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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.
//! A timestamp oracle backed by "Postgres" for persistence/durability and where
//! all oracle operations are self-sufficiently linearized, without requiring
//! any external precautions/machinery.
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::{Arc, RwLock};
use std::time::{Duration, SystemTime};
use async_trait::async_trait;
use deadpool_postgres::{Object, PoolError};
use dec::Decimal;
use mz_adapter_types::timestamp_oracle::{
DEFAULT_PG_TIMESTAMP_ORACLE_CONNECT_TIMEOUT, DEFAULT_PG_TIMESTAMP_ORACLE_CONNPOOL_MAX_SIZE,
DEFAULT_PG_TIMESTAMP_ORACLE_CONNPOOL_MAX_WAIT, DEFAULT_PG_TIMESTAMP_ORACLE_CONNPOOL_TTL,
DEFAULT_PG_TIMESTAMP_ORACLE_CONNPOOL_TTL_STAGGER, DEFAULT_PG_TIMESTAMP_ORACLE_TCP_USER_TIMEOUT,
};
use mz_ore::error::ErrorExt;
use mz_ore::instrument;
use mz_ore::metrics::MetricsRegistry;
use mz_pgrepr::Numeric;
use mz_postgres_client::{PostgresClient, PostgresClientConfig, PostgresClientKnobs};
use mz_repr::Timestamp;
use serde::{Deserialize, Serialize};
use tracing::{debug, info};
use crate::metrics::{Metrics, RetryMetrics};
use crate::retry::Retry;
use crate::WriteTimestamp;
use crate::{GenericNowFn, TimestampOracle};
// The timestamp columns are a `DECIMAL` that is big enough to hold
// `18446744073709551615`, the maximum value of `u64` which is our underlying
// timestamp type.
//
// These `sql_stats_automatic_collection_enabled` are for the cost-based
// optimizer but all the queries against this table are single-table and very
// carefully tuned to hit the primary index, so the cost-based optimizer doesn't
// really get us anything. OTOH, the background jobs that crdb creates to
// collect these stats fill up the jobs table (slowing down all sorts of
// things).
const SCHEMA: &str = "
CREATE TABLE IF NOT EXISTS timestamp_oracle (
timeline text NOT NULL,
read_ts DECIMAL(20,0) NOT NULL,
write_ts DECIMAL(20,0) NOT NULL,
PRIMARY KEY(timeline)
) WITH (sql_stats_automatic_collection_enabled = false);
";
/// A [`TimestampOracle`] backed by "Postgres".
#[derive(Debug)]
pub struct PostgresTimestampOracle<N>
where
N: GenericNowFn<Timestamp>,
{
timeline: String,
next: N,
postgres_client: Arc<PostgresClient>,
metrics: Arc<Metrics>,
/// A read-only timestamp oracle is NOT allowed to do operations that change
/// the backing Postgres/CRDB state.
read_only: bool,
}
/// Configuration to connect to a Postgres-backed implementation of
/// [`TimestampOracle`].
#[derive(Clone, Debug)]
pub struct PostgresTimestampOracleConfig {
url: String,
pub metrics: Arc<Metrics>,
/// Configurations that can be dynamically updated.
pub dynamic: Arc<DynamicConfig>,
}
impl From<PostgresTimestampOracleConfig> for PostgresClientConfig {
fn from(config: PostgresTimestampOracleConfig) -> Self {
let metrics = config.metrics.postgres_client.clone();
PostgresClientConfig::new(config.url.clone(), Arc::new(config), metrics)
}
}
impl PostgresTimestampOracleConfig {
pub(crate) const EXTERNAL_TESTS_POSTGRES_URL: &'static str = "COCKROACH_URL";
/// Returns a new instance of [`PostgresTimestampOracleConfig`] with default tuning.
pub fn new(url: &str, metrics_registry: &MetricsRegistry) -> Self {
let metrics = Arc::new(Metrics::new(metrics_registry));
let dynamic = DynamicConfig::default();
PostgresTimestampOracleConfig {
url: url.to_string(),
metrics,
dynamic: Arc::new(dynamic),
}
}
/// Returns a new [`PostgresTimestampOracleConfig`] for use in unit tests.
