chore(observability): emit component_sent events by source and service (vectordotdev#17549)

Closes vectordotdev#17580 
Closes vectordotdev#17581 

This is still in draft until I can get the following done.

- [ ] ~~There are way more clones that I am happy with here, especially
since this is in a hot path. These need reducing.~~

The remaining clones that I would like to remove are in the `get_tags`
functions. This didn't seem trivial, and given the fairly positive
regression numbers, I think it should be ok to defer for now.

- [x] Function documentation.
- [ ] Currently source schemas aren't being attached to the event at
runtime, so the service meaning can't be retrieved. That won't work
until this has been done. This will be a separate PR - vectordotdev#17692
- [x] I've only tested this with the kafka sink so far. I think it
should work with all Stream sinks without needing any further
modification - but further testing is needed.
- [x] Tests. A bunch of tests need writing. 
- [x] The Vector source tests are failing I think because we now have
`EventsSent` and `TaggedEventsSent` which both emit
`component_sent_event` events and the test framework doesn't like this.
This needs fixed.
- [ ] We will need to review every sink to ensure they work with this.
All the stream based sinks should, but the others are highly likely to
need some work.

---------

Signed-off-by: Stephen Wakely <[email protected]>

Author: StephenWakely

docs/tutorials/sinks/2_http_sink.md

@@ -366,9 +366,9 @@ impl DriverResponse for BasicResponse {
         EventStatus::Delivered
     }
 
