libvirt/src/util/virlog.h

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/*
2012-12-12 17:59:27 +00:00
* virlog.h: internal logging and debugging
*
* Copyright (C) 2006-2008, 2011-2012 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <http://www.gnu.org/licenses/>.
*
*/
#ifndef __VIRTLOG_H_
# define __VIRTLOG_H_
# include "internal.h"
# include "virbuffer.h"
# ifdef PACKAGER_VERSION
# ifdef PACKAGER
# define VIR_LOG_VERSION_STRING \
"libvirt version: " VERSION ", package: " PACKAGER_VERSION " (" PACKAGER ")"
# else
# define VIR_LOG_VERSION_STRING \
"libvirt version: " VERSION ", package: " PACKAGER_VERSION
# endif
# else
# define VIR_LOG_VERSION_STRING \
"libvirt version: " VERSION
# endif
/*
* To be made public
*/
typedef enum {
VIR_LOG_DEBUG = 1,
VIR_LOG_INFO,
VIR_LOG_WARN,
VIR_LOG_ERROR,
} virLogPriority;
# define VIR_LOG_DEFAULT VIR_LOG_WARN
typedef enum {
VIR_LOG_TO_STDERR = 0,
VIR_LOG_TO_SYSLOG,
VIR_LOG_TO_FILE,
VIR_LOG_TO_JOURNALD,
VIR_LOG_TO_OUTPUT_LAST,
} virLogDestination;
typedef struct _virLogSource virLogSource;
typedef virLogSource *virLogSourcePtr;
struct _virLogSource {
const char *name;
Switch to filtering based on log source name instead of filename Currently the log filter strings are used in a string comparison against the source filename each time log message is emitted. If no log filters at all are set, there's obviously no string comparison to be done. If any single log filter is set though, this imposes a compute burden on every logging call even if logs from the file in question are disabled. This string comparison must also be done while the logging mutex is held, which has implications for concurrency when multiple threads are emitting log messages. This changes the log filtering to be done based on the virLogSource object name. The virLogSource struct is extended to contain 'serial' and 'priority' fields. Any time the global log filter rules are changed a global serial number is incremented. When a log message is emitted, the serial in the virLogSource instance is compared with the global serial number. If out of date, then the 'priority' field in the virLogSource instance is updated based on the new filter rules. The 'priority' field is checked to see whether the log message should be sent to the log outputs. The comparisons of the 'serial' and 'priority' fields are done with no locks held. So in the common case each logging call has an overhead of 2 integer comparisons, with no locks held. Only if the decision is made to forward the message to the log output, or if the 'serial' value is out of date do locks need to be acquired. Technically the comparisons of the 'serial' and 'priority' fields should be done with locks held, or using atomic operations. Both of these options have a notable performance impact, however, and since all writes a protected by a global mutex, it is believed that worst case behaviour where the fields are read concurrently with being written would merely result in an mistaken emission or dropping of the log message in question. This is an acceptable tradeoff for the performance benefit of avoiding locking. As a quick benchmark, a demo program that registers 500 file descriptors with the event loop (eg equiv of 500 QEMU monitor commands), creates pending read I/O on every FD, and then runs virEventRunDefaultImpl() took 4.6 seconds to do 51200 iterations. After this optimization it only takes 3.3 seconds, with the log APIs no longer being a relevant factor in the running time. Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2014-02-28 13:55:11 +00:00
unsigned int priority;
unsigned int serial;
unsigned int flags;
};
/*
* ATTRIBUTE_UNUSED is to make gcc keep quiet if all the
* log statements in a file are conditionally disabled
* at compile time due to configure options.
*/
# define VIR_LOG_INIT(n) \
static ATTRIBUTE_UNUSED virLogSource virLogSelf = { \
.name = "" n "", \
.priority = VIR_LOG_ERROR, \
.serial = 0, \
.flags = 0, \
};
/*
* If configured with --enable-debug=yes then library calls
* are printed to stderr for debugging or to an appropriate channel
* defined at runtime from the libvirt daemon configuration file
*/
# ifdef ENABLE_DEBUG
# define VIR_DEBUG_INT(src, filename, linenr, funcname, ...) \
virLogMessage(src, VIR_LOG_DEBUG, filename, linenr, funcname, NULL, __VA_ARGS__)
# else
/**
* virLogEatParams:
*
* Do nothing but eat parameters.
*/
static inline void virLogEatParams(virLogSourcePtr unused, ...)
