userver: tracing::Span Class Reference
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tracing::Span Class Referencefinal

#include <userver/tracing/span.hpp>

Detailed Description

Measures the execution time of the current code block, links it with the parent tracing::Spans and stores that info in the log.

See Logging and Tracing for usage examples and more descriptions.

Warning
Shall be created only as a local variable. Do not use it as a class member!
Examples
samples/tcp_full_duplex_service/tcp_full_duplex_service.cpp.

Definition at line 30 of file span.hpp.

Public Member Functions

 Span (TracerPtr tracer, std::string name, const Span *parent, ReferenceType reference_type, logging::Level log_level=logging::Level::kInfo, utils::impl::SourceLocation source_location=utils::impl::SourceLocation::Current())
 
 Span (std::string name, ReferenceType reference_type=ReferenceType::kChild, logging::Level log_level=logging::Level::kInfo, utils::impl::SourceLocation source_location=utils::impl::SourceLocation::Current())
 
 Span (Span &&other) noexcept
 
Spanoperator= (const Span &)=delete
 
Spanoperator= (Span &&)=delete
 
Span CreateChild (std::string name) const
 
Span CreateFollower (std::string name) const
 
ScopeTime CreateScopeTime ()
 Creates a tracing::ScopeTime attached to the span.
 
ScopeTime CreateScopeTime (std::string name)
 Creates a tracing::ScopeTime attached to the Span and starts measuring execution time.
 
ScopeTime::Duration GetTotalDuration (const std::string &scope_name) const
 
ScopeTime::DurationMillis GetTotalElapsedTime (const std::string &scope_name) const
 
void AddTag (std::string key, logging::LogExtra::Value value)
 
void AddTagFrozen (std::string key, logging::LogExtra::Value value)
 
void AddNonInheritableTag (std::string key, logging::LogExtra::Value value)
 
void AddNonInheritableTags (const logging::LogExtra &)
 
void SetLogLevel (logging::Level log_level)
 Sets level for tags logging.
 
logging::Level GetLogLevel () const
 Returns level for tags logging.
 
void SetLocalLogLevel (std::optional< logging::Level > log_level)
 Sets the local log level that disables logging of this span if the local log level set and greater than the main log level of the Span.
 
std::optional< logging::LevelGetLocalLogLevel () const
 Returns the local log level that disables logging of this span if it is set and greater than the main log level of the Span.
 
void SetLink (std::string link)
 
void SetParentLink (std::string parent_link)
 Set parent_link - an ID . Can be called only once.
 
std::string GetLink () const
 
std::string GetParentLink () const
 
const std::string & GetTraceId () const
 
const std::string & GetSpanId () const
 Identifies a specific span. It does not propagate.
 
const std::string & GetParentId () const
 
bool ShouldLogDefault () const noexcept
 
void DetachFromCoroStack ()
 
void AttachToCoroStack ()
 
std::chrono::system_clock::time_point GetStartSystemTime () const
 

Static Public Member Functions

static SpanCurrentSpan ()
 Returns the Span of the current task.
 
static SpanCurrentSpanUnchecked ()
 Returns nullptr if called in non-coroutine context or from a task with no alive Span; otherwise returns the Span of the current task.
 
static Span MakeSpan (std::string name, std::string_view trace_id, std::string_view parent_span_id)
 
static Span MakeSpan (std::string name, std::string_view trace_id, std::string_view parent_span_id, std::string link)
 
static Span MakeRootSpan (std::string name, logging::Level log_level=logging::Level::kInfo)
 

Constructor & Destructor Documentation

◆ Span()

tracing::Span::Span ( std::string name,
ReferenceType reference_type = ReferenceType::kChild,
logging::Level log_level = logging::Level::kInfo,
utils::impl::SourceLocation source_location = utils::impl::SourceLocation::Current() )
explicit

Use default tracer and implicit coro local storage for parent identification, takes TraceID from the parent.

For extremely rare cases where a new Trace ID is required use tracing::Span::MakeSpan().

Member Function Documentation

◆ AddNonInheritableTag()

tracing::Span::AddNonInheritableTag ( std::string key,
logging::LogExtra::Value value )

Add a tag that is local to the Span (IOW, it is not propagated to future children) and logged only once in the destructor of the Span.