-    fn events_sent(&self) -> CountByteSize {
+    fn events_sent(&self) -> RequestCountByteSize {
         // (events count, byte size)
-        CountByteSize(1, self.byte_size)
+        CountByteSize(1, self.byte_size).into()
     }
 }
 ```

lib/vector-common/Cargo.toml

@@ -46,7 +46,7 @@ bytes = { version = "1.4.0", default-features = false, optional = true }
 chrono-tz = { version = "0.8.2", default-features = false, features = ["serde"] }
 chrono = { version = "0.4", default-features = false, optional = true, features = ["clock"] }
 crossbeam-utils = { version = "0.8.16", default-features = false }
-derivative = "2.1.3"
+derivative = { version = "2.2.0", default-features = false }
 futures = { version = "0.3.28", default-features = false, features = ["std"] }
 indexmap = { version = "~1.9.3", default-features = false }
 metrics = "0.21.0"

lib/vector-common/src/internal_event/cached_event.rs

@@ -0,0 +1,69 @@
+use std::{
+    collections::BTreeMap,
+    sync::{Arc, RwLock},
+};
+
+use derivative::Derivative;
+
+use super::{InternalEventHandle, RegisterInternalEvent};
+
+/// Metrics (eg. `component_sent_event_bytes_total`) may need to emit tags based on
+/// values contained within the events. These tags can't be determined in advance.
+///
+/// Metrics need to be registered and the handle needs to be held onto in order to
+/// prevent them from expiring and being dropped (this would result in the counter
+/// resetting to zero).
+/// `CachedEvent` is used to maintain a store of these registered metrics. When a
+/// new event is emitted for a previously unseen set of tags an event is registered
+/// and stored in the cache.
+#[derive(Derivative)]
+#[derivative(Clone(bound = ""), Default(bound = ""))]
+pub struct RegisteredEventCache<Event: RegisterTaggedInternalEvent> {
+    cache: Arc<
+        RwLock<
+            BTreeMap<
+                <Event as RegisterTaggedInternalEvent>::Tags,
+                <Event as RegisterInternalEvent>::Handle,
+            >,
+        >,
+    >,
+}
+
+/// This trait must be implemented by events that emit dynamic tags. `register` must
+/// be implemented to register an event based on the set of tags passed.
+pub trait RegisterTaggedInternalEvent: RegisterInternalEvent {
+    /// The type that will contain the data necessary to extract the tags
+    /// that will be used when registering the event.
+    type Tags;
+
+    fn register(tags: Self::Tags) -> <Self as RegisterInternalEvent>::Handle;
+}
+
+impl<Event, EventHandle, Data, Tags> RegisteredEventCache<Event>
+where
+    Data: Sized,
+    EventHandle: InternalEventHandle<Data = Data>,
+    Tags: Ord + Clone,
+    Event: RegisterInternalEvent<Handle = EventHandle> + RegisterTaggedInternalEvent<Tags = Tags>,
+{
+    /// Emits the event with the given tags.
+    /// It will register the event and store in the cache if this has not already
+    /// been done.
+    ///
+    /// # Panics
+    ///
+    /// This will panic if the lock is poisoned.
+    pub fn emit(&self, tags: &Tags, value: Data) {
+        let read = self.cache.read().unwrap();
+        if let Some(event) = read.get(tags) {
+            event.emit(value);
+        } else {
+            let event = <Event as RegisterTaggedInternalEvent>::register(tags.clone());
+            event.emit(value);
+
+            // Ensure the read lock is dropped so we can write.
+            drop(read);
+            self.cache.write().unwrap().insert(tags.clone(), event);
+        }
+    }
+}

lib/vector-common/src/internal_event/events_sent.rs

@@ -1,7 +1,11 @@
+use std::sync::Arc;
+
 use metrics::{register_counter, Counter};
 use tracing::trace;
 
-use super::{CountByteSize, Output, SharedString};
+use crate::{config::ComponentKey, request_metadata::EventCountTags};
+
+use super::{CountByteSize, OptionalTag, Output, SharedString};
 
 pub const DEFAULT_OUTPUT: &str = "_default";
 
@@ -44,3 +48,62 @@ impl From<Output> for EventsSent {
         Self { output: output.0 }
     }
 }
+
+/// Makes a list of the tags to use with the events sent event.
+fn make_tags(
+    source: &OptionalTag<Arc<ComponentKey>>,
+    service: &OptionalTag<String>,
+) -> Vec<(&'static str, String)> {
+    let mut tags = Vec::new();
+    if let OptionalTag::Specified(tag) = source {
+        tags.push((
+            "source",
+            tag.as_ref()
+                .map_or_else(|| "-".to_string(), |tag| tag.id().to_string()),
+        ));
+    }
+
+    if let OptionalTag::Specified(tag) = service {
+        tags.push(("service", tag.clone().unwrap_or("-".to_string())));
+    }
+
+    tags
+}
+
+crate::registered_event!(
+    TaggedEventsSent {
+        source: OptionalTag<Arc<ComponentKey>>,
+        service: OptionalTag<String>,
+    } => {
+        events: Counter = {
+            register_counter!("component_sent_events_total", &make_tags(&self.source, &self.service))
+        },
+        event_bytes: Counter = {
+            register_counter!("component_sent_event_bytes_total", &make_tags(&self.source, &self.service))
+        },
+    }
+
+    fn emit(&self, data: CountByteSize) {
+        let CountByteSize(count, byte_size) = data;
+        trace!(message = "Events sent.", %count, %byte_size);
+
+        self.events.increment(count as u64);
+        self.event_bytes.increment(byte_size.get() as u64);
+    }
+
+    fn register(tags: EventCountTags) {
+        super::register(TaggedEventsSent::new(
+            tags,
+        ))
+    }
+);
+
+impl TaggedEventsSent {
+    #[must_use]
+    pub fn new(tags: EventCountTags) -> Self {
+        Self {
+            source: tags.source,
+            service: tags.service,
+        }
+    }
+}

lib/vector-common/src/internal_event/mod.rs

@@ -1,18 +1,25 @@
 mod bytes_received;
 mod bytes_sent;
+mod cached_event;
 pub mod component_events_dropped;
 mod events_received;
 mod events_sent;
+mod optional_tag;
 mod prelude;
 pub mod service;
 
+use std::ops::{Add, AddAssign};
+
 pub use metrics::SharedString;
 
 pub use bytes_received::BytesReceived;
 pub use bytes_sent::BytesSent;
+#[allow(clippy::module_name_repetitions)]
+pub use cached_event::{RegisterTaggedInternalEvent, RegisteredEventCache};
 pub use component_events_dropped::{ComponentEventsDropped, INTENTIONAL, UNINTENTIONAL};
 pub use events_received::EventsReceived;
-pub use events_sent::{EventsSent, DEFAULT_OUTPUT};
+pub use events_sent::{EventsSent, TaggedEventsSent, DEFAULT_OUTPUT};
+pub use optional_tag::OptionalTag;
 pub use prelude::{error_stage, error_type};
 pub use service::{CallError, PollReadyError};
 
@@ -109,9 +116,24 @@ pub struct ByteSize(pub usize);
 pub struct Count(pub usize);
 
 /// Holds the tuple `(count_of_events, estimated_json_size_of_events)`.
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct CountByteSize(pub usize, pub JsonSize);
 
+impl AddAssign for CountByteSize {
+    fn add_assign(&mut self, rhs: Self) {
+        self.0 += rhs.0;
+        self.1 += rhs.1;
+    }
+}
+
+impl Add<CountByteSize> for CountByteSize {
+    type Output = CountByteSize;
+
+    fn add(self, rhs: CountByteSize) -> Self::Output {
+        CountByteSize(self.0 + rhs.0, self.1 + rhs.1)
+    }
+}
+
 // Wrapper types used to hold parameters for registering events
 
 pub struct Output(pub Option<SharedString>);
@@ -196,6 +218,9 @@ macro_rules! registered_event {
 
         fn emit(&$slf:ident, $data_name:ident: $data:ident)
             $emit_body:block
+
+        $(fn register($tags_name:ident: $tags:ty)
+            $register_body:block)?
     ) => {
         paste::paste!{
             #[derive(Clone)]
@@ -223,6 +248,17 @@ macro_rules! registered_event {
                 fn emit(&$slf, $data_name: $data)
                     $emit_body
             }
+
+            $(impl $crate::internal_event::cached_event::RegisterTaggedInternalEvent for $event {
+                type Tags = $tags;
+
+                fn register(
+                    $tags_name: $tags,
+                ) -> <TaggedEventsSent as super::RegisterInternalEvent>::Handle {
+                    $register_body
+                }
+            })?
+
         }
     };
 }

lib/vector-common/src/internal_event/optional_tag.rs

@@ -0,0 +1,14 @@
+/// The user can configure whether a tag should be emitted. If they configure it to
+/// be emitted, but the value doesn't exist - we should emit the tag but with a value
+/// of `-`.
+#[derive(Clone, Debug, PartialEq, PartialOrd, Eq, Ord, Hash)]
+pub enum OptionalTag<T> {
+    Ignored,
+    Specified(Option<T>),
+}
+
+impl<T> From<Option<T>> for OptionalTag<T> {
+    fn from(value: Option<T>) -> Self {
+        Self::Specified(value)
+    }
+}