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// Copyright Materialize, Inc. and contributors. All rights reserved.
//
// Use of this software is governed by the Business Source License
// included in the LICENSE file.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0.
use std::collections::BTreeMap;
use std::fmt::{Debug, Display, Formatter};
use std::future::Future;
use std::pin;
use std::sync::Arc;
use std::time::{Duration, Instant};
use anyhow::bail;
use chrono::{DateTime, Utc};
use derivative::Derivative;
use futures::{Stream, StreamExt};
use itertools::Itertools;
use mz_adapter_types::connection::{ConnectionId, ConnectionIdType};
use mz_build_info::BuildInfo;
use mz_ore::channel::OneshotReceiverExt;
use mz_ore::collections::CollectionExt;
use mz_ore::id_gen::{org_id_conn_bits, IdAllocator, IdAllocatorInnerBitSet, MAX_ORG_ID};
use mz_ore::instrument;
use mz_ore::now::{to_datetime, EpochMillis, NowFn};
use mz_ore::result::ResultExt;
use mz_ore::task::AbortOnDropHandle;
use mz_ore::thread::JoinOnDropHandle;
use mz_ore::tracing::OpenTelemetryContext;
use mz_repr::{GlobalId, Row, ScalarType};
use mz_sql::ast::{Raw, Statement};
use mz_sql::catalog::{EnvironmentId, SessionCatalog};
use mz_sql::session::hint::ApplicationNameHint;
use mz_sql::session::metadata::SessionMetadata;
use mz_sql::session::user::SUPPORT_USER;
use mz_sql::session::vars::{OwnedVarInput, Var, CLUSTER};
use mz_sql_parser::parser::{ParserStatementError, StatementParseResult};
use prometheus::Histogram;
use serde_json::json;
use tokio::sync::{mpsc, oneshot};
use tracing::error;
use uuid::Uuid;
use crate::catalog::Catalog;
use crate::command::{
CatalogDump, CatalogSnapshot, Command, ExecuteResponse, GetVariablesResponse, Response,
};
use crate::coord::{Coordinator, ExecuteContextExtra};
use crate::error::AdapterError;
use crate::metrics::Metrics;
use crate::optimize::{self, Optimize};
use crate::session::{
EndTransactionAction, PreparedStatement, Session, SessionConfig, TransactionId,
};
use crate::statement_logging::StatementEndedExecutionReason;
use crate::telemetry::{self, SegmentClientExt, StatementFailureType};
use crate::webhook::AppendWebhookResponse;
use crate::{AdapterNotice, AppendWebhookError, PeekResponseUnary, StartupResponse};
/// A handle to a running coordinator.
///
/// The coordinator runs on its own thread. Dropping the handle will wait for
/// the coordinator's thread to exit, which will only occur after all
/// outstanding [`Client`]s for the coordinator have dropped.
pub struct Handle {
pub(crate) session_id: Uuid,
pub(crate) start_instant: Instant,
pub(crate) _thread: JoinOnDropHandle<()>,
}
impl Handle {
/// Returns the session ID associated with this coordinator.
///
/// The session ID is generated on coordinator boot. It lasts for the
/// lifetime of the coordinator. Restarting the coordinator will result
/// in a new session ID.
pub fn session_id(&self) -> Uuid {
self.session_id
}
/// Returns the instant at which the coordinator booted.
pub fn start_instant(&self) -> Instant {
self.start_instant
}
}
/// A coordinator client.
///
/// A coordinator client is a simple handle to a communication channel with the
/// coordinator. It can be cheaply cloned.
///
/// Clients keep the coordinator alive. The coordinator will not exit until all
/// outstanding clients have dropped.
#[derive(Debug, Clone)]
pub struct Client {
build_info: &'static BuildInfo,
inner_cmd_tx: mpsc::UnboundedSender<(OpenTelemetryContext, Command)>,
id_alloc: IdAllocator<IdAllocatorInnerBitSet>,
now: NowFn,
metrics: Metrics,
environment_id: EnvironmentId,
segment_client: Option<mz_segment::Client>,
}
impl Client {
pub(crate) fn new(
build_info: &'static BuildInfo,
cmd_tx: mpsc::UnboundedSender<(OpenTelemetryContext, Command)>,
metrics: Metrics,
now: NowFn,
environment_id: EnvironmentId,
segment_client: Option<mz_segment::Client>,
) -> Client {
// Connection ids are 32 bits and have 3 parts.