{
/* Silence gcc */
unused = unused;
}
# define VIR_DEBUG_INT(src, filename, linenr, funcname, ...) \
virLogEatParams(src, filename, linenr, funcname, __VA_ARGS__)
# endif /* !ENABLE_DEBUG */
# define VIR_INFO_INT(src, filename, linenr, funcname, ...) \
virLogMessage(src, VIR_LOG_INFO, filename, linenr, funcname, NULL, __VA_ARGS__)
# define VIR_WARN_INT(src, filename, linenr, funcname, ...) \
virLogMessage(src, VIR_LOG_WARN, filename, linenr, funcname, NULL, __VA_ARGS__)
# define VIR_ERROR_INT(src, filename, linenr, funcname, ...) \
virLogMessage(src, VIR_LOG_ERROR, filename, linenr, funcname, NULL, __VA_ARGS__)
# define VIR_DEBUG(...) \
VIR_DEBUG_INT(&virLogSelf, __FILE__, __LINE__, __func__, __VA_ARGS__)
# define VIR_INFO(...) \
VIR_INFO_INT(&virLogSelf, __FILE__, __LINE__, __func__, __VA_ARGS__)
# define VIR_WARN(...) \
VIR_WARN_INT(&virLogSelf, __FILE__, __LINE__, __func__, __VA_ARGS__)
# define VIR_ERROR(...) \
VIR_ERROR_INT(&virLogSelf, __FILE__, __LINE__, __func__, __VA_ARGS__)
2009-01-06 18:32:03 +00:00
struct _virLogMetadata {
const char *key;
const char *s; /* String value, or NULL to use "i" */
int iv;
};
typedef struct _virLogMetadata virLogMetadata;
typedef struct _virLogMetadata *virLogMetadataPtr;
typedef struct _virLogOutput virLogOutput;
typedef virLogOutput *virLogOutputPtr;
typedef struct _virLogFilter virLogFilter;
typedef virLogFilter *virLogFilterPtr;
/**
* virLogOutputFunc:
* @src: the source of the log message
* @priority: the priority for the message
* @filename: file where the message was emitted
* @linenr: line where the message was emitted
* @funcname: the function emitting the message
* @timestamp: zero terminated string with timestamp of the message
* @metadata: NULL or metadata array, terminated by an item with NULL key
* @flags: flags associated with the message
* @rawstr: the unformatted message to log, zero terminated
* @str: the message to log, preformatted and zero terminated
* @data: extra output logging data
*
* Callback function used to output messages
*/
typedef void (*virLogOutputFunc) (virLogSourcePtr src,
virLogPriority priority,
const char *filename,
int linenr,
const char *funcname,
const char *timestamp,
virLogMetadataPtr metadata,
unsigned int flags,
const char *rawstr,
const char *str,
void *data);
/**
* virLogCloseFunc:
* @data: extra output logging data
*
* Callback function used to close a log output
*/
typedef void (*virLogCloseFunc) (void *data);
typedef enum {
VIR_LOG_STACK_TRACE = (1 << 0),
} virLogFilterFlags;
int virLogGetNbFilters(void);
int virLogGetNbOutputs(void);
char *virLogGetFilters(void);
char *virLogGetOutputs(void);
virLogPriority virLogGetDefaultPriority(void);
int virLogSetDefaultPriority(virLogPriority priority);
void virLogSetFromEnv(void);
void virLogOutputFree(virLogOutputPtr output);
void virLogOutputListFree(virLogOutputPtr *list, int count);
void virLogFilterFree(virLogFilterPtr filter);
void virLogFilterListFree(virLogFilterPtr *list, int count);
int virLogSetOutputs(const char *outputs);
int virLogSetFilters(const char *filters);
char *virLogGetDefaultOutput(void);
int virLogSetDefaultOutput(const char *fname, bool godaemon, bool privileged);
/*
* Internal logging API
*/
void virLogLock(void);
void virLogUnlock(void);
int virLogReset(void);
int virLogParseDefaultPriority(const char *priority);
int virLogPriorityFromSyslog(int priority);
void virLogMessage(virLogSourcePtr source,
virLogPriority priority,
const char *filename,
int linenr,
const char *funcname,
virLogMetadataPtr metadata,
const char *fmt, ...) ATTRIBUTE_FMT_PRINTF(7, 8);
void virLogVMessage(virLogSourcePtr source,
virLogPriority priority,
const char *filename,
int linenr,
const char *funcname,
virLogMetadataPtr metadata,
const char *fmt,
va_list vargs) ATTRIBUTE_FMT_PRINTF(7, 0);
bool virLogProbablyLogMessage(const char *str);
virLogOutputPtr virLogOutputNew(virLogOutputFunc f,
virLogCloseFunc c,
void *data,
virLogPriority priority,
virLogDestination dest,
const char *name) ATTRIBUTE_NONNULL(1);
virLogFilterPtr virLogFilterNew(const char *match,
virLogPriority priority,
unsigned int flags) ATTRIBUTE_NONNULL(1);
int virLogFindOutput(virLogOutputPtr *outputs, size_t noutputs,
virLogDestination dest, const void *opaque);
int virLogDefineOutputs(virLogOutputPtr *outputs,
size_t noutputs) ATTRIBUTE_NONNULL(1);
int virLogDefineFilters(virLogFilterPtr *filters, size_t nfilters);
virLogOutputPtr virLogParseOutput(const char *src) ATTRIBUTE_NONNULL(1);
virLogFilterPtr virLogParseFilter(const char *src) ATTRIBUTE_NONNULL(1);
int virLogParseOutputs(const char *src,
virLogOutputPtr **outputs) ATTRIBUTE_NONNULL(1);
int virLogParseFilters(const char *src,
virLogFilterPtr **filters) ATTRIBUTE_NONNULL(1);
#endif