mirror of
https://github.com/tomahawk-player/tomahawk.git
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* Added breakpad support for Linux.
This commit is contained in:
115
thirdparty/breakpad/third_party/glog/doc/designstyle.css
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115
thirdparty/breakpad/third_party/glog/doc/designstyle.css
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@@ -0,0 +1,115 @@
|
||||
body {
|
||||
background-color: #ffffff;
|
||||
color: black;
|
||||
margin-right: 1in;
|
||||
margin-left: 1in;
|
||||
}
|
||||
|
||||
|
||||
h1, h2, h3, h4, h5, h6 {
|
||||
color: #3366ff;
|
||||
font-family: sans-serif;
|
||||
}
|
||||
@media print {
|
||||
/* Darker version for printing */
|
||||
h1, h2, h3, h4, h5, h6 {
|
||||
color: #000080;
|
||||
font-family: helvetica, sans-serif;
|
||||
}
|
||||
}
|
||||
|
||||
h1 {
|
||||
text-align: center;
|
||||
font-size: 18pt;
|
||||
}
|
||||
h2 {
|
||||
margin-left: -0.5in;
|
||||
}
|
||||
h3 {
|
||||
margin-left: -0.25in;
|
||||
}
|
||||
h4 {
|
||||
margin-left: -0.125in;
|
||||
}
|
||||
hr {
|
||||
margin-left: -1in;
|
||||
}
|
||||
|
||||
/* Definition lists: definition term bold */
|
||||
dt {
|
||||
font-weight: bold;
|
||||
}
|
||||
|
||||
address {
|
||||
text-align: right;
|
||||
}
|
||||
/* Use the <code> tag for bits of code and <var> for variables and objects. */
|
||||
code,pre,samp,var {
|
||||
color: #006000;
|
||||
}
|
||||
/* Use the <file> tag for file and directory paths and names. */
|
||||
file {
|
||||
color: #905050;
|
||||
font-family: monospace;
|
||||
}
|
||||
/* Use the <kbd> tag for stuff the user should type. */
|
||||
kbd {
|
||||
color: #600000;
|
||||
}
|
||||
div.note p {
|
||||
float: right;
|
||||
width: 3in;
|
||||
margin-right: 0%;
|
||||
padding: 1px;
|
||||
border: 2px solid #6060a0;
|
||||
background-color: #fffff0;
|
||||
}
|
||||
|
||||
UL.nobullets {
|
||||
list-style-type: none;
|
||||
list-style-image: none;
|
||||
margin-left: -1em;
|
||||
}
|
||||
|
||||
/*
|
||||
body:after {
|
||||
content: "Google Confidential";
|
||||
}
|
||||
*/
|
||||
|
||||
/* pretty printing styles. See prettify.js */
|
||||
.str { color: #080; }
|
||||
.kwd { color: #008; }
|
||||
.com { color: #800; }
|
||||
.typ { color: #606; }
|
||||
.lit { color: #066; }
|
||||
.pun { color: #660; }
|
||||
.pln { color: #000; }
|
||||
.tag { color: #008; }
|
||||
.atn { color: #606; }
|
||||
.atv { color: #080; }
|
||||
pre.prettyprint { padding: 2px; border: 1px solid #888; }
|
||||
|
||||
.embsrc { background: #eee; }
|
||||
|
||||
@media print {
|
||||
.str { color: #060; }
|
||||
.kwd { color: #006; font-weight: bold; }
|
||||
.com { color: #600; font-style: italic; }
|
||||
.typ { color: #404; font-weight: bold; }
|
||||
.lit { color: #044; }
|
||||
.pun { color: #440; }
|
||||
.pln { color: #000; }
|
||||
.tag { color: #006; font-weight: bold; }
|
||||
.atn { color: #404; }
|
||||
.atv { color: #060; }
|
||||
}
|
||||
|
||||
/* Table Column Headers */
|
||||
.hdr {
|
||||
color: #006;
|
||||
font-weight: bold;
|
||||
background-color: #dddddd; }
|
||||
.hdr2 {
|
||||
color: #006;
|
||||
background-color: #eeeeee; }
|
554
thirdparty/breakpad/third_party/glog/doc/glog.html
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thirdparty/breakpad/third_party/glog/doc/glog.html
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|
||||
