test: tighten panic isolation classification

crates/obs/src/telemetry/isolation_probe_tests.rs

@@ -0,0 +1,811 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Test-only diagnostic isolation prototype. Nothing here is a GET hook.
+
+use super::local::build_json_log_layer;
+use opentelemetry::{
+    Context, InstrumentationScope, KeyValue,
+    baggage::BaggageExt,
+    logs::AnyValue,
+    trace::{SpanContext, SpanId, TraceContextExt, TraceFlags, TraceId, TraceState},
+};
+use opentelemetry_appender_tracing::layer::{OpenTelemetryTracingBridge, TracingSpanAttributes};
+use opentelemetry_sdk::{
+    Resource,
+    error::OTelSdkResult,
+    logs::{LogBatch, LogExporter, SdkLogRecord, SdkLoggerProvider},
+};
+use serde_json::Value;
+use std::{
+    collections::BTreeSet,
+    io::{self, Write},
+    sync::{Arc, Mutex},
+};
+use tracing::{Dispatch, dispatcher};
+use tracing_subscriber::{fmt::format::FmtSpan, layer::SubscriberExt};
+
+const TARGET: &str = "rustfs_isolation_probe_test";
+const FAKE_URI: &str = "/synthetic/private-object";
+const FAKE_AUTH: &str = "synthetic-private-header";
+
+#[derive(Clone, Debug, Default)]
+struct MemoryWriter(Arc<Mutex<Vec<u8>>>);
+
+impl<'a> tracing_subscriber::fmt::MakeWriter<'a> for MemoryWriter {
+    type Writer = Self;
+
+    fn make_writer(&'a self) -> Self::Writer {
+        self.clone()
+    }
+}
+
+impl Write for MemoryWriter {
+    fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
+        self.0.lock().expect("capture JSON output").extend_from_slice(bytes);
+        Ok(bytes.len())
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        Ok(())
+    }
+}
+
+#[derive(Clone, Debug, Default)]
+struct MemoryExporter {
+    records: Arc<Mutex<Vec<(SdkLogRecord, InstrumentationScope)>>>,
+    resource: Arc<Mutex<Option<Resource>>>,
+}
+
+impl LogExporter for MemoryExporter {
+    async fn export(&self, batch: LogBatch<'_>) -> OTelSdkResult {
+        self.records
+            .lock()
+            .expect("capture exporter records")
+            .extend(batch.iter().map(|(record, scope)| (record.clone(), scope.clone())));
+        Ok(())
+    }
+
+    fn set_resource(&mut self, resource: &Resource) {
+        *self.resource.lock().expect("capture exporter resource") = Some(resource.clone());
+    }
+}
+
+struct Sinks {
+    dispatch: Dispatch,
+    json: MemoryWriter,
+    exporter: MemoryExporter,
+    _provider: SdkLoggerProvider,
+}
+
+impl Sinks {
+    fn new(span_list: bool, enrich_spans: bool) -> Self {
+        let json = MemoryWriter::default();
+        let exporter = MemoryExporter::default();
+        let provider = SdkLoggerProvider::builder()
+            .with_resource(Resource::builder_empty().build())
+            .with_simple_exporter(exporter.clone())
+            .build();
+        let bridge = OpenTelemetryTracingBridge::builder(&provider);
+        let bridge = if enrich_spans {
+            bridge.with_tracing_span_attributes(TracingSpanAttributes::all()).build()
+        } else {
+            bridge.build()
+        };
+        let subscriber = tracing_subscriber::registry()
+            .with(build_json_log_layer(json.clone(), false, FmtSpan::NONE, span_list))
+            .with(bridge);
+        Self {
+            dispatch: Dispatch::new(subscriber),
+            json,
+            exporter,
+            _provider: provider,
+        }
+    }
+
+    fn json_records(&self) -> Vec<Value> {
+        let bytes = self.json.0.lock().expect("capture JSON output").clone();
+        let text = String::from_utf8(bytes).expect("JSON output is UTF-8");
+        text.lines()
+            .map(|line| serde_json::from_str(line).expect("each captured record is JSON"))
+            .collect()
+    }
+
+    fn exported_records(&self) -> Vec<(SdkLogRecord, InstrumentationScope)> {
+        self.exporter.records.lock().expect("capture exporter records").clone()
+    }
+}
+
+fn fake_ambient_context() -> Context {
+    Context::new()
+        .with_remote_span_context(SpanContext::new(
+            TraceId::from(17),
+            SpanId::from(19),
+            TraceFlags::SAMPLED,
+            true,
+            TraceState::default(),
+        ))
+        .with_baggage([KeyValue::new("synthetic-secret", FAKE_AUTH)])
+}
+
+fn emit_root_event(phase: u64) {
+    tracing::info!(target: TARGET, parent: None, expected = 1024_u64, emitted = 64_u64, phase, "diagnostic fixture");
+}
+
+// This prototype is synchronous and must use a fresh, span-free dispatcher.
