## Problem
Follows on from #5299
- We didn't have a generic way to protect a tenant undergoing changes:
`Tenant` had states, but for our arbitrary transitions between
secondary/attached, we need a general way to say "reserve this tenant
ID, and don't allow any other ops on it, but don't try and report it as
being in any particular state".
- The TenantsMap structure was behind an async RwLock, but it was never
correct to hold it across await points: that would block any other
changes for all tenants.
## Summary of changes
- Add the `TenantSlot::InProgress` value. This means:
- Incoming administrative operations on the tenant should retry later
- Anything trying to read the live state of the tenant (e.g. a page
service reader) should retry later or block.
- Store TenantsMap in `std::sync::RwLock`
- Provide an extended `get_active_tenant_with_timeout` for page_service
to use, which will wait on InProgress slots as well as non-active
tenants.
Closes: https://github.com/neondatabase/neon/issues/5378
---------
Co-authored-by: Christian Schwarz <christian@neon.tech>
## Problem
When shutting down a Tenant, it isn't just important to cause any
background tasks to stop. It's also important to wait until they have
stopped before declaring shutdown complete, in cases where we may re-use
the tenant's local storage for something else, such as running in
secondary mode, or creating a new tenant with the same ID.
## Summary of changes
A `Gate` class is added, inspired by
[seastar::gate](https://docs.seastar.io/master/classseastar_1_1gate.html).
For types that have an important lifetime that corresponds to some
physical resource, use of a Gate as well as a CancellationToken provides
a robust pattern for async requests & shutdown:
- Requests must always acquire the gate as long as they are using the
object
- Shutdown must set the cancellation token, and then `close()` the gate
to wait for requests in progress before returning.
This is not for memory safety: it's for expressing the difference
between "Arc<Tenant> exists", and "This tenant's files on disk are
eligible to be read/written".
- Both Tenant and Timeline get a Gate & CancellationToken.
- The Timeline gate is held during eviction of layers, and during
page_service requests.
- Existing cancellation support in page_service is refined to use the
timeline-scope cancellation token instead of a process-scope
cancellation token. This replaces the use of `task_mgr::associate_with`:
tasks no longer change their tenant/timelineidentity after being
spawned.
The Tenant's Gate is not yet used, but will be important for
Tenant-scoped operations in secondary mode, where we must ensure that
our secondary-mode downloads for a tenant are gated wrt the activity of
an attached Tenant.
This is part of a broader move away from using the global-state driven
`task_mgr` shutdown tokens:
- less global state where we rely on implicit knowledge of what task a
given function is running in, and more explicit references to the
cancellation token that a particular function/type will respect, making
shutdown easier to reason about.
- eventually avoid the big global TASKS mutex.
---------
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
Improve the serde impl for several types (`Lsn`, `TenantId`,
`TimelineId`) by making them sensitive to
`Serializer::is_human_readadable` (true for json, false for bincode).
Fixes#3511 by:
- Implement the custom serde for `Lsn`
- Implement the custom serde for `Id`
- Add the helper module `serde_as_u64` in `libs/utils/src/lsn.rs`
- Remove the unnecessary attr `#[serde_as(as = "DisplayFromStr")]` in
all possible structs
Additionally some safekeeper types gained serde tests.
---------
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
Implement a new `struct Layer` abstraction which manages downloadness
internally, requiring no LayerMap locking or rewriting to download or
evict providing a property "you have a layer, you can read it". The new
`struct Layer` provides ability to keep the file resident via a RAII
structure for new layers which still need to be uploaded. Previous
solution solved this `RemoteTimelineClient::wait_completion` which lead
to bugs like #5639. Evicting or the final local deletion after garbage
collection is done using Arc'd value `Drop`.
With a single `struct Layer` the closed open ended `trait Layer`, `trait
PersistentLayer` and `struct RemoteLayer` are removed following noting
that compaction could be simplified by simply not using any of the
traits in between: #4839.
The new `struct Layer` is a preliminary to remove
`Timeline::layer_removal_cs` documented in #4745.
Preliminaries: #4936, #4937, #5013, #5014, #5022, #5033, #5044, #5058,
#5059, #5061, #5074, #5103, epic #5172, #5645, #5649. Related split off:
#5057, #5134.
This does two things: first a minor refactor to not use HTTP/1.x
style header names and also to not panic if some certain requests had no
"Accept" header. As a second thing, it addresses the third bullet point
from #3689:
> Change `get_lsn_by_timestamp` API method to return LSN even if we only
found commit before the specified timestamp.