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
|
||||
|
||||
<html>
|
||||
<head>
|
||||
<title>How To Use Google Logging Library (glog)</title>
|
||||
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
||||
<link href="http://www.google.com/favicon.ico" type="image/x-icon"
|
||||
rel="shortcut icon">
|
||||
<link href="designstyle.css" type="text/css" rel="stylesheet">
|
||||
<style type="text/css">
|
||||
<!--
|
||||
ol.bluelist li {
|
||||
color: #3366ff;
|
||||
font-family: sans-serif;
|
||||
}
|
||||
ol.bluelist li p {
|
||||
color: #000;
|
||||
font-family: "Times Roman", times, serif;
|
||||
}
|
||||
ul.blacklist li {
|
||||
color: #000;
|
||||
font-family: "Times Roman", times, serif;
|
||||
}
|
||||
//-->
|
||||
</style>
|
||||
</head>
|
||||
|
||||
<body>
|
||||
|
||||
<h1>How To Use Google Logging Library (glog)</h1>
|
||||
<small>(as of
|
||||
<script type=text/javascript>
|
||||
var lm = new Date(document.lastModified);
|
||||
document.write(lm.toDateString());
|
||||
</script>)
|
||||
</small>
|
||||
<br>
|
||||
|
||||
<h2> <A NAME=intro>Introduction</A> </h2>
|
||||
|
||||
<p><b>Google glog</b> is a library that implements application-level
|
||||
logging. This library provides logging APIs based on C++-style
|
||||
streams and various helper macros.
|
||||
You can log a message by simply streaming things to LOG(<a
|
||||
particular <a href="#severity">severity level</a>>), e.g.
|
||||
|
||||
<pre>
|
||||
#include <glog/logging.h>
|
||||
|
||||
int main(int argc, char* argv[]) {
|
||||
// Initialize Google's logging library.
|
||||
google::InitGoogleLogging(argv[0]);
|
||||
|
||||
// ...
|
||||
LOG(INFO) << "Found " << num_cookies << " cookies";
|
||||
}
|
||||
</pre>
|
||||
|
||||
<p>Google glog defines a series of macros that simplify many common logging
|
||||
tasks. You can log messages by severity level, control logging
|
||||
behavior from the command line, log based on conditionals, abort the
|
||||
program when expected conditions are not met, introduce your own
|
||||
verbose logging levels, and more. This document describes the
|
||||
functionality supported by glog. Please note that this document
|
||||
doesn't describe all features in this library, but the most useful
|
||||
ones. If you want to find less common features, please check
|
||||
header files under <code>src/glog</code> directory.
|
||||
|
||||
<h2> <A NAME=severity>Severity Level</A> </h2>
|
||||
|
||||
<p>
|
||||
You can specify one of the following severity levels (in
|
||||
increasing order of severity): <code>INFO</code>, <code>WARNING</code>,
|
||||
<code>ERROR</code>, and <code>FATAL</code>.
|
||||
Logging a <code>FATAL</code> message terminates the program (after the
|
||||
message is logged).
|
||||
Note that messages of a given severity are logged not only in the
|
||||
logfile for that severity, but also in all logfiles of lower severity.
|
||||
E.g., a message of severity <code>FATAL</code> will be logged to the
|
||||
logfiles of severity <code>FATAL</code>, <code>ERROR</code>,
|
||||
<code>WARNING</code>, and <code>INFO</code>.
|
||||
|
||||
<p>
|
||||
The <code>DFATAL</code> severity logs a <code>FATAL</code> error in
|
||||
debug mode (i.e., there is no <code>NDEBUG</code> macro defined), but
|
||||
avoids halting the program in production by automatically reducing the
|
||||
severity to <code>ERROR</code>.