///
/// By default, postgres oracle tests are no-ops so that `cargo test` works
/// on new environments without any configuration. To activate the tests for
/// [`PostgresTimestampOracle`] set the `COCKROACH_URL` environment variable
/// with a valid connection url [1].
///
/// [1]: https://docs.rs/tokio-postgres/latest/tokio_postgres/config/struct.Config.html#url
pub fn new_for_test() -> Option<Self> {
let url = match std::env::var(Self::EXTERNAL_TESTS_POSTGRES_URL) {
Ok(url) => url,
Err(_) => {
if mz_ore::env::is_var_truthy("CI") {
panic!("CI is supposed to run this test but something has gone wrong!");
}
return None;
}
};
let dynamic = DynamicConfig::default();
let config = PostgresTimestampOracleConfig {
url: url.to_string(),
metrics: Arc::new(Metrics::new(&MetricsRegistry::new())),
dynamic: Arc::new(dynamic),
};
Some(config)
}
}
/// Part of [`PostgresTimestampOracleConfig`] that can be dynamically updated.
///
/// The timestamp oracle is expected to react to each of these such that
/// updating the value returned by the function takes effect (i.e. no caching
/// it). This should happen "as promptly as reasonably possible" where that's
/// defined by the tradeoffs of complexity vs promptness.
///
/// These are hooked up to LaunchDarkly. Specifically, LaunchDarkly configs are
/// serialized into a [`PostgresTimestampOracleParameters`]. In environmentd,
/// these are applied directly via [`PostgresTimestampOracleParameters::apply`]
/// to the [`PostgresTimestampOracleConfig`].
#[derive(Debug)]
pub struct DynamicConfig {
/// The maximum size of the connection pool to Postgres/CRDB.
pg_connection_pool_max_size: AtomicUsize,
/// The maximum time to wait when attempting to obtain a connection from the pool.
pg_connection_pool_max_wait: RwLock<Option<Duration>>,
/// The minimum TTL of a connection to Postgres/CRDB before it is
/// proactively terminated. Connections are routinely culled to balance load
/// against the downstream database.
pg_connection_pool_ttl: RwLock<Duration>,
/// The minimum time between TTLing connections to Postgres/CRDB. This delay
/// is used to stagger reconnections to avoid stampedes and high tail
/// latencies. This value should be much less than `connection_pool_ttl` so
/// that reconnections are biased towards terminating the oldest connections
/// first. A value of `connection_pool_ttl / connection_pool_max_size` is
/// likely a good place to start so that all connections are rotated when
/// the pool is fully used.
pg_connection_pool_ttl_stagger: RwLock<Duration>,
/// The duration to wait for a Postgres/CRDB connection to be made before
/// retrying.
pg_connection_pool_connect_timeout: RwLock<Duration>,
/// The TCP user timeout for a Postgres/CRDB connection. Specifies the
/// amount of time that transmitted data may remain unacknowledged before
/// the TCP connection is forcibly closed.
pg_connection_pool_tcp_user_timeout: RwLock<Duration>,
}
impl Default for DynamicConfig {
fn default() -> Self {
Self {
// TODO(aljoscha): These defaults are taken as is from the persist
// Consensus tuning. Once we're sufficiently advanced we might want
// to pick defaults that are different from the persist defaults.
pg_connection_pool_max_size: AtomicUsize::new(
DEFAULT_PG_TIMESTAMP_ORACLE_CONNPOOL_MAX_SIZE,
),
pg_connection_pool_max_wait: RwLock::new(Some(
DEFAULT_PG_TIMESTAMP_ORACLE_CONNPOOL_MAX_WAIT,
)),
pg_connection_pool_ttl: RwLock::new(DEFAULT_PG_TIMESTAMP_ORACLE_CONNPOOL_TTL),
pg_connection_pool_ttl_stagger: RwLock::new(
DEFAULT_PG_TIMESTAMP_ORACLE_CONNPOOL_TTL_STAGGER,
),
pg_connection_pool_connect_timeout: RwLock::new(
DEFAULT_PG_TIMESTAMP_ORACLE_CONNECT_TIMEOUT,
),
pg_connection_pool_tcp_user_timeout: RwLock::new(
DEFAULT_PG_TIMESTAMP_ORACLE_TCP_USER_TIMEOUT,
),
}
}
}
impl DynamicConfig {
// TODO: Decide if we can relax these.
