cargo-hackerman

Hackerman solves following problems

• Avoiding unnecessary recompilations

• Explaining why workspace depends on a certain crate

• Explaining what crates are needed for a certain crate

• Finding crates that a workspace needs in multiple versions

• Quick lookup for crate documentation, homepage, etc

Command line summary

Feature unification, what does this mean for me as a user?

As a part of working with workspaces cargo performs feature unification: https://doc.rust-lang.org/cargo/reference/features.html#feature-unification

What does this mean?

Suppose you have a workspace

[workspace]
members = [ "mega", "potato" ]

With two members: mega

[package]
name = "mega"

[dependencies]
potatoer = { version = "0.2.1", features = ["mega"] }

And potato

[package]
name = "potato"

[dependencies]
potatoer = { version = "0.2.1", features = ["potato"] }

Both of which depend on a common third party crate potatoer but with different features: mega is interested in "mega" feature, potato is interested in "potato" one.

when running different commands you end up requiring several different versions of potatoer crate.

• Whole workspace commands will use version with unified features:

  cargo check # this will use potatoer with both "mega" and "potato"
  

• Commands operating on a single crate will use versions without unification:

  cargo check -p mega           # this will use potatoer with "mega" feature
  cargo check -p potatoer       # this will use potatoer with "potato" feature
  cargo check -p mega -p potato # this will require both "mega" and "potato"
  

If a dependency with required combination is not present - cargo will compile it.

One way to avoid this problem is to make sure that if members of a workspace depend on a crate - they depend on it with the same set of features. Maintaining it by hand is error prone and that's when hackerman hack and hackerman restore come in.

When used with --lock option hackerman will take a checksum of all the dependencies and will save it inside Cargo.toml file under ["package.metadata.hackerman.lock"] and subsequent calls to check will confirm that this checksum is still valid.

This is required to make sure that original (unhacked) dependencies are saved and can be restored at a later point.

It is possible to hardcode --lock option in a Cargo.toml file that defines the workspace:

[workspace.metadata.hackerman]
lock = true

At the moment unification is performed for current target only and without crosscompilation support. Automatic update for workspace toml files might not work if you are specifying dependencies using syntax different than by version or {}:

potato = "3.14"               # this is okay
banana = { version = "3.14" } # this is also okay

Hackerman mergetool

Resolves merge and rebase conflicts for Cargo.toml files changed by hackerman

To use it you want something like this

global .gitconfig or local .git/config.

[merge "hackerman"]
    name = merge restored files with hackerman
    driver = cargo hackerman merge %O %A %B %P

gitattributes file, could be local per project or global

Cargo.toml merge=hackerman

To create a global gitattributes file you need to specify a path to it inside the global git config:

[core]
    attributesfile = ~/.gitattributes

Hackerman vs no hack vs single hack crate

Here I'm comparing effects of different approaches to unification on a workspace. Without any changes clean check over the whole workspace that involves compiling of all the external dependencies takes 672 seconds.

Workspace contains a bunch of crates, from which I selected crates a, b, c, etc, such that crate b imports crate a, crate c imports crate b, etc. crate a contains no external dependencies, other crates to.

• no hack - checks are done without any hacks.
• hackerman - hack was generated with cargo hackerman hack command and new dependencies are added to every crate
• manual hack - hack consists of a single crate with all the crates that have different combinations of features and this new crate is included as a dependency to every crate in the workspace

Before runnining the command I clean the compilation results then commands for each column sequentially

command	no hack	hackerman	manual hack
check -p a	0.86s	0.80s	215.39s
check -p b	211.30s	240.15s	113.56s
check -p c	362.69s	233.38s	176.73s
check -p d	36.16s	0.24s	0.25s
check -p e	385.35s	66.34s	375.22s
check	267.06s	93.29s	81.50s
total	1263.42	634.20	962.65

Command summary

• cargo hackerman↴
• cargo hackerman hack↴
• cargo hackerman restore↴
• cargo hackerman check↴
• cargo hackerman merge↴
• cargo hackerman explain↴
• cargo hackerman dupes↴
• cargo hackerman tree↴
• cargo hackerman show↴

cargo hackerman

A collection of tools that help your workspace to compile fast

Usage: cargo hackerman COMMAND ...

Available options:

• -h, --help — Prints help information

• -V, --version — Prints version information

Available commands:

• hack — Unify crate dependencies across individual crates in the workspace

• restore — Remove crate dependency unification added by the hack command

• check — Check if unification is required and if checksums are correct

• merge — Restore files and merge with the default merge driver

• explain — Explain why some dependency is present. Both feature and version are optional

• dupes — Lists all the duplicates in the workspace

• tree — Make a tree out of dependencies

• show — Show crate manifest, readme, repository or documentation

You can pass --help twice for more detailed help

cargo hackerman hack

Unify crate dependencies across individual crates in the workspace

Usage: cargo hackerman hack CARGO_OPTS [--dry] [--lock] [-D]

You can undo those changes using cargo hackerman restore.

Cargo options:

• --manifest-path=PATH — Path to Cargo.toml file

• --frozen — Require Cargo.lock and cache are up to date

• --locked — Require Cargo.lock is up to date

• --offline — Run without accessing the network

• -v, --verbose — increase verbosity, can be used several times

Available options:

• --dry — Don't perform action, only display it

• --lock — Include dependencies checksum into stash

  This helps to ensure you can go back to original (unhacked) dependencies: to be able to restore the original dependencies hackerman needs to have them stashed in Cargo.toml file. If CI detects checksum mismatch this means dependencies were updated on hacked sources. You should instead restore them, update and hack again.

