## Problem
Previously, we were using `observe_closure_duration` in `VirtualFile`
file opening code, but this doesn't support async open operations, which
we want to use as part of #4743.
## Summary of changes
* Move the duration measurement from the `with_file` macro into a
`observe_duration` macro.
* Some smaller drive-by fixes to replace the old strings with the new
variant names introduced by #5273
Part of #4743, follow-up of #5247.
## Problem
For #4743, we want to convert everything up to the actual I/O operations
of `VirtualFile` to `async fn`.
## Summary of changes
This PR is the last change in a series of changes to `VirtualFile`:
#5189, #5190, #5195, #5203, and #5224.
It does the last preparations before the I/O operations are actually
made async. We are doing the following things:
* First, we change the locks for the file descriptor cache to tokio's
locks that support Send. This is important when one wants to hold locks
across await points (which we want to do), otherwise the Future won't be
Send. Also, one shouldn't generally block in async code as executors
don't like that.
* Due to the lock change, we now take an approach for the `VirtualFile`
destructors similar to the one proposed by #5122 for the page cache, to
use `try_write`. Similarly to the situation in the linked PR, one can
make an argument that if we are in the destructor and the slot has not
been reused yet, we are the only user accessing the slot due to owning
the lock mutably. It is still possible that we are not obtaining the
lock, but the only cause for that is the clock algorithm touching the
slot, which should be quite an unlikely occurence. For the instance of
`try_write` failing, we spawn an async task to destroy the lock. As just
argued however, most of the time the code path where we spawn the task
should not be visited.
* Lastly, we split `with_file` into a macro part, and a function part
that contains most of the logic. The function part returns a lock
object, that the macro uses. The macro exists to perform the operation
in a more compact fashion, saving code from putting the lock into a
variable and then doing the operation while measuring the time to run
it. We take the locks approach because Rust has no support for async
closures. One can make normal closures return a future, but that
approach gets into lifetime issues the moment you want to pass data to
these closures via parameters that has a lifetime (captures work). For
details, see
[this](https://smallcultfollowing.com/babysteps/blog/2023/03/29/thoughts-on-async-closures/)
and
[this](https://users.rust-lang.org/t/function-that-takes-an-async-closure/61663)
link. In #5224, we ran into a similar problem with the `test_files`
function, and we ended up passing the path and the `OpenOptions`
by-value instead of by-ref, at the expense of a few extra copies. This
can be done as the data is cheaply copyable, and we are in test code.
But here, we are not, and while `File::try_clone` exists, it [issues
system calls
internally](1e746d7741/library/std/src/os/fd/owned.rs (L94-L111)).
Also, it would allocate an entirely new file descriptor, something that
the fd cache was built to prevent.
* We change the `STORAGE_IO_TIME` metrics to support async.
Part of #4743.
Introduce the `StorageIoOperation` enum, `StorageIoTime` struct, and
`STORAGE_IO_TIME_METRIC` static which provides lockless access to
histograms consumed by `VirtualFile`.
Closes#5131
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
## Problem
Detaching a tenant can involve many thousands of local filesystem
metadata writes, but the control plane would benefit from us not
blocking detach/delete responses on these.
## Summary of changes
After rename of local tenant directory ack tenant detach and delete
tenant directory in background
#5183
---------
Signed-off-by: Rahul Modpur <rmodpur2@gmail.com>
Prepare to upgrade rust version to latest stable.
- `rustfmt` has learned to format `let irrefutable = $expr else { ...
};` blocks
- There's a new warning about virtual (workspace) crate resolver, picked
the latest resolver as I suspect everyone would expect it to be the
latest; should not matter anyways
- Some new clippies, which seem alright
## Problem
Once we use async file system APIs for `VirtualFile`, these functions
will also need to be async fn.
## Summary of changes
Makes the functions `open, open_with_options, create,sync_all,with_file`
of `VirtualFile` async fn, including all functions that call it. Like in
the prior PRs, the actual I/O operations are not using async APIs yet,
as per request in the #4743 epic.