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

◆ AddTag()

void tracing::Span::AddTag ( std::string key,
logging::LogExtra::Value value )

Add a tag that is used on each logging in this Span and all future children.

◆ AddTagFrozen()

void tracing::Span::AddTagFrozen ( std::string key,
logging::LogExtra::Value value )

Add a tag that is used on each logging in this Span and all future children. It will not be possible to change its value.

◆ AttachToCoroStack()

void tracing::Span::AttachToCoroStack ( )

Attach the Span to current engine::Task so it is returned by CurrentSpan().

◆ CreateChild()

Span tracing::Span::CreateChild ( std::string name) const

Create a child which can be used independently from the parent.

The child shares no state with its parent. If you need to run code in parallel, create a child span and use the child in a separate task.

◆ CurrentSpan()

static Span & tracing::Span::CurrentSpan ( )
static

Returns the Span of the current task.

Should not be called in non-coroutine context. Should not be called from a task with no alive Span.

Rule of thumb: it is safe to call it from a task created by utils::Async/utils::CriticalAsync/utils::PeriodicTask. If current task was created with an explicit engine::impl::*Async(), you have to create a Span beforehand.

◆ DetachFromCoroStack()

void tracing::Span::DetachFromCoroStack ( )

Detach the Span from current engine::Task so it is not returned by CurrentSpan() any more.

◆ GetLink()

std::string tracing::Span::GetLink ( ) const

Get link - a request ID within the service.

Propagates within a single service, but not from client to server. A new link is generated for the "root" request handling task

◆ GetTotalDuration()

ScopeTime::Duration tracing::Span::GetTotalDuration ( const std::string & scope_name) const

Returns total time elapsed for a certain scope of this span. If there is no record for the scope, returns 0.

◆ GetTotalElapsedTime()

ScopeTime::DurationMillis tracing::Span::GetTotalElapsedTime ( const std::string & scope_name) const

Returns total time elapsed for a certain scope of this span. If there is no record for the scope, returns 0.

Prefer using Span::GetTotalDuration()

◆ GetTraceId()

const std::string & tracing::Span::GetTraceId ( ) const

An ID of the request that does not change from service to service.

Propagates both to sub-spans within a single service, and from client to server

◆ MakeRootSpan()

static Span tracing::Span::MakeRootSpan ( std::string name,
logging::Level log_level = logging::Level::kInfo )
static

Factory function for rare cases of creating a root Span that starts the trace_id chain, ignoring CurrentSpan, if any. Useful in background jobs, periodics, distlock tasks, cron tasks, etc. The result of such jobs is not directly requested by anything.

Returns
A new Span that is the root of a new Span hierarchy.
Parameters
nameName of a new Span
log_levelLog level for the span's own log record

◆ MakeSpan() [1/2]

static Span tracing::Span::MakeSpan ( std::string name,
std::string_view trace_id,
std::string_view parent_span_id )
static

Factory function for extremely rare cases of creating a Span with custom IDs; prefer Span constructor instead.

Returns
A new Span attached to current Span (if any) but with a new Trace ID.
Parameters
nameName of a new Span
trace_idNew Trace ID; if empty then the Trace ID is autogenerated
parent_span_idId of the parent Span, could be empty.

◆ MakeSpan() [2/2]

static Span tracing::Span::MakeSpan ( std::string name,
std::string_view trace_id,
std::string_view parent_span_id,
std::string link )
static

Factory function for extremely rare cases of creating a Span with custom IDs; prefer Span constructor instead.

Returns
A new Span attached to current Span (if any), sets link.
Parameters
nameName of a new Span
trace_idNew Trace ID; if empty then the Trace ID is autogenerated
parent_span_idId of the parent Span, could be empty.
linkThe new link

◆ SetLink()

void tracing::Span::SetLink ( std::string link)

Set link - a request ID within a service. Can be called only once.

Propagates within a single service, but not from client to server. A new link is generated for the "root" request handling task

◆ ShouldLogDefault()

bool tracing::Span::ShouldLogDefault ( ) const
noexcept
Returns
true if this span would be logged with the current local and global log levels to the default logger.

Friends And Related Symbol Documentation

◆ SpanBuilder

friend class SpanBuilder
friend

Definition at line 234 of file span.hpp.

◆ TagScope

friend class TagScope
friend

Definition at line 235 of file span.hpp.


The documentation for this class was generated from the following file: