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4903 commits

Author SHA1 Message Date
konsti
0199ad64bb
Fix bootstrap install script on windows (#1162)
Windows doesn't support symlinks, doesn't use a `bin` directory and all
pythons are called `python.exe`.

Note that this is still broken, `.\bin\python3.10.13` is missing its
.exe extension and renaming it to `.\bin\python3.10.13.exe` makes it
complain about not finding python310.dll.
2024-02-03 17:30:01 +01:00
Zanie Blue
bc2f8f5b1e
Fix direct use of range.simplify (#1236) 2024-02-02 18:08:25 +00:00
Zanie Blue
6db9db0079
Invert display of "no versions" incompatibilities with multiple ranges (#1233)
Closes #884 

e.g.

```
❯ cargo run -q -- pip compile --python-version 3.12 requirements.in
  × No solution found when resolving dependencies:
  ╰─▶ Because the requested Python version (3.12) does not satisfy Python>=3.6,<3.10 and recommenders==1.0.0 depends on Python>=3.6,<3.9, we can conclude that recommenders==1.0.0 cannot be used.
      And because only the following versions of recommenders are available:
          recommenders<=0.7
          recommenders==1.0.0
          recommenders==1.1.0
          recommenders==1.1.1
      we can conclude that recommenders>0.7,<1.1.0 cannot be used. (1)

      Because the requested Python version (3.12) does not satisfy Python>=3.6,<3.10 and recommenders>=1.1.0 depends on Python>=3.6,<3.10, we can conclude that recommenders>=1.1.0 cannot be used.
      And because we know from (1) that recommenders>0.7,<1.1.0 cannot be used, we can conclude that recommenders>0.7 cannot be used.
      And because you require recommenders>0.7, we can conclude that the requirements are unsatisfiable.
```
2024-02-02 12:00:25 -06:00
konsti
e3c1586310
gitignore packse scenarios folder (#1232)
Remove a directory i accidentally committed and gitignore it for the
future.
2024-02-02 18:50:18 +01:00
konsti
f10f902570
Yield after channel send and move cpu tasks to thread (#1163)
## Summary

Previously, we were blocking operations that could run in parallel. We
would send request through our main requests channel, but not yield so
that the receiver could only start processing requests much later than
necessary. We solve this by switching to the async
`tokio::sync::mpsc::channel`, where send is an async functions that
yields.

Due to the increased parallelism cache deserialization and the
conversion from simple api request to version map became bottlenecks, so
i moved them to `spawn_blocking`. Together these result in a 30-60%
speedup for larger warm cache resolution. Small cases such as black
already resolve in 5.7 ms on my machine so there's no speedup to be
gained, refresh and no cache were to noisy to get signal from.

Note for the future: Revisit the bounded channel if we want to produce
requests from `process_request`, too, (this would be good for
prefetching) to avoid deadlocks.

## Details

We can look at the behavior change through the spans:

```
RUST_LOG=puffin=info TRACING_DURATIONS_FILE=target/traces/jupyter-warm-branch.ndjson cargo run --features tracing-durations-export --bin puffin-dev --profile profiling -- resolve jupyter 2> /dev/null
```

Below, you can see how on main, we have discrete phases: All (cached)
simple api requests in parallel, then all (cached) metadata requests in
parallel, repeat until done. The solver is mostly waiting until it has
it's version map from the simple API query to be able to choose a
version. The main thread is blocked by process requests.

In the PR branch, the simple api requests succeeds much earlier,
allowing the solver to advance and also to schedule more prefetching.
Due to that `parse_cache` and `from_metadata` became bottlenecks, so i
moved them off the main thread (green color, and their spans can now
overlap because they can run on multiple threads in parallel). The main
thread isn't blocked on `process_request` anymore, instead it has
frequent idle times. The spans are all much shorter, which indicates
that on main they could have finished much earlier, but a task didn't
yield so they weren't scheduled to finish (though i haven't dug deep
enough to understand the exact scheduling between the process request
stream and the solver here).