We switch towards not using `VirtualFile` in the par_fsync module,
hopefully this is only temporary until we can actually do fully async
I/O in `VirtualFile`. This might cause us to exhaust fd limits in the
tests, but it should only be an issue for the local developer as we have
high ulimits in prod.
This PR is a follow-up of #5189, #5190, #5195, and #5203. Part of #4743.
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>
It was easy to interpret comment in the page cache initialization code
to be about justifying why we leak here at all, not just why this
specific type of leaking is done (which the comment was actually meant
to describe).
See
https://github.com/neondatabase/neon/pull/5125#discussion_r1308445993
---------
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
## Problem
We want to convert the `VirtualFile` APIs to async fn so that we can
adopt one of the async I/O solutions.
## Summary of changes
This PR is a follow-up of #5189, #5190, and #5195, and does the
following:
* Move the used `Write` trait functions of `VirtualFile` into inherent
functions
* Add optional buffering to `WriteBlobWriter`. The buffer is discarded
on drop, similarly to how tokio's `BufWriter` does it: drop is neither
async nor does it support errors.
* Remove the generics by `Write` impl of `WriteBlobWriter`, alwaays
using `VirtualFile`
* Rename `WriteBlobWriter` to `BlobWriter`
* Make various functions in the write path async, like
`VirtualFile::{write,write_all}`.
Part of #4743.
## 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>
## Problem
- Scrubber's `tidy` command requires presence of a control plane
- Scrubber has no tests at all
## Summary of changes
- Add re-usable async streams for reading metadata from a bucket
- Add a `scan-metadata` command that reads from those streams and calls
existing `checks.rs` code to validate metadata, then returns a summary
struct for the bucket. Command returns nonzero status if errors are
found.
- Add an `enable_scrub_on_exit()` function to NeonEnvBuilder so that
tests using remote storage can request to have the scrubber run after
they finish
- Enable remote storarge and scrub_on_exit in test_pageserver_restart
and test_pageserver_chaos
This is a "toe in the water" of the overall space of validating the
scrubber. Later, we should:
- Enable scrubbing at end of tests using remote storage by default
- Make the success condition stricter than "no errors": tests should
declare what tenants+timelines they expect to see in the bucket (or
sniff these from the functions tests use to create them) and we should
require that the scrubber reports on these particular tenants/timelines.
The `tidy` command is untouched in this PR, but it should be refactored
later to use similar async streaming interface instead of the current
batch-reading approach (the streams are faster with large buckets), and
to also be covered by some tests.
---------
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
Co-authored-by: Alexander Bayandin <alexander@neon.tech>
Co-authored-by: Christian Schwarz <christian@neon.tech>
Co-authored-by: Conrad Ludgate <conrad@neon.tech>
Fixes#3830 by adding the `#[cfg(not(feature = "testing"))]` attribute
to unnecessary loggings in `pageserver/src/tenant/tasks.rs`.
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
## Problem
We want to convert the `VirtualFile` APIs to async fn so that we can
adopt one of the async I/O solutions.
## Summary of changes
Convert the following APIs of `VirtualFile` to async fn (as well as all
of the APIs calling it):
* `VirtualFile::seek`
* `VirtualFile::metadata`
* Also, prepare for deletion of the write impl by writing the summary to
a buffer before writing it to disk, as suggested in
https://github.com/neondatabase/neon/issues/4743#issuecomment-1700663864
. This change adds an additional warning for the case when the summary
exceeds a block. Previously, we'd have silently corrupted data in this
(unlikely) case.
* `WriteBlobWriter::write_blob`, in preparation for making
`VirtualFile::write_all` async.
## Problem
`VirtualFile` does both reading and writing, and it would be nice if
both could be converted to async, so that it doesn't have to support an
async read path and a blocking write path (especially for the locks this
is annoying as none of the lock implementations in std, tokio or
parking_lot have support for both async and blocking access).
## Summary of changes
This PR is some initial work on making the `VirtualFile` APIs async. It
can be reviewed commit-by-commit.
* Introduce the `MaybeVirtualFile` enum to be generic in a test that
compares real files with virtual files.