This is done by adding a version parameter to the `get_lsn_by_timestamp`
API call and making its behaviour depend on the version number.
Part of #3414 (but doesn't address it in its entirety).
---------
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
## Problem
See #5468.
## Summary of changes
Add a new `get_timestamp_of_lsn` endpoint, returning the timestamp
associated with the given lsn.
Fixes#5468.
---------
Co-authored-by: Shany Pozin <shany@neon.tech>
## Problem
I found some issues with the `/location_config` API when writing new
tests.
## Summary of changes
- Calling the API with the "Detached" state is now idempotent.
- `Tenant::spawn_attach` now takes a boolean to indicate whether to
expect a marker file. Marker files are used in the old attach path, but
not in the new location conf API. They aren't needed because in the New
World, the choice of whether to attach via remote state ("attach") or to
trust local state ("load") will be revised to cope with the transitions
between secondary & attached (see
https://github.com/neondatabase/neon/issues/5550). It is okay to merge
this change ahead of that ticket, because the API is not used in the
wild yet.
- Instead of using `schedule_local_tenant_processing`, the location conf
API handler does its own directory creation and calls `spawn_attach`
directly.
- A new `unsafe_create_dir_all` is added. This differs from
crashsafe::create_dir_all in two ways:
- It is intentionally not crashsafe, because in the location conf API we
are no longer using directory or config existence as the signal for any
important business logic.
- It is async and uses `tokio::fs`.
For 2 weeks we've seen rare, spurious, not-reproducible page
reconstruction
failures with PG16 in prod.
One of the commits we deployed this week was
Commit
commit fc467941f9
Author: Joonas Koivunen <joonas@neon.tech>
Date: Wed Oct 4 16:19:19 2023 +0300
walredo: log retryed error (#546)
With the logs from that commit, we learned that some read() or write()
system call that walredo does fails with `EAGAIN`, aka
`Resource temporarily unavailable (os error 11)`.
But we have no idea where exactly in the code we get back that error.
So, use anyhow instead of fake std::io::Error's as an easy way to get
a backtrace when the error happens, and change the logging to print
that backtrace (i.e., use `{:?}` instead of
`utils::error::report_compact_sources(e)`).
The `WalRedoError` type had to go because we add additional `.context()`
further up the call chain before we `{:?}`-print it. That additional
`.context()` further up doesn't see that there's already an
anyhow::Error
inside the `WalRedoError::ApplyWalRecords` variant, and hence captures
another backtrace and prints that one on `{:?}`-print instead of the
original one inside `WalRedoError::ApplyWalRecords`.
If we ever switch back to `report_compact_sources`, we should make sure
we have some other way to uniquely identify the places where we return
an error in the error message.
## Problem
These types/functions are public and it prevents clippy from catching
unused things.
## Summary of changes
Move to `pub(crate)` and remove the error enum that becomes clearly
unused as a result.
## Problem
If a caller detaches a tenant and then attaches it again, pending
deletions from the old attachment might not have happened yet. This is
not a correctness problem, but it causes:
- Risk of leaking some objects in S3
- Some warnings from the deletion queue when pending LSN updates and
pending deletions don't pass validation.
## Summary of changes
- Deletion queue now uses UnboundedChannel so that the push interfaces
don't have to be async.
- This was pulled out of https://github.com/neondatabase/neon/pull/5397,
where it is also useful to be able to drive the queue from non-async
contexts.
- Why is it okay for this to be unbounded? The only way the
unbounded-ness of the channel can become a problem is if writing out
deletion lists can't keep up, but if the system were that overloaded
then the code generating deletions (GC, compaction) would also be
impacted.
- DeletionQueueClient gets a new `flush_advisory` function, which is
like flush_execute, but doesn't wait for completion: this is appropriate
for use in contexts where we would like to encourage the deletion queue
to flush, but don't need to block on it.
- This function is also expected to be useful in next steps for seamless
migration, where the option to flush to S3 while transitioning into
AttachedStale will also include flushing deletion queue, but we wouldn't
want to block on that flush.
- The tenant_detach code in mgr.rs invokes flush_advisory after stopping
the `Tenant` object.
---------
Co-authored-by: Arpad Müller <arpad-m@users.noreply.github.com>
Part of #5172. First commits show that we used to allow starting up a
compute or creating a branch off a not yet uploaded timeline. This PR
moves activation of a timeline to happen **after** initial layer file(s)
(if any) and `index_part.json` have been uploaded. Simply moving
activation to be *after* downloads have finished works because we now
spawn a task per http request handler.
