Commit Graph

214 Commits

Author SHA1 Message Date
Arthur Petukhovsky
d9a1329834 Make postgres_backend use generic IO type (#3789)
- Support measuring inbound and outbound traffic in MeasuredStream
- Start using MeasuredStream in safekeepers code
2023-03-13 12:18:10 +03:00
Heikki Linnakangas
34d3385b2e Add unit tests for JWT encoding and decoding. 2023-03-10 16:09:32 +02:00
Heikki Linnakangas
bebf76c461 Accept RS384 and RS512 JWT tokens.
Previously, we only accepted RS256. Seems like a pointless limitation,
and when I was testing it with RS512 tokens, it took me a while to
understand why it wasn't working.
2023-03-10 16:09:32 +02:00
Arseny Sher
b80fe41af3 Refactor postgres protocol parsing.
1) Remove allocation and data copy during each message read. Instead, parsing
functions now accept BytesMut from which data they form messages, with
pointers (e.g. in CopyData) pointing directly into BytesMut buffer. Accordingly,
move ConnectionError containing IO error subtype into framed.rs providing this
and leave in pq_proto only ProtocolError.

2) Remove anyhow from pq_proto.

3) Move FeStartupPacket out of FeMessage. Now FeStartupPacket::parse returns it
directly, eliminating dead code where user wants startup packet but has to match
for others.

proxy stream.rs is adapted to framed.rs with minimal changes. It also benefits
from framed.rs improvements described above.
2023-03-09 20:45:56 +03:00
Arseny Sher
0d8ced8534 Remove sync postgres_backend, tidy up its split usage.
- Add support for splitting async postgres_backend into read and write halfes.
  Safekeeper needs this for bidirectional streams. To this end, encapsulate
  reading-writing postgres messages to framed.rs with split support without any
  additional changes (relying on BufRead for reading and BytesMut out buffer for
  writing).
- Use async postgres_backend throughout safekeeper (and in proxy auth link
  part).
- In both safekeeper COPY streams, do read-write from the same thread/task with
  select! for easier error handling.
- Tidy up finishing CopyBoth streams in safekeeper sending and receiving WAL
  -- join split parts back catching errors from them before returning.

Initially I hoped to do that read-write without split at all, through polling
IO:
https://github.com/neondatabase/neon/pull/3522
However that turned out to be more complicated than I initially expected
due to 1) borrow checking and 2) anon Future types. 1) required Rc<Refcell<...>>
which is Send construct just to satisfy the checker; 2) can be workaround with
transmute. But this is so messy that I decided to leave split.
2023-03-09 20:45:56 +03:00
Arseny Sher
7627d85345 Move async postgres_backend to its own crate.
To untie cyclic dependency between sync and async versions of postgres_backend,
copy QueryError and some logging/error routines to postgres_backend.rs. This is
temporal glue to make commits smaller, sync version will be dropped by the
upcoming commit completely.
2023-03-09 20:45:56 +03:00
Arseny Sher
3f11a647c0 Rename write_message to write_message_noflush in postgres_backend_async.rs
To make it unifrom across the project; proxy stream.rs and older
postgres_backend uses write_message_noflush.
2023-03-09 20:45:56 +03:00
Kirill Bulatov
03a2ce9d13 Add tracing spans with request_id into pageserver management API handlers (#3755)
Adds a newtype that creates a span with request_id from
https://github.com/neondatabase/neon/pull/3708 for every HTTP request
served.

Moves request logging and error handlers under the new wrapper, so every request-related event now is logged under the request span.
For compatibility reasons, error handler is left on the general router, since not every service uses the new handler wrappers yet.
2023-03-09 09:24:01 +02:00
Arthur Petukhovsky
b23742e09c Create /v1/debug_dump safekeepers endpoint (#3710)
Add HTTP endpoint to get full safekeeper state of all existing timelines
(all in-memory values and info about all files stored on disk).

