文盤Rust -- 本地庫引發的依賴衝突

作者：京東科技賈世聞

問題描述

clickhouse 的原生 rust 使用者端目前比較好的有兩個clickhouse-rs 和 clickhouse.rs 。clickhouse-rs 是 tcp 連線；clickhouse.rs 是 http 連線。兩個庫在單獨使用時沒有任何問題，但是，在同一工程同時參照時會報錯。

Cargo.toml

# clickhouse http
clickhouse = {git = "https://github.com/loyd/clickhouse.rs", features =      ["test-util"]}

# clickhouse tcp
clickhouse-rs = { git = "https://github.com/suharev7/clickhouse-rs",     features = ["default"]}

報錯如下

    Blocking waiting for file lock on package cache
    Updating git repository `https://github.com/suharev7/clickhouse-rs`
    Updating crates.io index
error: failed to select a version for `clickhouse-rs-cityhash-sys`.
    ... required by package `clickhouse-rs v1.0.0-alpha.1 (https://github.  com/suharev7/clickhouse-rs#ecf28f46)`
    ... which satisfies git dependency `clickhouse-rs` of package   `conflict v0.1.0 (/Users/jiashiwen/rustproject/conflict)`
versions that meet the requirements `^0.1.2` are: 0.1.2

the package `clickhouse-rs-cityhash-sys` links to the native library   `clickhouse-rs`, but it conflicts with a previous package which links to   `clickhouse-rs` as well:
package `clickhouse-rs-cityhash-sys v0.1.2`
    ... which satisfies dependency `clickhouse-rs-cityhash-sys = "^0.1.2"`   (locked to 0.1.2) of package `clickhouse v0.11.2 (https://github.com/  loyd/clickhouse.rs#4ba31e65)`
    ... which satisfies git dependency `clickhouse` (locked to 0.11.2) of   package `conflict v0.1.0 (/Users/jiashiwen/rustproject/conflict)`
Only one package in the dependency graph may specify the same links value.   This helps ensure that only one copy of a native library is linked in the   final binary. Try to adjust your dependencies so that only one package   uses the links ='clickhouse-rs-cityhash-sys' value. For more information,   see https://doc.rust-lang.org/cargo/reference/resolver.html#links.

failed to select a version for `clickhouse-rs-cityhash-sys` which could   resolve this conflict

錯誤描述還是很清楚的，clickhouse-rs-cityhash-sys 這個庫衝突了。仔細看了一下兩個庫的原始碼，參照 clickhouse-rs-cityhash-sys 庫的方式是不一樣的。clickhouse.rs 是在其Cargo.toml 檔案中使用最普遍的方式參照的

clickhouse-rs-cityhash-sys = { version = "0.1.2", optional = true }

clickhouse-rs 是通過本地方式參照的

[dependencies.clickhouse-rs-cityhash-sys]
path = "clickhouse-rs-cityhash-sys"
version = "0.1.2"

clickhouse-rs-cityhash-sys 的原始碼直接放在 clickhouse-rs 工程目錄下面。

一開始是有個直觀的想法，如果在一個工程中通過workspace 進行隔離，是不是會解決衝突問題呢？於是，工程的目錄結構從這樣

.
├── Cargo.lock
├── Cargo.toml
└── src
    └── main.rs

改成了這樣

.
├── Cargo.lock
├── Cargo.toml
├── ck_http
│   ├── Cargo.toml
│   └── src
├── ck_tcp
│   ├── Cargo.toml
│   └── src
└── src
    └── main.rs

新建了兩個lib

cargo new ck_http --lib
cargo new ck_tcp --lib

在 workspace 中分別應用 clickhouse-rs 和 clickhouse.rs ,刪除根下 Cargo.toml 檔案中的依賴關係。很可惜，workspace 沒有解決問題，報錯沒有一點兒差別。

又仔細看了看報錯，裡面有這樣一段

  the package `clickhouse-rs-cityhash-sys` links to the native library   `clickhouse-rs`, but it conflicts with a previous package which links to   `clickhouse-rs`

難道是 clickhouse-rs 這個名字衝突了？直接把clickhouse-rs原始碼拉下來作為本地庫來試試呢？於是把 clickhouse-rs clone 到本地，稍稍修改一下ck_tcp workspace 的 Cargo.toml

clickhouse-rs = { path = "../../clickhouse-rs", features = ["default"]}

編譯後衝突依舊存在。翻翻 clickhouse-rs/clickhouse-rs-cityhash-sys/Cargo.toml，裡面的一個設定很可疑

[package]
...
...
links = "clickhouse-rs"

把 links 隨便改個名字比如：links = "ck-rs-cityhash-sys"，編譯就通過了。

錯誤提示中這句話很重要

Only one package in the dependency graph may specify the same links value.

看了一下 links 欄位的含義

The links field
The links field specifies the name of a native library that is being linked to. More information can be found in the links section of the build script guide.

links 指定了本地包被連結的名字，在這裡引起了衝突，改掉本地包中的名字自然解決了衝突，在依賴圖中保證唯一性很重要。

本文涉及程式碼github倉庫，有興趣的同學可以親自試一試

下期見。

文盤Rust -- 本地庫引發的依賴衝突

作者：京東科技 賈世聞

問題描述

作者：京東科技賈世聞