Current behaviour of uploading on the timelines on next startup is kept,
to be removed later as part of #5172.
Adds:
- `NeonCli.map_branch` and corresponding `neon_local` implementation:
allow creating computes for timelines managed via pageserver http
client/api
- possibly duplicate tests (I did not want to search for, will cleanup
in a follow-up if these duplicated)
Changes:
- make `wait_until_tenant_state` return immediatedly on `Broken` and not
wait more
If there are any layermap or layer file related problems, having a
reproducable `get_page@lsn` easily usable for fast debugging iteration
is helpful.
Split off from #4938.
Later evolved to add http apis for:
- `get_page@lsn` at
`/v1/tenant/:tenant_id/timeline/:timeline_id/get?key=<hex>&lsn=<lsn
string>`
- collecting the keyspace at
`/v1/tenant/:tenant_id/timeline/:timeline_id/keyspace?[at_lsn=<lsn
string>]`
- defaults to `last_record_lsn`
collecting the keyspace seems to yield some ranges for which there is no
key.
503 Resource Unavailable appears as error in logs, but is not really an
error which should ever fail a test on, or even log an error in prod,
[evidence].
Changes:
- log 503 as `info!` level
- use `Cow<'static, str>` instead of `String`
- add an additional `wait_until_tenant_active` in
`test_actually_duplicate_l1`
We ought to have in tests "wait for tenants to complete loading" but
this is easier to implement for now.
[evidence]:
https://neon-github-public-dev.s3.amazonaws.com/reports/pr-5485/6423110295/index.html#/testresult/182de66203864fc0
## Problem
These changes are part of building seamless tenant migration, as
described in the RFC:
- https://github.com/neondatabase/neon/pull/5029
## Summary of changes
- A new configuration type `LocationConf` supersedes `TenantConfOpt` for
storing a tenant's configuration in the pageserver repo dir. It contains
`TenantConfOpt`, as well as a new `mode` attribute that describes what
kind of location this is (secondary, attached, attachment mode etc). It
is written to a file called `config-v1` instead of `config` -- this
prepares us for neatly making any other profound changes to the format
of the file in future. Forward compat for existing pageserver code is
achieved by writing out both old and new style files. Backward compat is
achieved by checking for the old-style file if the new one isn't found.
- The `TenantMap` type changes, to hold `TenantSlot` instead of just
`Tenant`. The `Tenant` type continues to be used for attached tenants
only. Tenants in other states (such as secondaries) are represented by a
different variant of `TenantSlot`.
- Where `Tenant` & `Timeline` used to hold an Arc<Mutex<TenantConfOpt>>,
they now hold a reference to a AttachedTenantConf, which includes the
extra information from LocationConf. This enables them to know the
current attachment mode.
- The attachment mode is used as an advisory input to decide whether to
do compaction and GC (AttachedStale is meant to avoid doing uploads,
AttachedMulti is meant to avoid doing deletions).
- A new HTTP API is added at `PUT /tenants/<tenant_id>/location_config`
to drive new location configuration. This provides a superset of the
functionality of attach/detach/load/ignore:
- Attaching a tenant is just configuring it in an attached state
- Detaching a tenant is configuring it to a detached state
- Loading a tenant is just the same as attaching it
- Ignoring a tenant is the same as configuring it into Secondary with
warm=false (i.e. retain the files on disk but do nothing else).
Caveats:
- AttachedMulti tenants don't do compaction in this PR, but they do in
the follow on #5397
- Concurrent updates to the `location_config` API are not handled
elegantly in this PR, a better mechanism is added in the follow on
https://github.com/neondatabase/neon/pull/5367
- Secondary mode is just a placeholder in this PR: the code to upload
heatmaps and do downloads on secondary locations will be added in a
later PR (but that shouldn't change any external interfaces)
Closes: https://github.com/neondatabase/neon/issues/5379
---------
Co-authored-by: Christian Schwarz <christian@neon.tech>
## Problem
The 500 status code should only be used for bugs or unrecoverable
failures: situations we did not expect. Currently, the pageserver is
misusing this response code for some situations that are totally normal,
like requests targeting tenants that are in the process of activating.
The 503 response is a convenient catch-all for "I can't right now, but I
will be able to".
## Summary of changes
- Change some transient availability error conditions to return 503
instead of 500
- Update the HTTP client configuration in integration tests to retry on
503
After these changes, things like creating a tenant and then trying to
create a timeline within it will no longer require carefully checking
its status first, or retrying on 500s. Instead, a client which is
properly configured to retry on 503 can quietly handle such situations.