const LOAD_ORDERING: Ordering = Ordering::SeqCst;
const STORE_ORDERING: Ordering = Ordering::SeqCst;
fn connection_pool_max_size(&self) -> usize {
self.pg_connection_pool_max_size.load(Self::LOAD_ORDERING)
}
fn connection_pool_max_wait(&self) -> Option<Duration> {
*self
.pg_connection_pool_max_wait
.read()
.expect("lock poisoned")
}
fn connection_pool_ttl(&self) -> Duration {
*self.pg_connection_pool_ttl.read().expect("lock poisoned")
}
fn connection_pool_ttl_stagger(&self) -> Duration {
*self
.pg_connection_pool_ttl_stagger
.read()
.expect("lock poisoned")
}
fn connect_timeout(&self) -> Duration {
*self
.pg_connection_pool_connect_timeout
.read()
.expect("lock poisoned")
}
fn tcp_user_timeout(&self) -> Duration {
*self
.pg_connection_pool_tcp_user_timeout
.read()
.expect("lock poisoned")
}
}
impl PostgresClientKnobs for PostgresTimestampOracleConfig {
fn connection_pool_max_size(&self) -> usize {
self.dynamic.connection_pool_max_size()
}
fn connection_pool_max_wait(&self) -> Option<Duration> {
self.dynamic.connection_pool_max_wait()
}
fn connection_pool_ttl(&self) -> Duration {
self.dynamic.connection_pool_ttl()
}
fn connection_pool_ttl_stagger(&self) -> Duration {
self.dynamic.connection_pool_ttl_stagger()
}
fn connect_timeout(&self) -> Duration {
self.dynamic.connect_timeout()
}
fn tcp_user_timeout(&self) -> Duration {
self.dynamic.tcp_user_timeout()
}
}
/// Updates to values in [`PostgresTimestampOracleConfig`].
///
/// These reflect updates made to LaunchDarkly.
///
/// Parameters can be set (`Some`) or unset (`None`). Unset parameters should be
/// interpreted to mean "use the previous value".
#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
pub struct PostgresTimestampOracleParameters {
/// Configures `DynamicConfig::pg_connection_pool_max_size`.
pub pg_connection_pool_max_size: Option<usize>,
/// Configures `DynamicConfig::pg_connection_pool_max_wait`.
///
/// NOTE: Yes, this is an `Option<Option<...>>`. Fields in this struct are
/// all `Option` to signal the presence or absence of a system var
/// configuration. A `Some(None)` value in this field signals the desire to
/// have no `max_wait`. This is different from `None`, which signals that
/// there is no actively set system var, although this case is not currently
/// possible with how the code around this works.
pub pg_connection_pool_max_wait: Option<Option<Duration>>,
/// Configures `DynamicConfig::pg_connection_pool_ttl`.
pub pg_connection_pool_ttl: Option<Duration>,
/// Configures `DynamicConfig::pg_connection_pool_ttl_stagger`.
pub pg_connection_pool_ttl_stagger: Option<Duration>,
/// Configures `DynamicConfig::pg_connection_pool_connect_timeout`.
pub pg_connection_pool_connect_timeout: Option<Duration>,
/// Configures `DynamicConfig::pg_connection_pool_tcp_user_timeout`.
pub pg_connection_pool_tcp_user_timeout: Option<Duration>,
}
impl PostgresTimestampOracleParameters {
/// Update the parameter values with the set ones from `other`.
pub fn update(&mut self, other: PostgresTimestampOracleParameters) {
// Deconstruct self and other so we get a compile failure if new fields
// are added.