|
||||
|
||||
<p>Unless otherwise specified, glog writes to the filename
|
||||
"/tmp/<program name>.<hostname>.<user name>.log.<severity level>.<date>.<time>.<pid>"
|
||||
(e.g., "/tmp/hello_world.example.com.hamaji.log.INFO.20080709-222411.10474").
|
||||
By default, glog copies the log messages of severity level
|
||||
<code>ERROR</code> or <code>FATAL</code> to standard error (stderr)
|
||||
in addition to log files.
|
||||
|
||||
<h2><A NAME=flags>Setting Flags</A></h2>
|
||||
|
||||
<p>Several flags influence glog's output behavior.
|
||||
If the <a href="http://code.google.com/p/google-gflags/">Google
|
||||
gflags library</a> is installed on your machine, the
|
||||
<code>configure</code> script (see the INSTALL file in the package for
|
||||
detail of this script) will automatically detect and use it,
|
||||
allowing you to pass flags on the command line. For example, if you
|
||||
want to turn the flag <code>--logtostderr</code> on, you can start
|
||||
your application with the following command line:
|
||||
|
||||
<pre>
|
||||
./your_application --logtostderr=1
|
||||
</pre>
|
||||
|
||||
If the Google gflags library isn't installed, you set flags via
|
||||
environment variables, prefixing the flag name with "GLOG_", e.g.
|
||||
|
||||
<pre>
|
||||
GLOG_logtostderr=1 ./your_application
|
||||
</pre>
|
||||
|
||||
<!-- TODO(hamaji): Fill the version number
|
||||
<p>By glog version 0.x.x, you can use GLOG_* environment variables
|
||||
even if you have gflags. If both an environment variable and a flag
|
||||
are specified, the value specified by a flag wins. E.g., if GLOG_v=0
|
||||
and --v=1, the verbosity will be 1, not 0.
|
||||
-->
|
||||
|
||||
<p>The following flags are most commonly used:
|
||||
|
||||
<dl>
|
||||
<dt><code>logtostderr</code> (<code>bool</code>, default=<code>false</code>)
|
||||
<dd>Log messages to stderr instead of logfiles.<br>
|
||||
Note: you can set binary flags to <code>true</code> by specifying
|
||||
<code>1</code>, <code>true</code>, or <code>yes</code> (case
|
||||
insensitive).
|
||||
Also, you can set binary flags to <code>false</code> by specifying
|
||||
<code>0</code>, <code>false</code>, or <code>no</code> (again, case
|
||||
insensitive).
|
||||
<dt><code>stderrthreshold</code> (<code>int</code>, default=2, which
|
||||
is <code>ERROR</code>)
|
||||
<dd>Copy log messages at or above this level to stderr in
|
||||
addition to logfiles. The numbers of severity levels
|
||||
<code>INFO</code>, <code>WARNING</code>, <code>ERROR</code>, and
|
||||
<code>FATAL</code> are 0, 1, 2, and 3, respectively.
|
||||
<dt><code>minloglevel</code> (<code>int</code>, default=0, which
|
||||
is <code>INFO</code>)
|
||||
<dd>Log messages at or above this level. Again, the numbers of
|
||||
severity levels <code>INFO</code>, <code>WARNING</code>,
|
||||
<code>ERROR</code>, and <code>FATAL</code> are 0, 1, 2, and 3,
|
||||
respectively.
|
||||
<dt><code>log_dir</code> (<code>string</code>, default="")
|
||||
<dd>If specified, logfiles are written into this directory instead
|
||||
of the default logging directory.
|
||||
<dt><code>v</code> (<code>int</code>, default=0)
|
||||
<dd>Show all <code>VLOG(m)</code> messages for <code>m</code> less or
|
||||
equal the value of this flag. Overridable by --vmodule.
|
||||
See <a href="#verbose">the section about verbose logging</a> for more
|
||||
detail.