+fn emit_candidate(dispatch: &Dispatch, phase: u64) {
+    let _context_guard = Context::new().attach();
+    dispatcher::with_default(dispatch, || {
+        assert!(
+            Context::current().baggage().get("synthetic-secret").is_none(),
+            "ambient baggage must be hidden"
+        );
+        assert!(!Context::current().has_active_span(), "ambient OTEL span must be hidden");
+        emit_root_event(phase);
+    });
+}
+
+#[test]
+fn parent_none_alone_keeps_json_parent_and_otel_thread_context() {
+    let sinks = Sinks::new(true, true);
+    let _context_guard = fake_ambient_context().attach();
+
+    dispatcher::with_default(&sinks.dispatch, || {
+        let span = tracing::info_span!("http-request", uri = FAKE_URI, authorization = FAKE_AUTH, request_id = "synthetic-id");
+        let _span_guard = span.enter();
+        emit_root_event(0);
+    });
+
+    let json = sinks.json_records();
+    let logs = sinks.exported_records();
+    assert_eq!(json.len(), 1, "the control event must be captured");
+    assert_eq!(logs.len(), 1, "the control event must reach the exporter");
+    assert_eq!(json[0]["span"]["uri"].as_str(), Some(FAKE_URI));
+    assert_eq!(json[0]["span"]["authorization"].as_str(), Some(FAKE_AUTH));
+    let context = logs[0].0.trace_context().expect("ambient OTEL trace context is present");
+    assert_eq!(context.trace_id, TraceId::from(17));
+    assert_eq!(context.span_id, SpanId::from(19));
+}
+
+#[test]
+fn diagnostic_fixture_is_detached_for_both_sinks_and_restores_context() {
+    for span_list in [false, true] {
+        for enrich_spans in [false, true] {
+            let outer = Sinks::new(span_list, enrich_spans);
+            let isolated = Sinks::new(span_list, enrich_spans);
+            let _context_guard = fake_ambient_context().attach();
+
+            dispatcher::with_default(&outer.dispatch, || {
+                let span =
+                    tracing::info_span!("http-request", uri = FAKE_URI, authorization = FAKE_AUTH, request_id = "synthetic-id");
+                let _span_guard = span.enter();
+                for phase in [0, 1] {
+                    emit_candidate(&isolated.dispatch, phase);
+                    assert_eq!(tracing::Span::current().id(), span.id(), "restore the outer tracing span");
+                    assert_eq!(Context::current().span().span_context().trace_id(), TraceId::from(17));
+                    assert!(Context::current().baggage().get("synthetic-secret").is_some());
+                }
+            });
+
+            assert!(outer.json_records().is_empty(), "diagnostic events must not reach the outer JSON sink");
+            assert!(outer.exported_records().is_empty(), "diagnostic events must not reach the outer exporter");
+            let json = isolated.json_records();
+            let logs = isolated.exported_records();
+            assert_eq!(json.len(), 2, "both diagnostic events must reach the isolated JSON sink");
+            assert_eq!(logs.len(), 2, "both diagnostic events must reach the isolated exporter");
+
+            let json_keys: BTreeSet<&str> = [
+                "timestamp",
+                "level",
+                "target",
+                "filename",
+                "line_number",
+                "threadName",
+                "threadId",
+                "message",
+                "expected",
+                "emitted",
+                "phase",
+            ]
+            .into_iter()
+            .collect();
+            let otel_keys: BTreeSet<&str> = [
+                "code.namespace",
+                "code.filepath",
+                "code.filename",
+                "code.lineno",
+                "expected",
+                "emitted",
+                "phase",
+            ]
+            .into_iter()
+            .collect();
+            let resource = isolated.exporter.resource.lock().expect("capture exporter resource");
+            assert!(
+                resource
+                    .as_ref()
+                    .expect("resource was passed to exporter")
+                    .iter()
+                    .next()
+                    .is_none()
