Tracer Class Reference

#include <tracer.h>

Inheritance diagram for Tracer:

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Classes
struct	BufferEntry

Public Types
enum	TraceEvents {   kEventOpen = 1, kEventOpenDir, kEventReadlink, kEventLookup,   kEventStatFs, kEventGetAttr, kEventListAttr, kEventGetXAttr }

Public Member Functions
	Tracer ()
	~Tracer ()
void	Activate (const int buffer_size, const int flush_threshold, const std::string &trace_file)
void	Spawn ()
void	Flush ()
void	__attribute__ ((used)) Trace(const int event
bool	__attribute__ ((used)) IsActive()

Public Attributes
void const PathString &	path
void const PathString const std::string &	msg

Private Member Functions
void	GetTimespecRel (const int64_t ms, timespec *ts)
int	WriteCsvFile (FILE *fp, const std::string &field)
int32_t	DoTrace (const int event, const PathString &path, const std::string &msg)
Private Member Functions inherited from SingleCopy
	SingleCopy ()

Static Private Member Functions
static void *	MainFlush (void *data)

Private Attributes
bool	active_
bool	spawned_
std::string	trace_file_
int	buffer_size_
int	flush_threshold_
BufferEntry *	ring_buffer_
atomic_int32 *	commit_buffer_
pthread_t	thread_flush_
pthread_cond_t	sig_flush_
pthread_mutex_t	sig_flush_mutex_
pthread_cond_t	sig_continue_trace_
pthread_mutex_t	sig_continue_trace_mutex_
atomic_int32	seq_no_
atomic_int32	flushed_
atomic_int32	terminate_flush_thread_
atomic_int32	flush_immediately_

Static Private Attributes
static const int	kEventStart = -1
static const int	kEventStop = -2
static const int	kEventFlush = -3

Detailed Description

This file is part of the CernVM File System. Tracer is a thread-safe logging helper. It uses a ring buffer and spawns a helper thread, that flushes the messages onto the disk when necessary. The output file is in csv format. Usually tracing a message is a lock-free process, which therefore should have minimal overhead.

This is not supposed to be a debugging system. It is optimized for speed and does not try to gather any additional information (like threadid, status of variables, etc.).

Csv output is adapted from libcsv.

Todo:

If anything goes wrong, the whole thing breaks down on assertion. This might be not desired behavior.

Definition at line 35 of file tracer.h.

Member Enumeration Documentation

enum Tracer::TraceEvents

Enumerator
kEventOpen
kEventOpenDir
kEventReadlink
kEventLookup
kEventStatFs
kEventGetAttr
kEventListAttr
kEventGetXAttr

Definition at line 37 of file tracer.h.

Constructor & Destructor Documentation

Tracer::Tracer

(

)

Definition at line 223 of file tracer.cc.

Tracer::~Tracer

(

)

Definition at line 239 of file tracer.cc.

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Member Function Documentation

void Tracer::__attribute__ ( (used)  ) const

inline

bool Tracer::__attribute__ ( (used)  )

inline

Definition at line 62 of file tracer.h.

void Tracer::Activate	(	const int	buffer_size,
		const int	flush_threshold,
		const std::string &	trace_file
	)

Definition at line 25 of file tracer.cc.

Referenced by MountPoint::CreateTracer().

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int32_t Tracer::DoTrace ( const int  event, const PathString &  path, const std::string &  msg  )

private

Trace a message. This is usually a lock-free procedure that just requires two fetch_and_add operations and a gettimeofday syscall. There are two exceptions:

1. If the ring buffer is full, the function blocks until the flush thread made some space. Avoid that by carefully choosing size and threshold.
2. If this message reaches the threshold, the flush thread gets signaled.

Parameters

[in]	event	Arbitrary code, for consistency applications should use one of the TraceEvents constants. Negative codes are reserved for internal use.
[in]	id	Arbitrary id, for example file name or module name which is doing the trace.

Returns

The sequence number which was used to trace the record

Definition at line 69 of file tracer.cc.

Referenced by ~Tracer().

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void Tracer::Flush

(

)

Definition at line 106 of file tracer.cc.

Referenced by TalkManager::MainResponder().