## Problem
Pageservers must not delete objects or advertise updates to
remote_consistent_lsn without checking that they hold the latest
generation for the tenant in question (see [the RFC](
https://github.com/neondatabase/neon/blob/main/docs/rfcs/025-generation-numbers.md))
In this PR:
- A new "deletion queue" subsystem is introduced, through which
deletions flow
- `RemoteTimelineClient` is modified to send deletions through the
deletion queue:
- For GC & compaction, deletions flow through the full generation
verifying process
- For timeline deletions, deletions take a fast path that bypasses
generation verification
- The `last_uploaded_consistent_lsn` value in `UploadQueue` is replaced
with a mechanism that maintains a "projected" lsn (equivalent to the
previous property), and a "visible" LSN (which is the one that we may
share with safekeepers).
- Until `control_plane_api` is set, all deletions skip generation
validation
- Tests are introduced for the new functionality in
`test_pageserver_generations.py`
Once this lands, if a pageserver is configured with the
`control_plane_api` configuration added in
https://github.com/neondatabase/neon/pull/5163, it becomes safe to
attach a tenant to multiple pageservers concurrently.
---------
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
Co-authored-by: Christian Schwarz <christian@neon.tech>
Add a `walreceiver_state` field to `TimelineInfo` (response of `GET /v1/tenant/:tenant_id/timeline/:timeline_id`) and while doing that, refactor out a common `Timeline::walreceiver_state(..)`. No OpenAPI changes, because this is an internal debugging addition.
Fixes#3115.
Co-authored-by: Joonas Koivunen <joonas.koivunen@gmail.com>
## Problem
- #5050
Closes: https://github.com/neondatabase/neon/issues/5136
## Summary of changes
- A new configuration property `control_plane_api` controls other
functionality in this PR: if it is unset (default) then everything still
works as it does today.
- If `control_plane_api` is set, then on startup we call out to control
plane `/re-attach` endpoint to discover our attachments and their
generations. If an attachment is missing from the response we implicitly
detach the tenant.
- Calls to pageserver `/attach` API may include a `generation`
parameter. If `control_plane_api` is set, then this parameter is
mandatory.
- RemoteTimelineClient's loading of index_part.json is generation-aware,
and will try to load the index_part with the most recent generation <=
its own generation.
- The `neon_local` testing environment now includes a new binary
`attachment_service` which implements the endpoints that the pageserver
requires to operate. This is on by default if running `cargo neon` by
hand. In `test_runner/` tests, it is off by default: existing tests
continue to run with in the legacy generation-less mode.
Caveats:
- The re-attachment during startup assumes that we are only re-attaching
tenants that have previously been attached, and not totally new tenants
-- this relies on the control plane's attachment logic to keep retrying
so that we should eventually see the attach API call. That's important
because the `/re-attach` API doesn't tell us which timelines we should
attach -- we still use local disk state for that. Ref:
https://github.com/neondatabase/neon/issues/5173
- Testing: generations are only enabled for one integration test right
now (test_pageserver_restart), as a smoke test that all the machinery
basically works. Writing fuller tests that stress tenant migration will
come later, and involve extending our test fixtures to deal with
multiple pageservers.
- I'm not in love with "attachment_service" as a name for the neon_local
component, but it's not very important because we can easily rename
these test bits whenever we want.
- Limited observability when in re-attach on startup: when I add
generation validation for deletions in a later PR, I want to wrap up the
control plane API calls in some small client class that will expose
metrics for things like errors calling the control plane API, which will
act as a strong red signal that something is not right.
Co-authored-by: Christian Schwarz <christian@neon.tech>
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
- move them to pageserver which is the only dependant on the crate fail
- "move" the exported macro to the new module
- support at init time the same failpoints as runtime
Found while debugging test failures and making tests more repeatable by
allowing "exit" from pageserver start via environment variables. Made
those changes to `test_gc_cutoff.py`.
---------
Co-authored-by: Christian Schwarz <christian@neon.tech>
## Problem
`cargo +nightly doc` is giving a lot of warnings: broken links, naked
URLs, etc.
## Summary of changes
* update the `proc-macro2` dependency so that it can compile on latest
Rust nightly, see https://github.com/dtolnay/proc-macro2/pull/391 and
https://github.com/dtolnay/proc-macro2/issues/398
* allow the `private_intra_doc_links` lint, as linking to something
that's private is always more useful than just mentioning it without a
link: if the link breaks in the future, at least there is a warning due
to that. Also, one might enable
[`--document-private-items`](https://doc.rust-lang.org/cargo/commands/cargo-doc.html#documentation-options)
in the future and make these links work in general.