+            );
+            for (phase, (entry, (log, scope))) in [0_u64, 1].into_iter().zip(json.iter().zip(&logs)) {
+                let object = entry.as_object().expect("diagnostic JSON must be an object");
+                assert!(object.keys().all(|key| json_keys.contains(key.as_str())), "unexpected JSON field");
+                assert_eq!(entry["target"].as_str(), Some(TARGET));
+                assert_eq!(entry["phase"].as_u64(), Some(phase));
+                assert_eq!(entry["expected"].as_u64(), Some(1024));
+                assert_eq!(entry["emitted"].as_u64(), Some(64));
+                assert!(!entry.to_string().contains(FAKE_URI));
+                assert!(!entry.to_string().contains(FAKE_AUTH));
+
+                assert_eq!(log.target().map(|target| target.as_ref()), Some(TARGET));
+                assert!(log.trace_context().is_none(), "ambient OTEL context must not reach the exporter");
+                assert_eq!(scope.name(), "");
+                assert!(scope.version().is_none());
+                assert!(scope.schema_url().is_none());
+                assert!(scope.attributes().next().is_none());
+                assert!(
+                    log.attributes_iter().all(|(key, _)| otel_keys.contains(key.as_str())),
+                    "unexpected OTEL field"
+                );
+                let phase = i64::try_from(phase).expect("fixture phase fits into i64");
+                assert!(
+                    log.attributes_iter()
+                        .any(|(key, value)| key.as_str() == "phase" && value == &AnyValue::Int(phase))
+                );
+                assert!(
+                    log.attributes_iter()
+                        .any(|(key, value)| key.as_str() == "expected" && value == &AnyValue::Int(1024))
+                );
+                assert!(
+                    log.attributes_iter()
+                        .any(|(key, value)| key.as_str() == "emitted" && value == &AnyValue::Int(64))
+                );
+                assert!(!format!("{log:?}").contains(FAKE_URI));
+                assert!(!format!("{log:?}").contains(FAKE_AUTH));
+            }
+        }
+    }
+}
+
+mod async_isolation {
+    use super::*;
+    use std::{
+        collections::HashSet,
+        future::pending,
+        panic::{AssertUnwindSafe, catch_unwind},
+        sync::atomic::{AtomicBool, AtomicUsize, Ordering},
+        time::Duration,
+    };
+    use tracing::{Instrument, instrument::WithSubscriber};
+    use tracing_subscriber::EnvFilter;
+
+    const PARTICIPANTS: usize = 4;
+    const WAIT: Duration = Duration::from_secs(30);
+
+    fn parent_span(dispatch: &Dispatch) -> tracing::Span {
+        dispatcher::with_default(dispatch, || {
+            tracing::info_span!("http-request", uri = FAKE_URI, authorization = FAKE_AUTH, request_id = "synthetic-id")
+        })
+    }
+
+    fn observe_once(dispatch: &Dispatch, parent: &Option<tracing::span::Id>, phase: u64) {
+        let _context = fake_ambient_context().attach();
+        assert_eq!(&tracing::Span::current().id(), parent);
+        emit_candidate(dispatch, phase);
+        assert_eq!(&tracing::Span::current().id(), parent);
+        assert_eq!(Context::current().span().span_context().trace_id(), TraceId::from(17));
+        assert!(Context::current().baggage().get("synthetic-secret").is_some());
+    }
+
+    fn assert_isolated_events(sinks: &Sinks, expected_phases: &[u64]) {
+        let json = sinks.json_records();
+        let logs = sinks.exported_records();
+        assert_eq!(json.len(), expected_phases.len(), "each event must reach the isolated JSON sink");
+        assert_eq!(logs.len(), expected_phases.len(), "each event must reach the isolated exporter");
+        let json_keys: BTreeSet<&str> = [
+            "timestamp",
+            "level",
+            "target",
+            "filename",
+            "line_number",
+            "threadName",
+            "threadId",
+            "message",
+            "expected",
+            "emitted",
+            "phase",
+        ]
+        .into_iter()
+        .collect();
+        let otel_keys: BTreeSet<&str> = [