|
||||
<dt><code>vmodule</code> (<code>string</code>, default="")
|
||||
<dd>Per-module verbose level. The argument has to contain a
|
||||
comma-separated list of <module name>=<log level>.
|
||||
<module name>
|
||||
is a glob pattern (e.g., <code>gfs*</code> for all modules whose name
|
||||
starts with "gfs"), matched against the filename base
|
||||
(that is, name ignoring .cc/.h./-inl.h).
|
||||
<log level> overrides any value given by --v.
|
||||
See also <a href="#verbose">the section about verbose logging</a>.
|
||||
</dl>
|
||||
|
||||
<p>There are some other flags defined in logging.cc. Please grep the
|
||||
source code for "DEFINE_" to see a complete list of all flags.
|
||||
|
||||
<h2><A NAME=conditional>Conditional / Occasional Logging</A></h2>
|
||||
|
||||
<p>Sometimes, you may only want to log a message under certain
|
||||
conditions. You can use the following macros to perform conditional
|
||||
logging:
|
||||
|
||||
<pre>
|
||||
LOG_IF(INFO, num_cookies > 10) << "Got lots of cookies";
|
||||
</pre>
|
||||
|
||||
The "Got lots of cookies" message is logged only when the variable
|
||||
<code>num_cookies</code> exceeds 10.
|
||||
|
||||
If a line of code is executed many times, it may be useful to only log
|
||||
a message at certain intervals. This kind of logging is most useful
|
||||
for informational messages.
|
||||
|
||||
<pre>
|
||||
LOG_EVERY_N(INFO, 10) << "Got the " << google::COUNTER << "th cookie";
|
||||
</pre>
|
||||
|
||||
<p>The above line outputs a log messages on the 1st, 11th,
|
||||
21st, ... times it is executed. Note that the special
|
||||
<code>google::COUNTER</code> value is used to identify which repetition is
|
||||
happening.
|
||||
|
||||
<p>You can combine conditional and occasional logging with the
|
||||
following macro.
|
||||
|
||||
<pre>
|
||||
LOG_IF_EVERY_N(INFO, (size > 1024), 10) << "Got the " << google::COUNTER
|
||||
<< "th big cookie";
|
||||
</pre>
|
||||
|
||||
<p>Instead of outputting a message every nth time, you can also limit
|
||||
the output to the first n occurrences:
|
||||
|
||||
<pre>
|
||||
LOG_FIRST_N(INFO, 20) << "Got the " << google::COUNTER << "th cookie";
|
||||
</pre>
|
||||
|
||||
<p>Outputs log messages for the first 20 times it is executed. Again,
|
||||
the <code>google::COUNTER</code> identifier indicates which repetition is
|
||||
happening.
|
||||
|
||||
<h2><A NAME=debug>Debug Mode Support</A></h2>
|
||||
|
||||
<p>Special "debug mode" logging macros only have an effect in debug
|
||||
mode and are compiled away to nothing for non-debug mode
|
||||
compiles. Use these macros to avoid slowing down your production
|
||||
application due to excessive logging.
|
||||
|
||||
<pre>
|
||||
DLOG(INFO) << "Found cookies";
|
||||
|
||||
DLOG_IF(INFO, num_cookies > 10) << "Got lots of cookies";
|
||||
|
||||
DLOG_EVERY_N(INFO, 10) << "Got the " << google::COUNTER << "th cookie";
|
||||
</pre>
|
||||
|
||||
<h2><A NAME=check>CHECK Macros</A></h2>
|
||||
|
||||
<p>It is a good practice to check expected conditions in your program
|
||||
frequently to detect errors as early as possible. The
|
||||
<code>CHECK</code> macro provides the ability to abort the application
|
||||
when a condition is not met, similar to the <code>assert</code> macro
|
||||
defined in the standard C library.