* fix all the remaining warnings given by `cargo +nightly doc`
* make it possible to run `cargo doc` on stable Rust by updating
`opentelemetry` and associated crates to version 0.19, pulling in a fix
that previously broke `cargo doc` on stable:
https://github.com/open-telemetry/opentelemetry-rust/pull/904
* Add `cargo doc` to CI to ensure that it won't get broken in the
future.
Fixes#2557
## Future work
* Potentially, it might make sense, for development purposes, to publish
the generated rustdocs somewhere, like for example [how the rust
compiler does
it](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_driver/index.html).
I will file an issue for discussion.
## Problem
Lets keep 500 for unusual stuff that is not considered normal. Came up
during one of the discussions around console logs now seeing this 500's.
## Summary of changes
- Return 409 Conflict instead of 500
- Remove 200 ok status because it is not used anymore
The consumption metrics synthetic size worker does logical size
calculation. Logical size calculation currently does synchronous disk
IO. This blocks the MGMT_REQUEST_RUNTIME's executor threads, starving
other futures.
While there's work on the way to move the synchronous disk IO into
spawn_blocking, the quickfix here is to use the BACKGROUND_RUNTIME
instead of MGMT_REQUEST_RUNTIME.
Actually it's not just a quickfix. We simply shouldn't be blocking
MGMT_REQUEST_RUNTIME executor threads on CPU or sync disk IO.
That work isn't done yet, as many of the mgmt tasks still _do_ disk IO.
But it's not as intensive as the logical size calculations that we're
fixing here.
While we're at it, fix disk-usage-based eviction in a similar way. It
wasn't the culprit here, according to prod logs, but it can
theoretically be a little CPU-intensive.
More context, including graphs from Prod:
https://neondb.slack.com/archives/C03F5SM1N02/p1687541681336949
## Problem
During timeline creation we create special mark file which presense
indicates that initialization didnt complete successfully. In case of a
crash restart we can remove such half-initialized timeline and following
retry from control plane side should perform another attempt.
So in case of a possible crash restart during initial loading we have
following picture:
```
timelines
| - <timeline_id>___uninit
| - <timeline_id>
| - | <timeline files>
```
We call `std::fs::read_dir` to walk files in `timelines` directory one
by one. If we see uninit file
we proceed with deletion of both, timeline directory and uninit file. If
we see timeline we check if uninit file exists and do the same cleanup.
But in fact its possible to get both branches to be true at the same
time. Result of readdir doesnt reflect following directory state
modifications. So you can still get "valid" entry on the next iteration
of the loop despite the fact that it was deleted in one of the previous
iterations of the loop.
To see that you can apply the following patch (it disables uninit mark
cleanup on successful timeline creation):
```diff
diff --git a/pageserver/src/tenant.rs b/pageserver/src/tenant.rs
index 4beb2664..b3cdad8f 100644
--- a/pageserver/src/tenant.rs
+++ b/pageserver/src/tenant.rs
@@ -224,11 +224,6 @@ impl UninitializedTimeline<'_> {
)
})?;
}
- uninit_mark.remove_uninit_mark().with_context(|| {
- format!(
- "Failed to remove uninit mark file for timeline {tenant_id}/{timeline_id}"
- )
- })?;
v.insert(Arc::clone(&new_timeline));
new_timeline.maybe_spawn_flush_loop();
```
And perform the following steps:
```bash
neon_local init
neon_local start
neon_local tenant create
neon_local stop
neon_local start
```
The error is:
```log
INFO load{tenant_id=X}:blocking: Found an uninit mark file .neon/tenants/X/timelines/Y.___uninit, removing the timeline and its uninit mark
2023-06-09T18:43:41.664247Z ERROR load{tenant_id=X}: load failed, setting tenant state to Broken: failed to load metadata
Caused by:
0: Failed to read metadata bytes from path .neon/tenants/X/timelines/Y/metadata
1: No such file or directory (os error 2)
```
So uninit mark got deleted together with timeline directory but we still
got directory entry for it and tried to load it.
The bug prevented tenant from being successfully loaded.
## Summary of changes
Ideally I think we shouldnt place uninit marks in the same directory as timeline directories but move them to separate directory and
gather them as an input to actual listing, but that would be sort of an
on-disk format change, so just check whether entries are still valid
before operating on them.
