[WIP] histroy: Adjust cache size OnMemoryStateChange()

components/history/core/browser/history_database.cc

 // Copyright (c) 2012 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 "components/history/core/browser/history_database.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 #include <set>
@@ skipping 22 matching lines @@
 
 namespace {
 
 // Current version number. We write databases at the "current" version number,
 // but any previous version that can read the "compatible" one can make do with
 // our database without *too* many bad effects.
 const int kCurrentVersionNumber = 32;
 const int kCompatibleVersionNumber = 16;
 const char kEarlyExpirationThresholdKey[] = "early_expiration_threshold";
 const int kMaxHostsInMemory = 10000;
+const int kDefaultCacheSize = 1000;
 
 }  // namespace
 
 HistoryDatabase::HistoryDatabase(
     DownloadInterruptReason download_interrupt_reason_none,
     DownloadInterruptReason download_interrupt_reason_crash)
     : DownloadDatabase(download_interrupt_reason_none,
                        download_interrupt_reason_crash) {
 }
 
 HistoryDatabase::~HistoryDatabase() {
 }
 
 sql::InitStatus HistoryDatabase::Init(const base::FilePath& history_name) {
   db_.set_histogram_tag("History");
 
   // Set the database page size to something a little larger to give us
   // better performance (we're typically seek rather than bandwidth limited).
   // This only has an effect before any tables have been created, otherwise
   // this is a NOP. Must be a power of 2 and a max of 8192.
   db_.set_page_size(4096);
 
   // Set the cache size. The page size, plus a little extra, times this
   // value, tells us how much memory the cache will use maximum.
   // 1000 * 4kB = 4MB
   // TODO(brettw) scale this value to the amount of available memory.
-  db_.set_cache_size(1000);
+  db_.set_cache_size(kDefaultCacheSize);
 
   // Note that we don't set exclusive locking here. That's done by
   // BeginExclusiveMode below which is called later (we have to be in shared
   // mode to start out for the in-memory backend to read the data).
 
   if (!db_.Open(history_name))
     return sql::INIT_FAILURE;
 
   // Wrap the rest of init in a tranaction. This will prevent the database from
   // getting corrupted if we crash in the middle of initialization or migration.
@@ skipping 208 matching lines @@
 void HistoryDatabase::Vacuum() {
   DCHECK_EQ(0, db_.transaction_nesting()) <<
       "Can not have a transaction when vacuuming.";
   ignore_result(db_.Execute("VACUUM"));
 }
 
 void HistoryDatabase::TrimMemory(bool aggressively) {
   db_.TrimMemory(aggressively);
 }
 
+void HistoryDatabase::AdjustCacheMemory(memory_coordinator::MemoryState state) {
+  int cache_size = kDefaultCacheSize;
+  if (state == memory_coordinator::MemoryState::THROTTLED) {
+    cache_size = cache_size / 2;
+  } else if (state == memory_coordinator::MemoryState::SUSPENDED) {
+    cache_size = cache_size / 4;
+  }
+  db_.UpdateCacheSize(cache_size);
+}
+
 bool HistoryDatabase::Raze() {
   return db_.Raze();
 }
 
 std::string HistoryDatabase::GetDiagnosticInfo(int extended_error,
                                                sql::Statement* statement) {
   return db_.GetDiagnosticInfo(extended_error, statement);
 }
 
 bool HistoryDatabase::SetSegmentID(VisitID visit_id, SegmentID segment_id) {
@@ skipping 237 matching lines @@
       "SET visit_time = visit_time + 11644473600000000 "
       "WHERE id IN (SELECT id FROM visits WHERE visit_time > 0);"));
   ignore_result(db_.Execute(
       "UPDATE segment_usage "
       "SET time_slot = time_slot + 11644473600000000 "
       "WHERE id IN (SELECT id FROM segment_usage WHERE time_slot > 0);"));
 }
 #endif
 
 }  // namespace history