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/* Copyright 2013 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 <boost/scoped_ptr.hpp>
#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 and a minimum severity.
*
* 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;
/**
* 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;
public:
AppenderHandle() {}
private:
explicit AppenderHandle(size_t index) : _index(index) {}
size_t _index;
};
// TODO(schwerin): Replace with unique_ptr in C++11.
typedef std::auto_ptr<EventAppender> AppenderAutoPtr;
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);
/**
* Predicate that answers the question, "Should I, the caller, append to you, the log
* domain, messages of the given severity?" True means yes.
*/
bool shouldLog(LogSeverity severity) { return severity >= _minimumLoggedSeverity; }
/**
* Gets the minimum severity of messages that should be sent to this LogDomain.
*/
LogSeverity getMinimumLogSeverity() { return _minimumLoggedSeverity; }
/**
* Sets the minimum severity of messages that should be sent to this LogDomain.
*/
void setMinimumLoggedSeverity(LogSeverity severity) { _minimumLoggedSeverity = severity; }
/**
* 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(AppenderAutoPtr appender);
/**
* Detaches the appender referenced by "handle" from this domain, releasing ownership of it.
* Returns an auto_ptr to the handler to the caller, who is now responsible for its
* deletion. Caller should consider "handle" is invalid after this call.
*/
AppenderAutoPtr detachAppender(AppenderHandle handle);
/**
* Destroy all attached appenders, invalidating all handles.
*/
void clearAppenders();
private:
typedef std::vector<EventAppender*> AppenderVector;
LogSeverity _minimumLoggedSeverity;
AppenderVector _appenders;
bool _abortOnFailure;
};
} // namespace logger
} // namespace mongo
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