This is preliminary work for/from #4220 (async `Layer::get_value_reconstruct_data`).
# Full Stack Of Preliminary PRs
Thanks to the countless preliminary PRs, this conversion is relatively
straight-forward.
1. Clean-ups
* https://github.com/neondatabase/neon/pull/4316
* https://github.com/neondatabase/neon/pull/4317
* https://github.com/neondatabase/neon/pull/4318
* https://github.com/neondatabase/neon/pull/4319
* https://github.com/neondatabase/neon/pull/4321
* Note: these were mostly to find an alternative to #4291, which I
thought we'd need in my original plan where we would need to convert
`Tenant::timelines` into an async locking primitive (#4333). In reviews,
we walked away from that, but these cleanups were still quite useful.
2. https://github.com/neondatabase/neon/pull/4364
3. https://github.com/neondatabase/neon/pull/4472
4. https://github.com/neondatabase/neon/pull/4476
5. https://github.com/neondatabase/neon/pull/4477
6. https://github.com/neondatabase/neon/pull/4485
# Significant Changes In This PR
## `compact_level0_phase1` & `create_delta_layer`
This commit partially reverts
"pgserver: spawn_blocking in compaction (#4265)"
4e359db4c7.
Specifically, it reverts the `spawn_blocking`-ificiation of
`compact_level0_phase1`.
If we didn't revert it, we'd have to use `Timeline::layers.blocking_read()`
inside `compact_level0_phase1`. That would use up a thread in the
`spawn_blocking` thread pool, which is hard-capped.
I considered wrapping the code that follows the second
`layers.read().await` into `spawn_blocking`, but there are lifetime
issues with `deltas_to_compact`.
Also, this PR switches the `create_delta_layer` _function_ back to
async, and uses `spawn_blocking` inside to run the code that does sync
IO, while keeping the code that needs to lock `Timeline::layers` async.
## `LayerIter` and `LayerKeyIter` `Send` bounds
I had to add a `Send` bound on the `dyn` type that `LayerIter`
and `LayerKeyIter` wrap. Why? Because we now have the second
`layers.read().await` inside `compact_level0_phase`, and these
iterator instances are held across that await-point.
More background:
https://github.com/neondatabase/neon/pull/4462#issuecomment-1587376960
## `DatadirModification::flush`
Needed to replace the `HashMap::retain` with a hand-rolled variant
because `TimelineWriter::put` is now async.
Delete data from s3 when timeline deletion is requested
## Summary of changes
UploadQueue is altered to support scheduling of delete operations in
stopped state. This looks weird, and I'm thinking whether there are
better options/refactorings for upload client to make it look better.
Probably can be part of https://github.com/neondatabase/neon/issues/4378
Deletion is implemented directly in existing endpoint because changes are not
that significant. If we want more safety we can separate those or create
feature flag for new behavior.
resolves [#4193](https://github.com/neondatabase/neon/issues/4193)
---------
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
## Problem
Attach failures are not reported in public part of the api (in
`attachment_status` field of TenantInfo).
## Summary of changes
Expose TenantState::Broken as TenantAttachmentStatus::Failed
In the way its written Failed status will be reported even if no
attachment happened. (I e if tenant become broken on startup). This is
in line with other members. I e Active will be resolved to Attached even
if no actual attach took place.
This can be tweaked if needed. At the current stage it would be overengineering without clear motivation
resolves#4344
We now spawn a new task for every HTTP request, and wait on the
JoinHandle. If Hyper drops the Future, the spawned task will keep
running. This protects the rest of the pageserver code from unexpected
async cancellations.
This creates a CancellationToken for each request and passes it to the
handler function. If the HTTP request is dropped by the client, the
CancellationToken is signaled. None of the handler functions make use
for the CancellationToken currently, but they now they could.
The CancellationToken arguments also work like documentation. When
you're looking at a function signature and you see that it takes a
CancellationToken as argument, it's a nice hint that the function might
run for a long time, and won't be async cancelled. The default
assumption in the pageserver is now that async functions are not
cancellation-safe anyway, unless explictly marked as such, but this is a
nice extra reminder.
Spawning a task for each request is OK from a performance point of view
because spawning is very cheap in Tokio, and none of our HTTP requests
are very performance critical anyway.
Fixes issue #3478
This is preliminary work for/from #4220 (async
`Layer::get_value_reconstruct_data`).
The motivation is to avoid locking `Tenant::timelines` in places that
can't be `async`, because in #4333 we want to convert Tenant::timelines
from `std::sync::Mutex` to `tokio::sync::Mutex`.