// 1. MSB bit is always 0 because these are interpreted as an i32, and it is possible some
// driver will not handle a negative id since postgres has never produced one because it
// uses process ids.
// 2. Next 12 bits are the lower 12 bits of the org id. This allows balancerd to route
// incoming cancel messages to a subset of the environments.
// 3. Last 19 bits are random.
let env_lower = org_id_conn_bits(&environment_id.organization_id());
Client {
build_info,
inner_cmd_tx: cmd_tx,
id_alloc: IdAllocator::new(1, MAX_ORG_ID, env_lower),
now,
metrics,
environment_id,
segment_client,
}
}
/// Allocates a client for an incoming connection.
pub fn new_conn_id(&self) -> Result<ConnectionId, AdapterError> {
self.id_alloc.alloc().ok_or(AdapterError::IdExhaustionError)
}
/// Creates a new session associated with this client for the given user.
///
/// It is the caller's responsibility to have authenticated the user.
pub fn new_session(&self, config: SessionConfig) -> Session {
// We use the system clock to determine when a session connected to Materialize. This is not
// intended to be 100% accurate and correct, so we don't burden the timestamp oracle with
// generating a more correct timestamp.
Session::new(self.build_info, config)
}
/// Upgrades this client to a session client.
///
/// A session is a connection that has successfully negotiated parameters,
/// like the user. Most coordinator operations are available only after
/// upgrading a connection to a session.
///
/// Returns a new client that is bound to the session and a response
/// containing various details about the startup.
#[mz_ore::instrument(level = "debug")]
pub async fn startup(&self, session: Session) -> Result<SessionClient, AdapterError> {
let user = session.user().clone();
let conn_id = session.conn_id().clone();
let secret_key = session.secret_key();
let uuid = session.uuid();
let application_name = session.application_name().into();
let notice_tx = session.retain_notice_transmitter();
let (tx, rx) = oneshot::channel();
// ~~SPOOKY ZONE~~
//
// This guard prevents a race where the startup command finishes, but the Future returned
// by this function is concurrently dropped, so we never create a `SessionClient` and thus
// never cleanup the initialized Session.
let rx = rx.with_guard(|_| {
self.send(Command::Terminate {
conn_id: conn_id.clone(),
tx: None,
});
});
self.send(Command::Startup {
tx,
user,
conn_id: conn_id.clone(),
secret_key,
uuid,
application_name,
notice_tx,
});
// When startup fails, no need to call terminate (handle_startup does this). Delay creating
// the client until after startup to sidestep the panic in its `Drop` implementation.
let response = rx.await.expect("sender dropped")?;
// Create the client as soon as startup succeeds (before any await points) so its `Drop` can
// handle termination.
let mut client = SessionClient {
inner: Some(self.clone()),
session: Some(session),
timeouts: Timeout::new(),
environment_id: self.environment_id.clone(),
segment_client: self.segment_client.clone(),
};
let StartupResponse {
role_id,
write_notify,
session_defaults,
catalog,
} = response;
// Before we do ANYTHING, we need to wait for our BuiltinTable writes to complete. We wait
// for the writes here, as opposed to during the Startup command, because we don't want to
// block the coordinator on a Builtin Table write.
write_notify.await;
let session = client.session();
session.initialize_role_metadata(role_id);
let vars_mut = session.vars_mut();
for (name, val) in session_defaults {
if let Err(err) = vars_mut.set_default(&name, val.borrow()) {
// Note: erroring here is unexpected, but we don't want to panic if somehow our
// assumptions are wrong.
tracing::error!("failed to set peristed default, {err:?}");
}
}
session
.vars_mut()
.end_transaction(EndTransactionAction::Commit);
let catalog = catalog.for_session(session);
if catalog.active_database().is_none() {
let db = session.vars().database().into();
session.add_notice(AdapterNotice::UnknownSessionDatabase(db));
}
let cluster_active = session.vars().cluster().to_string();
if session.vars().welcome_message() {
let cluster_info = if catalog.resolve_cluster(Some(&cluster_active)).is_err() {
format!("{cluster_active} (does not exist)")
} else {
cluster_active.to_string()
};
// Emit a welcome message, optimized for readability by humans using
// interactive tools. If you change the message, make sure that it
// formats nicely in both `psql` and the console's SQL shell.
session.add_notice(AdapterNotice::Welcome(format!(
"connected to Materialize v{}
Org ID: {}
Region: {}
User: {}
Cluster: {}
Database: {}
{}
Issue a SQL query to get started. Need help?