+            "code.namespace",
+            "code.filepath",
+            "code.filename",
+            "code.lineno",
+            "expected",
+            "emitted",
+            "phase",
+        ]
+        .into_iter()
+        .collect();
+        let mut json_phases = Vec::new();
+        for entry in &json {
+            let object = entry.as_object().expect("diagnostic JSON must be an object");
+            assert!(object.keys().all(|key| json_keys.contains(key.as_str())), "unexpected JSON field");
+            assert_eq!(entry["target"].as_str(), Some(TARGET));
+            assert_eq!(entry["message"].as_str(), Some("diagnostic fixture"));
+            assert_eq!(entry["expected"].as_u64(), Some(1024));
+            assert_eq!(entry["emitted"].as_u64(), Some(64));
+            json_phases.push(entry["phase"].as_u64().expect("phase is an unsigned number"));
+            assert!(!entry.to_string().contains(FAKE_URI));
+            assert!(!entry.to_string().contains(FAKE_AUTH));
+        }
+        let mut otel_phases = Vec::new();
+        for (log, scope) in &logs {
+            assert_eq!(log.target().map(|target| target.as_ref()), Some(TARGET));
+            assert!(log.trace_context().is_none());
+            assert!(log.attributes_iter().all(|(key, _)| otel_keys.contains(key.as_str())));
+            assert!(matches!(log.body(), Some(AnyValue::String(body)) if body.as_str() == "diagnostic fixture"));
+            assert!(
+                log.attributes_iter()
+                    .any(|(key, value)| key.as_str() == "expected" && value == &AnyValue::Int(1024))
+            );
+            assert!(
+                log.attributes_iter()
+                    .any(|(key, value)| key.as_str() == "emitted" && value == &AnyValue::Int(64))
+            );
+            let phase = log
+                .attributes_iter()
+                .find_map(|(key, value)| match (key.as_str(), value) {
+                    ("phase", AnyValue::Int(phase)) => u64::try_from(*phase).ok(),
+                    _ => None,
+                })
+                .expect("phase is a nonnegative OTEL integer");
+            otel_phases.push(phase);
+            assert_eq!(scope.name(), "");
+            assert!(scope.version().is_none());
+            assert!(scope.schema_url().is_none());
+            assert!(scope.attributes().next().is_none());
+            assert!(!format!("{log:?}").contains(FAKE_URI));
+            assert!(!format!("{log:?}").contains(FAKE_AUTH));
+        }
+        json_phases.sort_unstable();
+        otel_phases.sort_unstable();
+        let mut expected_phases = expected_phases.to_vec();
+        expected_phases.sort_unstable();
+        assert_eq!(json_phases, expected_phases);
+        assert_eq!(otel_phases, expected_phases);
+        let resource = sinks.exporter.resource.lock().expect("capture exporter resource");
+        assert!(resource.as_ref().expect("exporter resource exists").iter().next().is_none());
+    }
+
+    #[test]
+    fn separate_threads_keep_their_contexts_across_async_suspension() {
+        let outer = Sinks::new(true, true);
+        let isolated = Sinks::new(true, true);
+        let barrier = Arc::new(tokio::sync::Barrier::new(PARTICIPANTS));
+        let thread_ids: HashSet<_> = std::thread::scope(|scope| {
+            let mut handles = Vec::new();
+            for _ in 0..PARTICIPANTS {
+                let outer_dispatch = outer.dispatch.clone();
+                let isolated_dispatch = isolated.dispatch.clone();
+                let barrier = Arc::clone(&barrier);
+                handles.push(scope.spawn(move || {
+                    let thread_id = std::thread::current().id();
+                    let span = parent_span(&outer_dispatch);
+                    let span_id = span.id();
+                    let runtime = tokio::runtime::Builder::new_current_thread()
+                        .enable_all()
+                        .build()
+                        .expect("build a test-only runtime");
+                    runtime.block_on(
+                        async move {
+                            for phase in [0_u64, 1] {