But, the changes here are useful in general because they clean up &
document tenant state transitions.
That also paves the way for #4350, which is an alternative to #4333 that
refactors the pageserver code so that we can keep the
`Tenant::timelines` mutex sync.
This patch consists of the following core insights and changes:
* spawn_load and spawn_attach own the tenant state until they're done
* once load()/attach() calls are done ...
* if they failed, transition them to Broken directly (we know that
there's no background activity because we didn't call activate yet)
* if they succeed, call activate. We can make it infallible. How? Later.
* set_broken() and set_stopping() are changed to wait for spawn_load() /
spawn_attach() to finish.
* This sounds scary because it might hinder detach or shutdown, but
actually, concurrent attach+detach, or attach+shutdown, or
load+shutdown, or attach+shutdown were just racy before this PR.
So, with this change, they're not anymore.
In the future, we can add a `CancellationToken` stored in Tenant to
cancel `load` and `attach` faster, i.e., make `spawn_load` /
`spawn_attach` transition them to Broken state sooner.
See the doc comments on TenantState for the state transitions that are
now possible.
It might seem scary, but actually, this patch reduces the possible state
transitions.
We introduce a new state `TenantState::Activating` to avoid grabbing the
`Tenant::timelines` lock inside the `send_modify` closure.
These were the humble beginnings of this PR (see Motivation section),
and I think it's still the right thing to have this `Activating` state,
even if we decide against async `Tenant::timelines` mutex. The reason is
that `send_modify` locks internally, and by moving locking of
Tenant::timelines out of the closure, the internal locking of
`send_modify` becomes a leaf of the lock graph, and so, we eliminate
deadlock risk.
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
Previously, you used it like this:
|r| RequestSpan(my_handler).handle(r)
But I don't see the point of the RequestSpan struct. It's just a
wrapper around the handler function. With this commit, the call
becomes:
|r| request_span(r, my_handler)
Which seems a little simpler.
At first I thought that the RequestSpan struct would allow "chaining"
other kinds of decorators like RequestSpan, so that you could do
something like this:
|r| CheckPermissions(RequestSpan(my_handler)).handle(r)
But it doesn't work like that. If each of those structs wrap a handler
*function*, it would actually look like this:
|r| CheckPermissions(|r| RequestSpan(my_handler).handle(r))).handle(r)
This commit doesn't make that kind of chaining any easier, but seems a
little more straightforward anyway.
We used to generate the ID, if the caller didn't specify it. That's bad
practice, however, because network is never fully reliable, so it's
possible we create a new tenant but the caller doesn't know about it,
and because it doesn't know the tenant ID, it has no way of retrying or
checking if it succeeded. To discourage that, make it mandatory. The web
control plane has not relied on the auto-generation for a long time.
(This is prep work to make `Timeline::activate` infallible.)
This patch removes the global storage_broker client instance from the
pageserver codebase.
Instead, pageserver startup instantiates it and passes it down to the
`Timeline::activate` function, which in turn passes it to the
WalReceiver, which is the entity that actually uses it.
Patch series:
- #4316
- #4317
- #4318
- #4319
Before this patch, it would use error type `TenantStateError` which has
many more error variants than can actually happen with
`mgr::get_tenant`.
Along the way, I also introduced `SetNewTenantConfigError` because it
uses `mgr::get_tenant` and also can only fail in much fewer ways than
`TenantStateError` suggests.
The new `page_service.rs`'s `GetActiveTimelineError` and
`GetActiveTenantError` types were necessary to avoid an `Other` variant
on the `GetTenantError`.
This patch is a by-product of reading code that subscribes to
`Tenant::state` changes.
Can't really connect it to any given project.
This PR enforces that the tenant create / update-config APIs reject
requests with unknown fields.
This is a desirable property because some tenant config settings control
the lifetime of user data (e.g., GC horizon or PITR interval).
Suppose we inadvertently rename the `pitr_interval` field in the Rust
code.
Then, right now, a client that still uses the old name will send a
tenant config request to configure a new PITR interval.
Before this PR, we would accept such a request, ignore the old name
field, and use the pageserver.toml default value for what the new PITR
interval is.
With this PR, we will instead reject such a request.
One might argue that the client could simply check whether the config it
sent has been applied, using the `/v1/tenant/.../config` endpoint.
That is correct for tenant create and update-config.
But, attach will soon [^1] grow the ability to have attach-time config
as well.
If we ignore unknown fields and fall back to global defaults in that
case, we risk data loss.
