Divide test run between multiple travis builds.

Author: Yamakaky

.travis.yml

@@ -12,6 +12,10 @@ matrix:
   fast_finish: true
   include:
     # Linux builders, all docker images
+    - env: IMAGE=x86_64-gnu-llvm-3.7 ALLOW_PR=1 RUST_BACKTRACE=1 BOOTSTRAP_ARGS="--slice 0 --number-slices 4"
+    - env: IMAGE=x86_64-gnu-llvm-3.7 ALLOW_PR=1 RUST_BACKTRACE=1 BOOTSTRAP_ARGS="--slice 1 --number-slices 4"
+    - env: IMAGE=x86_64-gnu-llvm-3.7 ALLOW_PR=1 RUST_BACKTRACE=1 BOOTSTRAP_ARGS="--slice 2 --number-slices 4"
+    - env: IMAGE=x86_64-gnu-llvm-3.7 ALLOW_PR=1 RUST_BACKTRACE=1 BOOTSTRAP_ARGS="--slice 3 --number-slices 4"
     - env: IMAGE=android DEPLOY=1
     - env: IMAGE=armhf-gnu
     - env: IMAGE=cross DEPLOY=1
@@ -33,7 +37,6 @@ matrix:
     - env: IMAGE=x86_64-gnu-aux
     - env: IMAGE=x86_64-gnu-debug
     - env: IMAGE=x86_64-gnu-nopt
-    - env: IMAGE=x86_64-gnu-llvm-3.7 ALLOW_PR=1 RUST_BACKTRACE=1
     - env: IMAGE=x86_64-gnu-distcheck
     - env: IMAGE=x86_64-gnu-incremental
 

src/bootstrap/flags.rs

@@ -60,6 +60,7 @@ pub enum Subcommand {
     Test {
         paths: Vec<PathBuf>,
         test_args: Vec<String>,
+        split: Option<(usize, usize)>,
     },
     Bench {
         paths: Vec<PathBuf>,
@@ -224,10 +225,27 @@ To learn more about a subcommand, run `./x.py <command> -h`
             }
             "test" => {
                 opts.optmulti("", "test-args", "extra arguments", "ARGS");
+                opts.optopt("",
+                            "number-slices",
+                            "divide the test run in N segments",
+                            "N");
+                opts.optopt("",
+                            "slice",
+                            "run ith segment",
+                            "i");
                 m = parse(&opts);
+                let split = match (m.opt_str("slice"), m.opt_str("number-slices")) {
+                    (Some(raw_slice), Some(raw_nb_slices)) => {
+                        Some((raw_slice.parse().unwrap(),
+                              raw_nb_slices.parse().unwrap()))
+                    }
+                    (None, None) => None,
+                    _ => panic!("You must provide --slice and --number-slices"),
+                };
                 Subcommand::Test {
                     paths: remaining_as_path(&m),
                     test_args: m.opt_strs("test-args"),
+                    split: split,
                 }
             }
             "bench" => {

src/bootstrap/step.rs

@@ -28,6 +28,7 @@
 
 use std::collections::{HashMap, HashSet};
 use std::mem;
+use std::cmp::min;
 
 use check::{self, TestKind};
 use compile;
@@ -982,10 +983,14 @@ invalid rule dependency graph detected, was a rule added and maybe typo'd?
         // product of the two and then create a step based off them. Note that
         // the stage each step is associated was specified with the `--step`
         // flag on the command line.
+        let mut split = None;
         let (kind, paths) = match self.build.flags.cmd {
             Subcommand::Build { ref paths } => (Kind::Build, &paths[..]),
             Subcommand::Doc { ref paths } => (Kind::Doc, &paths[..]),
-            Subcommand::Test { ref paths, test_args: _ } => (Kind::Test, &paths[..]),
+            Subcommand::Test { ref paths, test_args: _, split: new_split } => {
+                split = new_split;
+                (Kind::Test, &paths[..])
+            }
             Subcommand::Bench { ref paths, test_args: _ } => (Kind::Bench, &paths[..]),
             Subcommand::Dist { ref paths, install } => {
                 if install {
@@ -996,8 +1001,7 @@ invalid rule dependency graph detected, was a rule added and maybe typo'd?
             }
             Subcommand::Clean => panic!(),
         };
-
-        self.rules.values().filter(|rule| rule.kind == kind).filter(|rule| {
+        let steps = self.rules.values().filter(|rule| rule.kind == kind).filter(|rule| {
             (paths.len() == 0 && rule.default) || paths.iter().any(|path| {
                 path.ends_with(rule.path)
             })
@@ -1041,7 +1045,23 @@ invalid rule dependency graph detected, was a rule added and maybe typo'd?
                     self.sbuild.name(rule.name).target(target).host(host)
                 })
             })
-        }).collect()
+        }).collect::<Vec<_>>();
+
+        if let Some((offset, nb_split)) = split {
+            assert!(nb_split <= steps.len(),
+                    "you asked for {} slices but there are only {} tasks",
+                    nb_split,
+                    steps.len());
+            let index = |i| {
+                i * (steps.len() / nb_split) + min(steps.len() % nb_split, i)
+            };
+            let from = index(offset);
+            let to = index(offset + 1);
+            steps[from..to].into()
+        } else {
+            steps
+        }
+
     }
 
     /// Execute all top-level targets indicated by `steps`.