View documentation: https://materialize.com/s/docs
Join our Slack community: https://materialize.com/s/chat
",
session.vars().build_info().semver_version(),
self.environment_id.organization_id(),
self.environment_id.region(),
session.vars().user().name,
cluster_info,
session.vars().database(),
match session.vars().search_path() {
[schema] => format!("Schema: {}", schema),
schemas => format!(
"Search path: {}",
schemas.iter().map(|id| id.to_string()).join(", ")
),
},
)));
}
// Users stub their toe on their default cluster not existing, so we provide a notice to
// help guide them on what do to.
let cluster_var = session
.vars()
.inspect(CLUSTER.name())
.expect("cluster should exist");
if catalog.resolve_cluster(Some(&cluster_active)).is_err() {
let cluster_notice = 'notice: {
// If the user provided a cluster via a connection configuration parameter, do not
// notify them if that cluster does not exist. We omit the notice here because even
// if they were to update the role or system default, it would not make a
// difference since the connection parameter takes precedence over the defaults.
if cluster_var.inspect_session_value().is_some() {
break 'notice None;
}
let role_default = catalog.get_role(catalog.active_role_id());
let role_cluster = match role_default.vars().get(CLUSTER.name()) {
Some(OwnedVarInput::Flat(name)) => Some(name),
None => None,
// This is unexpected!
Some(v @ OwnedVarInput::SqlSet(_)) => {
tracing::warn!(?v, "SqlSet found for cluster Role Default");
break 'notice None;
}
};
let alter_role = "with `ALTER ROLE <role> SET cluster TO <cluster>;`";
match role_cluster {
// If there is no default, suggest a Role default.
None => Some(AdapterNotice::DefaultClusterDoesNotExist {
name: cluster_active,
kind: None,
suggested_action: format!(
"Set a default cluster for the current role {alter_role}."
),
}),
// If the default does not exist, suggest to change it.
Some(_) => Some(AdapterNotice::DefaultClusterDoesNotExist {
name: cluster_active,
kind: Some("role"),
suggested_action: format!(
"Change the default cluster for the current role {alter_role}."
),
}),
}
};
if let Some(notice) = cluster_notice {
session.add_notice(notice);
}
}
Ok(client)
}
/// Cancels the query currently running on the specified connection.
pub fn cancel_request(&mut self, conn_id: ConnectionIdType, secret_key: u32) {
self.send(Command::CancelRequest {
conn_id,
secret_key,
});
}
/// Executes a single SQL statement that returns rows as the
/// `mz_support` user.
pub async fn introspection_execute_one(&self, sql: &str) -> Result<Vec<Row>, anyhow::Error> {
// Connect to the coordinator.
let conn_id = self.new_conn_id()?;
let session = self.new_session(SessionConfig {
conn_id,
user: SUPPORT_USER.name.clone(),
external_metadata_rx: None,
});
let mut session_client = self.startup(session).await?;
// Parse the SQL statement.
let stmts = mz_sql::parse::parse(sql)?;
if stmts.len() != 1 {
bail!("must supply exactly one query");
}
let StatementParseResult { ast: stmt, sql } = stmts.into_element();
const EMPTY_PORTAL: &str = "";
session_client.start_transaction(Some(1))?;
session_client
.declare(EMPTY_PORTAL.into(), stmt, sql.to_string())
.await?;
match session_client
.execute(EMPTY_PORTAL.into(), futures::future::pending(), None)
.await?