+                                tokio::time::timeout(WAIT, barrier.wait())
+                                    .await
+                                    .expect("all threads reach the barrier");
+                                observe_once(&isolated_dispatch, &span_id, phase);
+                                tokio::task::yield_now().await;
+                            }
+                        }
+                        .instrument(span)
+                        .with_subscriber(outer_dispatch),
+                    );
+                    thread_id
+                }));
+            }
+            handles
+                .into_iter()
+                .map(|handle| handle.join().expect("thread completes"))
+                .collect()
+        });
+        assert_eq!(thread_ids.len(), PARTICIPANTS, "the fixture must use distinct OS threads");
+        assert!(outer.json_records().is_empty());
+        assert!(outer.exported_records().is_empty());
+        assert_isolated_events(&isolated, &[0, 1, 0, 1, 0, 1, 0, 1]);
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+    async fn shared_runtime_reenters_outer_context_after_each_await() {
+        let outer = Sinks::new(true, true);
+        let isolated = Sinks::new(true, true);
+        let barrier = Arc::new(tokio::sync::Barrier::new(PARTICIPANTS));
+        let mut tasks = Vec::new();
+        for _ in 0..PARTICIPANTS {
+            let outer_dispatch = outer.dispatch.clone();
+            let isolated_dispatch = isolated.dispatch.clone();
+            let barrier = Arc::clone(&barrier);
+            let span = parent_span(&outer_dispatch);
+            let span_id = span.id();
+            tasks.push(tokio::spawn(
+                async move {
+                    for phase in [0_u64, 1] {
+                        tokio::time::timeout(WAIT, barrier.wait())
+                            .await
+                            .expect("all tasks reach the barrier");
+                        observe_once(&isolated_dispatch, &span_id, phase);
+                        tokio::task::yield_now().await;
+                    }
+                }
+                .instrument(span)
+                .with_subscriber(outer_dispatch),
+            ));
+        }
+        for task in tasks {
+            tokio::time::timeout(WAIT, task)
+                .await
+                .expect("task finishes")
+                .expect("task succeeds");
+        }
+        assert!(outer.json_records().is_empty());
+        assert!(outer.exported_records().is_empty());
+        assert_isolated_events(&isolated, &[0, 1, 0, 1, 0, 1, 0, 1]);
+    }
+
+    #[test]
+    fn either_isolation_step_alone_leaves_ambient_context() {
+        let outer = Sinks::new(true, true);
+        let separate = Sinks::new(true, true);
+        dispatcher::with_default(&outer.dispatch, || {
+            let span = parent_span(&outer.dispatch);
+            let _span = span.enter();
+            let _context = fake_ambient_context().attach();
+            dispatcher::with_default(&separate.dispatch, || emit_root_event(0));
+            let _empty_context = Context::new().attach();
+            emit_root_event(1);
+        });
+
+        let separate_json = separate.json_records();
+        let separate_logs = separate.exported_records();
+        assert_eq!(separate_json.len(), 1);
+        assert_eq!(separate_logs.len(), 1);
+        assert!(separate_json[0].get("span").is_none());
+        assert_eq!(
+            separate_logs[0]
+                .0
+                .trace_context()
+                .expect("ambient trace still exists")
+                .trace_id,
+            TraceId::from(17)
+        );
+
+        let outer_json = outer.json_records();
+        let outer_logs = outer.exported_records();
+        assert_eq!(outer_json.len(), 1);
+        assert_eq!(outer_logs.len(), 1);
+        assert_eq!(outer_json[0]["span"]["uri"].as_str(), Some(FAKE_URI));
+        assert_eq!(outer_json[0]["span"]["authorization"].as_str(), Some(FAKE_AUTH));
+        assert!(outer_logs[0].0.trace_context().is_none());
+    }
+