Example:
https://gist.github.com/petuhovskiy/3cbb8f870401e9f486731d145161c286
2023-03-03 14:01:05 +03:00
Shany Pozin
d19c5248c9 Add UUID header to mgmt API (#3708)
## Describe your changes

## Issue ticket number and link
#3479
## Checklist before requesting a review
- [x] I have performed a self-review of my code.
- [ ] If it is a core feature, I have added thorough tests.
- [ ] Do we need to implement analytics? if so did you add the relevant
metrics to the dashboard?
- [ ] If this PR requires public announcement, mark it with
/release-notes label and add several sentences in this section.
2023-03-01 18:09:08 +02:00
Heikki Linnakangas
f51b48fa49 Fix UNLOGGED tables.
Instead of trying to create missing files on the way, send init fork contents as
main fork from pageserver during basebackup. Add test for that. Call
put_rel_drop for init forks; previously they weren't removed. Bump
vendor/postgres to revert previous approach on Postgres side.

Co-authored-by: Arseny Sher <sher-ars@yandex.ru>

ref https://github.com/neondatabase/postgres/pull/264
ref https://github.com/neondatabase/postgres/pull/259
ref https://github.com/neondatabase/neon/issues/1222
2023-02-24 23:30:02 +04:00
Dmitry Rodionov
eb403da814 Use debug level for successful GET http requests (#3681)
We started rather frequently scrap some apis for metadata. This includes
layer eviction tester, I believe console does that too.

It should eliminate these logs:
https://neonprod.grafana.net/goto/rr_ace1Vz?orgId=1 (Note the rate
around 2k messages per minute)
2023-02-22 22:19:05 +03:00
Joonas Koivunen
b8b8c19fb4 fix: hold permit until GetObject eof (#3663)
previously we applied the ratelimiting only up to receiving the headers
from s3, or somewhere near it. the commit adds an adapter which carries
the permit until the AsyncRead has been disposed.

fixes #3662.
2023-02-21 21:14:08 +02:00
Joonas Koivunen
d7d3f451f0 Use tracing panic hook in all binaries (#3634)
Enables tracing panic hook in addition to pageserver introduced in
#3475:

- proxy
- safekeeper
- storage_broker

For proxy, a drop guard which resets the original std panic hook was
added on the first commit. Other binaries don't need it so they never
reset anything by `disarm`ing the drop guard.

The aim of the change is to make sure all panics a) have span
information b) are logged similar to other messages, not interleaved
with other messages as happens right now. Interleaving happens right now
because std prints panics to stderr, and other logging happens in
stdout. If this was handled gracefully by some utility, the log message
splitter would treat panics as belonging to the previous message because
it expects a message to start with a timestamp.

Cc: #3468
2023-02-21 10:03:55 +02:00
Heikki Linnakangas
ddbdcdddd7 Tenant size calculation: refactor, rewrite, and add SVG (#2817)
Refactor the tenant_size_model code. Segment now contains just the
minimum amount of information needed to calculate the size. Other
information that is useful for building up the segment tree, and for
display purposes, is now kept elsewhere. The code in 'main.rs' has a new
ScenarioBuilder struct for that.

Calculating which Segments are "needed" is now the responsibility of the
caller of tenant_size_mode, not part of the calculation itself. So it's
up to the caller to make all the decisions with retention periods for
each branch.

The output of the sizing calculation is now a Vec of SizeResults, rather
than a tree. It uses a tree representation internally, when doing the
calculation, but it's not exposed to the caller anymore.

Refactor the way the recursive calculation is performed.

Rewrite the code in size.rs that builds the Segment model. Get rid of
the intermediate representation with Update structs. Build the Segments
directly, with some local HashMaps and Vecs to track branch points to
help with that.

retention_period is now an input to gather_inputs(), rather than an
output.

Update pageserver http API: rename /size endpoint to /synthetic_size
with following parameters:
    - /synthetic_size?inputs_only to get debug info;
- /synthetic_size?retention_period=0 to override cutoff that is used to
calculate the size;
pass header -H "Accept: text/html" to get HTML output, otherwise JSON is
returned

Update python tests and openapi spec.

---------

Co-authored-by: Anastasia Lubennikova <anastasia@neon.tech>
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
2023-02-16 10:53:46 +02:00
Dmitry Ivanov
1d9d7c02db [proxy] Don't forward empty options to compute nodes
Clients may specify endpoint/project name via `options=project=...`,
so we should not only remove `project=` from `options` but also
drop `options` entirely, because connection pools don't support it.

