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//! Recursive trees, conditional ref revalidation and cache healing.
use super::transport::Conditional;
use super::{API, GitHubClient};
use crate::types::{RepoMeta, TreeResponse};
use rootle_provider::{ErrorKind, ProviderError, ProviderResult};
impl GitHubClient {
/// Fetch a repo's full recursive tree with the sha-keyed cache
/// (PLAN.md §8): revalidate the branch ref with If-None-Match
/// (304 = free, tree unchanged), cache tree bodies by their sha.
/// Also returns the default branch (URL building, yank). v1.5:
/// `ref_` pins another branch/tag/sha — the tree endpoint takes
/// any ref, and a sha's tree is immutable, so the same etag
/// revalidation is correct there.
pub fn fetch_tree(
&self,
owner: &str,
repo: &str,
ref_: Option<&str>,
) -> ProviderResult<(
TreeResponse,
/*truncated*/ bool,
/*branch*/ String,
)> {
if let Some(r) = ref_ {
return self.fetch_tree_on(owner, repo, r);
}
// Cache-first branch resolution: a repo we've opened before
// costs zero extra calls here (no GET /repos/{o}/{r}).
let cached_branch = crate::cache::cached_branch(owner, repo);
let branch = match &cached_branch {
Some(b) => {
rootle_provider::trace(&format!("tree branch cached {owner}/{repo} {b}"));
b.clone()
}
None => {
rootle_provider::trace(&format!("tree branch meta-fetch {owner}/{repo}"));
let meta: RepoMeta = self.get(&format!("{API}/repos/{owner}/{repo}"))?;
meta.default_branch
}
};
match self.fetch_tree_on(owner, repo, &branch) {
// The default branch was renamed since we cached it:
// resolve fresh and try once more.
Err(e) if cached_branch.is_some() && e.kind == ErrorKind::NotFound => {
let meta: RepoMeta = self.get(&format!("{API}/repos/{owner}/{repo}"))?;
self.fetch_tree_on(owner, repo, &meta.default_branch)
}
other => other,
}
}
fn fetch_tree_on(
&self,
owner: &str,
repo: &str,
branch: &str,
) -> ProviderResult<(
TreeResponse,
/*truncated*/ bool,
/*branch*/ String,
)> {
let cached_ref = crate::cache::read_ref(owner, repo, branch);
let url = format!("{API}/repos/{owner}/{repo}/git/trees/{branch}?recursive=1");
let etag = cached_ref.as_ref().and_then(|r| r.etag.clone());
match self.get_conditional::<TreeResponse>(&url, etag.as_deref())? {
Conditional::NotModified => {
let sha = cached_ref.expect("304 without a cached ref").tree_sha;
match crate::cache::read_tree(&sha) {
Some(tree) => Ok((tree.clone(), tree.truncated, branch.to_string())),
None => {
// A cache read that cannot be satisfied is a
// miss, not an error. The startup orphan sweep
// can race a fetch's tree-then-ref write order
// and delete a tree its ref already points at;
// the etag then 304s forever against a missing
// body (sticky unopenable repo). Refetch
// unconditionally — the cache is only an
// optimization, and this re-stores the tree
// and ref, healing both.
rootle_provider::trace(&format!(
"304 but tree {sha} missing from cache; refetching"
));
let Conditional::Fresh { body, etag } =
self.get_conditional::<TreeResponse>(&url, None)?
else {
return Err(ProviderError::other(
"unconditional revalidation returned 304",
));
};
self.store_tree(owner, repo, branch, body, etag)
}
}
}
Conditional::Fresh { body, etag } => self.store_tree(owner, repo, branch, body, etag),
}
}
/// Persist a fetched tree + its ref (tree first — durable before
/// discoverable; the sweep race above is absorbed by the miss
/// fallback).
fn store_tree(
&self,
owner: &str,
repo: &str,
branch: &str,
body: TreeResponse,
etag: Option<String>,
) -> ProviderResult<(
TreeResponse,
/*truncated*/ bool,
/*branch*/ String,
)> {
crate::cache::write_tree(&body).map_err(|e| ProviderError::other(e.to_string()))?;
crate::cache::write_ref(
owner,
repo,
branch,
&crate::cache::RefCache {
tree_sha: body.sha.clone(),
etag,
},
)
.map_err(|e| ProviderError::other(e.to_string()))?;
let truncated = body.truncated;
Ok((body, truncated, branch.to_string()))
}
}