+    fn filtered_sinks(filter: &str, sensitive_resource: bool) -> Sinks {
+        let json = MemoryWriter::default();
+        let exporter = MemoryExporter::default();
+        let resource = if sensitive_resource {
+            Resource::builder_empty()
+                .with_attributes([KeyValue::new("synthetic.resource", FAKE_AUTH)])
+                .build()
+        } else {
+            Resource::builder_empty().build()
+        };
+        let provider = SdkLoggerProvider::builder()
+            .with_resource(resource)
+            .with_simple_exporter(exporter.clone())
+            .build();
+        let bridge = OpenTelemetryTracingBridge::builder(&provider)
+            .with_tracing_span_attributes(TracingSpanAttributes::all())
+            .build();
+        let subscriber = tracing_subscriber::registry()
+            .with(EnvFilter::new(filter))
+            .with(build_json_log_layer(json.clone(), false, FmtSpan::NONE, true))
+            .with(bridge);
+        Sinks {
+            dispatch: Dispatch::new(subscriber),
+            json,
+            exporter,
+            _provider: provider,
+        }
+    }
+
+    #[test]
+    fn filters_and_resources_do_not_cross_dispatchers() {
+        let outer = filtered_sinks("info,rustfs_isolation_probe_test=off", true);
+        let isolated = filtered_sinks("off,rustfs_isolation_probe_test=info", false);
+        let disabled = filtered_sinks("off", false);
+        dispatcher::with_default(&outer.dispatch, || {
+            let span = parent_span(&outer.dispatch);
+            let _span = span.enter();
+            let parent_id = span.id();
+            observe_once(&isolated.dispatch, &parent_id, 0);
+            observe_once(&disabled.dispatch, &parent_id, 1);
+            tracing::info!(target: "isolation_outer_control", value = 1_u64, "outer control");
+        });
+        let outer_json = outer.json_records();
+        let outer_logs = outer.exported_records();
+        assert_eq!(outer_json.len(), 1);
+        assert_eq!(outer_logs.len(), 1);
+        assert_eq!(outer_json[0]["target"].as_str(), Some("isolation_outer_control"));
+        assert_eq!(outer_logs[0].0.target().map(|target| target.as_ref()), Some("isolation_outer_control"));
+        assert!(
+            outer
+                .exporter
+                .resource
+                .lock()
+                .expect("capture outer resource")
+                .as_ref()
+                .expect("outer resource exists")
+                .get(&opentelemetry::Key::new("synthetic.resource"))
+                .is_some()
+        );
+        assert_isolated_events(&isolated, &[0]);
+        assert!(disabled.json_records().is_empty());
+        assert!(disabled.exported_records().is_empty());
+    }
+
+    struct CancellationProbe {
+        outer: Dispatch,
+        isolated: Dispatch,
+        drops: Arc<AtomicUsize>,
+        restored: Arc<AtomicBool>,
+    }
+
+    impl Drop for CancellationProbe {
+        fn drop(&mut self) {
+            dispatcher::with_default(&self.outer, || {
+                let span = parent_span(&self.outer);
+                let _span = span.enter();
+                let _context = fake_ambient_context().attach();
+                emit_candidate(&self.isolated, 1);
+                let restored = tracing::Span::current().id() == span.id()
+                    && Context::current().span().span_context().trace_id() == TraceId::from(17)
+                    && Context::current().baggage().get("synthetic-secret").is_some();
+                self.restored.store(restored, Ordering::SeqCst);
+            });
+            self.drops.fetch_add(1, Ordering::SeqCst);
+        }
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    async fn cancellation_drop_emits_in_isolation_and_restores_context() {
+        let outer = Sinks::new(true, true);
+        let isolated = Sinks::new(true, true);
+        let drops = Arc::new(AtomicUsize::new(0));
+        let restored = Arc::new(AtomicBool::new(false));
+        let probe = CancellationProbe {
+            outer: outer.dispatch.clone(),
+            isolated: isolated.dispatch.clone(),
