fix: create ephemeral workspace for git source #13689

Rustin170506 · 2024-04-02T13:37:38Z

What does this PR try to resolve?

Root cause

The root cause of this problem is that cargo install creates a non-ephemeral workspace for git sources, that would try finding all member packages in that git repo, and add them as path dependencies.

However, when computing fingerprints to determine if a rebuild is needed, Cargo doesn't hash git revision into fingerprint directly. Instead, it checks if source file path has changed. For git source, it is an absolute path to ~/.cargo/git/checkouts//, so commit SHA is always there. For path dependency, it is relative to workspace root, so nothing change and Cargo doesn't rebuild even it is from a different git revision.

Sloution

If any time we create an ephemeral workspace, then we will update the git source every time and that would help us use the right code and rebuild the binary correctly.

There are some historical PRs related to this change:

4 years ago, we tried to all use ephemeral workspace in Simplify install #5350. But it caused cargo install doesn't follow workspace target #5662 so we revert that change in Fix cargo install using a workspace target dir #5685.
Search for root manifest with ephemeral workspaces #7768 In this PR, we try to search the root manifest by using Workspace::new, but it also caused the cargo install not working correctly when using git repo #13259.

So in my fix, I just rollback to use ephemera workspace but using find_root to achieve the same goal of searching the root manifest. You can find more in the test: git_install_reads_workspace_manifest

How should we test and review this PR?

manually test fix: create ephemeral workspace for git source #13689 (comment)
unit test

Additional information

None

rustbot · 2024-04-02T13:37:43Z

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Rustin170506 · 2024-04-07T02:02:01Z

Debugging note:

The failed case was caused by my change.
The reason is that we don't check the package content in Workspace::ephemera function, but in Workspace::new we will try to load the package again. This way, it can bail out the correct error from the manifest.
Perhaps we should explicitly check the manifest in the ephemera function or find a way to abort the process before make_ws_rustc_target.

Rustin170506 · 2024-04-13T04:47:44Z

Tested locally:

Add a new config

[build] 
target-dir = "/Volumes/t7/code/cargo/target/tmp1"

Install the video_in_waveform with new cargo build:

./target/debug/cargo install --git https://github.com/hi-rustin/cargo-information --rev 5fd64bb6afe37092ee1dd7c518f4fc4865175c22
   Compiling bytesize v1.3.0
   Compiling cargo-information v0.4.2 (https://github.com/hi-rustin/cargo-information?rev=5fd64bb6afe37092ee1dd7c518f4fc4865175c22#5fd64bb6)
    Finished `release` profile [optimized] target(s) in 1m 26s
  Installing /Users/hi-rustin/.cargo/bin/cargo-info
   Installed package `cargo-information v0.4.2 (https://github.com/hi-rustin/cargo-information?rev=5fd64bb6afe37092ee1dd7c518f4fc4865175c22#5fd64bb6)` (executable `cargo-info`)

Calculate the hash:

md5 ~/.cargo/bin/cargo-info
MD5 (/Users/hi-rustin/.cargo/bin/cargo-info) = 3a7ccae20527098730fda436790ddf72

Install it again with a different version:

./target/debug/cargo install --git https://github.com/hi-rustin/cargo-information --rev e8b3419bc033d3252ad19081f516946c94e0c02e
    Updating git repository `https://github.com/hi-rustin/cargo-information`
    Updating crates.io index
   Compiling cargo-information v0.4.2 (https://github.com/hi-rustin/cargo-information?rev=e8b3419bc033d3252ad19081f516946c94e0c02e#e8b3419b)
    Finished `release` profile [optimized] target(s) in 7.85s
   Replacing /Users/hi-rustin/.cargo/bin/cargo-info
    Replaced package `cargo-information v0.4.2 (https://github.com/hi-rustin/cargo-information?rev=5fd64bb6afe37092ee1dd7c518f4fc4865175c22#5fd64bb6)` with `cargo-information v0.4.2 (https://github.com/hi-rustin/cargo-information?rev=e8b3419bc033d3252ad19081f516946c94e0c02e#e8b3419b)` (executable `cargo-info`)

Calculate the hash:

md5 ~/.cargo/bin/cargo-info
MD5 (/Users/hi-rustin/.cargo/bin/cargo-info) = abd82eed7d6f3f88cf7a5371bf75d469

Rustin170506 · 2024-04-13T04:49:08Z

@weihanglo
Could you please take a look? Thanks! 💚 💙 💜 💛 ❤️

weihanglo

Thanks for looking back into the history!

weihanglo · 2024-04-14T01:32:49Z

src/cargo/core/workspace.rs

@@ -283,6 +283,10 @@ impl<'gctx> Workspace<'gctx> {
        ws.member_ids.insert(id);
        ws.default_members.push(ws.current_manifest.clone());
        ws.set_resolve_behavior();
+        // The find_root function is used here to traverse the directory tree and locate the root of the workspace.


