New architecture of the activity logging: Policies for summarization (and compression)

chrome/browser/extensions/activity_log/fullstream_ui_policy.h

+// Copyright (c) 2013 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_EXTENSIONS_ACTIVITY_LOG_FULLSTREAM_UI_POLICY_H_
+#define CHROME_BROWSER_EXTENSIONS_ACTIVITY_LOG_FULLSTREAM_UI_POLICY_H_
+
+#include <sstream>
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "chrome/browser/extensions/activity_log/activity_log_policy.h"
+#include "content/public/browser/browser_thread.h"
+
+class GURL;
+
+namespace extensions {
+
+class ActivityDatabase;
+
+class FullStreamUIPolicy : public ActivityLogPolicy {
+  public:
+
+    // For more info about these member functions, see the super class.
+    explicit FullStreamUIPolicy(Profile*);
+
+    virtual ~FullStreamUIPolicy();
+
+    virtual void SaveState() OVERRIDE {}
+
+    // TODO(felt,dbabic) This is overly specific to FullStreamUIPolicy.

[felt, 2013/05/22 21:17:59]

I don't understand why this too specific. Can you explain?

[dbabic, 2013/05/23 01:35:04]

It assumes that the callback can return a sorted vector of actions.  Some
policies might not do that.  For instance, imagine a trivial policy that just
counts the frequency of certain actions within some time period, this call would
be meaningless, as it couldn't return anything useful.

[felt, 2013/05/23 04:20:01]

Ahhh, OK. Can you add this to the comment so that I remember?

On 2013/05/23 01:35:04, dbabic wrote:

[dbabic, 2013/05/24 00:35:07]

Done.

+    virtual void ReadData(const std::string&, const int,
+        const
+        base::Callback<void(scoped_ptr<std::vector<scoped_refptr<Action> > >)>&)
+        const OVERRIDE;
+
+    // Returns the actual key for a given key type
+    virtual void GetKey(ActivityLogPolicy::KeyType, std::string&) const OVERRIDE;

[felt, 2013/05/22 21:17:59]

Line too long?

[dbabic, 2013/05/23 01:35:04]

Done.

+
+    // An error has happened; we want to rollback and close the db.
+    // Needs to be public so the error delegate can call it.
+    virtual void KillActivityLogDatabase();
+
+  protected:
+    // Concatenates arguments efficiently using stringstream
+    virtual void ProcessArguments(const base::ListValue*, std::stringstream&)
+        const;
+
+    // The Schedule methods dispatch the calls to the database on a
+    // separate thread. We dispatch to the UI thread if the DB thread doesn't
+    // exist, which should only happen in tests where there is no DB thread.
+    template<typename DatabaseFunc>
+    void ScheduleAndForget(DatabaseFunc func) {
+      content::BrowserThread::PostTask(dispatch_thread_,
+                              FROM_HERE,
+                              base::Bind(func, base::Unretained(db_)));
+    }
+
+    template<typename DatabaseFunc, typename ArgA>
+    void ScheduleAndForget(DatabaseFunc func, ArgA a) {
+      content::BrowserThread::PostTask(dispatch_thread_,
+                              FROM_HERE,
+                              base::Bind(func, base::Unretained(db_), a));
+    }
+
+    template<typename DatabaseFunc, typename ArgA, typename ArgB>
+    void ScheduleAndForget(DatabaseFunc func, ArgA a, ArgB b) {
+      content::BrowserThread::PostTask(dispatch_thread_,
+                              FROM_HERE,
+                              base::Bind(func, base::Unretained(db_), a, b));
+    }
+
+    // We initialize this on the same thread as the ActivityLog, but then
+    // subsequent operations occur on the DB thread. Instead of destructing the
+    // ActivityDatabase, we call its Close() method on the DB thread and it
+    // commits suicide.
+    ActivityDatabase* db_;
+
+    // Normally the DB thread. In some cases (tests), it might not exist
+    // we dispatch to the UI thread.
+    content::BrowserThread::ID dispatch_thread_;

[felt, 2013/05/22 21:17:59]

Could the Activity Log specify the thread, instead of leaving it up to the
policy? (So, take it in the constructor?) More generally, could the templating
be in the parent class so it only has to be done once?

[dbabic, 2013/05/23 01:35:04]

Sure, it could be easily passed as a param.  Sorry, didn't quite understand how
would you template the parent class and what would be the benefit of that?

[felt, 2013/05/23 04:20:01]

Sorry to be unclear: by "the templating" I meant the code for ScheduleAndForget,
so that it doesn't have to be re-implemented in all of the policies.

On 2013/05/23 01:35:04, dbabic wrote:

[dbabic, 2013/05/24 00:35:07]

Done.

+
+  private:
+    virtual void DoProcessAction(ActionType, const Extension&,
+        const std::string&, const GURL*, const base::ListValue*,
+        const base::DictionaryValue*) OVERRIDE;
+};
+
+} // End of the extensions namespace
+
+#endif  // CHROME_BROWSER_EXTENSIONS_ACTIVITY_LOG_FULLSTREAM_UI_POLICY_H_