+            drops: Arc::clone(&drops),
+            restored: Arc::clone(&restored),
+        };
+        let (started_tx, started_rx) = tokio::sync::oneshot::channel();
+        let task = tokio::spawn(async move {
+            let _probe = probe;
+            started_tx.send(()).expect("signal that the cancellation fixture is active");
+            pending::<()>().await;
+        });
+        tokio::time::timeout(WAIT, started_rx)
+            .await
+            .expect("task starts")
+            .expect("start signal");
+        task.abort();
+        let error = tokio::time::timeout(WAIT, task)
+            .await
+            .expect("cancelled task finishes")
+            .expect_err("the task must be cancelled");
+        assert!(error.is_cancelled());
+        assert_eq!(drops.load(Ordering::SeqCst), 1);
+        assert!(restored.load(Ordering::SeqCst));
+        assert!(outer.json_records().is_empty());
+        assert!(outer.exported_records().is_empty());
+        assert_isolated_events(&isolated, &[1]);
+    }
+
+    #[derive(Clone)]
+    struct PanicWriter;
+
+    impl<'a> tracing_subscriber::fmt::MakeWriter<'a> for PanicWriter {
+        type Writer = Self;
+
+        fn make_writer(&'a self) -> Self::Writer {
+            self.clone()
+        }
+    }
+
+    impl Write for PanicWriter {
+        fn write(&mut self, _: &[u8]) -> io::Result<usize> {
+            panic!("synthetic writer panic");
+        }
+
+        fn flush(&mut self) -> io::Result<()> {
+            Ok(())
+        }
+    }
+
+    #[test]
+    fn panic_during_sink_write_restores_the_outer_context() {
+        let outer = Sinks::new(true, true);
+        let panic_dispatch =
+            Dispatch::new(tracing_subscriber::registry().with(build_json_log_layer(PanicWriter, false, FmtSpan::NONE, true)));
+        dispatcher::with_default(&outer.dispatch, || {
+            let span = parent_span(&outer.dispatch);
+            let _span = span.enter();
+            let _context = fake_ambient_context().attach();
+            let panic = catch_unwind(AssertUnwindSafe(|| emit_candidate(&panic_dispatch, 0)));
+            assert!(panic.is_err(), "the fixture must panic while writing the isolated event");
+            assert_eq!(tracing::Span::current().id(), span.id());
+            assert_eq!(Context::current().span().span_context().trace_id(), TraceId::from(17));
+            assert!(Context::current().baggage().get("synthetic-secret").is_some());
+            tracing::info!(target: "isolation_outer_control", value = 1_u64, "outer control");
+        });
+        let json = outer.json_records();
+        let logs = outer.exported_records();
+        assert_eq!(json.len(), 1);
+        assert_eq!(logs.len(), 1);
+        assert_eq!(json[0]["target"].as_str(), Some("isolation_outer_control"));
+        assert_eq!(logs[0].0.target().map(|target| target.as_ref()), Some("isolation_outer_control"));
+    }
+
+    #[derive(Clone)]
+    struct ObservedPanicWriter(Arc<AtomicBool>);
+
+    impl<'a> tracing_subscriber::fmt::MakeWriter<'a> for ObservedPanicWriter {
+        type Writer = Self;
+
+        fn make_writer(&'a self) -> Self::Writer {
+            self.clone()
+        }
+    }
+
+    impl Write for ObservedPanicWriter {
+        fn write(&mut self, _: &[u8]) -> io::Result<usize> {
+            self.0.store(true, Ordering::SeqCst);
+            panic!("synthetic writer panic");
+        }
+
+        fn flush(&mut self) -> io::Result<()> {
+            Ok(())
+        }
+    }
+
+    fn classify_panic_isolation() -> &'static str {
+        let outer = Sinks::new(true, true);
+        let reached = Arc::new(AtomicBool::new(false));
+        let panic_dispatch = Dispatch::new(tracing_subscriber::registry().with(build_json_log_layer(
+            ObservedPanicWriter(Arc::clone(&reached)),
+            false,
+            FmtSpan::NONE,
+            true,
+        )));
+        let early_result = dispatcher::with_default(&outer.dispatch, || {
+            let span = parent_span(&outer.dispatch);
+            let _span = span.enter();
+            let _context = fake_ambient_context().attach();