**main**


![jupyter-warm-main](693c53cc-1090-41b7-b02a-a607fcd2cd99)

**PR**


![jupyter-warm-branch](33435f34-b39b-4b0a-a9d7-4bfc22f55f05)

## Benchmarks

```
$ hyperfine --warmup 3 "target/profiling/main-dev resolve jupyter" "target/profiling/branch-dev resolve jupyter"
Benchmark 1: target/profiling/main-dev resolve jupyter
  Time (mean ± σ):      29.1 ms ±   0.7 ms    [User: 22.9 ms, System: 11.1 ms]
  Range (min … max):    27.7 ms …  32.2 ms    103 runs
 
Benchmark 2: target/profiling/branch-dev resolve jupyter
  Time (mean ± σ):      18.8 ms ±   1.1 ms    [User: 37.0 ms, System: 22.7 ms]
  Range (min … max):    16.5 ms …  21.9 ms    154 runs
 
Summary
  target/profiling/branch-dev resolve jupyter ran
    1.55 ± 0.10 times faster than target/profiling/main-dev resolve jupyter

$ hyperfine --warmup 3 "target/profiling/main-dev resolve meine_stadt_transparent" "target/profiling/branch-dev resolve meine_stadt_transparent"
Benchmark 1: target/profiling/main-dev resolve meine_stadt_transparent
  Time (mean ± σ):      37.8 ms ±   0.9 ms    [User: 30.7 ms, System: 14.1 ms]
  Range (min … max):    36.6 ms …  41.5 ms    79 runs
 
Benchmark 2: target/profiling/branch-dev resolve meine_stadt_transparent
  Time (mean ± σ):      24.7 ms ±   1.5 ms    [User: 47.0 ms, System: 39.3 ms]
  Range (min … max):    21.5 ms …  28.7 ms    113 runs
 
Summary
  target/profiling/branch-dev resolve meine_stadt_transparent ran
    1.53 ± 0.10 times faster than target/profiling/main-dev resolve meine_stadt_transparent

$ hyperfine --warmup 3 "target/profiling/main pip compile scripts/requirements/home-assistant.in" "target/profiling/branch pip compile scripts/requirements/home-assistant.in"
Benchmark 1: target/profiling/main pip compile scripts/requirements/home-assistant.in
  Time (mean ± σ):     229.0 ms ±   2.8 ms    [User: 197.3 ms, System: 63.7 ms]
  Range (min … max):   225.8 ms … 234.0 ms    13 runs
 
Benchmark 2: target/profiling/branch pip compile scripts/requirements/home-assistant.in
  Time (mean ± σ):      91.4 ms ±   5.3 ms    [User: 289.2 ms, System: 176.9 ms]
  Range (min … max):    81.0 ms … 104.7 ms    32 runs
 
Summary
  target/profiling/branch pip compile scripts/requirements/home-assistant.in ran
    2.50 ± 0.15 times faster than target/profiling/main pip compile scripts/requirements/home-assistant.in
```
2024-02-02 18:18:24 +01:00
konsti
3771f6656e
Allow additional assertions on command output (#1226)
In the scenario tests, we want to make sure we're actually conforming to
the scenario's expectations, so we now have an extra assertion on
whether resolution failed or succeeded as well as that it includes the
given packages.

Closes #1112
Closes #1030
2024-02-02 09:41:35 +00:00
konsti
b16422a108
Remove insta_cmd (#1225)
We need more flexible filters than those `inta` offers, and `insta_cmd`
makes it impossible to plug in programmatic filters. At the same time we
use barely any of `insta_cmd`'s features. We can replace the subset we
need in about 50 loc.
2024-02-02 09:37:04 +00:00
konsti
0925e446a8
Refactor remaining integration tests (#1220)
Mostly a mechanical refactor to use the `puffin_snapshot!` and
`TestContext` infrastructure in the add, remove, venv and pip uninstall
tests, in preparation for adding programmatic windows testing filters.
The is only one remaining usage of `assert_cmd_snapshot!` now in the
`puffin_snapshot!` macro.
2024-02-02 10:26:59 +01:00
konsti
6b050a1972
Refactor pip install and sync tests (#1213)
Mostly a mechanical refactor to use the `puffin_snapshot!` and
`TestContext` infrastructure in the pip install and pip sync tests, in
preparation for adding programmatic windows testing filters.
2024-02-02 10:26:31 +01:00
Charlie Marsh
d77d129e8d
Run cargo update (#1230) 2024-02-01 11:14:38 -05:00
Charlie Marsh
bb49ebee1e
Avoid race condition in clone file replacement (#1229)
## Summary