Discussion: https://neondb.slack.com/archives/C033A2WE6BZ/p1676464382670119
2023-02-15 22:05:03 +03:00
Christian Schwarz
175a577ad4 automatic layer eviction
This patch adds a per-timeline periodic task that executes an eviction
policy. The eviction policy is configurable per tenant.

Two policies exist:
- NoEviction (the default one)
- LayerAccessThreshold

The LayerAccessThreshold policy examines the last access timestamp per
layer in the layer map and evicts the layer if that last access is
further in the past than a configurable threshold value.
This policy kind is evaluated periodically at a configurable period.
It logs a summary statistic at `info!()` or `warn!()` level, depending
on whether any evictions failed.

This feature has no explicit killswitch since it's off by default.
2023-02-09 13:33:55 +01:00
Christian Schwarz
58fa4f0eb7 maintain access stats for historic layers
This patch adds basic access statistics for historic layers
and exposes them in the management API's `LayerMapInfo`.

We record the accesses in the `{Delta,Image}Layer::load()` function
because it's the common path of
* page_service (`Timline::get_reconstruct_data()`)
* Compaction (`PersistentLayer::iter()` and `PersistentLayer::key_iter()`)

The stats survive residence status changes, and record these as well.

When scraping the layer map endpoint to record its evolution over time,
one must account for stat resets because they are in-memory only and
will reset on pageserver restart.
Use the launch timestamp header added by (#3527) to identify pageserver restarts.

This is PR https://github.com/neondatabase/neon/pull/3496
2023-02-06 17:01:38 +01:00
Kirill Bulatov
ec3a3aed37 Dump current tenant config (#3534)
The PR adds an endpoint to show tenant's current config: `GET
/v1/tenant/:tenant_id/config`

Tenant's config consists of two parts: tenant overrides (could be
changed via other management API requests) and the default part,
substituting all missing overrides (constant, hardcoded in pageserver).
The API returns the custom overrides and the final tenant config, after
applying all the defaults.

Along the way, it had to fix two things in the config:

* allow to shorten the json version and omit all `null`'s (same as toml
serializer behaves by default), and to understand such shortened format
when deserialized. A unit test is added
* fix a bug, when `PUT /v1/tenant/config` endpoint rewritten the local
file with what had came in the request, but updating (not rewriting the
old values) the in-memory state instead.
That got uncovered during adjusting the e2e test and fixed to do the
replacement everywhere, otherwise there's no way to revert existing
overrides. Fixes #3471 (commit
dc688affe8)
* fixes https://github.com/neondatabase/neon/issues/3472 by reordering
the config saving operations
2023-02-04 01:32:29 +02:00
Christian Schwarz
87cd2bae77 introduce LaunchTimestamp to identify process restarts
This patch adds a LaunchTimestamp type to the `metrics` crate,
along with a `libmetric_` Prometheus metric.

The initial user is pageserver.
In addition to exposing the Prometheus metric, it also reproduces
the launch timestamp as a header in the API responses.

The motivation for this is that we plan to scrape the pageserver's
/v1/tenant/:tenant_id/timeline/:timeline_id/layer
HTTP endpoint over time. It will soon expose access metrics (#3496)
which reset upon process restart. We will use the pageserver's launch
ID to identify a restart between two scrape points.

However, there are other potential uses. For example, we could use
the Prometheus metric to annotate Grafana plots whenever the launch
timestamp changes.
2023-02-03 18:12:17 +01:00
bojanserafimov
ada933eb42 Pageserver read trace utils (#2795)
List, dump, and analyze read traces.
2023-02-02 15:33:40 -05:00
Kirill Bulatov
2759f1a22e Evict layers on demand (#3486)
Closes https://github.com/neondatabase/neon/issues/3439

Adds a set of commands to manipulate the layer map:
* dump the layer map contents
* evict the layer form the layer map (remove the local file, put the
remote layer instead in the layer map)
* download the layer (operation, reversing the eviction)

The commands will change later, when the statistics is added on top, so
the swagger schema is not adjusted.

