Integrate Tokio v1.46.1 task spawn locations (#2)

Tokio PRs tokio-rs/tokio#7417 and tokio-rs/tokio#7440 add the source
code locations at which a task was spawned to the `TaskMeta` structure
provided to the runtime task hook callbacks. These will give us the
ability to associate task IDs (which identify a task at runtime) with a
source code location in the instrumented program, which is going to make
everything a lot easier. This PR picks up those changes and updates the
minimum Tokio dependency to 1.46.1.

Closes #1

Author: hawkw

Cargo.lock

@@ -9,11 +9,11 @@ license = "MIT OR Apache-2.0"
 
 [dependencies]
 thiserror = "2.0.12"
-tokio = { version = "1.45.1", features = ["rt"] }
+tokio = { version = "1.46.1", features = ["rt"] }
 usdt = "0.5.0"
 
 [dev-dependencies.tokio]
-version = "1.45.1"
+version = "1.46.1"
 features = ["rt", "rt-multi-thread", "time", "signal", "macros"]
 
 [lints.rust]

Cargo.toml

@@ -1,3 +1,4 @@
+#!/usr/sbin/dtrace -s
 /*
  * When a task is spawned, count the stack that spawned it.
  */

examples/count-spawns.d

@@ -1,11 +1,11 @@
+#!/usr/sbin/dtrace -s
 /*
  * This script profiles the following:
  * - distribution of poll durations across all tasks
  * - distribution of total duration for which a task exists
  * - distribution of total duration for which a task was actively being polled
  */
 
-
 tokio$1:::task-spawn
 {
     task_poll_times[arg0] = 0;
@@ -21,13 +21,13 @@ tokio$1:::task-poll-end
 /self->poll_start_ts/
 {
     duration = timestamp - self->poll_start_ts;
-    @durations["task poll duration"] = quantize(duration);
+    @durations["task poll duration", copyinstr(arg1), arg2, arg3] = quantize(duration);
     task_poll_times[arg0] += duration;
     self->poll_start_ts = 0;
 }
 
 tokio$1:::task-terminate
 {
-    @durations["task total lifetime"] = quantize(timestamp - task_spawn_times[arg0]);
-    @durations["task active time"] = quantize(task_poll_times[arg0]);
+    @durations["task total lifetime", copyinstr(arg1), arg2, arg3] = quantize(timestamp - task_spawn_times[arg0]);
+    @durations["task active time", copyinstr(arg1), arg2, arg3] = quantize(task_poll_times[arg0]);
 }

examples/pollstats.d

@@ -409,22 +409,22 @@ pub mod hooks {
 
     /// Hook function to be used in [`tokio::runtime::Builder::on_task_spawn`].
     pub fn on_task_spawn(meta: &TaskMeta<'_>) {
-        probes::task__spawn!(|| meta_to_id(meta));
+        probes::task__spawn!(|| unpack_meta(meta));
     }
 
     /// Hook function to be used in [`tokio::runtime::Builder::on_before_task_poll`].
     pub fn on_before_task_poll(meta: &TaskMeta<'_>) {
-        probes::task__poll__start!(|| meta_to_id(meta));
+        probes::task__poll__start!(|| unpack_meta(meta));
     }
 
     /// Hook function to be used in [`tokio::runtime::Builder::on_after_task_poll`].
     pub fn on_after_task_poll(meta: &TaskMeta<'_>) {
-        probes::task__poll__end!(|| meta_to_id(meta));
+        probes::task__poll__end!(|| unpack_meta(meta));
     }
 
     /// Hook function to be used in [`tokio::runtime::Builder::on_task_terminate`].
     pub fn on_task_terminate(meta: &TaskMeta<'_>) {
-        probes::task__terminate!(|| meta_to_id(meta));
+        probes::task__terminate!(|| unpack_meta(meta));
     }
 
     /// Hook function to be used in [`tokio::runtime::Builder::on_thread_start`].
@@ -448,26 +448,36 @@ pub mod hooks {
     }
 
     #[inline]
-    fn meta_to_id(meta: &TaskMeta<'_>) -> u64 {
+    fn unpack_meta(meta: &TaskMeta<'_>) -> (u64, String, u32, u32) {
+        let id = id_to_u64(meta.id());
+        let location = meta.spawned_at();
+        let file = location.file().to_string();
+        let line = location.line();
+        let col = location.column();
+        (id, file, line, col)
+    }
+
+    #[inline]
+    fn id_to_u64(id: tokio::task::Id) -> u64 {
         unsafe {
             // SAFETY: Based on training and experience, I know that a
             // `tokio::task::Id` is represented as a single `NonZeroU64`.
             union TrustMeOnThis {
                 id: tokio::task::Id,
                 int: NonZeroU64,
             }
-            TrustMeOnThis { id: meta.id() }.int.get()
+            TrustMeOnThis { id }.int.get()
         }
     }
 }
 
 #[usdt::provider(provider = "tokio")]
 #[allow(non_snake_case)]
 mod probes {
-    fn task__spawn(task_id: u64) {}
-    fn task__poll__start(task_id: u64) {}
-    fn task__poll__end(task_id: u64) {}
-    fn task__terminate(task_id: u64) {}
+    fn task__spawn(task_id: u64, file: String, line: u32, col: u32) {}
+    fn task__poll__start(task_id: u64, file: String, line: u32, col: u32) {}
+    fn task__poll__end(task_id: u64, file: String, line: u32, col: u32) {}
+    fn task__terminate(task_id: u64, file: String, line: u32, col: u32) {}
 
     fn worker__thread__start() {}
     fn worker__thread__stop() {}