+            let outer_span = span.id();
+            if outer_span.is_none() {
+                return Some("outer_span_missing");
+            }
+            let caught = catch_unwind(AssertUnwindSafe(|| emit_candidate(&panic_dispatch, 0))).is_err();
+            if !reached.load(Ordering::SeqCst) {
+                return Some("writer_not_reached");
+            }
+            if !caught {
+                return Some("writer_panic_not_caught");
+            }
+            let dispatcher_restored = dispatcher::get_default(|current| {
+                current
+                    .downcast_ref::<MemoryWriter>()
+                    .is_some_and(|writer| Arc::ptr_eq(&writer.0, &outer.json.0))
+            });
+            if !dispatcher_restored {
+                return Some("dispatcher_not_restored");
+            }
+            if tracing::Span::current().id() != outer_span {
+                return Some("tracing_not_restored");
+            }
+            let current = Context::current();
+            if current.span().span_context().trace_id() != TraceId::from(17) {
+                return Some("trace_not_restored");
+            }
+            if current.span().span_context().span_id() != SpanId::from(19) {
+                return Some("span_id_not_restored");
+            }
+            if current.baggage().get("synthetic-secret").map(|value| value.as_str()) != Some(FAKE_AUTH) {
+                return Some("baggage_not_restored");
+            }
+            tracing::info!(target: "isolation_outer_control", value = 1_u64, "outer control");
+            None
+        });
+        if let Some(class) = early_result {
+            return class;
+        }
+        let bytes = match outer.json.0.lock() {
+            Ok(bytes) => bytes.clone(),
+            Err(_) => return "outer_json_unknown",
+        };
+        let text = match std::str::from_utf8(&bytes) {
+            Ok(text) => text,
+            Err(_) => return "outer_json_unknown",
+        };
+        let json: Vec<Value> = match text.lines().map(serde_json::from_str).collect() {
+            Ok(json) => json,
+            Err(_) => return "outer_json_unknown",
+        };
+        let logs = outer.exported_records();
+        if json.len() == 2
+            && json[0]["target"].as_str() == Some(TARGET)
+            && json[1]["target"].as_str() == Some("isolation_outer_control")
+        {
+            return "stale_isolated_json";
+        }
+        if json.len() != 1 || json[0]["target"].as_str() != Some("isolation_outer_control") {
+            return "outer_json_unexpected";
+        }
+        if logs.len() != 1 || logs[0].0.target().map(|target| target.as_ref()) != Some("isolation_outer_control") {
+            return "outer_otel_unexpected";
+        }
+        "clean"
+    }
+
+    type PanicHook = Box<dyn Fn(&std::panic::PanicHookInfo<'_>) + Send + Sync + 'static>;
+
+    struct RestorePanicHook(Option<PanicHook>);
+
+    impl Drop for RestorePanicHook {
+        fn drop(&mut self) {
+            if let Some(previous) = self.0.take() {
+                std::panic::set_hook(previous);
+            }
+        }
+    }
+
+    #[test]
+    fn classify_panic_writer_isolation_without_raw_output() {
+        // This process-global hook is used only by the workflow's single exact test.
+        let hook = RestorePanicHook(Some(std::panic::take_hook()));
+        std::panic::set_hook(Box::new(|_| {
+            let _ = writeln!(std::io::stderr(), "\nRUSTFS_PANIC_HOOK=redacted");
+        }));
+        let result = catch_unwind(AssertUnwindSafe(|| {
+            let class = catch_unwind(AssertUnwindSafe(classify_panic_isolation)).unwrap_or("diagnostic_internal_panic");
+            println!("\nRUSTFS_PANIC_DIAGNOSTIC={class}");
+            assert!(class == "clean", "isolation diagnostic failed");
+        }));
+        drop(hook);
+        if let Err(payload) = result {
+            std::panic::resume_unwind(payload);
+        }
+    }
+}

crates/obs/src/telemetry/mod.rs

@@ -43,6 +43,8 @@
 pub mod dial9;
 mod filter;
 mod guard;
+#[cfg(test)]
+mod isolation_probe_tests;
 mod local;
 mod otel;
 mod recorder;