ARCHIVE/rippled
1
0
Fork 0
mirror of https://github.com/XRPLF/rippled.git synced 2026-07-25 08:00:22 +00:00
Code Issues Packages Projects Releases Wiki Activity

refactor(telemetry): split SpanGuard into unscoped SpanGuard + scoped ScopedSpanGuard

Browse Source 
Separate the two responsibilities the old SpanGuard fused: span ownership
(thread-free) and scope activation (thread-bound TLS push).

- SpanGuard now owns ONLY the span. Its Impl drops the optional<Scope>,
  the owner thread-id, the Detached tag and the scope-less ctor; ~Impl is
  just `if (span) span->End()`. The guard never binds a thread-local
  context stack, so it may be moved to and destroyed on any thread.
- ScopedSpanGuard is a new pimpl type that wraps a SpanGuard plus an
  optional<Scope>. Member order (guard first, scope second) pops the
  scope before the span ends. It is non-copyable and non-movable;
  factories return unnamed temporaries so guaranteed copy elision covers
  `auto s = ScopedSpanGuard::freshRoot(...)`.
- `operator SpanGuard() &&` replaces detached()/detachInPlace(): it pops
  the scope eagerly on the origin thread and yields a thread-free
  SpanGuard for handoff to a job or another thread. detached(),
  detachInPlace() (both overloads) and the Detached apparatus are deleted.
- Move-assignment is re-enabled on SpanGuard (no Scope to re-bind), in
  both the real class and the no-op stub.
- rootSpan() renamed to freshRoot() in both classes (behavior unchanged:
  still forces kIsRootSpanKey).
- hashSpan behavior is intentionally unchanged (only builds the now
  unscoped Impl); the true-root IdGenerator fix is a separate later task.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Pratik Mankawde
2026-07-21 18:03:20 +01:00
parent f9b2d725a0
commit 508c91d36c
2 changed files with 639 additions and 220 deletions
Download Patch File Download Diff File Expand all files Collapse all files