* Make various APIs of `VirtualFile` async, including `write_all_at`,
`read_at`, `read_exact_at`.
Part of #4743 , successor of #5180.
Co-authored-by: Christian Schwarz <me@cschwarz.com>
## Problem
The `VirtualFile::crashsafe_overwrite` function was introduced by #5186
but it was not turned `async fn` yet. We want to make these functions
async fn as part of #4743.
## Summary of changes
Make `VirtualFile::crashsafe_overwrite` async fn, as well as all the
functions calling it. Don't make anything inside `crashsafe_overwrite`
use async functionalities, as per #4743 instructions.
Also, add rustdoc to `crashsafe_overwrite`.
Part of #4743.
## Problem
If a pageserver crashes partway through deleting a tenant's directory,
it might leave a partial state that confuses a subsequent
startup/attach.
## Summary of changes
Rename tenant directory to a temporary path before deleting.
Timeline deletions already have deletion markers to provide safety.
In future, it would be nice to exploit this to send responses to detach
requests earlier: https://github.com/neondatabase/neon/issues/5183
(part of #4743)
(preliminary to #5180)
This PR adds a special-purpose API to `VirtualFile` for write-once
files.
It adopts it for `save_metadata` and `persist_tenant_conf`.
This is helpful for the asyncification efforts (#4743) and specifically
asyncification of `VirtualFile` because above two functions were the
only ones that needed the VirtualFile to be an `std::io::Write`.
(There was also `manifest.rs` that needed the `std::io::Write`, but, it
isn't used right now, and likely won't be used because we're taking a
different route for crash consistency, see #5172. So, let's remove it.
It'll be in Git history if we need to re-introduce it when picking up
the compaction work again; that's why it was introduced in the first
place).
We can't remove the `impl std::io::Write for VirtualFile` just yet
because of the `BufWriter` in
```rust
struct DeltaLayerWriterInner {
...
blob_writer: WriteBlobWriter<BufWriter<VirtualFile>>,
}
```
But, @arpad-m and I have a plan to get rid of that by extracting the
append-only-ness-on-top-of-VirtualFile that #4994 added to
`EphemeralFile` into an abstraction that can be re-used in the
`DeltaLayerWriterInner` and `ImageLayerWriterInner`.
That'll be another PR.
### Performance Impact
This PR adds more fsyncs compared to before because we fsync the parent
directory every time.
1. For `save_metadata`, the additional fsyncs are unnecessary because we
know that `metadata` fits into a kernel page, and hence the write won't
be torn on the way into the kernel. However, the `metadata` file in
general is going to lose signficance very soon (=> see #5172), and the
NVMes in prod can definitely handle the additional fsync. So, let's not
worry about it.
2. For `persist_tenant_conf`, which we don't check to fit into a single
kernel page, this PR makes it actually crash-consistent. Before, we
could crash while writing out the tenant conf, leaving a prefix of the
tenant conf on disk.
For
[#5086](https://github.com/neondatabase/neon/pull/5086#issuecomment-1701331777)
we will require remote storage to be configured in pageserver.
This PR enables `localfs`-based storage for all Rust unit tests.
Changes:
- In `TenantHarness`, set up localfs remote storage for the tenant.
- `create_test_timeline` should mimic what real timeline creation does,
and real timeline creation waits for the timeline to reach remote
storage. With this PR, `create_test_timeline` now does that as well.
- All the places that create the harness tenant twice need to shut down
the tenant before the re-create through a second call to `try_load` or
`load`.
- Without shutting down, upload tasks initiated by/through the first
incarnation of the harness tenant might still be ongoing when the second
incarnation of the harness tenant is `try_load`/`load`ed. That doesn't
make sense in the tests that do that, they generally try to set up a
scenario similar to pageserver stop & start.
- There was one test that recreates a timeline, not the tenant. For that
case, I needed to create a `Timeline::shutdown` method. It's a
refactoring of the existing `Tenant::shutdown` method.
- The remote_timeline_client tests previously set up their own
`GenericRemoteStorage` and `RemoteTimelineClient`. Now they re-use the
one that's pre-created by the TenantHarness. Some adjustments to the
assertions were needed because the assertions now need to account for
the initial image layer that's created by `create_test_timeline` to be
present.