{
(ExecuteResponse::SendingRows { future }, _) => match future.await {
PeekResponseUnary::Rows(rows) => Ok(rows),
PeekResponseUnary::Canceled => bail!("query canceled"),
PeekResponseUnary::Error(e) => bail!(e),
},
r => bail!("unsupported response type: {r:?}"),
}
}
/// Returns the metrics associated with the adapter layer.
pub fn metrics(&self) -> &Metrics {
&self.metrics
}
/// The current time according to the [`Client`].
pub fn now(&self) -> DateTime<Utc> {
to_datetime((self.now)())
}
/// Get a metadata and a channel that can be used to append to a webhook source.
pub async fn get_webhook_appender(
&self,
database: String,
schema: String,
name: String,
) -> Result<AppendWebhookResponse, AppendWebhookError> {
let (tx, rx) = oneshot::channel();
// Send our request.
self.send(Command::GetWebhook {
database,
schema,
name,
tx,
});
// Using our one shot channel to get the result, returning an error if the sender dropped.
let response = rx
.await
.map_err(|_| anyhow::anyhow!("failed to receive webhook response"))?;
response
}
#[instrument(level = "debug")]
fn send(&self, cmd: Command) {
self.inner_cmd_tx
.send((OpenTelemetryContext::obtain(), cmd))
.expect("coordinator unexpectedly gone");
}
}
/// A coordinator client that is bound to a connection.
///
/// See also [`Client`].
pub struct SessionClient {
// Invariant: inner may only be `None` after the session has been terminated.
// Once the session is terminated, no communication to the Coordinator
// should be attempted.
inner: Option<Client>,
// Invariant: session may only be `None` during a method call. Every public
// method must ensure that `Session` is `Some` before it returns.
session: Option<Session>,
timeouts: Timeout,
segment_client: Option<mz_segment::Client>,
environment_id: EnvironmentId,
}
impl SessionClient {
/// Parses a SQL expression, reporting failures as a telemetry event if
/// possible.
pub fn parse<'a>(
&self,
sql: &'a str,
) -> Result<Result<Vec<StatementParseResult<'a>>, ParserStatementError>, String> {
match mz_sql::parse::parse_with_limit(sql) {
Ok(Err(e)) => {
self.track_statement_parse_failure(&e);
Ok(Err(e))
}
r => r,
}
}
fn track_statement_parse_failure(&self, parse_error: &ParserStatementError) {
let session = self.session.as_ref().expect("session invariant violated");
let Some(user_id) = session.user().external_metadata.as_ref().map(|m| m.user_id) else {
return;
};
let Some(segment_client) = &self.segment_client else {
return;
};
let Some(statement_kind) = parse_error.statement else {
return;
};
let Some((action, object_type)) = telemetry::analyze_audited_statement(statement_kind)
else {
return;
};
let event_type = StatementFailureType::ParseFailure;
let event_name = format!(
"{} {} {}",
object_type.as_title_case(),
action.as_title_case(),
event_type.as_title_case(),
);
segment_client.environment_track(
&self.environment_id,
session.application_name(),
user_id,
event_name,
json!({
"statement_kind": statement_kind,
"error": &parse_error.error,
}),
);
}
// Verify and return the named prepared statement. We need to verify each use
// to make sure the prepared statement is still safe to use.
pub async fn get_prepared_statement(
&mut self,
name: &str,
) -> Result<&PreparedStatement, AdapterError> {
let catalog = self.catalog_snapshot().await;
Coordinator::verify_prepared_statement(&catalog, self.session(), name)?;
Ok(self
.session()
.get_prepared_statement_unverified(name)
.expect("must exist"))
}
/// Saves the parsed statement as a prepared statement.
///
/// The prepared statement is saved in the connection's [`crate::session::Session`]
/// under the specified name.
pub async fn prepare(
&mut self,
name: String,
stmt: Option<Statement<Raw>>,
sql: String,
param_types: Vec<Option<ScalarType>>,
) -> Result<(), AdapterError> {
let catalog = self.catalog_snapshot().await;
// Note: This failpoint is used to simulate a request outliving the external connection
// that made it.
let mut async_pause = false;
(|| {
fail::fail_point!("async_prepare", |val| {
async_pause = val.map_or(false, |val| val.parse().unwrap_or(false))
});
})();
if async_pause {
tokio::time::sleep(Duration::from_secs(1)).await;
};
let desc = Coordinator::describe(&catalog, self.session(), stmt.clone(), param_types)?;
let now = self.now();
self.session().set_prepared_statement(
name,
stmt,
sql,
desc,
catalog.transient_revision(),
now,
);
Ok(())
}
/// Binds a statement to a portal.