The commands might have issues with big amount of layers: no pagination
is done for the dump command, eviction and download commands look for
the layer to evict/download by iterating all layers sequentially and
comparing the layer names.
For now, that seems to be tolerable ("big" number of layers is ~2_000)
and further experiments are needed.

---------

Co-authored-by: Christian Schwarz <christian@neon.tech>
2023-02-02 12:14:44 +02:00
Christian Schwarz
590695e845 improve query param parsing
- add parse_query_param()
- use Cow<> where possible
- move param parsing code to utils::http::request

This was originally PR https://github.com/neondatabase/neon/pull/3502
which targeted a different branch.

closes  #3510
2023-02-01 14:11:12 +01:00
Lassi Pölönen
20b38acff0 Replace per timeline pageserver_storage_operations_seconds with a global one (#3409)
Related to: https://github.com/neondatabase/neon/issues/2848

`pageserver_storage_operations_seconds` is the most expensive metric we
have, as there are a lot of tenants/timelines and the histogram had 42
buckets. These are quite sparse too, so instead of having a histogram
per timeline, create a new histogram
`pageserver_storage_operations_seconds_global` without tenant and
timeline dimensions and replace `pageserver_storage_operations_seconds`
with sum and counter.

Co-authored-by: Joonas Koivunen <joonas@neon.tech>
2023-01-30 17:10:29 +02:00
Shany Pozin
ddb9c2fe94 Add metrics for tenants state (#3448)
## Describe your changes
Added a metric that allow to monitor tenants state 
## Issue ticket number and link
https://github.com/neondatabase/neon/issues/3161

## Checklist before requesting a review
- [X] I have performed a self-review of my code.
- [X] I have added an e2e test for it.
- [ ] Do we need to implement analytics? if so did you add the relevant
metrics to the dashboard?
- [ ] If this PR requires public announcement, mark it with
/release-notes label and add several sentences in this section.
2023-01-29 14:04:06 +02:00
Heikki Linnakangas
0c0e15b81d compute_ctl: Extract tracing context from incoming HTTP requests.
This allows tracing the handling of HTTP requests as part of the caller's
trace.
2023-01-26 15:20:03 +02:00
Heikki Linnakangas
006ee5f94a Configure 'compute_ctl' to use OpenTelemetry exporter.
This allows tracing the startup actions e.g. with Jaeger
(https://www.jaegertracing.io/). We use the "tracing-opentelemetry"
crate, which turns tracing spans into OpenTelemetry spans, so you can
use the usual "#[instrument]" directives to add tracing.

I put the tracing initialization code to a separate crate,
`tracing-utils`, so that we can reuse it in other programs. We
probably want to set up tracing in the same way in all our programs.

Co-authored-by: Joonas Koivunen <joonas@neon.tech>
2023-01-26 15:20:03 +02:00
Kirill Bulatov
9fbef1159f Tone down http error printing (#3434)
Only print backtraces for internal server error variants of the API
error.
2023-01-25 10:36:30 +00:00
Kirill Bulatov
fd18692dfb Output coloured pageserver logs for tty stdout 2023-01-24 09:58:08 +02:00
Christian Schwarz
6b6570b580 remove TimelineState::Suspended, introduce TimelineState::Loading
The TimelineState::Suspsended was dubious to begin with. I suppose
that the intention was that timelines could transition back and
forth between Active and Suspended states.
But practically, the code before this patch never did that.
The transitions were:

    () ==Timeline::new==> Suspended ==*==> {Active,Broken,Stopping}

One exception: Tenant::set_stopping() could transition timelines like
so:

    !Broken ==Tenant::set_stopping()==> Suspended

But Tenant itself cannot transition from stopping state to any other
state.

Thus, this patch removes TimelineState::Suspended and introduces a new
state Loading. The aforementioned transitions change as follows:

    - () ==Timeline::new==> Suspended ==*==> {Active,Broken,Stopping}
    + () ==Timeline::new==> Loading   ==*==> {Active,Broken,Stopping}

    - !Broken ==Tenant::set_stopping()==> Suspended
    + !Broken ==Tenant::set_stopping()==> Stopping

Walreceiver's connection manager loop watches TimelineState to decide
whether it should retry connecting, or exit.
This patch changes the loop to exit when it observes the transition
into Stopping state.

