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// Copyright (c) 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROME_BROWSER_SYNC_ENGINE_MODEL_SAFE_WORKER_H_
#define CHROME_BROWSER_SYNC_ENGINE_MODEL_SAFE_WORKER_H_
#pragma once
#include <map>
#include <string>
#include <vector>
#include "base/callback.h"
#include "base/ref_counted.h"
#include "chrome/browser/sync/syncable/model_type.h"
namespace browser_sync {
enum ModelSafeGroup {
GROUP_PASSIVE = 0, // Models that are just "passively" being synced; e.g.
// changes to these models don't need to be pushed to a
// native model.
GROUP_UI, // Models that live on UI thread and are being synced.
GROUP_DB, // Models that live on DB thread and are being synced.
GROUP_HISTORY, // Models that live on history thread and are being
// synced.
GROUP_PASSWORD, // Models that live on the password thread and are
// being synced. On windows and linux, this runs on the
// DB thread.
MODEL_SAFE_GROUP_COUNT,
};
std::string ModelSafeGroupToString(ModelSafeGroup group);
// The Syncer uses a ModelSafeWorker for all tasks that could potentially
// modify syncable entries (e.g under a WriteTransaction). The ModelSafeWorker
// only knows how to do one thing, and that is take some work (in a fully
// pre-bound callback) and have it performed (as in Run()) from a thread which
// is guaranteed to be "model-safe", where "safe" refers to not allowing us to
// cause an embedding application model to fall out of sync with the
// syncable::Directory due to a race.
class ModelSafeWorker : public base::RefCountedThreadSafe<ModelSafeWorker> {
public:
ModelSafeWorker() { }
virtual ~ModelSafeWorker() { }
// Any time the Syncer performs model modifications (e.g employing a
// WriteTransaction), it should be done by this method to ensure it is done
// from a model-safe thread.
virtual void DoWorkAndWaitUntilDone(Callback0::Type* work) {
work->Run(); // For GROUP_PASSIVE, we do the work on the current thread.
}
virtual ModelSafeGroup GetModelSafeGroup() {
return GROUP_PASSIVE;
}
// Check the current thread and see if it's the thread associated with
// this worker. If this returns true, then it should be safe to operate
// on models that are in this worker's group. If this returns false,
// such work should not be attempted.
virtual bool CurrentThreadIsWorkThread() {
// The passive group is not the work thread for any browser model.
return false;
}
private:
friend class base::RefCountedThreadSafe<ModelSafeWorker>;
DISALLOW_COPY_AND_ASSIGN(ModelSafeWorker);
};
// A map that details which ModelSafeGroup each syncable::ModelType
// belongs to. Routing info can change in response to the user enabling /
// disabling sync for certain types, as well as model association completions.
typedef std::map<syncable::ModelType, ModelSafeGroup>
ModelSafeRoutingInfo;
ModelSafeGroup GetGroupForModelType(const syncable::ModelType type,
const ModelSafeRoutingInfo& routes);
// Maintain the up-to-date state regarding which ModelSafeWorkers exist and
// which types get routed to which worker. When a sync session begins, it will
// snapshot the state at that instant, and will use that for the entire
// session. This means if a model becomes synced (or unsynced) by the user
// during a sync session, that session will complete and be unaware of this
// change -- it will only get picked up for the next session.
// TODO(tim): That's really the only way I can make sense of it in the Syncer
// HOWEVER, it is awkward for running ModelAssociation. We need to make sure
// we don't run such a thing until an active session wraps up.
class ModelSafeWorkerRegistrar {
public:
ModelSafeWorkerRegistrar() { }
// Get the current list of active ModelSafeWorkers. Should be threadsafe.
virtual void GetWorkers(std::vector<ModelSafeWorker*>* out) = 0;
// Get the current routing information for all enabled model types.
// If a model type is not enabled (that is, if the syncer should not
// be trying to sync it), it is not in this map.
virtual void GetModelSafeRoutingInfo(ModelSafeRoutingInfo* out) = 0;
protected:
virtual ~ModelSafeWorkerRegistrar() {}
private:
DISALLOW_COPY_AND_ASSIGN(ModelSafeWorkerRegistrar);
};
} // namespace browser_sync
#endif // CHROME_BROWSER_SYNC_ENGINE_MODEL_SAFE_WORKER_H_
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