I've never seen this in practice but in theory it is possible, and we
have the same guardrail in the hardlink path.
2024-02-01 10:55:23 -05:00
konsti
809c6d676f
Use normalized display in tests and other small windows fixes (#1228)
Split out from the large test refactoring PR. Use `normalized_display`
in tests and two more thiserror derives to match snapshots and output,
and other small windows fixes.
2024-02-01 16:12:30 +01:00
Charlie Marsh
9487378ef9
Avoid TOCTOU errors in data directory installations (#1227)
## Summary

See: https://github.com/astral-sh/puffin/issues/1224

## Test Plan

Ran `python -m scripts.bench --puffin
scripts/requirements/compiled/jupyter.txt --min-runs 100 --benchmark
install-warm --verbose` several times, which failed eventually on `main`
but not on this branch.
2024-02-01 14:55:29 +00:00
Charlie Marsh
fcf848877c
Change 'duplication' to 'deduplication' (#1223) 2024-02-01 14:13:45 +00:00
konsti
ea0bfc565d
Refactor pip scenario tests (#1212)
Mostly a mechanical refactor to use the `puffin_snapshot!` and
`TestContext` infrastructure in the pip compile and pip install
scenarios, in preparation for adding programmatic windows testing
filters.
2024-02-01 10:31:40 +01:00
Charlie Marsh
0757862a7a
Accommodate minute-level filters in Insta (#1219)
I don't know why `compile_editable` took over a minute in this case, but
seems like it did? Hard to test this fix.


2108933895
2024-02-01 09:43:09 +01:00
Charlie Marsh
631ab51d6e
Use publicly available Apple Silicon runners (#1216) 2024-01-31 23:41:51 -05:00
Charlie Marsh
8cbe1d220c
Remove double-download for source distributions (#1218)
## Summary

Oops -- this was using a different cache key than the route above (this
is the wheel _metadata_ route vs. the wheel build route), so we were
saving and building source distributions twice in `pip install`.
2024-02-01 04:41:29 +00:00
Charlie Marsh
51e8609ee8
Use Python 3.12 in benchmarks (#1215)
I originally used Python 3.10, since 3.10 and 3.11 are by far the most
common (at least for [Ruff](https://pypistats.org/packages/ruff)). But
3.12 should give Python tools the most favorable benchmarks.
2024-01-31 15:51:13 -05:00
Charlie Marsh
ee69fb51ea
Add PDM to benchmark script (#1214)
## Summary

Overall, similar to Poetry, with some simplifications (e.g., we don't
need to translate to Poetry's dependency syntax), and the need to adjust
how we manage the cache and virtual environment.
2024-01-31 20:31:45 +00:00
Charlie Marsh
c4bfb6efee
Add a BENCHMARKS.md with rendered benchmarks (#1211)
As a precursor to the release, I want to include a structured document
with detailed benchmarks.

Closes https://github.com/astral-sh/puffin/issues/1210.
2024-01-31 20:11:52 +00:00
Andrew Gallant
b9d89e7624
puffin-client: generalize SimpleMetadaRaw into OwnedArchive<A> (#1208)
It turns out that the pattern I coded up for SimpleMetadataRaw is
generally useful when working with rkyv. This commit makes it generic by
supporting any type that implements rkyv's traits, and makes a few
simplifying assumptions by picking a concrete serializer, validator and
deserializer. In effect, this lets use own any archived value.

We also rejigger the API a little bit and double-down on
`OwnedArchive<A>` just being a owned wrapper for `Archived<A>`. Namely,
we implement `Deref` and turn its inherent methods into methods that
require fully qualified syntax. (As is standard for things that
implement `Deref` to avoid ambiguity with the deref target's methods.)

(This PR also makes a couple small simplifications to our custom rkyv
serializer since we no longer need to use it directly. We do still need
to name the type in trait bounds, so it has to be public.)
2024-01-31 11:56:34 -05:00
konsti
234e8d0bb7
Abstract away test duplication in pip-compile (#1187)
In preparation for the new windows handling, i want to introduce a
`TestContext` and `puffin_snapshot!` abstraction. This PR applies those
changes for pip-compile. My plan is to use those for all venv-based
integration tests and build the custom windows filters on top of
`puffin_snapshot!`.
2024-01-31 16:11:10 +00:00
Charlie Marsh
01258c1bb3
Report number of bytes deleted when clearing cache (#1203)
## Summary

This is based on Cargo's `clean` implementation, with modifications
based on some of my own preferences, and to better adhere to patterns we
use in our codebase:

![Screenshot 2024-01-31 at 1 31
10 AM](38704798-b17f-4972-ab67-00484ce63d62)
2024-01-31 10:48:28 -05:00
Charlie Marsh
ec816a3322
Update Python discovery documentation (#1194)
Closes https://github.com/astral-sh/puffin/issues/1109.
2024-01-31 15:42:32 +00:00
Charlie Marsh
35113c1d06
Enable macOS checks on CI (#1193)
## Summary

Enables tests for macOS in CI, using the M1 runners (which are free in
public, but count against our quota in private
repos). For now, I'm just running them on `main` to save quota.