let Self {
pg_connection_pool_max_size: self_pg_connection_pool_max_size,
pg_connection_pool_max_wait: self_pg_connection_pool_max_wait,
pg_connection_pool_ttl: self_pg_connection_pool_ttl,
pg_connection_pool_ttl_stagger: self_pg_connection_pool_ttl_stagger,
pg_connection_pool_connect_timeout: self_pg_connection_pool_connect_timeout,
pg_connection_pool_tcp_user_timeout: self_pg_connection_pool_tcp_user_timeout,
} = self;
let Self {
pg_connection_pool_max_size: other_pg_connection_pool_max_size,
pg_connection_pool_max_wait: other_pg_connection_pool_max_wait,
pg_connection_pool_ttl: other_pg_connection_pool_ttl,
pg_connection_pool_ttl_stagger: other_pg_connection_pool_ttl_stagger,
pg_connection_pool_connect_timeout: other_pg_connection_pool_connect_timeout,
pg_connection_pool_tcp_user_timeout: other_pg_connection_pool_tcp_user_timeout,
} = other;
if let Some(v) = other_pg_connection_pool_max_size {
*self_pg_connection_pool_max_size = Some(v);
}
if let Some(v) = other_pg_connection_pool_max_wait {
*self_pg_connection_pool_max_wait = Some(v);
}
if let Some(v) = other_pg_connection_pool_ttl {
*self_pg_connection_pool_ttl = Some(v);
}
if let Some(v) = other_pg_connection_pool_ttl_stagger {
*self_pg_connection_pool_ttl_stagger = Some(v);
}
if let Some(v) = other_pg_connection_pool_connect_timeout {
*self_pg_connection_pool_connect_timeout = Some(v);
}
if let Some(v) = other_pg_connection_pool_tcp_user_timeout {
*self_pg_connection_pool_tcp_user_timeout = Some(v);
}
}
/// Applies the parameter values to the given in-memory config object.
///
/// Note that these overrides are not all applied atomically: i.e. it's
/// possible for the timestamp oracle/postgres client to race with this and
/// see some but not all of the parameters applied.
pub fn apply(&self, cfg: &PostgresTimestampOracleConfig) {
info!(params = ?self, "Applying configuration update!");
// Deconstruct self so we get a compile failure if new fields are added.
let Self {
pg_connection_pool_max_size,
pg_connection_pool_max_wait,
pg_connection_pool_ttl,
pg_connection_pool_ttl_stagger,
pg_connection_pool_connect_timeout,
pg_connection_pool_tcp_user_timeout,
} = self;
if let Some(pg_connection_pool_max_size) = pg_connection_pool_max_size {
cfg.dynamic
.pg_connection_pool_max_size
.store(*pg_connection_pool_max_size, DynamicConfig::STORE_ORDERING);
}
if let Some(pg_connection_pool_max_wait) = pg_connection_pool_max_wait {
let mut max_wait = cfg
.dynamic
.pg_connection_pool_max_wait
.write()
.expect("lock poisoned");
*max_wait = *pg_connection_pool_max_wait;
}
if let Some(pg_connection_pool_ttl) = pg_connection_pool_ttl {
let mut ttl = cfg
.dynamic
.pg_connection_pool_ttl
.write()
.expect("lock poisoned");
*ttl = *pg_connection_pool_ttl;
}
if let Some(pg_connection_pool_ttl_stagger) = pg_connection_pool_ttl_stagger {
let mut ttl_stagger = cfg
.dynamic
.pg_connection_pool_ttl_stagger
.write()
.expect("lock poisoned");
*ttl_stagger = *pg_connection_pool_ttl_stagger;
}
if let Some(pg_connection_pool_connect_timeout) = pg_connection_pool_connect_timeout {
let mut timeout = cfg
.dynamic
.pg_connection_pool_connect_timeout
.write()
.expect("lock poisoned");
*timeout = *pg_connection_pool_connect_timeout;
}
if let Some(pg_connection_pool_tcp_user_timeout) = pg_connection_pool_tcp_user_timeout {
let mut timeout = cfg
.dynamic
.pg_connection_pool_tcp_user_timeout
.write()
.expect("lock poisoned");
*timeout = *pg_connection_pool_tcp_user_timeout;
}
}
}
impl<N> PostgresTimestampOracle<N>
where
N: GenericNowFn<Timestamp> + std::fmt::Debug + 'static,
{
/// Open a Postgres [`TimestampOracle`] instance with `config`, for the
/// timeline named `timeline`. `next` generates new timestamps when invoked.