|
||||
|
||||
<p><code>CHECK</code> aborts the application if a condition is not
|
||||
true. Unlike <code>assert</code>, it is *not* controlled by
|
||||
<code>NDEBUG</code>, so the check will be executed regardless of
|
||||
compilation mode. Therefore, <code>fp->Write(x)</code> in the
|
||||
following example is always executed:
|
||||
|
||||
<pre>
|
||||
CHECK(fp->Write(x) == 4) << "Write failed!";
|
||||
</pre>
|
||||
|
||||
<p>There are various helper macros for
|
||||
equality/inequality checks - <code>CHECK_EQ</code>,
|
||||
<code>CHECK_NE</code>, <code>CHECK_LE</code>, <code>CHECK_LT</code>,
|
||||
<code>CHECK_GE</code>, and <code>CHECK_GT</code>.
|
||||
They compare two values, and log a
|
||||
<code>FATAL</code> message including the two values when the result is
|
||||
not as expected. The values must have <code>operator<<(ostream,
|
||||
...)</code> defined.
|
||||
|
||||
<p>You may append to the error message like so:
|
||||
|
||||
<pre>
|
||||
CHECK_NE(1, 2) << ": The world must be ending!";
|
||||
</pre>
|
||||
|
||||
<p>We are very careful to ensure that each argument is evaluated exactly
|
||||
once, and that anything which is legal to pass as a function argument is
|
||||
legal here. In particular, the arguments may be temporary expressions
|
||||
which will end up being destroyed at the end of the apparent statement,
|
||||
for example:
|
||||
|
||||
<pre>
|
||||
CHECK_EQ(string("abc")[1], 'b');
|
||||
</pre>
|
||||
|
||||
<p>The compiler reports an error if one of the arguments is a
|
||||
pointer and the other is NULL. To work around this, simply static_cast
|
||||
NULL to the type of the desired pointer.
|
||||
|
||||
<pre>
|
||||
CHECK_EQ(some_ptr, static_cast<SomeType*>(NULL));
|
||||
</pre>
|
||||
|
||||
<p>Better yet, use the CHECK_NOTNULL macro:
|
||||
|
||||
<pre>
|
||||
CHECK_NOTNULL(some_ptr);
|
||||
some_ptr->DoSomething();
|
||||
</pre>
|
||||
|
||||
<p>Since this macro returns the given pointer, this is very useful in
|
||||
constructor initializer lists.
|
||||
|
||||
<pre>
|
||||
struct S {
|
||||
S(Something* ptr) : ptr_(CHECK_NOTNULL(ptr)) {}
|
||||
Something* ptr_;
|
||||
};
|
||||
</pre>
|
||||
|
||||
<p>Note that you cannot use this macro as a C++ stream due to this
|
||||
feature. Please use <code>CHECK_EQ</code> described above to log a
|
||||
custom message before aborting the application.
|
||||
|
||||
<p>If you are comparing C strings (char *), a handy set of macros
|
||||
performs case sensitive as well as case insensitive comparisons -
|
||||
<code>CHECK_STREQ</code>, <code>CHECK_STRNE</code>,
|
||||
<code>CHECK_STRCASEEQ</code>, and <code>CHECK_STRCASENE</code>. The
|
||||
CASE versions are case-insensitive. You can safely pass <code>NULL</code>
|
||||
pointers for this macro. They treat <code>NULL</code> and any
|
||||
non-<code>NULL</code> string as not equal. Two <code>NULL</code>s are
|
||||
equal.
|
||||
|
||||
<p>Note that both arguments may be temporary strings which are
|
||||
destructed at the end of the current "full expression"
|
||||
(e.g., <code>CHECK_STREQ(Foo().c_str(), Bar().c_str())</code> where
|
||||
<code>Foo</code> and <code>Bar</code> return C++'s
|
||||
<code>std::string</code>).
|
||||
|
||||
<p>The <code>CHECK_DOUBLE_EQ</code> macro checks the equality of two
|
||||
floating point values, accepting a small error margin.
|
||||
<code>CHECK_NEAR</code> accepts a third floating point argument, which
|
||||
specifies the acceptable error margin.