#[mz_ore::instrument(level = "debug")]
pub async fn declare(
&mut self,
name: String,
stmt: Statement<Raw>,
sql: String,
) -> Result<(), AdapterError> {
let catalog = self.catalog_snapshot().await;
let param_types = vec![];
let desc =
Coordinator::describe(&catalog, self.session(), Some(stmt.clone()), param_types)?;
let params = vec![];
let result_formats = vec![mz_pgwire_common::Format::Text; desc.arity()];
let now = self.now();
let logging = self.session().mint_logging(sql, Some(&stmt), now);
self.session().set_portal(
name,
desc,
Some(stmt),
logging,
params,
result_formats,
catalog.transient_revision(),
)?;
Ok(())
}
/// Executes a previously-bound portal.
///
/// Note: the provided `cancel_future` must be cancel-safe as it's polled in a `select!` loop.
#[mz_ore::instrument(level = "debug")]
pub async fn execute(
&mut self,
portal_name: String,
cancel_future: impl Future<Output = std::io::Error> + Send,
outer_ctx_extra: Option<ExecuteContextExtra>,
) -> Result<(ExecuteResponse, Instant), AdapterError> {
let execute_started = Instant::now();
let response = self
.send_with_cancel(
|tx, session| Command::Execute {
portal_name,
session,
tx,
outer_ctx_extra,
},
cancel_future,
)
.await?;
Ok((response, execute_started))
}
fn now(&self) -> EpochMillis {
(self.inner().now)()
}
fn now_datetime(&self) -> DateTime<Utc> {
to_datetime(self.now())
}
/// Starts a transaction based on implicit:
/// - `None`: InTransaction
/// - `Some(1)`: Started
/// - `Some(n > 1)`: InTransactionImplicit
/// - `Some(0)`: no change
pub fn start_transaction(&mut self, implicit: Option<usize>) -> Result<(), AdapterError> {
let now = self.now_datetime();
let session = self.session.as_mut().expect("session invariant violated");
let result = match implicit {
None => session.start_transaction(now, None, None),
Some(stmts) => {
session.start_transaction_implicit(now, stmts);
Ok(())
}
};
result
}
/// Ends a transaction.
#[instrument(level = "debug")]
pub async fn end_transaction(
&mut self,
action: EndTransactionAction,
) -> Result<ExecuteResponse, AdapterError> {
self.send(|tx, session| Command::Commit {
action,
session,
tx,
})
.await
}
/// Fails a transaction.
pub fn fail_transaction(&mut self) {
let session = self.session.take().expect("session invariant violated");
let session = session.fail_transaction();
self.session = Some(session);
}
/// Fetches the catalog.
#[instrument(level = "debug")]
pub async fn catalog_snapshot(&self) -> Arc<Catalog> {
let CatalogSnapshot { catalog } = self
.send_without_session(|tx| Command::CatalogSnapshot { tx })
.await;
catalog
}
/// Dumps the catalog to a JSON string.
///
/// No authorization is performed, so access to this function must be limited to internal
/// servers or superusers.
pub async fn dump_catalog(&mut self) -> Result<CatalogDump, AdapterError> {
let catalog = self.catalog_snapshot().await;
catalog.dump().map_err(AdapterError::from)
}
/// Checks the catalog for internal consistency, returning a JSON object describing the
/// inconsistencies, if there are any.
///
/// No authorization is performed, so access to this function must be limited to internal
/// servers or superusers.
pub async fn check_catalog(&mut self) -> Result<(), serde_json::Value> {
let catalog = self.catalog_snapshot().await;
catalog.check_consistency()
}
/// Checks the coordinator for internal consistency, returning a JSON object describing the
/// inconsistencies, if there are any. This is a superset of checks that check_catalog performs,
///
/// No authorization is performed, so access to this function must be limited to internal
/// servers or superusers.
