From f57760c609d636d2e4698a26848f5c990d417265 Mon Sep 17 00:00:00 2001
From: Ben Blum <bblum@andrew.cmu.edu>
Date: Fri, 3 Aug 2012 19:26:25 -0400
Subject: [PATCH] Add task-perf-linked-failure.rs

---
 .../bench/task-perf-jargon-metal-smoke.rs     |  4 +-
 src/test/bench/task-perf-linked-failure.rs    | 67 +++++++++++++++++++
 2 files changed, 69 insertions(+), 2 deletions(-)
 create mode 100644 src/test/bench/task-perf-linked-failure.rs

diff --git a/src/test/bench/task-perf-jargon-metal-smoke.rs b/src/test/bench/task-perf-jargon-metal-smoke.rs
index c2e25c5e5e33a..0542204bf99c5 100644
--- a/src/test/bench/task-perf-jargon-metal-smoke.rs
+++ b/src/test/bench/task-perf-jargon-metal-smoke.rs
@@ -3,12 +3,12 @@
 // Each child task has to enlist as a descendant in each of its ancestor
 // groups, but that shouldn't have to happen for already-dead groups.
 //
-// The filename is a reference; google it in quotes.
+// The filename is a song reference; google it in quotes.
 
 fn child_generation(gens_left: uint) {
     // This used to be O(n^2) in the number of generations that ever existed.
     // With this code, only as many generations are alive at a time as tasks
-    // alive at a time, 
+    // alive at a time,
     do task::spawn_supervised {
         if gens_left & 1 == 1 {
             task::yield(); // shake things up a bit
diff --git a/src/test/bench/task-perf-linked-failure.rs b/src/test/bench/task-perf-linked-failure.rs
new file mode 100644
index 0000000000000..a806950d0f758
--- /dev/null
+++ b/src/test/bench/task-perf-linked-failure.rs
@@ -0,0 +1,67 @@
+/**
+ * Test performance of killing many tasks in a taskgroup.
+ * Along the way, tests various edge cases of ancestor group management.
+ * In particular, this tries to get each grandchild task to hit the
+ * "nobe_is_dead" case in each_ancestor only during task exit, but not during
+ * task spawn. This makes sure that defunct ancestor groups are handled correctly
+ * w.r.t. possibly leaving stale *rust_tasks lying around.
+ */
+
+// Creates in the background 'num_tasks' tasks, all blocked forever.
+// Doesn't return until all such tasks are ready, but doesn't block forever itself.
+fn grandchild_group(num_tasks: uint) {
+    let po = comm::port();
+    let ch = comm::chan(po);
+
+    for num_tasks.times {
+        do task::spawn { // linked
+            comm::send(ch, ());
+            comm::recv(comm::port::<()>()); // block forever
+        }
+    }
+    #error["Grandchild group getting started"];
+    for num_tasks.times {
+        // Make sure all above children are fully spawned; i.e., enlisted in
+        // their ancestor groups.
+        comm::recv(po);
+    }
+    #error["Grandchild group ready to go."];
+    // Master grandchild task exits early.
+}
+
+fn spawn_supervised_blocking(myname: &str, +f: fn~()) {
+    let mut res = none;
+    task::task().future_result(|-r| res = some(r)).supervised().spawn(f);
+    #error["%s group waiting", myname];
+    let x = future::get(option::unwrap(res));
+    assert x == task::success;
+}
+
+fn main(args: ~[~str]) {
+    let args = if os::getenv(~"RUST_BENCH").is_some() {
+        ~[~"", ~"100000"]
+    } else if args.len() <= 1u {
+        ~[~"", ~"100"]
+    } else {
+        copy args
+    };
+
+    let num_tasks = uint::from_str(args[1]).get();
+
+    // Main group #0 waits for unsupervised group #1.
+    // Grandparent group #1 waits for middle group #2, then fails, killing #3.
+    // Middle group #2 creates grandchild_group #3, waits for it to be ready, exits.
+    let x: result::result<(),()> = do task::try { // unlinked
+        do spawn_supervised_blocking("grandparent") {
+            do spawn_supervised_blocking("middle") {
+                grandchild_group(num_tasks);
+            }
+            // When grandchild group is ready to go, make the middle group exit.
+            #error["Middle group wakes up and exits"];
+        }
+        // Grandparent group waits for middle group to be gone, then fails
+        #error["Grandparent group wakes up and fails"];
+        fail;
+    };
+    assert x.is_err();
+}