|
||||
|
||||
<h2><A NAME=verbose>Verbose Logging</A></h2>
|
||||
|
||||
<p>When you are chasing difficult bugs, thorough log messages are very
|
||||
useful. However, you may want to ignore too verbose messages in usual
|
||||
development. For such verbose logging, glog provides the
|
||||
<code>VLOG</code> macro, which allows you to define your own numeric
|
||||
logging levels. The <code>--v</code> command line option controls
|
||||
which verbose messages are logged:
|
||||
|
||||
<pre>
|
||||
VLOG(1) << "I'm printed when you run the program with --v=1 or higher";
|
||||
VLOG(2) << "I'm printed when you run the program with --v=2 or higher";
|
||||
</pre>
|
||||
|
||||
<p>With <code>VLOG</code>, the lower the verbose level, the more
|
||||
likely messages are to be logged. For example, if
|
||||
<code>--v==1</code>, <code>VLOG(1)</code> will log, but
|
||||
<code>VLOG(2)</code> will not log. This is opposite of the severity
|
||||
level, where <code>INFO</code> is 0, and <code>ERROR</code> is 2.
|
||||
<code>--minloglevel</code> of 1 will log <code>WARNING</code> and
|
||||
above. Though you can specify any integers for both <code>VLOG</code>
|
||||
macro and <code>--v</code> flag, the common values for them are small
|
||||
positive integers. For example, if you write <code>VLOG(0)</code>,
|
||||
you should specify <code>--v=-1</code> or lower to silence it. This
|
||||
is less useful since we may not want verbose logs by default in most
|
||||
cases. The <code>VLOG</code> macros always log at the
|
||||
<code>INFO</code> log level (when they log at all).
|
||||
|
||||
<p>Verbose logging can be controlled from the command line on a
|
||||
per-module basis:
|
||||
|
||||
<pre>
|
||||
--vmodule=mapreduce=2,file=1,gfs*=3 --v=0
|
||||
</pre>
|
||||
|
||||
<p>will:
|
||||
|
||||
<ul>
|
||||
<li>a. Print VLOG(2) and lower messages from mapreduce.{h,cc}
|
||||
<li>b. Print VLOG(1) and lower messages from file.{h,cc}
|
||||
<li>c. Print VLOG(3) and lower messages from files prefixed with "gfs"
|
||||
<li>d. Print VLOG(0) and lower messages from elsewhere
|
||||
</ul>
|
||||
|
||||
<p>The wildcarding functionality shown by (c) supports both '*'
|
||||
(matches 0 or more characters) and '?' (matches any single character)
|
||||
wildcards. Please also check the section about <a
|
||||
href="#flags">command line flags</a>.
|
||||
|
||||
<p>There's also <code>VLOG_IS_ON(n)</code> "verbose level" condition
|
||||
macro. This macro returns true when the <code>--v</code> is equal or
|
||||
greater than <code>n</code>. To be used as
|
||||
|
||||
<pre>
|
||||
if (VLOG_IS_ON(2)) {
|
||||
// do some logging preparation and logging
|
||||
// that can't be accomplished with just VLOG(2) << ...;
|
||||
}
|
||||
</pre>
|
||||
|
||||
<p>Verbose level condition macros <code>VLOG_IF</code>,
|
||||
<code>VLOG_EVERY_N</code> and <code>VLOG_IF_EVERY_N</code> behave
|
||||
analogous to <code>LOG_IF</code>, <code>LOG_EVERY_N</code>,
|
||||
<code>LOF_IF_EVERY</code>, but accept a numeric verbosity level as
|
||||
opposed to a severity level.
