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resource_info.rs
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resource_info.rs
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// Copyright 2022 The Native Link Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
use error::{error_if, make_input_err, Error, ResultExt};
const ERROR_MSG: &str = concat!(
"Expected resource_name to be of pattern ",
"'{?instance_name/}(?uploads/{uuid}/)blobs/{?/digest_function}{/hash}/{size}{?/optional_metadata}' or ",
"'{?instance_name/}(?uploads/{uuid}/)compressed-blobs{?/compressor}{?/digest_function}{/hash}/{size}{?/optional_metadata}'",
);
const COMPRESSORS: [&str; 4] = ["identity", "zstd", "deflate", "brotli"];
const DIGEST_FUNCTIONS: [&str; 9] = [
"sha256",
"sha1",
"md5",
"vso",
"sha384",
"sha512",
"murmur3",
"sha256tree",
"blake3",
];
// Named struct to make the code easier to read when adding the slash size.
const SLASH_SIZE: usize = 1;
// Rules are as follows:
//
// "instance_name" may contain slashes and may contain or equal "uploads", "compressed-blobs" and "blobs".
// if is_upload is false:
// {instance_name}/ compressed-blobs/{compressor}/{digest_function/}{hash}/{size}{/optional_metadata}
// {instance_name}/ compressed-blobs/{compressor}/{digest_function/}{hash}/{size}
// {instance_name}/ blobs/ {digest_function/}{hash}/{size}{/optional_metadata}
// {instance_name}/ blobs/ {digest_function/}{hash}/{size}
// compressed-blobs/{compressor}/{digest_function/}{hash}/{size}{/optional_metadata}
// compressed-blobs/{compressor}/{digest_function/}{hash}/{size}
// blobs/ {digest_function/}{hash}/{size}{/optional_metadata}
// blobs/ {digest_function/}{hash}/{size}
// {instance_name}/ compressed-blobs/{compressor}/ {hash}/{size}{/optional_metadata}
// {instance_name}/ compressed-blobs/{compressor}/ {hash}/{size}
// {instance_name}/ blobs/ {hash}/{size}{/optional_metadata}
// {instance_name}/ blobs/ {hash}/{size}
// compressed-blobs/{compressor}/ {hash}/{size}{/optional_metadata}
// compressed-blobs/{compressor}/ {hash}/{size}
//
// blobs/ {hash}/{size}{/optional_metadata}
// blobs/ {hash}/{size}
//
// if is_upload is true:
// {instance_name}/uploads/{uuid}/compressed-blobs/{compressor}/{digest_function/}{hash}/{size}{/optional_metadata}
// {instance_name}/uploads/{uuid}/compressed-blobs/{compressor}/{digest_function/}{hash}/{size}
// {instance_name}/uploads/{uuid}/blobs/ {digest_function/}{hash}/{size}{/optional_metadata}
// {instance_name}/uploads/{uuid}/blobs/ {digest_function/}{hash}/{size}
// uploads/{uuid}/compressed-blobs/{compressor}/{digest_function/}{hash}/{size}{/optional_metadata}
// uploads/{uuid}/compressed-blobs/{compressor}/{digest_function/}{hash}/{size}
// uploads/{uuid}/blobs/ {digest_function/}{hash}/{size}{/optional_metadata}
// uploads/{uuid}/blobs/ {digest_function/}{hash}/{size}
// {instance_name}/uploads/{uuid}/compressed-blobs/{compressor}/ {hash}/{size}{/optional_metadata}
// {instance_name}/uploads/{uuid}/compressed-blobs/{compressor}/ {hash}/{size}
// {instance_name}/uploads/{uuid}/blobs/ {hash}/{size}{/optional_metadata}
// {instance_name}/uploads/{uuid}/blobs/ {hash}/{size}
// uploads/{uuid}/compressed-blobs/{compressor}/ {hash}/{size}{/optional_metadata}
// uploads/{uuid}/compressed-blobs/{compressor}/ {hash}/{size}
// uploads/{uuid}/blobs/ {hash}/{size}{/optional_metadata}
// uploads/{uuid}/blobs/ {hash}/{size}
//
// Useful utility struct for converting bazel's (uri-like path) into it's parts.
