AddEngagementBudget and SpendBudget added to BudgetDatabase.

chrome/browser/budget_service/budget_database.cc

 // Copyright 2016 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.
 
 #include "chrome/browser/budget_service/budget_database.h"
 
 #include "base/containers/adapters.h"
 #include "base/time/clock.h"
 #include "base/time/default_clock.h"
 #include "chrome/browser/budget_service/budget.pb.h"
 #include "components/leveldb_proto/proto_database_impl.h"
 #include "content/public/browser/browser_thread.h"
 #include "url/gurl.h"
 
 using content::BrowserThread;
 
 namespace {
 
 // UMA are logged for the database with this string as part of the name.
 // They will be LevelDB.*.BudgetManager. Changes here should be synchronized
 // with histograms.xml.
 const char kDatabaseUMAName[] = "BudgetManager";
 
 // The default amount of time during which a budget will be valid.
 // This is 3 days = 72 hours.
 constexpr double kBudgetDurationInHours = 72;
 
 }  // namespace
 
+BudgetDatabase::BudgetInfo::BudgetInfo() {}
+
+BudgetDatabase::BudgetInfo::BudgetInfo(const BudgetInfo&& other)
+    : last_engagement_award(other.last_engagement_award) {
+  chunks = std::move(other.chunks);
+}
+
+BudgetDatabase::BudgetInfo::~BudgetInfo() {}
+
 BudgetDatabase::BudgetDatabase(
     const base::FilePath& database_dir,
     const scoped_refptr<base::SequencedTaskRunner>& task_runner)
     : db_(new leveldb_proto::ProtoDatabaseImpl<budget_service::Budget>(
           task_runner)),
       clock_(base::WrapUnique(new base::DefaultClock)),
       weak_ptr_factory_(this) {
   db_->Init(kDatabaseUMAName, database_dir,
             base::Bind(&BudgetDatabase::OnDatabaseInit,
                        weak_ptr_factory_.GetWeakPtr()));
@@ skipping 25 matching lines @@
 }
 
 void BudgetDatabase::AddBudget(const GURL& origin,
                                double amount,
                                const StoreBudgetCallback& callback) {
   DCHECK_EQ(origin.GetOrigin(), origin);
 
   // Add a new chunk of budget for the origin at the default expiration time.
   base::Time expiration =
       clock_->Now() + base::TimeDelta::FromHours(kBudgetDurationInHours);
-  budget_map_[origin.spec()].emplace_back(amount, expiration);
+  budget_map_[origin.spec()].chunks.emplace_back(amount, expiration);
 
   // Now that the cache is updated, write the data to the database.
   WriteCachedValuesToDatabase(origin, callback);
 }
 
+void BudgetDatabase::AddEngagementBudget(const GURL& origin,
+                                         double score,
+                                         const StoreBudgetCallback& callback) {
+  DCHECK_EQ(origin.GetOrigin(), origin);
+
+  // By default we award the "full" award. Then that ratio is decreased if
+  // there have been other awards recently.
+  double ratio = 1.0;
+
+  // Calculate how much budget should be awarded. If the origin is not cached,
+  // then we award a full amount.
+  if (IsCached(origin)) {
+    base::TimeDelta elapsed =
+        clock_->Now() - budget_map_[origin.spec()].last_engagement_award;
+    int elapsed_hours = elapsed.InHours();
+    if (elapsed_hours == 0) {
+      // Don't give engagement awards for periods less than an hour.
+      callback.Run(true);
+      return;
+    }
+    if (elapsed_hours < kBudgetDurationInHours)
+      ratio = elapsed_hours / kBudgetDurationInHours;
+  }
+
+  // Update the last_engagement_award to the current time. If the origin wasn't
+  // already in the map, this adds a new entry for it.
+  budget_map_[origin.spec()].last_engagement_award = clock_->Now();
+
+  // Pass to the base AddBudget to update the cache and write to the database.
+  AddBudget(origin, score * ratio, callback);
+}
+
+void BudgetDatabase::SpendBudget(const GURL& origin,
+                                 double amount,
+                                 const StoreBudgetCallback& callback) {
+  DCHECK_EQ(origin.GetOrigin(), origin);
+
+  // First, cleanup any expired budget chunks for the origin.
+  CleanupExpiredBudget(origin);
+
+  if (!IsCached(origin)) {
+    callback.Run(false);
+    return;
+  }
+
+  // Walk the list of budget chunks to see if the origin has enough budget.
+  double total = 0;
+  BudgetInfo& info = budget_map_[origin.spec()];
+  for (const BudgetChunk& chunk : info.chunks)
+    total += chunk.amount;
+
+  if (total < amount) {
+    callback.Run(false);
+    return;
+  }
+
+  // Walk the chunks and remove enough budget to cover the needed amount.
+  double bill = amount;
+  for (auto iter = info.chunks.begin(); iter != info.chunks.end();) {
+    if (iter->amount > bill) {
+      iter->amount -= bill;
+      bill = 0;
+      ++iter;
+      break;
+    }
+    bill -= iter->amount;
+    iter = info.chunks.erase(iter);
+  }
+
+  // There should have been enough budget to cover the entire bill.
+  DCHECK_EQ(0, bill);
+
+  // Now that the cache is updated, write the data to the database.
+  // TODO(harkness): Consider adding a second parameter to the callback so the
+  // caller can distinguish between not enough budget and a failed database
+  // write.
+  // TODO(harkness): If the database write fails, the cache will be out of sync
+  // with the database. Consider ways to mitigate this.
+  WriteCachedValuesToDatabase(origin, callback);
+}
+
 void BudgetDatabase::OnDatabaseInit(bool success) {
   // TODO(harkness): Consider caching the budget database now?
 }
 
 bool BudgetDatabase::IsCached(const GURL& origin) const {
   return budget_map_.find(origin.spec()) != budget_map_.end();
 }
 
 void BudgetDatabase::AddToCache(
     const GURL& origin,
     const AddToCacheCallback& callback,
     bool success,
     std::unique_ptr<budget_service::Budget> budget_proto) {
   // If the database read failed, there's nothing to add to the cache.
   if (!success || !budget_proto) {
     callback.Run(success);
     return;
   }
 