pub async fn check_coordinator(&mut self) -> Result<(), serde_json::Value> {
self.send_without_session(|tx| Command::CheckConsistency { tx })
.await
.map_err(|inconsistencies| {
serde_json::to_value(inconsistencies).unwrap_or_else(|_| {
serde_json::Value::String("failed to serialize inconsistencies".to_string())
})
})
}
pub async fn dump_coordinator_state(&mut self) -> Result<serde_json::Value, anyhow::Error> {
self.send_without_session(|tx| Command::Dump { tx }).await
}
/// Tells the coordinator a statement has finished execution, in the cases
/// where we have no other reason to communicate with the coordinator.
pub fn retire_execute(
&mut self,
data: ExecuteContextExtra,
reason: StatementEndedExecutionReason,
) {
if !data.is_trivial() {
let cmd = Command::RetireExecute { data, reason };
self.inner().send(cmd);
}
}
/// Inserts a set of rows into the given table.
///
/// The rows only contain the columns positions in `columns`, so they
/// must be re-encoded for adding the default values for the remaining
/// ones.
pub async fn insert_rows(
&mut self,
id: GlobalId,
columns: Vec<usize>,
rows: Vec<Row>,
ctx_extra: ExecuteContextExtra,
) -> Result<ExecuteResponse, AdapterError> {
// TODO: Remove this clone once we always have the session. It's currently needed because
// self.session returns a mut ref, so we can't call it twice.
let pcx = self.session().pcx().clone();
let catalog = self.catalog_snapshot().await;
let conn_catalog = catalog.for_session(self.session());
// Collect optimizer parameters.
let optimizer_config = optimize::OptimizerConfig::from(conn_catalog.system_vars());
// Build an optimizer for this VIEW.
let mut optimizer = optimize::view::Optimizer::new(optimizer_config, None);
let result: Result<_, AdapterError> =
mz_sql::plan::plan_copy_from(&pcx, &conn_catalog, id, columns, rows)
.err_into()
.and_then(|values| optimizer.optimize(values).err_into())
.and_then(|values| {
// Copied rows must always be constants.
Coordinator::insert_constant(&catalog, self.session(), id, values.into_inner())
});
self.retire_execute(ctx_extra, (&result).into());
result
}
/// Gets the current value of all system variables.
pub async fn get_system_vars(&mut self) -> Result<GetVariablesResponse, AdapterError> {
let conn_id = self.session().conn_id().clone();
self.send_without_session(|tx| Command::GetSystemVars { conn_id, tx })
.await
}
/// Updates the specified system variables to the specified values.
pub async fn set_system_vars(
&mut self,
vars: BTreeMap<String, String>,
) -> Result<(), AdapterError> {
let conn_id = self.session().conn_id().clone();
self.send_without_session(|tx| Command::SetSystemVars { vars, conn_id, tx })
.await
}
/// Terminates the client session.
pub async fn terminate(&mut self) {
let conn_id = self.session().conn_id().clone();
let res = self
.send_without_session(|tx| Command::Terminate {
conn_id,
tx: Some(tx),
})
.await;
if let Err(e) = res {
// Nothing we can do to handle a failed terminate so we just log and ignore it.
error!("Unable to terminate session: {e:?}");
}
// Prevent any communication with Coordinator after session is terminated.
self.inner = None;
}
/// Returns a mutable reference to the session bound to this client.
pub fn session(&mut self) -> &mut Session {
self.session.as_mut().expect("session invariant violated")
}
/// Returns a reference to the inner client.
pub fn inner(&self) -> &Client {
self.inner.as_ref().expect("inner invariant violated")
}
async fn send_without_session<T, F>(&self, f: F) -> T
where
F: FnOnce(oneshot::Sender<T>) -> Command,
{
let (tx, rx) = oneshot::channel();
self.inner().send(f(tx));
rx.await.expect("sender dropped")
}
#[instrument(level = "debug")]
async fn send<T, F>(&mut self, f: F) -> Result<T, AdapterError>
where
F: FnOnce(oneshot::Sender<Response<T>>, Session) -> Command,
{
self.send_with_cancel(f, futures::future::pending()).await
}
/// Send a [`Command`] to the Coordinator, with the ability to cancel the command.
///
/// Note: the provided `cancel_future` must be cancel-safe as it's polled in a `select!` loop.