I did the math, and the M1 runners are the best value:

![Screenshot 2024-01-30 at 9 33
36 PM](bd5a14b6-740c-487f-bcad-81c0fce5b62e)

Closes #1053.
2024-01-31 15:27:04 +00:00
Charlie Marsh
462fec1968
Remove readarray from install.sh (#1198)
## Summary

This isn't available on macOS (see, e.g.,
https://stackoverflow.com/questions/23842261/alternative-to-readarray-because-it-does-not-work-on-mac-os-x),
but this version works both on macOS and Linux.

Closes https://github.com/astral-sh/puffin/issues/1196. (Verified
locally and on CI.)
2024-01-31 10:22:13 -05:00
Charlie Marsh
8f9258fae3
Invert default feature for testing (#1200)
## Summary

We have some flags in Puffin that enable us to opt-in to certain tests.
To date, they've been opt-in, so we've run our tests with
`--all-features`. This PR makes them opt-out, and we now run tests with
default features.

The main motivation here is that I want to get tests working for macOS
on CI, but for unknown reasons, macOS can't compile the PyO3 features at
the same time as everything else due to strange linker issues. By
avoiding `--all-features` for tests, we thus avoid unnecessarily
including features that we don't actually use in Puffin.

I verified that the exact same number of tests (439) are run before and
after this change. For users, the primary difference is that you now
need to specify `--no-default-features --features pypi --features
python` to avoid (e.g.) including the Git tests.
2024-01-31 09:44:26 -05:00
Charlie Marsh
b2f1bbaa63
Add a Ctrl+C handler to the confirm workflow (#1202)
Fixes an issue whereby exiting the confirmation prompt can lead to your
cursor disappearing: https://github.com/console-rs/dialoguer/issues/294.

See:
b839a2c5b7/rye/src/main.rs (L36-L48).
2024-01-31 02:08:27 +00:00
Charlie Marsh
262f29b558
Add missing --exclude-newer to executable tests (#1201)
A new version of `platformdirs` came out, which broke these.
2024-01-30 20:26:11 -05:00
Charlie Marsh
b88b9e1f3d
Remove dedicated flate2 features from Puffin (#1199)
We should be able to enable and disable these without crate-internal
features.
2024-01-30 19:41:08 -05:00
Andrew Gallant
b47f70917f
puffin-client: simplify use of http-cache-semantics (#1197)
The `http-cache-semantics` crate is polymorphic on the types of requests
and responses it accepts. We had previously been explicitly converting
between `http` and `reqwest` types, but this isn't necessary. We can
provide impls of the traits in `http-cache-semantics` for `reqwest`'s
types (via a wrapper). This saves us from the awkward request/response
type conversions.

While this does clone the request, this is:

1. Not new. We were previously cloning the request to do the conversion.
2. An artifact (I believe) of http-cache-semantics API. (It kind of
   seems like an API bug to me?)

There is also a little bit of messiness around inter-operating between
http::uri::Uri and url::Url. But overall shouldn't be a big deal.
2024-01-30 18:20:44 -05:00
Charlie Marsh
7ae9d3c631
Remove Windows limitation from README (#1195) 2024-01-30 21:39:15 +00:00
Charlie Marsh
3f5e7306a5
Remove WaitMap dependency (#1183)
## Summary

This is an attempt to https://github.com/astral-sh/puffin/pull/1163 by
removing the `WaitMap` and gaining more granular control over the values
that we hold over `await` boundaries.
2024-01-30 15:25:22 -05:00
Charlie Marsh
c129717b41
Add support for --no-deps to pip install (#1191)
## Summary

Closes https://github.com/astral-sh/puffin/issues/1188.
2024-01-30 19:54:57 +00:00
Charlie Marsh
8305acc584
Add a builder for resolution options (#1192) 2024-01-30 19:50:16 +00:00
Charlie Marsh
aa3b79ec63
Prompt user for missing -r and -e flags in pip install (#1180)
## Summary