The `remote_timeline_client` tests use `#[tokio::test]` and rely on the
fact that the test runtime that is set up by this macro is
single-threaded.
In PR https://github.com/neondatabase/neon/pull/5164, we observed
interesting flakiness with the `upload_scheduling` test case:
it would observe the upload of the third layer (`layer_file_name_3`)
before we did `wait_completion`.
Under the single-threaded-runtime assumption, that wouldn't be possible,
because the test code doesn't await inbetween scheduling the upload
and calling `wait_completion`.
However, RemoteTimelineClient was actually using `BACKGROUND_RUNTIME`.
That means there was parallelism where the tests didn't expect it,
leading to flakiness such as execution of an UploadOp task before
the test calls `wait_completion`.
The most confusing scenario is code like this:
```
schedule upload(A);
wait_completion.await; // B
schedule_upload(C);
wait_completion.await; // D
```
On a single-threaded executor, it is guaranteed that the upload up C
doesn't run before D, because we (the test) don't relinquish control
to the executor before D's `await` point.
However, RemoteTimelineClient actually scheduled onto the
BACKGROUND_RUNTIME, so, `A` could start running before `B` and
`C` could start running before `D`.
This would cause flaky tests when making assertions about the state
manipulated by the operations. The concrete issue that led to discover
of this bug was an assertion about `remote_fs_dir` state in #5164.
## Problem
The S3 scrubber currently lives at
https://github.com/neondatabase/s3-scrubber
We don't have tests that use it, and it has copies of some data
structures that can get stale.
## Summary of changes
- Import the s3-scrubber as `s3_scrubber/
- Replace copied_definitions/ in the scrubber with direct access to the
`utils` and `pageserver` crates
- Modify visibility of a few definitions in `pageserver` to allow the
scrubber to use them
- Update scrubber code for recent changes to `IndexPart`
- Update `KNOWN_VERSIONS` for IndexPart and move the definition into
index.rs so that it is easier to keep up to date
As a future refinement, it would be good to pull the remote persistence
types (like IndexPart) out of `pageserver` into a separate library so
that the scrubber doesn't have to link against the whole pageserver, and
so that it's clearer which types need to be public.
Co-authored-by: Kirill Bulatov <kirill@neon.tech>
Co-authored-by: Dmitry Rodionov <dmitry@neon.tech>
Co-authored-by: Arpad Müller <arpad-m@users.noreply.github.com>
## Problem
To implement split brain protection, we need tenants and timelines to be
aware of their current generation, and use it when composing S3 keys.
## Summary of changes
- A `Generation` type is introduced in the `utils` crate -- it is in
this broadly-visible location because it will later be used from
`control_plane/` as well as `pageserver/`. Generations can be a number,
None, or Broken, to support legacy content (None), and Tenants in the
broken state (Broken).
- Tenant, Timeline, and RemoteTimelineClient all get a generation
attribute
- IndexPart's IndexLayerMetadata has a new `generation` attribute.
Legacy layers' metadata will deserialize to Generation::none().
- Remote paths are composed with a trailing generation suffix. If a
generation is equal to Generation::none() (as it currently always is),
then this suffix is an empty string.
- Functions for composing remote storage paths added in
remote_timeline_client: these avoid the way that we currently always
compose a local path and then strip the prefix, and avoid requiring a
PageserverConf reference on functions that want to create remote paths
(the conf is only needed for local paths). These are less DRY than the
old functions, but remote storage paths are a very rarely changing
thing, so it's better to write out our paths clearly in the functions
than to compose timeline paths from tenant paths, etc.
- Code paths that construct a Tenant take a `generation` argument in
anticipation that we will soon load generations on startup before
constructing Tenant.
Until the whole feature is done, we don't want any generation-ful keys
though: so initially we will carry this everywhere with the special
Generation::none() value.
Closes: https://github.com/neondatabase/neon/issues/5135
Co-authored-by: Christian Schwarz <christian@neon.tech>