/// Timestamps that are returned are made durable and will never retract.
pub async fn open(
config: PostgresTimestampOracleConfig,
timeline: String,
initially: Timestamp,
next: N,
read_only: bool,
) -> Self {
info!(config = ?config, "opening PostgresTimestampOracle");
let fallible = || async {
let metrics = Arc::clone(&config.metrics);
let postgres_client = PostgresClient::open(config.clone().into())?;
let client = postgres_client.get_connection().await?;
// The `timestamp_oracle` table creates and deletes rows at a high
// frequency, generating many tombstoned rows. If Cockroach's GC
// interval is set high (the default is 25h) and these tombstones
// accumulate, scanning over the table will take increasingly and
// prohibitively long.
//
// See: https://github.com/MaterializeInc/materialize/issues/13975
// See: https://www.cockroachlabs.com/docs/stable/configure-zone.html#variables
client
.batch_execute(&format!(
"{} {}",
SCHEMA,
"ALTER TABLE timestamp_oracle CONFIGURE ZONE USING gc.ttlseconds = 600;",
))
.await?;
let oracle = PostgresTimestampOracle {
timeline: timeline.clone(),
next: next.clone(),
postgres_client: Arc::new(postgres_client),
metrics,
read_only,
};
// Create a row for our timeline, if it doesn't exist. The
// `apply_write` call below expects the row to be present. If we
// didn't have this here we would always need CHECK EXISTS calls or
// something in `apply_write`, making it more complicated, so we
// only do it once here, on initialization.
let q = r#"
INSERT INTO timestamp_oracle (timeline, read_ts, write_ts)
VALUES ($1, $2, $3)
ON CONFLICT (timeline) DO NOTHING;
"#;
let statement = client.prepare_cached(q).await?;
let initially_coerced = Self::ts_to_decimal(initially);
let _ = client
.execute(
&statement,
&[&oracle.timeline, &initially_coerced, &initially_coerced],
)
.await?;
// Forward timestamps to what we're given from outside. Remember,
// the above query will only create the row at the initial timestamp
// if it didn't exist before.
if !read_only {
TimestampOracle::apply_write(&oracle, initially).await;
}
Result::<_, anyhow::Error>::Ok(oracle)
};
let metrics = &config.metrics.retries.open;
let oracle = retry_fallible(metrics, fallible).await;
oracle
}
async fn get_connection(&self) -> Result<Object, PoolError> {
self.postgres_client.get_connection().await
}
/// Returns a `Vec` of all known timelines along with their current greatest
/// timestamp (max of read_ts and write_ts).
///
/// For use when initializing another [`TimestampOracle`] implementation
/// from another oracle's state.
///
/// NOTE: This method can have linearizability violations, but it's hard to
/// get around those. They will only occur during bootstrap, and only
/// if/when we migrate between different oracle implementations. Once we
/// migrated from the catalog-backed oracle to the postgres/crdb-backed
/// oracle we can remove this code and it's callsite.
pub async fn get_all_timelines(
config: PostgresTimestampOracleConfig,
) -> Result<Vec<(String, Timestamp)>, anyhow::Error> {
let fallible = || async {
let postgres_client = PostgresClient::open(config.clone().into())?;
let mut client = postgres_client.get_connection().await?;
let txn = client.transaction().await?;
// Using `table_schema = CURRENT_SCHEMA` makes sure we only include
// tables that are queryable by us. Otherwise this check might
// return true but then the query below fails with a confusing
// "table does not exist" error.