A bit worried about this change. The in-memory property isn't held for ephemeral workspaces after this patch. It is also a bit fragile because the workspace discovery logic is only guarded by the other place, which is not immediately clear and hard to track.

I wonder if we really need this line here. git_install_reads_workspace_manifest seems to fail if we don't do find_root, but does cargo ever use profile or anything from there? Things we might want to figure out:

What kind of workspace support cargo install --git current provide?

Can we skip this and still find all members and inheritable fields?

but does cargo ever use profile or anything from there?

After this PR we can only check the manifest for errors. Before that, I belive that we could use any information defined by the workspace. For example lints etc.

What kind of workspace support cargo install --git current provide?

Before this PR, we just load the whole workspace and create a workspace based on the root manifest.
After this PR, we create the workspace based on the specific package and we don't use the information from the root manifest. Only searched the root to see if there is an error in the manifest.

Can we skip this and still find all members and inheritable fields?

After this PR, we only checked the manifest, we don't respect workspace information anymore.

For example:
If we try cargo install --git https://github.com/hi-rustin/test-cargo-git-install bin-tool;

Before this change:

test-cargo-git-install on  master via 🦀 v1.77.2 ❯ cargo install --git https://github.com/hi-rustin/test-cargo-git-install bin-tool Updating git repository `https://github.com/hi-rustin/test-cargo-git-install` warning: virtual workspace defaulting to `resolver = "1"` despite one or more workspace members being on edition 2021 which implies `resolver = "2"` note: to keep the current resolver, specify `workspace.resolver = "1"` in the workspace root's manifest note: to use the edition 2021 resolver, specify `workspace.resolver = "2"` in the workspace root's manifest note: for more details see https://doc.rust-lang.org/cargo/reference/resolver.html#resolver-versions Installing bin-tool v0.1.0 (https://github.com/hi-rustin/test-cargo-git-install#d7a594e5) Compiling lib1 v0.1.0 (/Users/hi-rustin/.cargo/git/checkouts/test-cargo-git-install-fae8728302b9b2da/d7a594e/lib1) Compiling bin-tool v0.1.0 (/Users/hi-rustin/.cargo/git/checkouts/test-cargo-git-install-fae8728302b9b2da/d7a594e/bin-tool) error: usage of an `unsafe` block --> bin-tool/src/main.rs:2:5 | 2 | / unsafe { 3 | | println!("Hello, world!"); 4 | | } | |_____^ | = note: requested on the command line with `-F unsafe-code` warning: unnecessary `unsafe` block --> bin-tool/src/main.rs:2:5 | 2 | unsafe { | ^^^^^^ unnecessary `unsafe` block | = note: `#[warn(unused_unsafe)]` on by default warning: `bin-tool` (bin "bin-tool") generated 1 warning error: could not compile `bin-tool` (bin "bin-tool") due to 1 previous error; 1 warning emitted error: failed to compile `bin-tool v0.1.0 (https://github.com/hi-rustin/test-cargo-git-install#d7a594e5)`, intermediate artifacts can be found at `/var/folders/j1/7l6snwpx6svgqxh79bz_d27m0000gn/T/cargo-installbO7SHc`. To reuse those artifacts with a future compilation, set the environment variable `CARGO_TARGET_DIR` to that path.

After this change:

test-cargo-git-install on  master via 🦀 v1.77.2 ❯ ../cargo/target/debug/cargo install --git https://github.com/hi-rustin/test-cargo-git-install bin-tool Updating git repository `https://github.com/hi-rustin/test-cargo-git-install` Installing bin-tool v0.1.0 (https://github.com/hi-rustin/test-cargo-git-install#d7a594e5) Compiling lib1 v0.1.0 (https://github.com/hi-rustin/test-cargo-git-install#d7a594e5) Compiling bin-tool v0.1.0 (https://github.com/hi-rustin/test-cargo-git-install#d7a594e5) Finished `release` profile [optimized] target(s) in 2.57s Installing /Users/hi-rustin/.cargo/bin/bin-tool Installed package `bin-tool v0.1.0 (https://github.com/hi-rustin/test-cargo-git-install#d7a594e5)` (executable `bin-tool`)

From a workspace information perspective, I think this PR introduces some regression.

From a workspace information perspective, I think this PR introduces some regression.

workspace is a feature which should not be there as it complicates all optimizations? it is only there because CARGO_TARGET_DIR does not work very well, isn't it?

workspace is already there so to move forward we need to first figure out the feature set cargo install --git offers. However, I agree with soloturn, we may need to step back a bit to re-evaludate the bug.

Both workspace initialization and CARGO_TARGET_DIR are symptoms of the bug. From my previous investigation, the bug is in workspace, members are collected as from PathSource, hence cargo install recognizes the as path dependencies. In contrast, when using in git dependency, workspace members will be marked as from GitSource. I wonder if we should mark the entire workspace with the same source as the root one for cargo install. Thinking of nested packages rust-lang/rfcs#3452, if we had that today, we might also need this, otherwise nested package will be marked as from local path and never get updated.

workspace is a feature which should not be there as it complicates all optimizations? it is only there because CARGO_TARGET_DIR does not work very well, isn't it?

