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/* Copyright 2013 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 <memory>
#include <string>
#include <vector>
#include "mongo/base/disallow_copying.h"
#include "mongo/logger/appender.h"
#include "mongo/logger/log_severity.h"
namespace mongo {
namespace logger {
/**
* Logging domain for events of type E.
*
* A logging domain consists of a set of Appenders.
*
* TODO: The severity doesn't seem to apply for auditing, maybe it only belongs on the
* MessageLogManager? We don't really have multiple tunable logging domains, right now. Other
* than the global domain, shouldLog doesn't matter.
*
* Usage: Configure the log domain in a single threaded context, using attachAppender,
* detachAppender and clearAppenders(). The domain takes ownership of any attached appender,
* returning an AppenderHandle for each attached appender. That handle may be used later to
* detach the appender, causing the domain to release ownership of it. Mostly, this
* attach/detach behavior is useful in testing, since you do not want to change the appenders of
* a domain that is currently receiving append() calls.
*
* Once you've configured the domain, call append() from potentially many threads, to add log
* messages.
*/
template <typename E>
class LogDomain {
MONGO_DISALLOW_COPYING(LogDomain);
public:
typedef E Event;
typedef Appender<Event> EventAppender;
typedef std::unique_ptr<EventAppender> AppenderAutoPtr;
/**
* Opaque handle returned by attachAppender(), which can be subsequently passed to
* detachAppender() to detach an appender from an instance of LogDomain.
*/
class AppenderHandle {
friend class LogDomain;
static const size_t invalid_handle = (size_t)-1;
public:
AppenderHandle() : _index(invalid_handle) {}
explicit operator bool() const noexcept {
return _index != invalid_handle;
}
void reset() {
_index = invalid_handle;
}
private:
explicit AppenderHandle(size_t index) : _index(index) {}
size_t _index;
};
LogDomain();
~LogDomain();
/**
* Receives an event for logging, calling append(event) on all attached appenders.
*
* If any appender fails, the behavior is determined by the abortOnFailure flag:
* *If abortOnFailure is set, ::abort() is immediately called.
* *If abortOnFailure is not set, the error is returned and no further appenders are called.
*/
Status append(const Event& event);
/**
* Gets the state of the abortOnFailure flag.
*/
bool getAbortOnFailure() const {
return _abortOnFailure;
}
/**
* Sets the state of the abortOnFailure flag.
*/
void setAbortOnFailure(bool abortOnFailure) {
_abortOnFailure = abortOnFailure;
}
//
// Configuration methods. Must be synchronized with each other and calls to "append" by the
// caller.
//
/**
* Attaches "appender" to this domain, taking ownership of it. Returns a handle that may be
* used later to detach this appender.
*/
AppenderHandle attachAppender(std::unique_ptr<EventAppender> appender);
template <typename Ptr>
AppenderHandle attachAppender(Ptr appender) {
return attachAppender(std::unique_ptr<EventAppender>(std::move(appender)));
}
/**
* Detaches the appender referenced by "handle" from this domain, releasing ownership of it.
* Returns an unique_ptr to the handler to the caller, who is now responsible for its
* deletion. Caller should consider "handle" is invalid after this call.
*/
std::unique_ptr<EventAppender> detachAppender(AppenderHandle handle);
/**
* Destroy all attached appenders, invalidating all handles.
*/
void clearAppenders();
private:
std::vector<std::unique_ptr<EventAppender>> _appenders;
bool _abortOnFailure;
};
} // namespace logger
} // namespace mongo
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