mbx 0.5.0

A build cache for Rust projects
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258

use super::*;

fn test_config(cache_dir: &Path) -> Config {
    Config {
        cache_dir: cache_dir.to_path_buf(),
        stats_report: None,
        verify: false,
        incremental: false,
        share_out_dir: false,
        remote: Default::default(),
        http: Default::default(),
        gc: Default::default(),
        target: crate::config::TargetSettings {
            views: false,
            root: cache_dir.join("targets"),
        },
    }
}

#[tokio::test]
async fn session_environment_directs_cargo_at_the_shim() {
    let cache = tempfile::tempdir().unwrap();
    let session_dir = tempfile::tempdir().unwrap();
    let session = CacheSession::start(session_dir.path(), &test_config(cache.path()))
        .await
        .unwrap();

    let workspace = tempfile::tempdir().unwrap();
    let mut values = BTreeMap::from([("RUSTC_WRAPPER".into(), "existing".into())]);
    let run = session
        .begin(
            workspace.path(),
            &workspace.path().join("target"),
            &["build".to_string()],
            &mut values,
        )
        .await;

    assert!(run.is_some());
    assert!(values.contains_key(SOCKET_ENV));
    assert!(values.contains_key(STAGING_ENV));
    assert_eq!(values.get(BUILD_ENV).unwrap().len(), 64);
    // The shim carries an .exe suffix on Windows, so compare stems.
    let wrapper = Path::new(values.get("RUSTC_WRAPPER").unwrap());
    assert_eq!(wrapper.file_stem().unwrap(), RUSTC_SHIM_STEM);
    assert_eq!(values.get(PREVIOUS_RUSTC_WRAPPER_ENV).unwrap(), "existing");
    assert_eq!(values.get("CARGO_INCREMENTAL").unwrap(), "0");
    assert_eq!(values.get(VERIFY_ENV).unwrap(), "0");

    session.finish().await.unwrap();
}

#[tokio::test]
async fn incremental_builds_leave_cargo_incremental_alone() {
    let cache = tempfile::tempdir().unwrap();
    let session_dir = tempfile::tempdir().unwrap();
    let mut config = test_config(cache.path());
    config.incremental = true;
    let session = CacheSession::start(session_dir.path(), &config)
        .await
        .unwrap();

    let workspace = tempfile::tempdir().unwrap();
    let mut values = BTreeMap::new();
    session
        .begin(
            workspace.path(),
            &workspace.path().join("target"),
            &["build".to_string()],
            &mut values,
        )
        .await;

    // Absent, not "1": cargo's own per-profile default is what we want, and
    // forcing the value on would turn incremental on for release too.
    assert!(!values.contains_key("CARGO_INCREMENTAL"));

    session.finish().await.unwrap();
}

#[tokio::test]
async fn verify_mode_is_passed_to_the_shim() {
    let cache = tempfile::tempdir().unwrap();
    let session_dir = tempfile::tempdir().unwrap();
    let mut config = test_config(cache.path());
    config.verify = true;
    let session = CacheSession::start(session_dir.path(), &config)
        .await
        .unwrap();

    let workspace = tempfile::tempdir().unwrap();
    let mut values = BTreeMap::new();
    session
        .begin(
            workspace.path(),
            &workspace.path().join("target"),
            &["build".to_string()],
            &mut values,
        )
        .await;

    assert_eq!(values.get(VERIFY_ENV).unwrap(), "1");

    session.finish().await.unwrap();
}

#[test]
fn identity_follows_the_dependency_graph_not_the_path() {
    let first = tempfile::tempdir().unwrap();
    let second = tempfile::tempdir().unwrap();
    std::fs::write(first.path().join("Cargo.lock"), "version = 4\n").unwrap();
    std::fs::write(second.path().join("Cargo.lock"), "version = 4\n").unwrap();
    let command = ["build".to_string()];

    assert_eq!(
        build_identity(first.path(), &command),
        build_identity(second.path(), &command),
        "separate worktrees of one project must share a manifest"
    );

    std::fs::write(second.path().join("Cargo.lock"), "version = 3\n").unwrap();
    assert_ne!(
        build_identity(first.path(), &command),
        build_identity(second.path(), &command),
    );
    assert_ne!(
        build_identity(first.path(), &command),
        build_identity(first.path(), &["test".to_string()]),
    );
}

#[test]
fn identity_falls_back_to_the_directory_name() {
    let directory = tempfile::tempdir().unwrap();
    let command = ["build".to_string()];
    assert_eq!(
        build_identity(directory.path(), &command).len(),
        64,
        "a project without a lockfile still gets an identity"
    );
}