#[derive(Debug, Default)]
pub struct ResourceInfo<'a> {
pub instance_name: &'a str,
pub uuid: Option<&'a str>,
pub compressor: Option<&'a str>,
pub digest_function: Option<&'a str>,
pub hash: &'a str,
pub expected_size: usize,
pub optional_metadata: Option<&'a str>,
}
impl<'a> ResourceInfo<'a> {
pub fn new(resource_name: &'a str, is_upload: bool) -> Result<ResourceInfo<'a>, Error> {
// The most amount of slashes there can be to get to "(compressed-)blobs" section is 7.
let mut rparts = resource_name.rsplitn(7, '/');
let mut output = ResourceInfo::default();
let mut end_bytes_processed = 0;
let end_state = recursive_parse(&mut rparts, &mut output, State::Unknown, &mut end_bytes_processed)?;
error_if!(
end_state != State::OptionalMetadata,
"Expected the final state to be OptionalMetadata. Got: {end_state:?}"
);
// Slice off the processed parts of `resource_name`.
let beginning_part = if end_bytes_processed == resource_name.len() {
""
} else {
&resource_name[..resource_name.len() - end_bytes_processed - SLASH_SIZE]
};
if !is_upload {
output.instance_name = beginning_part;
return Ok(output);
}
// If it's an upload, at this point it will have be:
// `{?instance_name}/uploads/{uuid}`.
// Remember, `instance_name` can contain slashes and/or special names
// like "blobs" or "uploads".
let mut parts = beginning_part.rsplitn(3, '/');
output.uuid = Some(parts.next().err_tip(|| ERROR_MSG)?);
{
// Sanity check that our next item is "uploads".
let uploads = parts.next().err_tip(|| ERROR_MSG)?;
error_if!(uploads != "uploads", "Expected part to be 'uploads'. Got: {uploads}");
}
// `instance_name` is optional.
if let Some(instance_name) = parts.next() {
output.instance_name = instance_name;
}
Ok(output)
}
}
#[derive(Debug, PartialEq)]
enum State {
Unknown,
Compressor,
DigestFunction,
Hash,
Size,
OptionalMetadata,
}
// Iterate backwards looking for "(compressed-)blobs", once found, move foward
// populating the output struct. This recursive function utilises the stack to
// temporarly hold the reference to the previous item reducing the need for
// a heap allocation.
fn recursive_parse<'a>(
rparts: &mut impl Iterator<Item = &'a str>,
output: &mut ResourceInfo<'a>,
mut state: State,
bytes_processed: &mut usize,
) -> Result<State, Error> {
let part = rparts.next().err_tip(|| ERROR_MSG)?;
if state == State::Unknown {
if part == "blobs" {
*bytes_processed = part.len() + SLASH_SIZE;
return Ok(State::DigestFunction);
}
if part == "compressed-blobs" {
*bytes_processed = part.len() + SLASH_SIZE;
return Ok(State::Compressor);
}
state = recursive_parse(rparts, output, state, bytes_processed)?;
}
loop {
match state {
State::Unknown => {
return Err(make_input_err!(
"Unknown state should never be reached in ResourceInfo::new"
))
}
State::Compressor => {
state = State::DigestFunction;
if COMPRESSORS.contains(&part) {
output.compressor = Some(part);
*bytes_processed += part.len() + SLASH_SIZE;
return Ok(state);
}
continue;
}
State::DigestFunction => {
state = State::Hash;
if DIGEST_FUNCTIONS.contains(&part) {
output.digest_function = Some(part);
*bytes_processed += part.len() + SLASH_SIZE;
return Ok(state);
}
continue;
}
State::Hash => {
output.hash = part;
*bytes_processed += part.len() + SLASH_SIZE;
// TODO(allada) Set the digest_function if it is not set based on the hash size.
return Ok(State::Size);
}
State::Size => {
output.expected_size = part
.parse::<usize>()
.map_err(|_| make_input_err!("Digest size_bytes was not convertible to usize. Got: {}", part))?;
*bytes_processed += part.len(); // Special case {size}, so it does not count one slash.
return Ok(State::OptionalMetadata);
}
State::OptionalMetadata => {
output.optional_metadata = Some(part);
*bytes_processed += part.len() + SLASH_SIZE;
// If we get here, we are done parsing backwards and have successfully parsed
// everything beyond the "(compressed-)blobs" section.
return Ok(State::OptionalMetadata);
}
}
}
}