#[instrument(level = "debug")]
async fn send_with_cancel<T, F>(
&mut self,
f: F,
cancel_future: impl Future<Output = std::io::Error> + Send,
) -> Result<T, AdapterError>
where
F: FnOnce(oneshot::Sender<Response<T>>, Session) -> Command,
{
let session = self.session.take().expect("session invariant violated");
let mut typ = None;
let application_name = session.application_name();
let name_hint = ApplicationNameHint::from_str(application_name);
let conn_id = session.conn_id().clone();
let (tx, rx) = oneshot::channel();
// Destructure self so we can hold a mutable reference to the inner client and session at
// the same time.
let Self {
inner: inner_client,
session: client_session,
..
} = self;
// TODO(parkmycar): Leaking this invariant here doesn't feel great, but calling
// `self.client()` doesn't work because then Rust takes a borrow on the entirity of self.
let inner_client = inner_client.as_ref().expect("inner invariant violated");
// ~~SPOOKY ZONE~~
//
// This guard prevents a race where a `Session` is returned on `rx` but never placed
// back in `self` because the Future returned by this function is concurrently dropped
// with the Coordinator sending a response.
let mut guarded_rx = rx.with_guard(|response: Response<_>| {
*client_session = Some(response.session);
});
inner_client.send({
let cmd = f(tx, session);
// Measure the success and error rate of certain commands:
// - declare reports success of SQL statement planning
// - execute reports success of dataflow execution
match cmd {
Command::Execute { .. } => typ = Some("execute"),
Command::GetWebhook { .. } => typ = Some("webhook"),
Command::Startup { .. }
| Command::CatalogSnapshot { .. }
| Command::Commit { .. }
| Command::CancelRequest { .. }
| Command::PrivilegedCancelRequest { .. }
| Command::GetSystemVars { .. }
| Command::SetSystemVars { .. }
| Command::Terminate { .. }
| Command::RetireExecute { .. }
| Command::CheckConsistency { .. }
| Command::Dump { .. } => {}
};
cmd
});
let mut cancel_future = pin::pin!(cancel_future);
let mut cancelled = false;
loop {
tokio::select! {
res = &mut guarded_rx => {
// We received a result, so drop our guard to drop our borrows.
drop(guarded_rx);
let res = res.expect("sender dropped");
let status = if res.result.is_ok() {
"success"
} else {
"error"
};
if let Some(typ) = typ {
inner_client
.metrics
.commands
.with_label_values(&[typ, status, name_hint.as_str()])
.inc();
}
*client_session = Some(res.session);
return res.result;
},
_err = &mut cancel_future, if !cancelled => {
cancelled = true;
inner_client.send(Command::PrivilegedCancelRequest {
conn_id: conn_id.clone(),
});
}
};
}
}
pub fn add_idle_in_transaction_session_timeout(&mut self) {
let session = self.session();
let timeout_dur = session.vars().idle_in_transaction_session_timeout();
if !timeout_dur.is_zero() {
let timeout_dur = timeout_dur.clone();
if let Some(txn) = session.transaction().inner() {
let txn_id = txn.id.clone();
let timeout = TimeoutType::IdleInTransactionSession(txn_id);
self.timeouts.add_timeout(timeout, timeout_dur);
}
}
}
pub fn remove_idle_in_transaction_session_timeout(&mut self) {
let session = self.session();
if let Some(txn) = session.transaction().inner() {
let txn_id = txn.id.clone();
self.timeouts
.remove_timeout(&TimeoutType::IdleInTransactionSession(txn_id));
}
}
/// # Cancel safety
///
/// This method is cancel safe. If `recv` is used as the event in a
/// `tokio::select!` statement and some other branch
/// completes first, it is guaranteed that no messages were received on this
/// channel.
pub async fn recv_timeout(&mut self) -> Option<TimeoutType> {
self.timeouts.recv().await
}
}
impl Drop for SessionClient {
fn drop(&mut self) {
// We may not have a session if this client was dropped while awaiting
// a response. In this case, it is the coordinator's responsibility to
// terminate the session.
if let Some(session) = self.session.take() {
// We may not have a connection to the Coordinator if the session was
// prematurely terminated, for example due to a timeout.