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void Tracer::GetTimespecRel ( const int64_t  ms, timespec *  ts  )

private

Definition at line 133 of file tracer.cc.

Referenced by MainFlush().

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void * Tracer::MainFlush ( void *  data )

staticprivate

Definition at line 147 of file tracer.cc.

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void Tracer::Spawn

(

)

Definition at line 212 of file tracer.cc.

Referenced by Spawn().

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int Tracer::WriteCsvFile ( FILE *  fp, const std::string &  field  )

private

Definition at line 269 of file tracer.cc.

Referenced by MainFlush().

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Member Data Documentation

bool Tracer::active_

private

Definition at line 103 of file tracer.h.

Referenced by __attribute__(), and ~Tracer().

int Tracer::buffer_size_

private

Definition at line 106 of file tracer.h.

Referenced by MainFlush().

atomic_int32* Tracer::commit_buffer_

private

Has the same size as the ring buffer. If a message is actually copied to the ring buffer memory, the respective flag is set to 1. Flags are reset to 0 by the flush thread.

Definition at line 114 of file tracer.h.

Referenced by MainFlush(), and ~Tracer().

atomic_int32 Tracer::flush_immediately_

private

Definition at line 131 of file tracer.h.

Referenced by MainFlush(), and Tracer().

int Tracer::flush_threshold_

private

Definition at line 107 of file tracer.h.

Referenced by MainFlush().

atomic_int32 Tracer::flushed_

private

Starts with 0 and gets incremented by the flush thread. Points to the first non-flushed message. flushed <= seq_no holds.

Definition at line 129 of file tracer.h.

Referenced by MainFlush(), and Tracer().

const int Tracer::kEventFlush = -3

staticprivate

Manual flush

Definition at line 78 of file tracer.h.

const int Tracer::kEventStart = -1

staticprivate

Code of the first log line in the trace file.

Definition at line 70 of file tracer.h.

const int Tracer::kEventStop = -2

staticprivate

Code of the lasr log line in the trace file.

Definition at line 74 of file tracer.h.

Referenced by ~Tracer().

void const PathString const std::string& Tracer::msg

Initial value:

{
    if (active_) DoTrace(event, path, msg)

Definition at line 58 of file tracer.h.

void const PathString& Tracer::path

Definition at line 56 of file tracer.h.

BufferEntry* Tracer::ring_buffer_

private

Definition at line 108 of file tracer.h.

Referenced by MainFlush(), and ~Tracer().

atomic_int32 Tracer::seq_no_

private

Starts with 0 and gets incremented by each call to trace. Contains the first non-used sequence number.

Definition at line 124 of file tracer.h.

Referenced by MainFlush(), and Tracer().

pthread_cond_t Tracer::sig_continue_trace_

private

Definition at line 118 of file tracer.h.

Referenced by MainFlush(), and ~Tracer().

pthread_mutex_t Tracer::sig_continue_trace_mutex_

private

Definition at line 119 of file tracer.h.

Referenced by MainFlush(), and ~Tracer().

pthread_cond_t Tracer::sig_flush_

private

Definition at line 116 of file tracer.h.

Referenced by MainFlush(), and ~Tracer().

pthread_mutex_t Tracer::sig_flush_mutex_

private

Definition at line 117 of file tracer.h.

Referenced by MainFlush(), and ~Tracer().

bool Tracer::spawned_

private

Definition at line 104 of file tracer.h.

Referenced by ~Tracer().

atomic_int32 Tracer::terminate_flush_thread_

private

Definition at line 130 of file tracer.h.

Referenced by MainFlush(), Tracer(), and ~Tracer().

pthread_t Tracer::thread_flush_

private

Definition at line 115 of file tracer.h.

Referenced by Tracer(), and ~Tracer().

std::string Tracer::trace_file_

private

Definition at line 105 of file tracer.h.

Referenced by MainFlush().

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

• /home/sftnight/jenkins/workspace/CvmfsDoxygen/label/docker-x86_64/cvmfs/cvmfs/tracer.h
• /home/sftnight/jenkins/workspace/CvmfsDoxygen/label/docker-x86_64/cvmfs/cvmfs/tracer.cc