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// ramlog.h
/* Copyright 2009 10gen Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <sstream>
#include <string>
#include <vector>
#include <boost/version.hpp>
#if BOOST_VERSION >= 105300
#include <boost/thread/lock_guard.hpp>
#endif
#include "mongo/base/disallow_copying.h"
#include "mongo/base/string_data.h"
#include "mongo/base/status.h"
#include "mongo/util/concurrency/mutex.h"
#include "mongo/logger/appender.h"
#include "mongo/logger/message_event.h"
#include "mongo/logger/tee.h"
namespace mongo {
/**
* Fixed-capacity log of line-oriented messages.
*
* Holds up to RamLog::N lines of up to RamLog::C bytes, each.
*
* RamLogs are stored in a global registry, accessed via RamLog::get() and
* RamLog::getIfExists().
*
* RamLogs and their registry are self-synchronizing. See documentary comments.
* To read a RamLog, instantiate a RamLog::LineIterator, documented below.
*/
class RamLog : public logger::Tee {
MONGO_DISALLOW_COPYING(RamLog);
public:
class LineIterator;
friend class RamLog::LineIterator;
/**
* Returns a pointer to the ramlog named "name", creating one if it did not already exist.
*
* Synchronizes on the RamLog catalog lock, _namedLock.
*/
static RamLog* get(const std::string& name);
/**
* Returns a pointer to the ramlog named "name", or NULL if no such ramlog exists.
*
* Synchronizes on the RamLog catalog lock, _namedLock.
*/
static RamLog* getIfExists(const std::string& name);
/**
* Writes the names of all existing ramlogs into "names".
*
* Synchronizes on the RamLog catalog lock, _namedLock.
*/
static void getNames( std::vector<std::string>& names );
/**
* Writes "str" as a line into the RamLog. If "str" is longer than the maximum
* line size, RamLog::C, truncates the line to the first C bytes. If "str"
* is shorter than RamLog::C and has a terminal '\n', it omits that character.
*
* Synchronized on the instance's own mutex, _mutex.
*/
void write(const std::string& str);
/**
* Writes an HTML representation of the log to "s".
*
* Synchronized on the instance's own mutex, _mutex.
*/
void toHTML(std::stringstream& s);
private:
static int repeats(const std::vector<const char *>& v, int i);
static string clean(const std::vector<const char *>& v, int i, string line="");
static string color(const std::string& line);
/* turn http:... into an anchor */
static string linkify(const char *s);
explicit RamLog( const std::string& name );
~RamLog(); // want this private as we want to leak so we can use them till the very end
enum {
N = 1024, // number of lines
C = 512 // max size of line
};
const char* getLine_inlock(unsigned lineNumber) const;
boost::mutex _mutex; // Guards all non-static data.
char lines[N][C];
unsigned h; // current position
unsigned n; // number of lines stores 0 o N
string _name;
long long _totalLinesWritten;
time_t _lastWrite;
};
/**
* Iterator over the lines of a RamLog.
*
* Also acts as a means of inspecting other properites of a ramlog consistently.
*
* Instances of LineIterator hold the lock for the underlying RamLog for their whole lifetime,
* and so should not be kept around.
*/
class RamLog::LineIterator {
MONGO_DISALLOW_COPYING(LineIterator);
public:
explicit LineIterator(RamLog* ramlog);
/**
* Returns true if there are more lines available to return by calls to next().
*/
bool more() const { return _nextLineIndex < _ramlog->n; }
/**
* Returns the next line and advances the iterator.
*/
const char* next() {
return _ramlog->getLine_inlock(_nextLineIndex++); // Postfix increment.
}
/**
* Returns the time of the last write to the ramlog.
*/
time_t lastWrite();
/**
* Returns the total number of lines ever written to the ramlog.
*/
long long getTotalLinesWritten();
private:
const RamLog* _ramlog;
boost::lock_guard<boost::mutex> _lock;
unsigned _nextLineIndex;
};
/**
* Appender for appending MessageEvents to a RamLog.
*/
class RamLogAppender : public logger::Appender<logger::MessageEventEphemeral> {
public:
explicit RamLogAppender(RamLog* ramlog);
virtual ~RamLogAppender();
virtual Status append(const logger::MessageEventEphemeral& event);
private:
RamLog* _ramlog;
};
}
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