Improve follows-from and parent span relationships

Cargo.lock

@@ -127,9 +127,9 @@ dependencies = [
 
 [[package]]
 name = "actix-server"
-version = "2.0.0-beta.9"
+version = "2.0.0-rc.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "411dd3296dd317ff5eff50baa13f31923ea40ec855dd7f2d3ed8639948f0195f"
+checksum = "78c9b22794b8af1c2e02434873ef858f2a7db40dbbf861ce77a04cd81ac6b767"
 dependencies = [
  "actix-rt",
  "actix-service",
@@ -137,7 +137,7 @@ dependencies = [
  "futures-core",
  "futures-util",
  "log",
- "mio",
+ "mio 0.8.0",
  "num_cpus",
  "socket2",
  "tokio",
@@ -1042,9 +1042,9 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.108"
+version = "0.2.109"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8521a1b57e76b1ec69af7599e75e38e7b7fad6610f037db8c79b127201b5d119"
+checksum = "f98a04dce437184842841303488f70d0188c5f51437d2a834dc097eafa909a01"
 
 [[package]]
 name = "linked-hash-map"
@@ -1154,6 +1154,19 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "mio"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ba272f85fa0b41fc91872be579b3bbe0f56b792aa361a380eb669469f68dafb2"
+dependencies = [
+ "libc",
+ "log",
+ "miow",
+ "ntapi",
+ "winapi",
+]
+
 [[package]]
 name = "miow"
 version = "0.3.7"
@@ -1442,9 +1455,9 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.32"
+version = "1.0.33"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ba508cc11742c0dc5c1659771673afbab7a0efab23aa17e854cbab0837ed0b43"
+checksum = "fb37d2df5df740e582f28f8560cf425f52bb267d872fe58358eadb554909f07a"
 dependencies = [
  "unicode-xid",
 ]
@@ -2096,7 +2109,7 @@ dependencies = [
  "bytes",
  "libc",
  "memchr",
- "mio",
+ "mio 0.7.14",
  "num_cpus",
  "once_cell",
  "parking_lot",
@@ -2302,9 +2315,9 @@ dependencies = [
 
 [[package]]
 name = "tracing-awc"
-version = "0.1.0-beta.11"
+version = "0.1.0-beta.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7b79f7237bb46dbb931e2daafc1b89371dcf0759054ec9a2b1df40096a937a8f"
+checksum = "8093ad66e1a7a3832eb450180abaf1e5f62ace52ff547b46a0b3fddfda8abf78"
 dependencies = [
  "actix-http",
  "actix-service",

src/id_or_span.rs

@@ -0,0 +1,34 @@
+use tracing::{Id, Span};
+
+pub(crate) enum IdOrSpan {
+    Id(Option<Id>),
+    Span(Span),
+}
+
+impl IdOrSpan {
+    pub(crate) fn take(&mut self) -> Self {
+        std::mem::replace(self, IdOrSpan::Id(None))
+    }
+
+    pub(crate) fn from_id(id: Option<Id>) -> Self {
+        IdOrSpan::Id(id)
+    }
+
+    fn span(&self) -> Option<&Span> {
+        match self {
+            IdOrSpan::Span(ref span) => Some(span),
+            _ => None,
+        }
+    }
+
+    pub(crate) fn as_span(&mut self, f: impl Fn(Option<Id>) -> Span) -> &Span {
+        let span = match self.take() {
+            Self::Id(opt) => f(opt),
+            Self::Span(span) => span,
+        };
+
+        *self = Self::Span(span);
+
+        self.span().expect("Span should always exist")
+    }
+}

src/main.rs

@@ -31,6 +31,7 @@ mod error;
 mod exiftool;
 mod ffmpeg;
 mod file;
+mod id_or_span;
 mod init_tracing;
 mod magick;
 mod map_error;

src/process.rs

@@ -1,4 +1,4 @@
-use crate::store::Store;
+use crate::{id_or_span::IdOrSpan, store::Store};
 use actix_rt::task::JoinHandle;
 use actix_web::web::Bytes;
 use std::{
@@ -13,14 +13,14 @@ use tokio::{
     sync::oneshot::{channel, Receiver},
 };
 use tracing::Instrument;
-use tracing::Span;
+use tracing::{Id, Span};
 
 #[derive(Debug)]
 struct StatusError;
 
 pub(crate) struct Process {
     child: Child,
-    span: Span,
+    id: Option<Id>,
 }
 
 struct DropHandle {
@@ -31,7 +31,7 @@ pin_project_lite::pin_project! {
     struct ProcessRead<I> {
         #[pin]
         inner: I,
-        span: Span,
+        span: IdOrSpan,
         err_recv: Receiver<std::io::Error>,
         err_closed: bool,
         handle: DropHandle,
@@ -46,21 +46,19 @@ impl Process {
     fn spawn_span(&self) -> Span {
         let span = tracing::info_span!(parent: None, "Spawned command writer",);
 
-        span.follows_from(self.span.clone());
+        span.follows_from(self.id.clone());
 
         span
     }
 
+    #[tracing::instrument(name = "Spawning Command")]
     pub(crate) fn spawn(cmd: &mut Command) -> std::io::Result<Self> {
         let cmd = cmd.stdin(Stdio::piped()).stdout(Stdio::piped());
 
-        let span = tracing::info_span!(
+        cmd.spawn().map(|child| Process {
-            "Spawning Command",
+            child,
-            command = &tracing::field::debug(&cmd),
+            id: Span::current().id(),
-            exception.message = &tracing::field::Empty,
+        })
-            exception.details = &tracing::field::Empty,
-        );
-        cmd.spawn().map(|child| Process { child, span })
     }
 
     pub(crate) async fn wait(mut self) -> std::io::Result<()> {
@@ -104,7 +102,7 @@ impl Process {
 
         Some(ProcessRead {
             inner: stdout,
-            span: self.span,
+            span: IdOrSpan::from_id(self.id),
             err_recv: rx,
             err_closed: false,
             handle: DropHandle { inner: handle },
@@ -137,7 +135,7 @@ impl Process {
 
         Some(ProcessRead {
             inner: stdout,
-            span: self.span,
+            span: IdOrSpan::from_id(self.id),
             err_recv: rx,
             err_closed: false,
             handle: DropHandle { inner: handle },
@@ -181,7 +179,7 @@ impl Process {
 
         Some(ProcessRead {
             inner: stdout,
-            span: self.span,
+            span: IdOrSpan::from_id(self.id),
             err_recv: rx,
             err_closed: false,
             handle: DropHandle { inner: handle },
@@ -200,11 +198,16 @@ where
     ) -> Poll<std::io::Result<()>> {
         let this = self.as_mut().project();
 
-        let span = this.span;
         let err_recv = this.err_recv;
         let err_closed = this.err_closed;
         let inner = this.inner;
 
+        let span = this.span.as_span(|id| {
+            let span = tracing::info_span!("Processing Command");
+            span.follows_from(id);
+            span
+        });
+
         span.in_scope(|| {
             if !*err_closed {
                 if let Poll::Ready(res) = Pin::new(err_recv).poll(cx) {