1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854
// 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/database-issues/issues/4001
// 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(())
}
}