Walreceiver isn't supposed to be started until the timeline transitions
into Active state. So, this patch also adds some warn!() messages
in case this happens anyways.
2023-01-23 17:22:49 +01:00
Joonas Koivunen
7704caa3ac More tenant size fixes (#3410)
Small changes, but hopefully this will help with the panic detected in
staging, for which we cannot get the debugging information right now
(end-of-branch before branch-point).
2023-01-23 17:12:51 +02:00
Kirill Bulatov
90f66aa51b Enable logs in unit tests 2023-01-18 17:43:27 +02:00
Christian Schwarz
58c8c1076c download_all_remote_layers API: require client to specify max_concurrent_downloads
Before this patch, we would start all layer downloads simultaneously.

There is at most one download_all_remote_layers task per timeline.
Hence, the specified limit is per timeline.

There is still no global concurrency limit for layer downloads.
We'll have to revisit that at some point and also prioritize on-demand
initiated downloads over download_all_remote_layers downloads.
But that's for another day.
2023-01-16 19:29:06 +01:00
Anastasia Lubennikova
2cbe84b78f Proxy metrics (#3290)
Implement proxy metrics collection.
Only collect metric for outbound traffic.

Add proxy CLI parameters:
- metric-collection-endpoint
- metric-collection-interval.

Add test_proxy_metric_collection test.

Move shared consumption metrics code to libs/consumption_metrics.
Refactor the code.
2023-01-16 15:17:28 +00:00
Kirill Bulatov
bce4233d3a Rework Cargo.toml dependencies (#3322)
* Use workspace variables from cargo, coming with rustc
[1.64](https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1640-2022-09-22)

See
https://doc.rust-lang.org/nightly/cargo/reference/workspaces.html#the-package-table
and
https://doc.rust-lang.org/nightly/cargo/reference/workspaces.html#the-dependencies-table
sections.

Now, all dependencies in all non-root `Cargo.toml` files are defined as 
```
clap.workspace = true
```

sometimes, when extra features are needed, as 
```
bytes = {workspace = true, features = ['serde'] }
```

With the actual declarations (with shared features and version
numbers/file paths/etc.) in the root Cargo.toml.
Features are additive:

https://doc.rust-lang.org/nightly/cargo/reference/specifying-dependencies.html#inheriting-a-dependency-from-a-workspace

* Uses the mechanism above to set common, 2021, edition and license across the
workspace

* Mechanically bumps a few dependencies

* Updates hakari format, as it suggested:
```
work/neon/neon kb/cargo-templated ❯ cargo hakari generate
info: no changes detected
info: new hakari format version available: 3 (current: 2)
(add or update `dep-format-version = "3"` in hakari.toml, then run `cargo hakari generate && cargo hakari manage-deps`)
```
2023-01-13 18:13:34 +02:00
Anastasia Lubennikova
26f39c03f2 review code cleanup:
- handle errors in calculate_synthetic_size_worker. Don't exit the bgworker if one tenant failed.

- add cached_synthetic_tenant_size to cache values calculated by the bgworker

- code cleanup: remove unneeded info! messages, clean comments

- handle collect_metrics_task() error. Don't exit collect_metrics worker if one task failed.

 - add unit test to cover case when we have multiple branches at the same lsn
2023-01-13 11:51:28 +02:00
Anastasia Lubennikova
148e020fb9 Fix logical size calculation:
sort updates in topological order so that the parent timeline always preceeds its children.
    fixes #3179
2023-01-13 11:51:28 +02:00
Anastasia Lubennikova
ba0190e3e8 Handle errors in tenant_size_model code 2023-01-13 11:51:28 +02:00
Kirill Bulatov
fe8cef3427 Use ready! rustc 1.64 macro (#3315)
rustc
[1.64](https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1640-2022-09-22)
had brought `ready!` macro:
https://doc.rust-lang.org/stable/std/task/macro.ready.html

Use it to shorten the code slightly.
2023-01-12 21:27:34 +02:00
Kirill Bulatov
8712e1899e Move initial timeline creation into pytest (#3270)
For every Python test, we start the storage first, and expect that
later, in the test, when we start a compute, it will work without
specific timeline and tenant creation or their IDs specified.

