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// background.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
namespace mongo {
/* object-orienty background thread dispatching.
subclass and define run()
It is ok to call go() more than once -- if the previous invocation
has finished. Thus one pattern of use is to embed a backgroundjob
in your object and reuse it (or same thing with inheritance).
*/
class BackgroundJob {
protected:
/* define this to do your work! */
virtual void run() = 0;
public:
enum State {
NotStarted,
Running,
Done
};
State getState() const {
return state;
}
bool running() const {
return state == Running;
}
bool deleteSelf; // delete self when Done?
BackgroundJob() {
deleteSelf = false;
state = NotStarted;
}
virtual ~BackgroundJob() { }
// start job. returns before it's finished.
BackgroundJob& go();
// wait for completion. this spins with sleep() so not terribly efficient.
// returns true if did not time out.
//
// note you can call wait() more than once if the first call times out.
bool wait(int msMax = 0);
private:
static BackgroundJob *grab;
static mongo::mutex mutex;
static void thr();
volatile State state;
};
} // namespace mongo
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