|
||||
|
||||
<pre>
|
||||
VLOG_IF(1, (size > 1024))
|
||||
<< "I'm printed when size is more than 1024 and when you run the "
|
||||
"program with --v=1 or more";
|
||||
VLOG_EVERY_N(1, 10)
|
||||
<< "I'm printed every 10th occurrence, and when you run the program "
|
||||
"with --v=1 or more. Present occurence is " << google::COUNTER;
|
||||
VLOG_IF_EVERY_N(1, (size > 1024), 10)
|
||||
<< "I'm printed on every 10th occurence of case when size is more "
|
||||
" than 1024, when you run the program with --v=1 or more. ";
|
||||
"Present occurence is " << google::COUNTER;
|
||||
</pre>
|
||||
|
||||
<h2> <A name="signal">Failure Signal Handler</A> </h2>
|
||||
|
||||
<p>
|
||||
The library provides a convenient signal handler that will dump useful
|
||||
information when the program crashes on certain signals such as SIGSEGV.
|
||||
The signal handler can be installed by
|
||||
google::InstallFailureSignalHandler(). The following is an example of output
|
||||
from the signal handler.
|
||||
|
||||
<pre>
|
||||
*** Aborted at 1225095260 (unix time) try "date -d @1225095260" if you are using GNU date ***
|
||||
*** SIGSEGV (@0x0) received by PID 17711 (TID 0x7f893090a6f0) from PID 0; stack trace: ***
|
||||
PC: @ 0x412eb1 TestWaitingLogSink::send()
|
||||
@ 0x7f892fb417d0 (unknown)
|
||||
@ 0x412eb1 TestWaitingLogSink::send()
|
||||
@ 0x7f89304f7f06 google::LogMessage::SendToLog()
|
||||
@ 0x7f89304f35af google::LogMessage::Flush()
|
||||
@ 0x7f89304f3739 google::LogMessage::~LogMessage()
|
||||
@ 0x408cf4 TestLogSinkWaitTillSent()
|
||||
@ 0x4115de main
|
||||
@ 0x7f892f7ef1c4 (unknown)
|
||||
@ 0x4046f9 (unknown)
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
By default, the signal handler writes the failure dump to the standard
|
||||
error. You can customize the destination by InstallFailureWriter().
|
||||
|
||||
<h2> <A name="misc">Miscellaneous Notes</A> </h2>
|
||||
|
||||
<h3><A NAME=message>Performance of Messages</A></h3>
|
||||
|
||||
<p>The conditional logging macros provided by glog (e.g.,
|
||||
<code>CHECK</code>, <code>LOG_IF</code>, <code>VLOG</code>, ...) are
|
||||
carefully implemented and don't execute the right hand side
|
||||
expressions when the conditions are false. So, the following check
|
||||
may not sacrifice the performance of your application.
|
||||
|
||||
<pre>
|
||||
CHECK(obj.ok) << obj.CreatePrettyFormattedStringButVerySlow();
|
||||
</pre>
|
||||
|
||||
<h3><A NAME=failure>User-defined Failure Function</A></h3>
|
||||
|
||||
<p><code>FATAL</code> severity level messages or unsatisfied
|
||||
<code>CHECK</code> condition terminate your program. You can change
|
||||
the behavior of the termination by
|
||||
<code>InstallFailureFunction</code>.
|
||||
|
||||
<pre>
|
||||
void YourFailureFunction() {
|
||||
// Reports something...
|
||||
exit(1);
|
||||
}
|
||||
|
||||
int main(int argc, char* argv[]) {
|
||||
google::InstallFailureFunction(&YourFailureFunction);
|
||||
}
|
||||
</pre>
|
||||
|
||||
<p>By default, glog tries to dump stacktrace and makes the program
|
||||
exit with status 1. The stacktrace is produced only when you run the
|
||||
program on an architecture for which glog supports stack tracing (as
|
||||
of September 2008, glog supports stack tracing for x86 and x86_64).
|
||||
|
||||
<h3><A NAME=raw>Raw Logging</A></h3>
|
||||
|
||||
<p>The header file <code><glog/raw_logging.h></code> can be
|
||||
used for thread-safe logging, which does not allocate any memory or
|
||||
acquire any locks. Therefore, the macros defined in this
|
||||
header file can be used by low-level memory allocation and
|
||||
synchronization code.
