`Message::Success`] - the session has been successfully reset and the server has entered
/// the [`Ready`](bolt_proto::ServerState::Ready) state.
/// - [`Message::Failure`] - the request could not be processed successfully and the server has
/// entered the [`Defunct`](bolt_proto::ServerState::Defunct) state. The server may choose to
/// include metadata describing the nature of the failure but will immediately close the
/// connection after the failure has been sent.
#[bolt_version(1, 2, 3, 4, 4.1, 4.2, 4.3)]
pub async fn reset(&mut self) -> CommunicationResult<Message> {
self.send_message(Message::Reset).await?;
loop {
match self.read_message().await? {
Message::Success(success) => return Ok(Message::Success(success)),
Message::Failure(failure) => return Ok(Message::Failure(failure)),
Message::Ignored => {}
_ => unreachable!(),
}
}
}
/// Send a [`GOODBYE`](Message::Goodbye) message to the server.
/// _(Bolt v3+ only.)_
///
/// # Description
/// The `GOODBYE` message notifies the server that the connection is terminating gracefully. On
/// receipt of this message, the server will immediately shut down the socket on its side
/// without sending a response. A client may shut down the socket at any time after sending the
/// `GOODBYE` message. This message interrupts the server's current work, if any.
#[bolt_version(3, 4, 4.1, 4.2, 4.3)]
pub async fn goodbye(&mut self) -> CommunicationResult<()> {
self.send_message(Message::Goodbye).await?;
self.server_state = Defunct;
Ok(self.stream.close().await?)
}
/// Send multiple messages to the server without waiting for a response. Returns a [`Vec`]
/// containing the server's response messages for each of the sent messages, in the order they
/// were provided.
///
/// # Description
/// The client is not required to wait for a response before sending more messages. Sending
/// multiple messages together like this is called _pipelining_. For performance reasons, it is
/// recommended that clients use pipelining wherever possible. Using pipelining, multiple
/// messages can be transmitted together in the same network package, significantly reducing
/// latency and increasing throughput.
///
/// A common technique is to buffer outgoing messages on the client until the last possible
/// moment, such as when a commit is issued or a result is read by the application, and then
/// sending all messages in the buffer together.
///
/// # Failure Handling
/// Because the protocol leverages pipelining, the client and the server need to agree on what
/// happens when a failure occurs, otherwise messages that were sent assuming no failure would
/// occur might have unintended effects.
///
/// When requests fail on the server, the server will send the client a
/// [`FAILURE`](Message::Failure) message. The client must clear the failure state by sending
/// a [`RESET`](Message::Reset) (Bolt v3+) or [`ACK_FAILURE`](Message::AckFailure) (Bolt v1 -
/// v2) message to the server. Until the server receives the `RESET`/`ACK_FAILURE` message, it
/// will send an [`IGNORED`](Message::Ignored) message in response to any other message from
/// the client, including messages that were sent in a pipeline.
pub async fn pipeline(&mut self, messages: Vec<Message>) -> CommunicationResult<Vec<Message>> {
// This Vec is too small if we're expecting some RECORD messages, so there's no "good" size
let mut responses = Vec::with_capacity(messages.len());
for message in &messages {
#[cfg(test)]
println!(">>> {:?}", message);
let chunks = message.clone().into_chunks().map_err(ProtocolError::from)?;
for chunk in chunks {
self.stream.write_all(&chunk).await?;
}
// Immediate state changes
match message {
Message::Reset => self.server_state = Interrupted,
Message::Goodbye => self.server_state = Disconnected,
_ => {}
}
}
self.stream.flush().await?;
self.sent_queue.extend(messages);
while !self.sent_queue.is_empty() {
responses.push(self.read_message().await?);
}
Ok(responses)
}
}