If the user runs a command like `pip install requirements.txt`, we now
prompt them to ask if they meant to include the `-r` flag:

![Screenshot 2024-01-29 at 8 38
29 PM](82b9f7a2-2526-4144-b200-a5015e5b8a4b)

![Screenshot 2024-01-29 at 8 38
33 PM](bd8ebb51-2537-4540-a0e0-718e66a1c69c)

The specific logic is: if the requirement ends in `.txt` or `.in`, and
the file exists locally, prompt the user for `-r`. If the requirement
contains a directory separator, and the directory exists locally, prompt
the user for `-e`.

Closes #1166.
2024-01-30 18:58:45 +00:00
Charlie Marsh
7a937e0f60
Error when parsing requirements.txt-like packages in requirements.txt file (#1179)
## Summary

Like https://github.com/astral-sh/puffin/pull/1180, this PR adds logic
for `requirements.txt` parsing whereby if a requirement _looks like_ a
local requirements file or an editable directory, we prompt the user to
correct the error (typically, by adding `-r`).
2024-01-30 18:55:11 +00:00
konsti
4ad0dc8b9e
Add windows aarch64 trampolines (#1190)
Lacking windows compatible aarch64 hardware, i cross compiled the
trampoline from x86_64 linux to aarch64-pc-windows-msvc; I added the
instructions to the puffin-trampoline readme. With some testing on an
aarch64 windows machine, this should be sufficient to build working
win_arm64 tagged wheels.

i686-pc-windows-msvc is failing with an error:

```
error: linking with `lld-link` failed: exit status: 1
  = note: lld-link: error: undefined symbol: __aulldiv
          >>> referenced by libcompiler_builtins-2fb09dee087e9f64.rlib(compiler_builtins-2fb09dee087e9f64.compiler_builtins.597f0152646f1b8-cgu.0.rcgu.o):(compiler_builtins::int::specialized_div_rem::u128_div_rem::h06aed1e23a3f8f5c)
          >>> referenced by libcompiler_builtins-2fb09dee087e9f64.rlib(compiler_builtins-2fb09dee087e9f64.compiler_builtins.597f0152646f1b8-cgu.0.rcgu.o):(compiler_builtins::int::specialized_div_rem::u128_div_rem::h06aed1e23a3f8f5c)
          >>> referenced by libcompiler_builtins-2fb09dee087e9f64.rlib(compiler_builtins-2fb09dee087e9f64.compiler_builtins.597f0152646f1b8-cgu.0.rcgu.o):(compiler_builtins::int::specialized_div_rem::u128_div_rem::h06aed1e23a3f8f5c)
          >>> referenced 4 more times

          lld-link: error: undefined symbol: __aullrem
          >>> referenced by libcompiler_builtins-2fb09dee087e9f64.rlib(compiler_builtins-2fb09dee087e9f64.compiler_builtins.597f0152646f1b8-cgu.0.rcgu.o):(compiler_builtins::int::specialized_div_rem::u128_div_rem::h06aed1e23a3f8f5c)
          >>> referenced by libcompiler_builtins-2fb09dee087e9f64.rlib(compiler_builtins-2fb09dee087e9f64.compiler_builtins.597f0152646f1b8-cgu.0.rcgu.o):(compiler_builtins::int::specialized_div_rem::u128_div_rem::h06aed1e23a3f8f5c)
          >>> referenced by libcompiler_builtins-2fb09dee087e9f64.rlib(compiler_builtins-2fb09dee087e9f64.compiler_builtins.597f0152646f1b8-cgu.0.rcgu.o):(compiler_builtins::int::specialized_div_rem::u128_div_rem::h06aed1e23a3f8f5c)
          >>> referenced 4 more times
```
2024-01-30 17:51:27 +00:00
konsti
614bb0cf52
Update async_http_range_reader to 0.5.0 (#1189)
Removes a git dep and removes itertools 0.11
2024-01-30 16:32:53 +00:00
Charlie Marsh
c479c26cab
Add compatibility arguments for pip sync (#1185)
## Summary

As with `pip compile`, we can provide useful error messages and warnings
when people pass `pip sync` arguments.