I think it's hard to say the workspace feature complicates all optimizations. As my example in https://github.com/hi-rustin/test-cargo-git-install, respect workspace information will help us avoid inconsistency.

The problem is not caused by the CARGO_TARGET_DIR. If users set a CARGO_TARGET_DIR, then all compilation would happen in the CARGO_TARGET_DIR.

The problem here is as @weihanglo said, we cannot rebuild the binary after the git repository is updated.

I wonder if we should mark the entire workspace with the same source as the root one for cargo install. Thinking of nested packages rust-lang/rfcs#3452, if we had that today, we might also need this, otherwise nested package will be marked as from local path and never get updated.

That sounds like a reasonable solution, I will take a look.

I wonder if we should mark the entire workspace with the same source as the root one for cargo install

I've looked at how we calculate the fingerprint of the path member.

pub fn path_args(ws: &Workspace<'_>, unit: &Unit) -> (PathBuf, PathBuf) { let ws_root = ws.root(); let src = match unit. target.src_path() { TargetSourcePath::Path(path) => path.to_path_buf(), TargetSourcePath::Metabuild => unit.pkg.manifest().metabuild_path(ws.target_dir()), }; assert!(src.is_absolute()); if unit.pkg.package_id().source_id().is_path() { if let Ok(path) = src.strip_prefix(ws_root) { return (path.to_path_buf(), ws_root.to_path_buf()); } } (src, unit.pkg.root().to_path_buf()) }

It seems we always try to track the workspace as much as possible.

So I am not sure what you mean by mark the entire workspace with the same source. Can you explain it a little bit?

When we read a dependency from a Git source, no matter it is a single package or workspace member, it always returns a PackageId with SourceKind::Git. Under the hood it is actually a PathSource assoicated with a Git SourceId. This helps Cargo track the actual source.

cargo/src/cargo/sources/git/source.rs

Lines 360 to 365 in b9d913e

let source_id = self

.source_id

.with_git_precise(Some(actual_rev.to_string()));

let path_source = PathSource::new_recursive(&checkout_path, source_id, self.gctx);

self.path_source = Some(path_source);

However, in cargo install we use workspace to find members so we lost that sticky fashion.

weihanglo · 2024-04-14T01:35:30Z

tests/testsuite/install.rs

+    )
+    .run();
+
+    cargo_process(&format!(


Should have a comment or two pointing out we want to observe a rebuild?
Or we can actually do a shasum comparsion like the original did?

bors · 2024-04-18T19:22:09Z

☔ The latest upstream changes (presumably #13769) made this pull request unmergeable. Please resolve the merge conflicts.

rustbot assigned weihanglo Apr 2, 2024

rustbot added Command-install S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 2, 2024

Rustin170506 changed the title ~~DO NOT READY FOR REVIEW: fix: always create ephemeral workspace for install~~ NOT READY FOR REVIEW: fix: always create ephemeral workspace for install Apr 2, 2024

rustbot added the A-workspaces Area: workspaces label Apr 12, 2024

Rustin170506 changed the title ~~NOT READY FOR REVIEW: fix: always create ephemeral workspace for install~~ fix: always create ephemeral workspace for install Apr 12, 2024

Rustin170506 force-pushed the rustin-patch-install-git branch 5 times, most recently from f74eabe to ce67365 Compare April 13, 2024 03:26

Rustin170506 added 2 commits April 13, 2024 11:31

test: add install same bin twice case

db02d39

fix: create ephemeral workspace for git source

beeac46

Rustin170506 force-pushed the rustin-patch-install-git branch from ce67365 to beeac46 Compare April 13, 2024 03:31

Rustin170506 marked this pull request as ready for review April 13, 2024 03:32

Rustin170506 changed the title ~~fix: always create ephemeral workspace for install~~ fix: create ephemeral workspace for git source Apr 13, 2024

weihanglo reviewed Apr 14, 2024

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fix: create ephemeral workspace for git source #13689

fix: create ephemeral workspace for git source #13689

Rustin170506 commented Apr 2, 2024 •

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bors commented Apr 18, 2024

	let source_id = self
	.source_id
	.with_git_precise(Some(actual_rev.to_string()));
	let path_source = PathSource::new_recursive(&checkout_path, source_id, self.gctx);

	self.path_source = Some(path_source);

fix: create ephemeral workspace for git source #13689

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fix: create ephemeral workspace for git source #13689

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Rustin170506 commented Apr 2, 2024 • edited Loading

What does this PR try to resolve?

Root cause

Sloution

How should we test and review this PR?

Additional information

rustbot commented Apr 2, 2024

Rustin170506 commented Apr 7, 2024

Rustin170506 commented Apr 13, 2024

Rustin170506 commented Apr 13, 2024

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