let q = r#"
SELECT EXISTS (SELECT * FROM information_schema.tables WHERE table_name = 'timestamp_oracle' AND table_schema = CURRENT_SCHEMA);
"#;
let statement = txn.prepare(q).await?;
let exists_row = txn.query_one(&statement, &[]).await?;
let exists: bool = exists_row.try_get("exists").expect("missing exists column");
if !exists {
return Ok(Vec::new());
}
let q = r#"
SELECT timeline, GREATEST(read_ts, write_ts) as ts FROM timestamp_oracle;
"#;
let statement = txn.prepare(q).await?;
let rows = txn.query(&statement, &[]).await?;
txn.commit().await?;
let result = rows
.into_iter()
.map(|row| {
let timeline: String =
row.try_get("timeline").expect("missing timeline column");
let ts: Numeric = row.try_get("ts").expect("missing ts column");
let ts = Self::decimal_to_ts(ts);
(timeline, ts)
})
.collect::<Vec<_>>();
Ok(result)
};
let metrics = &config.metrics.retries.get_all_timelines;
let result = retry_fallible(metrics, fallible).await;
Ok(result)
}
#[mz_ore::instrument(name = "oracle::write_ts")]
async fn fallible_write_ts(&self) -> Result<WriteTimestamp<Timestamp>, anyhow::Error> {
if self.read_only {
panic!("attempting write_ts in read-only mode");
}
let proposed_next_ts = self.next.now();
let proposed_next_ts = Self::ts_to_decimal(proposed_next_ts);
let q = r#"
UPDATE timestamp_oracle SET write_ts = GREATEST(write_ts+1, $2)
WHERE timeline = $1
RETURNING write_ts;
"#;
let client = self.get_connection().await?;
let statement = client.prepare_cached(q).await?;
let result = client
.query_one(&statement, &[&self.timeline, &proposed_next_ts])
.await?;
let write_ts: Numeric = result.try_get("write_ts").expect("missing column write_ts");
let write_ts = Self::decimal_to_ts(write_ts);
debug!(
timeline = ?self.timeline,
write_ts = ?write_ts,
proposed_next_ts = ?proposed_next_ts,
"returning from write_ts()");
let advance_to = write_ts.step_forward();
Ok(WriteTimestamp {
timestamp: write_ts,
advance_to,
})
}
#[mz_ore::instrument(name = "oracle::peek_write_ts")]
async fn fallible_peek_write_ts(&self) -> Result<Timestamp, anyhow::Error> {
let q = r#"
SELECT write_ts FROM timestamp_oracle
WHERE timeline = $1;
"#;
let client = self.get_connection().await?;
let statement = client.prepare_cached(q).await?;
let result = client.query_one(&statement, &[&self.timeline]).await?;
let write_ts: Numeric = result.try_get("write_ts").expect("missing column write_ts");
let write_ts = Self::decimal_to_ts(write_ts);
debug!(
timeline = ?self.timeline,
write_ts = ?write_ts,
"returning from peek_write_ts()");
Ok(write_ts)
}
#[mz_ore::instrument(name = "oracle::read_ts")]
async fn fallible_read_ts(&self) -> Result<Timestamp, anyhow::Error> {
let q = r#"
SELECT read_ts FROM timestamp_oracle
WHERE timeline = $1;
"#;
let client = self.get_connection().await?;
let statement = client.prepare_cached(q).await?;
let result = client.query_one(&statement, &[&self.timeline]).await?;
let read_ts: Numeric = result.try_get("read_ts").expect("missing column read_ts");
let read_ts = Self::decimal_to_ts(read_ts);
debug!(
timeline = ?self.timeline,
read_ts = ?read_ts,
"returning from read_ts()");
Ok(read_ts)
}
#[mz_ore::instrument(name = "oracle::apply_write")]
async fn fallible_apply_write(&self, write_ts: Timestamp) -> Result<(), anyhow::Error> {
if self.read_only {
panic!("attempting apply_write in read-only mode");
}
let q = r#"
UPDATE timestamp_oracle SET write_ts = GREATEST(write_ts, $2), read_ts = GREATEST(read_ts, $2)
WHERE timeline = $1;
"#;
let client = self.get_connection().await?;
let statement = client.prepare_cached(q).await?;
let write_ts = Self::ts_to_decimal(write_ts);
let _ = client
.execute(&statement, &[&self.timeline, &write_ts])
.await?;
debug!(
timeline = ?self.timeline,
write_ts = ?write_ts,
"returning from apply_write()");
Ok(())
}
// We could add `From` impls for these but for now keep the code local to
// the oracle.
fn ts_to_decimal(ts: Timestamp) -> Numeric {
let decimal = Decimal::from(ts);
Numeric::from(decimal)
}
// We could add `From` impls for these but for now keep the code local to
// the oracle.
fn decimal_to_ts(ts: Numeric) -> Timestamp {
ts.0 .0.try_into().expect("we only use u64 timestamps")
}
}
// A wrapper around the `fallible_` methods that adds operation metrics and
// retries.