   // Add the data to the cache, converting from the proto format to an STL
   // format which is better for removing things from the list.
-  BudgetChunks chunks;
+  BudgetInfo& info = budget_map_[origin.spec()];
   for (const auto& chunk : budget_proto->budget()) {
-    chunks.emplace_back(chunk.amount(),
-                        base::Time::FromInternalValue(chunk.expiration()));
+    info.chunks.emplace_back(chunk.amount(),
+                             base::Time::FromInternalValue(chunk.expiration()));
   }
 
-  budget_map_[origin.spec()] = std::move(chunks);
+  info.last_engagement_award =
+      base::Time::FromInternalValue(budget_proto->engagement_last_updated());
 
   callback.Run(success);
 }
 
 void BudgetDatabase::DidGetBudget(const GURL& origin,
                                   const GetBudgetDetailsCallback& callback,
                                   bool success) {
   // If the database wasn't able to read the information, return the
-  // failure and an empty BudgetExpectation.
+  // failure and an empty BudgetPrediction.
   if (!success) {
-    callback.Run(success, BudgetExpectation());
+    callback.Run(success, BudgetPrediction());
     return;
   }
 
   // First, cleanup any expired budget chunks for the origin.
   CleanupExpiredBudget(origin);
 
   // Now, build up the BudgetExpection. This is different from the format
   // in which the cache stores the data. The cache stores chunks of budget and
-  // when that budget expires. The BudgetExpectation describes a set of times
+  // when that budget expires. The BudgetPrediction describes a set of times
   // and the budget at those times.
-  BudgetExpectation expectation;
+  BudgetPrediction prediction;
   double total = 0;
 
   if (IsCached(origin)) {
     // Starting with the chunks that expire the farthest in the future, build up
-    // the budget expectations for those future times.
-    const BudgetChunks& chunks = budget_map_[origin.spec()];
+    // the budget predictions for those future times.
+    const BudgetChunks& chunks = budget_map_[origin.spec()].chunks;
     for (const auto& chunk : base::Reversed(chunks)) {
-      expectation.emplace_front(total, chunk.expiration);
+      prediction.emplace_front(total, chunk.expiration);
       total += chunk.amount;
     }
   }
 
   // Always add one entry at the front of the list for the total budget now.
-  expectation.emplace_front(total, clock_->Now());
+  prediction.emplace_front(total, clock_->Now());
 
-  callback.Run(true /* success */, expectation);
+  callback.Run(true /* success */, prediction);
 }
 
 void BudgetDatabase::SetClockForTesting(std::unique_ptr<base::Clock> clock) {
   clock_ = std::move(clock);
 }
 
 void BudgetDatabase::WriteCachedValuesToDatabase(
     const GURL& origin,
     const StoreBudgetCallback& callback) {
   // First, cleanup any expired budget chunks for the origin.
   CleanupExpiredBudget(origin);
 
   // Create the data structures that are passed to the ProtoDatabase.
   std::unique_ptr<
       leveldb_proto::ProtoDatabase<budget_service::Budget>::KeyEntryVector>
       entries(new leveldb_proto::ProtoDatabase<
               budget_service::Budget>::KeyEntryVector());
   std::unique_ptr<std::vector<std::string>> keys_to_remove(
       new std::vector<std::string>());
 
   // Each operation can either update the existing budget or remove the origin's
   // budget information.
   if (IsCached(origin)) {
     // Build the Budget proto object.
     budget_service::Budget budget;
-    const BudgetChunks& chunks = budget_map_[origin.spec()];
-    for (const auto& chunk : chunks) {
+    const BudgetInfo& info = budget_map_[origin.spec()];
+    for (const auto& chunk : info.chunks) {
       budget_service::BudgetChunk* budget_chunk = budget.add_budget();
       budget_chunk->set_amount(chunk.amount);
       budget_chunk->set_expiration(chunk.expiration.ToInternalValue());
     }
+    budget.set_engagement_last_updated(
+        info.last_engagement_award.ToInternalValue());
     entries->push_back(std::make_pair(origin.spec(), budget));
   } else {
     // If the origin doesn't exist in the cache, this is a remove operation.
     keys_to_remove->push_back(origin.spec());
   }
 
   // Send the updates to the database.
   db_->UpdateEntries(std::move(entries), std::move(keys_to_remove), callback);
 }
 
 void BudgetDatabase::CleanupExpiredBudget(const GURL& origin) {
   if (!IsCached(origin))
     return;
 
   base::Time now = clock_->Now();
 
-  BudgetChunks& chunks = budget_map_[origin.spec()];
+  BudgetChunks& chunks = budget_map_[origin.spec()].chunks;
   auto cleanup_iter = chunks.begin();
 
   // This relies on the list of chunks being in timestamp order.
   while (cleanup_iter != chunks.end() && cleanup_iter->expiration <= now)
     cleanup_iter = chunks.erase(cleanup_iter);
 
-  // If the entire budget is empty now, cleanup the map.
-  if (chunks.empty())
+  // If the entire budget is empty now AND there have been no engagements
+  // in the last kBudgetDurationInHours hours, remove this from the cache.
+  if (chunks.empty() &&
+      budget_map_[origin.spec()].last_engagement_award <
+          clock_->Now() - base::TimeDelta::FromHours(kBudgetDurationInHours))
     budget_map_.erase(origin.spec());
 }