Closes https://github.com/astral-sh/puffin/issues/1184.
2024-01-30 08:48:55 -05:00
konsti
ab27913f68
Instrument the main function and add jupyter.in (#1186)
Instrument the main function as anchor span for checking overhead and
update tracing-durations-export to 0.2.0 for differentiating
blocking/non-blocking tasks.

Add a `jupyter.in` requirement since `pip install jupyter` is a common
operation. I tried `jupyterlab` too but there is no difference in
performance (1.00 ± 0.07).
2024-01-30 11:03:24 +00:00
konsti
a6c4cbfe55
Cleanup puffin interpreter errors (#1169)
Use `virtualenv` consistently, remove unused error variants and hint the
user towards installing missing python versions.

I didn't touch the Readme but i replaced `virtualenv environment` with
`virtualenv` in the strings i found.

Fixes https://github.com/astral-sh/puffin/issues/1167
2024-01-30 10:52:46 +01:00
Charlie Marsh
bd934207e4
Accept relative file paths in CLI requirements (#1182)
## Summary

See: https://github.com/astral-sh/puffin/issues/1181.

## Test Plan

```
❯ cargo run -- pip install packse@../../zanieb/packse
    Finished dev [unoptimized + debuginfo] target(s) in 0.15s
     Running `target/debug/puffin pip install 'packse@../../zanieb/packse'`
error: Distribution not found at: file:///Users/crmarsh/zanieb/packse
```
2024-01-30 03:31:24 +00:00
Charlie Marsh
61a3060383
Run cargo update (#1178) 2024-01-29 21:01:37 -05:00
Charlie Marsh
fa3c9afdc1
Deduplicate pep440_rs in dependency tree (#1177)
## Summary

Closes https://github.com/astral-sh/puffin/issues/1176.

## Test Plan

`cargo tree -p puffin -i pep440_rs` runs without error. Previously, it
errored due to multiple versions.
2024-01-29 16:11:42 -05:00
konsti
d4ed5ea858
Fix the compile_python_37 test with python 3.7 installed (#1172)
Make the test `compile_python_37` pass whether python 3.7 is installed
or not by muting the warning for a missing 3.7. The resolution error is
independent of whether 3.7 is installed or not.
2024-01-29 18:59:28 +01:00
Charlie Marsh
67a09649f2
Support parsing --find-links, --index-url, and --extra-index-url in requirements.txt (#1146)
## Summary

This PR adds support for `--find-links`, `--index-url`, and
`--extra-index-url` arguments when specified in a `requirements.txt`.

It's a mostly-straightforward change. The only uncertain piece is what
to do when multiple files include these flags, and/or when we include
them on the CLI and in other files.

In general:

- If _anything_ specifies `--no-index`, we respect it.
- We combine all `--extra-index-url` and `--find-links` across all
sources, since those are just vectors.
- If we see multiple `--index-url` in requirements files, we error.
- We respect the `--index-url` from the command line over any provided
in a requirements file.

(`pip-compile` seems to just pick one semi-arbitrarily when multiple are
provided.)

Closes https://github.com/astral-sh/puffin/issues/1143.
2024-01-29 15:06:40 +00:00
Charlie Marsh
4b9daf9604
Use tokio_tar instead of async_tar (#1170)
## Summary

`tokio_tar` is a fork of `async_tar` that uses Tokio instead of
`async-std`. Using it removes a significant dependency from our tree.

(There is an open PR
(https://github.com/dignifiedquire/async-tar/pull/41) in `async-tar` to
add Tokio support, but it's over a year old.)

See:
https://github.com/astral-sh/puffin/pull/1157#discussion_r1469190249.
2024-01-29 10:00:30 -05:00
Andrew Gallant
a42b385e9b
puffin-client: add SimpleMetadataRaw (#1150)
This adds what is effectively an owned wrapper around
`Archived<SimpleMetadata>`. Normally, an `Archived<SimpleMetadata>`
has to be used behind a pointer (since it has a lifetime
attached to its underlying byte buffer), but we create a
wrapper around it that owns the underlying buffer and provides
free access to the archived type.

This in effect creates an anchor point for the archived type
and lets us pass it around easily. (There has to be an anchor
point for it somewhere.)

An alternative to this approach would be to store it as a file
backed memory map. But in practice, we're dealing with small
files, and just reading them on to the heap is likely to be
faster. (Memory maps also have wildly different perf characteristics
across platforms.)

Note that this commit just defines the type. It isn't actually
used anywhere yet.
2024-01-29 09:37:06 -05:00