//
// NOTE: This implementation is tied to [`mz_repr::Timestamp`]. We could change
// that, and also make the types we store in the backing "Postgres" table
// generic. But in practice we only use oracles for [`mz_repr::Timestamp`] so
// don't do that extra work for now.
#[async_trait]
impl<N> TimestampOracle<Timestamp> for PostgresTimestampOracle<N>
where
N: GenericNowFn<Timestamp> + std::fmt::Debug + 'static,
{
#[instrument]
async fn write_ts(&self) -> WriteTimestamp<Timestamp> {
let metrics = &self.metrics.retries.write_ts;
let res = retry_fallible(metrics, || {
self.metrics
.oracle
.write_ts
.run_op(|| self.fallible_write_ts())
})
.await;
res
}
#[instrument]
async fn peek_write_ts(&self) -> Timestamp {
let metrics = &self.metrics.retries.peek_write_ts;
let res = retry_fallible(metrics, || {
self.metrics
.oracle
.peek_write_ts
.run_op(|| self.fallible_peek_write_ts())
})
.await;
res
}
#[instrument]
async fn read_ts(&self) -> Timestamp {
let metrics = &self.metrics.retries.read_ts;
let res = retry_fallible(metrics, || {
self.metrics
.oracle
.read_ts
.run_op(|| self.fallible_read_ts())
})
.await;
res
}
#[instrument]
async fn apply_write(&self, write_ts: Timestamp) {
let metrics = &self.metrics.retries.apply_write;
let res = retry_fallible(metrics, || {
self.metrics
.oracle
.apply_write
.run_op(|| self.fallible_apply_write(write_ts.clone()))
})
.await;
res
}
}
pub const INFO_MIN_ATTEMPTS: usize = 3;
pub async fn retry_fallible<R, F, WorkFn>(metrics: &RetryMetrics, mut work_fn: WorkFn) -> R
where
F: std::future::Future<Output = Result<R, anyhow::Error>>,
WorkFn: FnMut() -> F,
{
let mut retry = metrics.stream(Retry::oracle_defaults(SystemTime::now()).into_retry_stream());
loop {
match work_fn().await {
Ok(x) => {
if retry.attempt() > 0 {
debug!(
"external operation {} succeeded after failing at least once",
metrics.name,
);
}
return x;
}
Err(err)
if err
.to_string()
.contains("\"timestamp_oracle\" does not exist") =>
{
// TODO(aljoscha): Re-consider this before enabling the oracle
// in production.
// It's a policy question whether this actually _is_ an
// unrecoverable error: an operator could go in an re-create the
// `timestamp_oracle` table once the problem is noticed.
// However, our tests currently assume that materialize will
// fail unrecoverably in cases where we do a rug-pull/remove
// expected tables from CRDB.
panic!(
"external operation {} failed unrecoverably, someone removed our database/schema/table: {}",
metrics.name,
err.display_with_causes()
);
}
Err(err) => {
if retry.attempt() >= INFO_MIN_ATTEMPTS {
info!(
"external operation {} failed, retrying in {:?}: {}",
metrics.name,
retry.next_sleep(),
err.display_with_causes()
);
} else {
info!(
"external operation {} failed, retrying in {:?}: {}",
metrics.name,
retry.next_sleep(),
err.display_with_causes()
);
}
retry = retry.sleep().await;
}
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[mz_ore::test(tokio::test)]
#[cfg_attr(miri, ignore)] // error: unsupported operation: can't call foreign function `TLS_client_method` on OS `linux`
async fn test_postgres_timestamp_oracle() -> Result<(), anyhow::Error> {
let config = match PostgresTimestampOracleConfig::new_for_test() {
Some(config) => config,
None => {
info!(
"{} env not set: skipping test that uses external service",
PostgresTimestampOracleConfig::EXTERNAL_TESTS_POSTGRES_URL
);
return Ok(());
}
};
crate::tests::timestamp_oracle_impl_test(|timeline, now_fn, initial_ts| {
let oracle = PostgresTimestampOracle::open(
config.clone(),
timeline,
initial_ts,
now_fn,
false, /* read-only */
);
async {
let arced_oracle: Arc<dyn TimestampOracle<Timestamp> + Send + Sync> =
Arc::new(oracle.await);
arced_oracle
}
})
.await?;
Ok(())
}
}