#[test]
fn handshake_rejects_version_skew() {
    let response = serde_json::to_string(&AgentResponse::Hello {
        protocol: AGENT_PROTOCOL_VERSION,
        agent_version: "another-version".into(),
    })
    .unwrap();
    assert!(validate_handshake_response(&response).is_err());
}

/// Build the statistics a test needs without naming every counter.
///
/// `AgentStats` is `#[non_exhaustive]` so that the agent can keep adding
/// counters, which also means no struct literal can be written from here.
fn agent_stats(fill: impl FnOnce(&mut AgentStats)) -> AgentStats {
    let mut stats = AgentStats::default();
    fill(&mut stats);
    stats
}

#[test]
fn qualification_results_are_not_reported_as_misses() {
    let stats = agent_stats(|stats| {
        stats.lookups = 5;
        stats.hits = 2;
        stats.verifications = 2;
    });
    assert_eq!(cache_misses(&stats), 1);
}

#[test]
fn compiler_only_sessions_are_reportable() {
    let stats = agent_stats(|stats| {
        stats.compiler =
            BTreeMap::from([("bypass".into(), mbx_cache_core::CompilerStats::new(1, 42))]);
    });

    assert!(should_display_stats(&stats));
}

#[test]
fn a_session_that_only_failed_its_remote_is_reportable() {
    // Nothing was looked up, stored or compiled, so every other signal this
    // gate reads is zero -- and a remote cache that answered nothing but
    // failures is the one thing the build most needs to be told about.
    let stats = agent_stats(|stats| stats.remote_failures = 3);

    assert!(should_display_stats(&stats));
}

#[test]
fn writes_versioned_stats_report() {
    let directory = tempfile::tempdir().unwrap();
    let path = directory.path().join("nested").join("stats.json");
    let stats = agent_stats(|stats| {
        stats.session_duration_ns = 42;
        stats.lookups = 5;
        stats.hits = 2;
        stats.verifications = 1;
        stats.prefetched_actions = 3;
        stats.downloaded_bytes = 1024;
        stats.restored_output_files = 7;
        stats.restored_output_bytes = 2048;
        stats.reflinked_output_files = 5;
        stats.reflinked_output_bytes = 1536;
        stats.copied_output_files = 2;
        stats.copied_output_bytes = 512;
        stats.avoided_compiler_duration_ns = 2_000;
        stats.compiler =
            BTreeMap::from([("miss".into(), mbx_cache_core::CompilerStats::new(3, 4_000))]);
        stats.slow_compilations = BTreeMap::from([("slow_crate".into(), 3_000)]);
        stats.remote_blob_requests = 4;
        stats.remote_blob_pack_requests = 2;
        stats.remote_blob_pack_blobs = 100;
        stats.materialization_duration_ns = 9;
    });

    write_stats_report(&path, &stats).unwrap();
    let report: serde_json::Value = serde_json::from_slice(&std::fs::read(path).unwrap()).unwrap();

    assert_eq!(report["version"], 2);
    assert_eq!(report["session_duration_ns"], 42);
    assert_eq!(report["hits"], 2);
    assert_eq!(report["misses"], 2);
    assert_eq!(report["compiler_invocations_avoided"], 2);
    assert_eq!(report["estimated_compiler_duration_avoided_ns"], 2_000);
    assert_eq!(report["compiler"]["miss"]["invocations"], 3);
    assert_eq!(report["compiler"]["miss"]["duration_ns"], 4_000);
    assert_eq!(report["slow_compilations"][0]["crate_name"], "slow_crate");
    assert_eq!(report["slow_compilations"][0]["duration_ns"], 3_000);
    assert_eq!(report["prefetched_actions"], 3);
    assert_eq!(report["downloaded_bytes"], 1024);
    assert_eq!(report["restored_output_files"], 7);
    assert_eq!(report["restored_output_bytes"], 2048);
    assert_eq!(report["reflinked_output_files"], 5);
    assert_eq!(report["reflinked_output_bytes"], 1536);
    assert_eq!(report["copied_output_files"], 2);
    assert_eq!(report["copied_output_bytes"], 512);
    assert_eq!(report["remote_blob_requests"], 4);
    assert_eq!(report["remote_blob_pack_requests"], 2);
    assert_eq!(report["remote_blob_pack_blobs"], 100);
    assert_eq!(report["materialization_duration_ns"], 9);
}

#[test]
fn finds_crate_names_in_transparent_invocations() {
    assert_eq!(
        crate_name_argument(&["--crate-name".into(), "fixture".into()]),
        Some("fixture".into())
    );
    assert_eq!(
        crate_name_argument(&["--crate-name=attached".into()]),
        Some("attached".into())
    );
    assert_eq!(crate_name_argument(&["--version".into()]), None);
}