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// ramlog.h
/* Copyright 2009 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects
* for all of the code used other than as permitted herein. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you do not
* wish to do so, delete this exception statement from your version. If you
* delete this exception statement from all source files in the program,
* then also delete it in the license file.
*/
#pragma once
#include <boost/version.hpp>
#include <sstream>
#include <string>
#include <vector>
#include "mongo/base/disallow_copying.h"
#include "mongo/base/status.h"
#include "mongo/base/string_data.h"
#include "mongo/logger/appender.h"
#include "mongo/logger/message_event.h"
#include "mongo/logger/tee.h"
#include "mongo/stdx/mutex.h"
#include "mongo/util/concurrency/mutex.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 std::string clean(const std::vector<const char*>& v, int i, std::string line = "");
static std::string color(const std::string& line);
/* turn http:... into an anchor */
static std::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;
stdx::mutex _mutex; // Guards all non-static data.
char lines[N][C];
unsigned h; // current position
unsigned n; // number of lines stores 0 o N
std::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;
stdx::lock_guard<stdx::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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