For that, we have a concept of "default" branch that was created on the
control plane level first, but that's not needed at all, given that it's
only Python tests that need it: let them create the initial timeline
during set-up.

Before, control plane started and stopped pageserver for timeline
creation, now Python harness runs an extra tenant creation request on
test env init.

I had to adjust the metrics test, turns out it registered the metrics
from the default tenant after an extra pageserver restart.
New model does not sent the metrics before the collection time happens,
and that was 30s before.
2023-01-05 17:48:27 +02:00
Kirill Bulatov
10dae79c6d Tone down safekeeper and pageserver walreceiver errors (#3227)
Closes https://github.com/neondatabase/neon/issues/3114

Adds more typization into errors that appear during protocol messages (`FeMessage`), postgres and walreceiver connections.

Socket IO errors are now better detected and logged with lesser (INFO, DEBUG) error level, without traces that they were logged before, when they were wrapped in anyhow context.
2023-01-03 20:42:04 +00:00
Vadim Kharitonov
0b428f7c41 Enable licenses check for 3rd-parties 2023-01-03 15:11:50 +01:00
Heikki Linnakangas
0a0e55c3d0 Replace 'tar' crate with 'tokio-tar' (#3202)
The synchronous 'tar' crate has required us to use block_in_place and
SyncIoBridge to work together with the async I/O in the client
connection. Switch to 'tokio-tar' crate that uses async I/O natively.

As part of this, move the CopyDataWriter implementation to
postgres_backend_async.rs. Even though it's only used in one place
currently, it's in principle generally applicable whenever you want to
use COPY out.

Unfortunately we cannot use the 'tokio-tar' as it is: the Builder
implementation requires the writer to have 'static lifetime. So we
have to use a modified version without that requirement. The 'static
lifetime was required just for the Drop implementation that writes
the end-of-archive sections if the Builder is dropped without calling
`finish`. But we don't actually want that behavior anyway; in fact
we had to jump through some hoops with the AbortableWrite hack to skip
those. With the modified version of 'tokio-tar' without that Drop
implementation, we don't need AbortableWrite either.

Co-authored-by: Kirill Bulatov <kirill@neon.tech>
2023-01-03 12:39:11 +02:00
Kirill Bulatov
a9cca7a0fd Use proper error code for BeMessage error responses (#3240)
Based on
https://github.com/neondatabase/neon/pull/3227#discussion_r1059430067

Seems that the constant, used for internal error during BeMessage error
response serialization is incorrect.
Currently used one is `CXX000`, yet all docs mention `XX000` instead:

* https://www.postgresql.org/docs/current/errcodes-appendix.html
* https://docs.rs/postgres/latest/postgres/error/struct.SqlState.html#associatedconstant.INTERNAL_ERROR

I have checked it with the patch and logs described in
https://github.com/neondatabase/neon/pull/3227#discussion_r1059949982
2023-01-02 16:51:05 +02:00
Arseny Sher
41b8e67305 Fix 81afd7011 by enabling reqwest feature for sentry.
It disabled transport altogether.
2023-01-02 15:29:33 +03:00
Heikki Linnakangas
81afd7011c Use rustls for everything.
I looked at "cargo tree" output and noticed that through various
dependencies, we are depending on both native-tls and rustls. We have
tried to standardize on rustls for everything, but dependencies on
native-tls have crept in recently. One such dependency came from
'reqwest' with default features in pageserver, used for
consumption_metrics. Another dependency was from 'sentry'. Both
'reqwest' and 'sentry' use native-tls by default, but can use 'rustls'
if compiled with the right feature flags.
2023-01-02 11:14:35 +02:00
Egor Suvorov
9f94d098aa Remove unused AuthType::MD5 2022-12-31 02:27:08 +03:00
Kirill Bulatov
fca25edae8 Fix 1.66 Clippy warnings (#3178)
1.66 release speeds up compile times for over 10% according to tests.