Example:
1. Default PITR in pageservers is 7 days.
2. Create a tenant and set its PITR to 30 days.
3. For 30 days, fill the tenant continuously with data.
4. Detach the tenant.
5. Attach tenant.
Attach must use the 30-day PITR setting in this scenario.
If it were to fall back to the 7-day default value, we would lose 23
days of PITR capability for the tenant.
So, the PR that adds attach-time tenant config will build on the
(clunky) infrastructure added in this PR
[^1]: https://github.com/neondatabase/neon/pull/4255
Implementation Notes
====================
This could have been a simple `#[serde(deny_unknown_fields)]` but sadly,
that is documented- but silent-at-compile-time-incompatible with
`#[serde(flatten)]`. But we are still using this by adding on outer struct and use unit tests to ensure it is correct.
`neon_local tenant config` now uses the `.remove()` pattern + bail if
there are leftover config args. That's in line with what
`neon_local tenant create` does. We should dedupe that logic in a future
PR.
---------
Signed-off-by: Alex Chi <iskyzh@gmail.com>
Co-authored-by: Alex Chi <iskyzh@gmail.com>
This is prep for https://github.com/neondatabase/neon/pull/4255
[1/X] OpenAPI: share a single definition of TenantConfig
DRYs up the pageserver OpenAPI YAML's representation of
tenant config.
All the fields of tenant config are now located in a model schema
called TenantConfig.
The tenant create & config-change endpoints have separate schemas,
TenantCreateInfo and TenantConfigureArg, respectively.
These schemas inherit from TenantConfig, using allOf 1.
The tenant config-GET handler's response was previously named
TenantConfig.
It's now named TenantConfigResponse.
None of these changes affect how the request looks on the wire.
The generated Go code will change for Console because the OpenAPI code
generator maps `allOf` to a Go struct embedding.
Luckily, usage of tenant config in Console is still very lightweigt,
but that will change in the near future.
So, this is a good chance to set things straight.
The console changes are tracked in
https://github.com/neondatabase/cloud/pull/5046
[2/x]: extract the tenant config parts of create & config requests
[3/x]: code movement: move TenantConfigRequestConfig next to
TenantCreateRequestConfig
[4/x] type-alias TenantConfigRequestConfig = TenantCreateRequestConfig;
They are exactly the same.
[5/x] switch to qualified use for tenant create/config request api
models
[6/x] rename models::TenantConfig{RequestConfig,} and remove the alias
[7/x] OpenAPI: sync tenant create & configure body names from Rust code
[8/x]: dedupe the two TryFrom<...> for TenantConfOpt impls
The only difference is that the TenantConfigRequest impl does
```
tenant_conf.max_lsn_wal_lag = request_data.max_lsn_wal_lag;
tenant_conf.trace_read_requests = request_data.trace_read_requests;
```
and the TenantCreateRequest impl does
```
if let Some(max_lsn_wal_lag) = request_data.max_lsn_wal_lag {
tenant_conf.max_lsn_wal_lag = Some(max_lsn_wal_lag);
}
if let Some(trace_read_requests) = request_data.trace_read_requests {
tenant_conf.trace_read_requests = Some(trace_read_requests);
}
```
As far as I can tell, these are identical.
With this patch, the attach handler now follows the same pattern as
tenant create with regards to instantiation of the new tenant:
1. Prepare on-disk state using `create_tenant_files`.
2. Use the same code path as pageserver startup to load it into memory
and start background loops (`schedule_local_tenant_processing`).
It's a bit sad we can't use the
`PageServerConfig::tenant_attaching_mark_file_path` method inside
`create_tenant_files` because it operates in a temporary directory.
However, it's a small price to pay for the gained simplicity.
During implementation, I noticed that we don't handle failures post
`create_tenant_files` well. I left TODO comments in the code linking to
the issue that I created for this [^1].
Also, I'll dedupe the spawn_load and spawn_attach code in a future
commit.
refs https://github.com/neondatabase/neon/issues/1555
part of https://github.com/neondatabase/neon/issues/886 (Tenant
Relocation)
[^1]: https://github.com/neondatabase/neon/issues/4233
Use an enum instead of an array. Before that there was no connection
between definition of the metric and point where it was used aside from
matching string literals. Now its possible to use IDE features to check
for references. Also this allows to avoid mismatch between set of
metrics that was defined and set of metrics that was actually used
What is interesting is that `init logical size` case is not used. I
think `LogicalSize` is a duplicate of `InitLogicalSize`. So removed the latter.
