Add pause/resume functionality to precache

components/precache/core/precache_session_tables.cc

Index: components/precache/core/precache_session_tables.cc
diff --git a/components/precache/core/precache_session_tables.cc b/components/precache/core/precache_session_tables.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7f2f5efb69c5de6eb464abbd2c81733137e95d8b
--- /dev/null
+++ b/components/precache/core/precache_session_tables.cc
@@ -0,0 +1,154 @@
+// 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 "components/precache/core/precache_session_tables.h"
+
+#include <string>
+
+#include "base/logging.h"
+#include "base/time/time.h"
+#include "sql/connection.h"
+#include "sql/statement.h"
+
+using sql::Statement;
+
+namespace {
+
+// Returns the spec of the given URL.
+std::string GetKey(const GURL& url) {
+  return url.spec();
+}
+
+}  // namespace
+
+namespace precache {
+
+PrecacheSessionTables::PrecacheSessionTables() : db_(nullptr) {}
+
+PrecacheSessionTables::~PrecacheSessionTables() {}
+
+bool PrecacheSessionTables::Init(sql::Connection* db) {
+  DCHECK(!db_);  // Init must only be called once.
+  DCHECK(db);    // The database connection must be non-NULL.
+  db_ = db;
+  return CreateTablesIfNonExistent();
+}
+
+void PrecacheSessionTables::GetURLs(std::list<GURL>* manifests,
+                                    std::list<GURL>* resources) {
+  manifests->clear();
+  resources->clear();
+  Statement statement(db_->GetCachedStatement(
+      SQL_FROM_HERE, "SELECT url, type FROM precache_task_urls"));
+  while (statement.Step()) {

[sclittle, 2016/05/10 00:01:27]

How large can the list of URLs get? e.g. 50? 500?

[bengr, 2016/05/19 01:25:44]

Covered in tests.

+    GURL url = GURL(statement.ColumnString(0));
+    URLType type = static_cast<URLType>(statement.ColumnInt64(1));
+    if (type == MANIFEST)
+      manifests->push_back(url);
+    else if (type == RESOURCE)
+      resources->push_back(url);
+    else
+      NOTREACHED();
+  }
+}
+
+void PrecacheSessionTables::GetStatistics(int64_t* total_response_bytes,
+                                          int64_t* network_response_bytes,
+                                          int64_t* num_manifest_urls_to_fetch,
+                                          base::TimeTicks* start_time) {
+  *total_response_bytes = 0;
+  *network_response_bytes = 0;
+  *num_manifest_urls_to_fetch = 0;
+  *start_time = base::TimeTicks();
+  Statement statement(db_->GetCachedStatement(
+      SQL_FROM_HERE, "SELECT type, value from precache_stats"));
+  while (statement.Step()) {
+    int type = statement.ColumnInt64(0);
+    int64_t value = statement.ColumnInt64(1);
+    switch (type) {
+      case TOTAL_RESPONSE_BYTES:
+        *total_response_bytes = value;
+        break;
+      case NETWORK_RESPONSE_BYTES:
+        *network_response_bytes = value;
+        break;
+      case NUM_MANIFEST_URLS_TO_FETCH:
+        *num_manifest_urls_to_fetch = value;
+        break;
+      case START_TIME:
+        *start_time = base::TimeTicks::FromInternalValue(value);
+        break;
+      default:
+        NOTREACHED();
+    }
+  }
+}
+
+void PrecacheSessionTables::StoreURLs(const std::list<GURL>& manifests,
+                                      const std::list<GURL>& resources) {
+  ClearURLs();
+  for (auto manifest : manifests)

[sclittle, 2016/05/10 00:01:27]

Use "const auto&" or "const GURL&" here to avoid copying the GURL every time.

[bengr, 2016/05/19 01:25:44]

Done.

+    StoreURL(manifest, MANIFEST);
+  for (auto resource : resources)

[sclittle, 2016/05/10 00:01:27]

Use "const auto&" or "const GURL&" here to avoid copying the GURL every time.

[bengr, 2016/05/19 01:25:44]

Done.

+    StoreURL(resource, RESOURCE);
+}
+
+void PrecacheSessionTables::StoreStatistics(
+    int64_t total_response_bytes,
+    int64_t network_response_bytes,
+    int64_t num_manifest_urls_to_fetch,
+    const base::TimeTicks& start_time) {
+  StoreStatistic(TOTAL_RESPONSE_BYTES, total_response_bytes);
+  StoreStatistic(NETWORK_RESPONSE_BYTES, network_response_bytes);
+  StoreStatistic(NUM_MANIFEST_URLS_TO_FETCH, num_manifest_urls_to_fetch);
+  StoreStatistic(START_TIME, start_time.ToInternalValue());
+}
+
+void PrecacheSessionTables::StoreURL(const GURL& url, URLType type) {
+  // TODO(bengr): Store start times and priorities per URL.
+  Statement statement(db_->GetCachedStatement(
+      SQL_FROM_HERE,
+      "INSERT OR REPLACE INTO precache_task_urls (url, time, priority, type) "
+      "VALUES(?,?,?,?)"));
+  statement.BindString(0, GetKey(url));
+  statement.BindInt64(1, 0);
+  statement.BindInt64(2, 0);
+  statement.BindInt(3, static_cast<int>(type));
+  statement.Run();
+}
+
+void PrecacheSessionTables::StoreStatistic(StatType type, int64_t value) {
+  Statement statement(db_->GetCachedStatement(
+      SQL_FROM_HERE,
+      "INSERT OR REPLACE INTO precache_stats (type, value) VALUES(?,?)"));
+  statement.BindInt(0, static_cast<int>(type));
+  statement.BindInt64(1, value);
+  statement.Run();
+}
+
+void PrecacheSessionTables::ClearURLs() {
+  Statement statement(
+      db_->GetCachedStatement(SQL_FROM_HERE, "DELETE FROM precache_task_urls"));
+  statement.Run();
+}
+
+void PrecacheSessionTables::ClearStatistics() {
+  Statement statement(
+      db_->GetCachedStatement(SQL_FROM_HERE, "DELETE FROM precache_stats"));
+  statement.Run();
+}
+
+bool PrecacheSessionTables::CreateTablesIfNonExistent() {
+  if (!db_->Execute(
+          "CREATE TABLE IF NOT EXISTS precache_task_urls ("
+          "url TEXT PRIMARY KEY, "
+          "time INTEGER, priority INTEGER, type INTEGER)")) {
+    return false;
+  }
+  return db_->Execute(
+      "CREATE TABLE IF NOT EXISTS precache_stats (type INTEGER PRIMARY_KEY, "
+      "value INTEGER)");
+}
+
+}  // namespace precache