if let Some(inner) = &self.inner {
inner.send(Command::Terminate {
conn_id: session.conn_id().clone(),
tx: None,
})
}
}
}
}
#[derive(Hash, PartialEq, Eq, PartialOrd, Ord, Clone, Debug)]
pub enum TimeoutType {
IdleInTransactionSession(TransactionId),
}
impl Display for TimeoutType {
fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
match self {
TimeoutType::IdleInTransactionSession(txn_id) => {
writeln!(f, "Idle in transaction session for transaction '{txn_id}'")
}
}
}
}
impl From<TimeoutType> for AdapterError {
fn from(timeout: TimeoutType) -> Self {
match timeout {
TimeoutType::IdleInTransactionSession(_) => {
AdapterError::IdleInTransactionSessionTimeout
}
}
}
}
struct Timeout {
tx: mpsc::UnboundedSender<TimeoutType>,
rx: mpsc::UnboundedReceiver<TimeoutType>,
active_timeouts: BTreeMap<TimeoutType, AbortOnDropHandle<()>>,
}
impl Timeout {
fn new() -> Self {
let (tx, rx) = mpsc::unbounded_channel();
Timeout {
tx,
rx,
active_timeouts: BTreeMap::new(),
}
}
/// # Cancel safety
///
/// This method is cancel safe. If `recv` is used as the event in a
/// `tokio::select!` statement and some other branch
/// completes first, it is guaranteed that no messages were received on this
/// channel.
///
/// <https://docs.rs/tokio/latest/tokio/sync/mpsc/struct.UnboundedReceiver.html#cancel-safety>
async fn recv(&mut self) -> Option<TimeoutType> {
self.rx.recv().await
}
fn add_timeout(&mut self, timeout: TimeoutType, duration: Duration) {
let tx = self.tx.clone();
let timeout_key = timeout.clone();
let handle = mz_ore::task::spawn(|| format!("{timeout_key}"), async move {
tokio::time::sleep(duration).await;
let _ = tx.send(timeout);
})
.abort_on_drop();
self.active_timeouts.insert(timeout_key, handle);
}
fn remove_timeout(&mut self, timeout: &TimeoutType) {
self.active_timeouts.remove(timeout);
// Remove the timeout from the rx queue if it exists.
let mut timeouts = Vec::new();
while let Ok(pending_timeout) = self.rx.try_recv() {
if timeout != &pending_timeout {
timeouts.push(pending_timeout);
}
}
for pending_timeout in timeouts {
self.tx.send(pending_timeout).expect("rx is in this struct");
}
}
}
/// A wrapper around an UnboundedReceiver of PeekResponseUnary that records when it sees the
/// first row data in the given histogram
#[derive(Derivative)]
#[derivative(Debug)]
pub struct RecordFirstRowStream {
#[derivative(Debug = "ignore")]
pub rows: Box<dyn Stream<Item = PeekResponseUnary> + Unpin + Send + Sync>,
pub execute_started: Instant,
pub time_to_first_row_seconds: Histogram,
saw_rows: bool,
}
impl RecordFirstRowStream {
/// Create a new [`RecordFirstRowStream`]
pub fn new(
rows: Box<dyn Stream<Item = PeekResponseUnary> + Unpin + Send + Sync>,
execute_started: Instant,
client: &SessionClient,
) -> Self {
let histogram = Self::histogram(client);
Self {
rows,
execute_started,
time_to_first_row_seconds: histogram,
saw_rows: false,
}
}
fn histogram(client: &SessionClient) -> Histogram {
let isolation_level = *client
.session
.as_ref()
.expect("session invariant")
.vars()
.transaction_isolation();
client
.inner()
.metrics()
.time_to_first_row_seconds
.with_label_values(&[isolation_level.as_str()])
}
/// If you want to match [`RecordFirstRowStream`]'s logic but don't need
/// a UnboundedReceiver, you can tell it when to record an observation.
pub fn record(execute_started: Instant, client: &SessionClient) {
Self::histogram(client).observe(execute_started.elapsed().as_secs_f64());
}
pub async fn recv(&mut self) -> Option<PeekResponseUnary> {
let msg = self.rows.next().await;
if !self.saw_rows && matches!(msg, Some(PeekResponseUnary::Rows(_))) {
self.saw_rows = true;
self.time_to_first_row_seconds
.observe(self.execute_started.elapsed().as_secs_f64());
}
msg
}
}