|
||||
Please check <code>src/glog/raw_logging.h.in</code> for detail.
|
||||
</p>
|
||||
|
||||
<h3><A NAME=plog>Google Style perror()</A></h3>
|
||||
|
||||
<p><code>PLOG()</code> and <code>PLOG_IF()</code> and
|
||||
<code>PCHECK()</code> behave exactly like their <code>LOG*</code> and
|
||||
<code>CHECK</code> equivalents with the addition that they append a
|
||||
description of the current state of errno to their output lines.
|
||||
E.g.
|
||||
|
||||
<pre>
|
||||
PCHECK(write(1, NULL, 2) >= 0) << "Write NULL failed";
|
||||
</pre>
|
||||
|
||||
<p>This check fails with the following error message.
|
||||
|
||||
<pre>
|
||||
F0825 185142 test.cc:22] Check failed: write(1, NULL, 2) >= 0 Write NULL failed: Bad address [14]
|
||||
</pre>
|
||||
|
||||
<h3><A NAME=syslog>Syslog</A></h3>
|
||||
|
||||
<p><code>SYSLOG</code>, <code>SYSLOG_IF</code>, and
|
||||
<code>SYSLOG_EVERY_N</code> macros are available.
|
||||
These log to syslog in addition to the normal logs. Be aware that
|
||||
logging to syslog can drastically impact performance, especially if
|
||||
syslog is configured for remote logging! Make sure you understand the
|
||||
implications of outputting to syslog before you use these macros. In
|
||||
general, it's wise to use these macros sparingly.
|
||||
|
||||
<h3><A NAME=strip>Strip Logging Messages</A></h3>
|
||||
|
||||
<p>Strings used in log messages can increase the size of your binary
|
||||
and present a privacy concern. You can therefore instruct glog to
|
||||
remove all strings which fall below a certain severity level by using
|
||||
the GOOGLE_STRIP_LOG macro:
|
||||
|
||||
<p>If your application has code like this:
|
||||
|
||||
<pre>
|
||||
#define GOOGLE_STRIP_LOG 1 // this must go before the #include!
|
||||
#include <glog/logging.h>
|
||||
</pre>
|
||||
|
||||
<p>The compiler will remove the log messages whose severities are less
|
||||
than the specified integer value. Since
|
||||
<code>VLOG</code> logs at the severity level <code>INFO</code>
|
||||
(numeric value <code>0</code>),
|
||||
setting <code>GOOGLE_STRIP_LOG</code> to 1 or greater removes
|
||||
all log messages associated with <code>VLOG</code>s as well as
|
||||
<code>INFO</code> log statements.
|
||||
|
||||
<h3><A NAME=windows>Notes for Windows users</A></h3>
|
||||
|
||||
<p>Google glog defines a severity level <code>ERROR</code>, which is
|
||||
also defined in <code>windows.h</code>
|
||||
There are two known workarounds to avoid this conflict:
|
||||
|
||||
<ul>
|
||||
<li>#define <code>WIN32_LEAN_AND_MEAN</code> or <code>NOGDI</code>
|
||||
<strong>before</strong> you #include <code>windows.h</code> .
|
||||
<li>#undef <code>ERROR</code> <strong>after</strong> you #include
|
||||
<code>windows.h</code> .
|
||||
</ul>
|
||||
|
||||
<p>See <a href="http://code.google.com/p/google-glog/issues/detail?id=33">
|
||||
this issue</a> for more detail.
|
||||
|
||||
<hr>
|
||||
<address>
|
||||
Shinichiro Hamaji<br>
|
||||
Gregor Hohpe<br>
|
||||
<script type=text/javascript>
|
||||
var lm = new Date(document.lastModified);
|
||||
document.write(lm.toDateString());
|
||||
</script>
|
||||
</address>
|
||||
|
||||
</body>
|
||||
</html>
|
Reference in New Issue
Block a user