314
src/libxrpl/telemetry/SpanGuard.cpp
View File

@@ -1,23 +1,26 @@
/**
* Pimpl implementation for SpanGuard and SpanContext.
* Pimpl implementation for SpanGuard, ScopedSpanGuard and SpanContext.
*
* All OpenTelemetry SDK types are confined to this translation unit.
* The public SpanGuard.h header contains only standard-library types
* and forward-declares the Impl struct.
* and forward-declares the Impl / ScopedImpl structs.
*
* Two guards with split responsibilities live here:
* - SpanGuard::Impl holds ONLY the OTel Span (shared_ptr). It never
* touches the thread-local context stack, so a SpanGuard is
* thread-free and may be moved to and destroyed on any thread.
* - ScopedSpanGuard::ScopedImpl holds a SpanGuard plus an optional
* Scope. The Scope pushes the span onto the constructing thread's
* context stack; member order (guard first, scope second) ensures
* the Scope pops BEFORE the span ends on destruction. It is
* thread-bound: construct and destroy on the same thread.
*
* Static factory methods access the global Telemetry instance via
* Telemetry::getInstance(), check whether the requested TraceCategory
* is enabled, and return either an active guard with a real Span+Scope
* or a null guard whose methods are all no-ops.
* is enabled, and return either an active guard with a real Span or a
* null guard whose methods are all no-ops.
*
* The Impl struct holds the OTel Span (shared_ptr) and an optional
* Scope. Scope is non-movable, but since Impl lives behind a
* unique_ptr, SpanGuard's move constructor simply transfers the
* pointer — no double-Scope issues. A scoped guard holds the Scope;
* detached() produces an Impl with no Scope (nullopt) so the guard
* carries no thread-local binding and is safe to move across threads.
*
* @see SpanGuard (SpanGuard.h), Telemetry (Telemetry.h),
* @see SpanGuard, ScopedSpanGuard (SpanGuard.h), Telemetry (Telemetry.h),
* FilteringSpanProcessor (Telemetry.cpp)
*/
@@ -79,65 +82,22 @@ SpanContext::isValid() const
struct SpanGuard::Impl
{
/**
* The OTel span being guarded. Set to nullptr after discard() or
* once detached() moves it into a new guard, so ~Impl skips End().
* The OTel span being guarded. Set to nullptr after discard() so
* ~Impl skips End().
*/
opentelemetry::nostd::shared_ptr<otel_trace::Span> span;
/**
* Scope that activates span on the current thread's context stack.
* nullopt for a detached guard, which holds the span with no
* thread-local binding and is therefore safe to move across threads.
*/
std::optional<otel_trace::Scope> scope;
/**
* Thread that constructed this Impl. Meaningful only when `scope`
* holds a value: a Scope is bound to the thread-local context stack
* of the thread that pushed it, so popping it (via ~Scope, when
* ~Impl runs) on a different thread corrupts that thread's stack.
* Checked in ~Impl() and detached() to turn a silent cross-thread
* corruption into an assertion failure in debug/test/fuzzing builds.
*/
std::thread::id owner{std::this_thread::get_id()};
/**
* Construct a scoped guard: the span is pushed onto this thread's
* active-context stack for the lifetime of the guard.
* Construct an unscoped guard: the span is owned but NOT pushed
* onto any thread's context stack. The guard is thread-free.
* @param s The span to guard.
*/
explicit Impl(opentelemetry::nostd::shared_ptr<otel_trace::Span> s) : span(std::move(s))
{
scope.emplace(span);
}
/**
* Tag type selecting the scope-less (detached) constructor.
*/
struct Detached
{
};
/**
* Construct a detached guard: the span is held with NO thread-local
* Scope, so the guard carries no context-stack binding and is safe
* to move to and destroy on another thread.
* @param s The span to guard.
*/
Impl(opentelemetry::nostd::shared_ptr<otel_trace::Span> s, Detached) : span(std::move(s))
{
}
~Impl()
{
// A live Scope (scope engaged) must be popped on the thread that
// pushed it; ending on any other thread corrupts that thread's
// context stack. A detached guard (scope == nullopt) carries no
// binding and may be destroyed anywhere, so the check is skipped.
XRPL_ASSERT(
!scope.has_value() || owner == std::this_thread::get_id(),
"xrpl::telemetry::SpanGuard::Impl::~Impl : scoped guard destroyed on "
"constructing thread");
if (span)
span->End();
}
@@ -155,6 +115,8 @@ struct SpanGuard::Impl
SpanGuard::SpanGuard() = default;
SpanGuard::~SpanGuard() = default;
SpanGuard::SpanGuard(SpanGuard&&) noexcept = default;
SpanGuard&
SpanGuard::operator=(SpanGuard&&) noexcept = default;
SpanGuard::SpanGuard(std::unique_ptr<Impl> impl) : impl_(std::move(impl))
{
@@ -237,7 +199,7 @@ SpanGuard::span(TraceCategory cat, std::string_view prefix, std::string_view nam
}
SpanGuard
SpanGuard::rootSpan(TraceCategory cat, std::string_view prefix, std::string_view name)
SpanGuard::freshRoot(TraceCategory cat, std::string_view prefix, std::string_view name)
{
auto* tel = Telemetry::getInstance();
if ((tel == nullptr) || !tel->isEnabled() || !isCategoryEnabled(*tel, cat))
@@ -327,43 +289,6 @@ SpanGuard::linkedSpan(std::string_view name, SpanContext const& linkCtx)
opts)));
}
SpanGuard
SpanGuard::detached() &&
{
if (!impl_)
return {};
// Popping the Scope (below, via impl_.reset()) must happen on the thread
// that pushed it; calling detached() elsewhere would pop the wrong stack.
XRPL_ASSERT(
!impl_->scope.has_value() || impl_->owner == std::this_thread::get_id(),
"xrpl::telemetry::SpanGuard::detached : called on constructing thread");
// Take the span out; the old Impl.span is now null so ~Impl won't End().
auto s = std::move(impl_->span);
// Resetting the old Impl destroys its Scope HERE, on the origin thread,
// popping this thread's context stack correctly. The returned guard holds
// the span with no Scope, so it is safe to move to another thread.
impl_.reset();
return SpanGuard(std::make_unique<Impl>(std::move(s), Impl::Detached{}));