  You can make locking the default behavior by adding this to Cargo.toml in the workspace

  [workspace.metadata.hackerman]
  lock = true
  

• -D, --no-dev — Don't unify dev dependencies

• -h, --help — Prints help information

cargo-hackerman hack calculates and adds a minimal set of extra dependencies to all the workspace members such that features of all the dependencies of this crate stay the same when it is used as part of the whole workspace or by itself.

Once dependencies are hacked you should restore them before making any changes.

cargo hackerman restore

Remove crate dependency unification added by the hack command

Usage: cargo hackerman restore CARGO_OPTS [TOML]...

Cargo options:

• --manifest-path=PATH — Path to Cargo.toml file

• --frozen — Require Cargo.lock and cache are up to date

• --locked — Require Cargo.lock is up to date

• --offline — Run without accessing the network

• -v, --verbose — increase verbosity, can be used several times

Available positional items:

• TOML — Restore individual files instead of the whole workspace

Available options:

• -h, --help — Prints help information

cargo hackerman check

Check if unification is required and if checksums are correct

Similar to cargo-hackerman hack --dry, but also sets exit status to 1 so you can use it as part of CI process

Usage: cargo hackerman check CARGO_OPTS [-D]

Cargo options:

• --manifest-path=PATH — Path to Cargo.toml file

• --frozen — Require Cargo.lock and cache are up to date

• --locked — Require Cargo.lock is up to date

• --offline — Run without accessing the network

• -v, --verbose — increase verbosity, can be used several times

Available options:

• -D, --no-dev — Don't unify dev dependencies

• -h, --help — Prints help information

cargo hackerman merge

Restore files and merge with the default merge driver

Usage: cargo hackerman merge BASE LOCAL REMOTE RESULT

Available options:

• -h, --help — Prints help information

To use it you would add something like this to ~/.gitconfig or .git/config

[merge "hackerman"]
name = merge restored files with hackerman
driver = cargo hackerman merge %O %A %B %P

And something like this to .git/gitattributes

Cargo.toml merge=hackerman

cargo hackerman explain

Explain why some dependency is present. Both feature and version are optional

Usage: cargo hackerman explain CARGO_OPTS [-T] [-P] [-s] CRATE [FEATURE] [VERSION]

Cargo options:

• --manifest-path=PATH — Path to Cargo.toml file

• --frozen — Require Cargo.lock and cache are up to date

• --locked — Require Cargo.lock is up to date

• --offline — Run without accessing the network

• -v, --verbose — increase verbosity, can be used several times

Available options:

• -T, --no-transitive-opt — Don't strip redundant links

• -P, --package-nodes — Use package nodes instead of feature nodes

• -s, --stdout — Print dot file to stdout instead of spawning xdot

• -h, --help — Prints help information

With large amount of dependencies it might be difficult to tell why exactly some sub-sub-sub dependency is included. hackerman explain solves this problem by tracing the dependency chain from the target and to the workspace.

explain starts at a given crate/feature and follows reverse dependency links until it reaches all the crossing points with the workspace but without entering the workspace itself.

White nodes represent workspace members, round nodes represent features, octagonal nodes represent base crates. Dotted line represents dev-only dependency, dashed line - both dev and normal but with different features across them. Target is usually highlighted. By default hackerman expands packages info feature nodes which can be reverted with -P and tries to reduce transitive dependencies to keep the tree more readable - this can be reverted with -T.

If a crate is present in several versions you can specify version of the one you are interested in but it's optional.

You can also specify which feature to look for, otherwise hackerman will be looking for all of them.

cargo hackerman dupes

Lists all the duplicates in the workspace

Usage: cargo hackerman dupes CARGO_OPTS

Cargo options:

• --manifest-path=PATH — Path to Cargo.toml file

• --frozen — Require Cargo.lock and cache are up to date

• --locked — Require Cargo.lock is up to date

• --offline — Run without accessing the network

• -v, --verbose — increase verbosity, can be used several times

Available options:

• -h, --help — Prints help information

cargo hackerman tree

Make a tree out of dependencies

Usage: cargo hackerman tree CARGO_OPTS [-T] [-D] [-P] [-w] [-s] [CRATE] [FEATURE] [VERSION]

Cargo options:

• --manifest-path=PATH — Path to Cargo.toml file

• --frozen — Require Cargo.lock and cache are up to date

• --locked — Require Cargo.lock is up to date

• --offline — Run without accessing the network

• -v, --verbose — increase verbosity, can be used several times

Available options:

• -T, --no-transitive-opt — Don't strip redundant links

• -D, --no-dev — Don't include dev dependencies

• -P, --package-nodes — Use package nodes instead of feature nodes

• -w, --workspace — Keep within the workspace

• -s, --stdout — Print dot file to stdout instead of spawning xdot

• -h, --help — Prints help information

Examples:

cargo hackerman tree rand 0.8.4
cargo hackerman tree serde_json preserve_order

cargo hackerman show

Show crate manifest, readme, repository or documentation

Usage: cargo hackerman show CARGO_OPTS [-m | -r | -d | -R] CRATE [VERSION]

Cargo options:

• --manifest-path=PATH — Path to Cargo.toml file

• --frozen — Require Cargo.lock and cache are up to date

• --locked — Require Cargo.lock is up to date

• --offline — Run without accessing the network

• -v, --verbose — increase verbosity, can be used several times

Available options:

• -m, --manifest — Show crate manifest

• -r, --readme — Show crate readme

• -d, --doc — Open documentation URL

• -R, --repository — Repository

• -h, --help — Prints help information

Examples:

cargo hackerman show --repository syn