Add in expiring budget

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"
@@ skipping 64 matching lines @@
 
   base::Time expiration =
       clock_->Now() + base::TimeDelta::FromHours(kBudgetDurationInHours);
   budget_map_[origin.spec()].second.push_back(
       std::make_pair(amount, expiration.ToInternalValue()));
 
   // Now that the cache is updated, write the data to the database.
   WriteCachedValuesToDatabase(origin, callback);
 }
 
-void BudgetDatabase::WriteCachedValuesToDatabase(
-    const GURL& origin,
-    const StoreBudgetCallback& callback) {
-  // 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 (budget_map_.find(origin.spec()) == budget_map_.end()) {
-    // If the origin doesn't exist in the cache, this is a remove operation.
-    keys_to_remove->push_back(origin.spec());
-  } else {
-    // Build the Budget proto object.
-    budget_service::Budget budget;
-    const BudgetInfo& info = budget_map_[origin.spec()];
-    budget.set_debt(info.first);
-    for (const auto& chunk : info.second) {
-      budget_service::BudgetChunk* budget_chunk = budget.add_budget();
-      budget_chunk->set_amount(chunk.first);
-      budget_chunk->set_expiration(chunk.second);
-    }
-    entries->push_back(std::make_pair(origin.spec(), budget));
-  }
-
-  // Send the updates to the database.
-  db_->UpdateEntries(std::move(entries), std::move(keys_to_remove), callback);
-}
-
 void BudgetDatabase::OnDatabaseInit(bool success) {
   // TODO(harkness): Consider caching the budget database now?
 }
 
 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.
@@ skipping 17 matching lines @@
 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.
   if (!success) {
     callback.Run(success, 0, BudgetExpectation());
     return;
   }
 
-  // Otherwise, build up the BudgetExpection. This is different from the format
+  // 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
   // and the budget at those times.
   const BudgetInfo& info = budget_map_[origin.spec()];
   BudgetExpectation expectation;
   double total = 0;
 
   // Starting with the chunks that expire the farthest in the future, build up
   // the budget expectations for those future times.
   for (const auto& chunk : base::Reversed(info.second)) {
-    expectation.push_front(std::make_pair(total, chunk.second));
+    expectation.push_front(
+        std::make_pair(total, base::Time::FromInternalValue(chunk.second)));
     total += chunk.first;
   }
 
-  // Always add one entry at the front of the list for the total budget right
-  // now.
-  expectation.push_front(std::make_pair(total, 0));
+  // Always add one entry at the front of the list for the total budget now.
+  expectation.push_front(std::make_pair(total, clock_->Now()));
 
   callback.Run(true /* success */, info.first, expectation);
 }
 
 // Override the default clock with the specified clock. Only used for testing.
 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 (budget_map_.find(origin.spec()) == budget_map_.end()) {
+    // If the origin doesn't exist in the cache, this is a remove operation.
+    keys_to_remove->push_back(origin.spec());
+  } else {
+    // Build the Budget proto object.
+    budget_service::Budget budget;
+    const BudgetInfo& info = budget_map_[origin.spec()];
+    budget.set_debt(info.first);
+    for (const auto& chunk : info.second) {
+      budget_service::BudgetChunk* budget_chunk = budget.add_budget();
+      budget_chunk->set_amount(chunk.first);
+      budget_chunk->set_expiration(chunk.second);
+    }
+    entries->push_back(std::make_pair(origin.spec(), budget));
+  }
+
+  // Send the updates to the database.
+  db_->UpdateEntries(std::move(entries), std::move(keys_to_remove), callback);
+}
+
+void BudgetDatabase::CleanupExpiredBudget(const GURL& origin) {
+  if (budget_map_.find(origin.spec()) == budget_map_.end())
+    return;
+
+  double now = clock_->Now().ToInternalValue();

[Peter Beverloo, 2016/08/08 15:02:55]

Supposedly we'd like to change the second double in BudgetChunks to base::Time
as well? (I.e. remove ToInternalValue() from line 79; add FromInternalValue() to
line 104.) That would allow removal of ToInternalValue() here.

[harkness, 2016/08/09 12:57:40]

I was thinking we would have the cache be a true mirror of the database, but
there's really no reason it needs to be, since we're already switching from
protos to stl structures. I'll move the translation boundary.

+
+  BudgetChunks& chunks = budget_map_[origin.spec()].second;
+  auto cleanup_iter = chunks.begin();
+
+  // This relies on the list of chunks being in timestamp order.
+  while (cleanup_iter != chunks.end() && cleanup_iter->second <= now) {

[Peter Beverloo, 2016/08/08 15:02:55]

nit: remove {} for one-line statements

[Peter Beverloo, 2016/08/08 15:02:55]

Not for this CL, but I'd hope you agree that all the |first|/|second| usage in
this file is not at all readable :-).

Maybe we could consider using small structures w/ named members instead?

[harkness, 2016/08/09 12:57:40]

Done.

[harkness, 2016/08/09 12:57:40]

As we discussed in person yesterday, I'm planning to remove the debt, and then
consider making a wrapper class/structure for BudgetChunks.

+    cleanup_iter = chunks.erase(cleanup_iter);
+  }
+
+  // If the entire budget is empty now, cleanup the map.
+  if (chunks.empty())
+    budget_map_.erase(origin.spec());

[Peter Beverloo, 2016/08/08 15:02:55]

Maybe add a test to verify that we actually remove entries from the database
when this happens?

[harkness, 2016/08/09 12:57:40]

Added a test and found a bug/incomplete implementation. Op success!

[Peter Beverloo, 2016/08/09 13:12:42]

As the British would say: "woop!"

+}