Also its Clippy finds plenty of old nits in our code:
* useless conversion, `foo as u8` where `foo: u8` and similar, removed
`as u8` and similar
* useless references and dereferenced (that were automatically adjusted
by the compiler), removed various `&` and `*`
* bool -> u8 conversion via `if/else`, changed to `u8::from`
* Map `.iter()` calls where only values were used, changed to
`.values()` instead

Standing out lints:
* `Eq` is missing in our protoc generated structs. Silenced, does not
seem crucial for us.
* `fn default` looks like the one from `Default` trait, so I've
implemented that instead and replaced the `dummy_*` method in tests with
`::default()` invocation
* Clippy detected that
```
if retry_attempt < u32::MAX {
    retry_attempt += 1;
}
```
is a saturating add and proposed to replace it.
2022-12-22 14:27:48 +02:00
Heikki Linnakangas
7ff591ffbf On-Demand Download
The code in this change was extracted from #2595 (Heikki’s on-demand
download draft PR).

High-Level Changes

- New RemoteLayer Type
- On-Demand Download As An Effect Of Page Reconstruction
- Breaking Semantics For Physical Size Metrics

There are several follow-up work items planned.
Refer to the Epic issue on GitHub: https://github.com/neondatabase/neon/issues/2029

closes https://github.com/neondatabase/neon/pull/3013

Co-authored-by: Kirill Bulatov <kirill@neon.tech>
Co-authored-by: Christian Schwarz <christian@neon.tech>

New RemoteLayer Type
====================

Instead of downloading all layers during tenant attach, we create
RemoteLayer instances for each of them and add them to the layer map.

On-Demand Download As An Effect Of Page Reconstruction
======================================================

At the heart of pageserver is Timeline::get_reconstruct_data(). It
traverses the layer map until it has collected all the data it needs to
produce the page image. Most code in the code base uses it, though many
layers of indirection.

Before this patch, the function would use synchronous filesystem IO to
load data from disk-resident layer files if the data was not cached.

That is not possible with RemoteLayer, because the layer file has not
been downloaded yet. So, we do the download when get_reconstruct_data
gets there, i.e., “on demand”.

The mechanics of how the download is done are rather involved, because
of the infamous async-sync-async sandwich problem that plagues the async
Rust world. We use the new PageReconstructResult type to work around
this. Its introduction is the cause for a good amount of code churn in
this patch. Refer to the block comment on `with_ondemand_download()`
for details.

Breaking Semantics For Physical Size Metrics
============================================

We rename prometheus metric pageserver_{current,resident}_physical_size to
reflect what this metric actually represents with on-demand download.
This intentionally BREAKS existing grafana dashboard and the cost model data
pipeline. Breaking is desirable because the meaning of this metrics has changed
with on-demand download. See
 https://docs.google.com/document/d/12AFpvKY-7FZdR5a4CaD6Ir_rI3QokdCLSPJ6upHxJBo/edit#
for how we will handle this breakage.

Likewise, we rename the new billing_metrics’s PhysicalSize => ResidentSize.
This is not yet used anywhere, so, this is not a breaking change.

There is still a field called TimelineInfo::current_physical_size. It
is now the sum of the layer sizes in layer map, regardless of whether
local or remote. To compute that sum, we added a new trait method
PersistentLayer::file_size().

When updating the Python tests, we got rid of
current_physical_size_non_incremental. An earlier commit removed it from
the OpenAPI spec already, so this is not a breaking change.

test_timeline_size.py has grown additional assertions on the
resident_physical_size metric.
2022-12-21 19:16:39 +01:00
Heikki Linnakangas
8e2edfcf39 Retry remote downloads.
Remote operations fail sometimes due to network failures or other
external reasons. Add retry logic to all the remote downloads, so that
a transient failure at pageserver startup or tenant attach doesn't
cause the whole tenant to be marked as Broken.

Like in the uploads retry logic, we print the failure to the log as a
WARNing after three retries, but keep retrying. We will retry up to 10
times now, before returning the error to the caller.

To test the retries, I created a new RemoteStorage wrapper that simulates
failures, by returning an error for the first N times that a remote
operation is performed. It can be enabled by setting a new
"test_remote_failures" option in the pageserver config file.

Fixes #3112
2022-12-20 14:27:24 +02:00