}
// ===== Detach-in-place helpers =============================================
void
detachInPlace(std::optional<SpanGuard>& guard)
{
if (!guard || !*guard)
return;
guard.emplace(std::move(*guard).detached());
}
std::shared_ptr<SpanGuard>
detachInPlace(std::shared_ptr<SpanGuard> guard)
{
if (!guard || !*guard)
return guard;
return std::make_shared<SpanGuard>(std::move(*guard).detached());
}
// ===== Context capture =====================================================
SpanContext
@@ -476,6 +401,201 @@ SpanGuard::discard()
}
}
// ===== ScopedSpanGuard::ScopedImpl =========================================
struct ScopedSpanGuard::ScopedImpl
{
/**
* The unscoped guard that owns the span. Declared FIRST so it is
* destroyed AFTER `scope`: the Scope must pop before the span ends.
*/
SpanGuard guard;
/**
* Active OTel Scope binding the span to this thread's context stack.
* Present while the guard is active; reset() (via operator SpanGuard)
* pops it eagerly on the origin thread. Declared AFTER `guard` so
* destruction order pops the scope before the span ends.
*/
std::optional<otel_trace::Scope> scope;
/**
* Thread that constructed this ScopedImpl. The Scope is bound to
* this thread's context stack, so popping it (via ~Scope or reset())
* on a different thread corrupts that thread's stack. Checked in the
* destructor and operator SpanGuard() to turn a silent cross-thread
* corruption into an assertion failure in debug/test/fuzzing builds.
*/
std::thread::id owner{std::this_thread::get_id()};
/**
* Wrap a SpanGuard and activate its span on this thread. If the
* guard is active, push its span onto the thread-local context
* stack; a null guard leaves `scope` empty.
* @param g The span-owning guard to activate.
*/
explicit ScopedImpl(SpanGuard g) : guard(std::move(g))
{
if (guard)
scope.emplace(guard.impl_->span);
}
};
// ===== ScopedSpanGuard core lifecycle ======================================
ScopedSpanGuard::ScopedSpanGuard(SpanGuard&& guard)
: impl_(std::make_unique<ScopedImpl>(std::move(guard)))
{
}
ScopedSpanGuard::~ScopedSpanGuard()
{
// A live Scope must be popped on the thread that pushed it; destroying
// the guard on any other thread corrupts that thread's context stack.
// A null guard holds no Scope, so the check is skipped.
XRPL_ASSERT(
!impl_ || !impl_->scope.has_value() || impl_->owner == std::this_thread::get_id(),
"xrpl::telemetry::ScopedSpanGuard::~ScopedSpanGuard : destroyed on "
"constructing thread");
}
// ===== ScopedSpanGuard factory methods =====================================
ScopedSpanGuard::ScopedSpanGuard(TraceCategory cat, std::string_view prefix, std::string_view name)
: ScopedSpanGuard(SpanGuard::span(cat, prefix, name))
{
}
ScopedSpanGuard
ScopedSpanGuard::freshRoot(TraceCategory cat, std::string_view prefix, std::string_view name)
{
return ScopedSpanGuard(SpanGuard::freshRoot(cat, prefix, name));
}
ScopedSpanGuard
ScopedSpanGuard::childSpan(std::string_view name) const
{
return ScopedSpanGuard(impl_->guard.childSpan(name));
}
ScopedSpanGuard
ScopedSpanGuard::childSpan(std::string_view name, SpanContext const& parentCtx)
{
return ScopedSpanGuard(SpanGuard::childSpan(name, parentCtx));
}
ScopedSpanGuard
ScopedSpanGuard::linkedSpan(std::string_view name) const
{
return ScopedSpanGuard(impl_->guard.linkedSpan(name));
}
ScopedSpanGuard
ScopedSpanGuard::linkedSpan(std::string_view name, SpanContext const& linkCtx)
{
return ScopedSpanGuard(SpanGuard::linkedSpan(name, linkCtx));
}
// ===== ScopedSpanGuard handoff bridge ======================================
ScopedSpanGuard::
operator SpanGuard() &&
{
// The scope must be popped on the thread that pushed it; handing off
// elsewhere would pop the wrong stack.
XRPL_ASSERT(
impl_->owner == std::this_thread::get_id(),
"xrpl::telemetry::ScopedSpanGuard::operator SpanGuard : handoff on "
"constructing thread");
impl_->scope.reset(); // eager pop, on the origin thread
return std::move(impl_->guard);
}
// ===== ScopedSpanGuard context capture =====================================
SpanContext
ScopedSpanGuard::captureContext() const
{
return impl_->guard.captureContext();
}
// ===== ScopedSpanGuard forwarding methods ==================================
void
ScopedSpanGuard::setAttribute(std::string_view key, std::string_view value)
{
impl_->guard.setAttribute(key, value);
}
void
ScopedSpanGuard::setAttribute(std::string_view key, char const* value)
{
impl_->guard.setAttribute(key, value);
}
void
ScopedSpanGuard::setAttribute(std::string_view key, std::int64_t value)
{
impl_->guard.setAttribute(key, value);
}
void
ScopedSpanGuard::setAttribute(std::string_view key, double value)
{
impl_->guard.setAttribute(key, value);
}
void
ScopedSpanGuard::setAttribute(std::string_view key, bool value)
{
impl_->guard.setAttribute(key, value);
}
void
ScopedSpanGuard::setOk()
{
impl_->guard.setOk();
}
void
ScopedSpanGuard::setError(std::string_view description)
{
impl_->guard.setError(description);
}
void
ScopedSpanGuard::addEvent(std::string_view name)
{
impl_->guard.addEvent(name);
}
void
ScopedSpanGuard::recordException(std::exception const& e)
{
impl_->guard.recordException(e);
}
void
ScopedSpanGuard::discard()
{
// A live Scope must be popped on the thread that pushed it; discarding
// on any other thread corrupts that thread's context stack. A null guard
// holds no Scope, so the check is skipped.
XRPL_ASSERT(
!impl_ || !impl_->scope.has_value() || impl_->owner == std::this_thread::get_id(),
"xrpl::telemetry::ScopedSpanGuard::discard : discarded on constructing thread");
// Pop the scope first (on this thread) so no span stays active on the
// stack, then discard the span via the owned guard.
impl_->scope.reset();
impl_->guard.discard();
}
ScopedSpanGuard::
operator bool() const
{
return impl_ && static_cast<bool>(impl_->guard);
}
} // namespace xrpl::telemetry
#endif // XRPL_ENABLE_TELEMETRY