Make DownloadHistory observe manager, items

chrome/browser/history/download_database.cc

Index: chrome/browser/history/download_database.cc
diff --git a/chrome/browser/history/download_database.cc b/chrome/browser/history/download_database.cc
index c9881156db31829652ffccc9ffd972e32777b381..1c5b7852867ca95761445c353200df9f8826bfdf 100644
--- a/chrome/browser/history/download_database.cc
+++ b/chrome/browser/history/download_database.cc
@@ -14,16 +14,17 @@
 #include "base/time.h"
 #include "base/utf_string_conversions.h"
 #include "build/build_config.h"
+#include "chrome/browser/history/download_persistent_store_info.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/download_item.h"
-#include "content/public/browser/download_persistent_store_info.h"
 #include "sql/statement.h"
 
 using content::DownloadItem;
-using content::DownloadPersistentStoreInfo;
 
 namespace history {
 
+const int64 DownloadDatabase::kUninitializedHandle = -1;
+
 namespace {
 
 static const char kSchema[] =
@@ -112,15 +113,6 @@ DownloadDatabase::DownloadDatabase()
 DownloadDatabase::~DownloadDatabase() {
 }
 
-void DownloadDatabase::CheckThread() {
-  if (owning_thread_set_) {
-    DCHECK(owning_thread_ == base::PlatformThread::CurrentId());
-  } else {
-    owning_thread_ = base::PlatformThread::CurrentId();
-    owning_thread_set_ = true;
-  }
-}
-
 bool DownloadDatabase::EnsureColumnExists(
     const std::string& name, const std::string& type) {
   std::string add_col = "ALTER TABLE downloads ADD COLUMN " + name + " " + type;
@@ -137,7 +129,6 @@ bool DownloadDatabase::MigrateDownloadsState() {
 }
 
 bool DownloadDatabase::InitDownloadTable() {
-  CheckThread();
   GetMetaTable().GetValue(kNextDownloadId, &next_id_);
   if (GetDB().DoesTableExist("downloads")) {
     return EnsureColumnExists("end_time", "INTEGER NOT NULL DEFAULT 0") &&
@@ -148,13 +139,11 @@ bool DownloadDatabase::InitDownloadTable() {
 }
 
 bool DownloadDatabase::DropDownloadTable() {
-  CheckThread();
   return GetDB().Execute("DROP TABLE downloads");
 }
 
 void DownloadDatabase::QueryDownloads(
     std::vector<DownloadPersistentStoreInfo>* results) {
-  CheckThread();
   results->clear();
   if (next_db_handle_ < 1)
     next_db_handle_ = 1;
@@ -194,7 +183,6 @@ void DownloadDatabase::QueryDownloads(
 }
 
 bool DownloadDatabase::UpdateDownload(const DownloadPersistentStoreInfo& data) {
-  CheckThread();
   DCHECK(data.db_handle > 0);
   int state = StateToInt(data.state);
   if (state == kStateInvalid) {
@@ -203,30 +191,20 @@ bool DownloadDatabase::UpdateDownload(const DownloadPersistentStoreInfo& data) {
   }
   sql::Statement statement(GetDB().GetCachedStatement(SQL_FROM_HERE,
       "UPDATE downloads "
-      "SET received_bytes=?, state=?, end_time=?, opened=? WHERE id=?"));
-  statement.BindInt64(0, data.received_bytes);
-  statement.BindInt(1, state);
-  statement.BindInt64(2, data.end_time.ToTimeT());
-  statement.BindInt(3, (data.opened ? 1 : 0));
-  statement.BindInt64(4, data.db_handle);
-
-  return statement.Run();
-}
-
-bool DownloadDatabase::UpdateDownloadPath(const FilePath& path,
-                                          DownloadID db_handle) {
-  CheckThread();
-  DCHECK(db_handle > 0);
-  sql::Statement statement(GetDB().GetCachedStatement(SQL_FROM_HERE,
-      "UPDATE downloads SET full_path=? WHERE id=?"));
-  BindFilePath(statement, path, 0);
-  statement.BindInt64(1, db_handle);
+      "SET full_path=?, received_bytes=?, state=?, end_time=?, total_bytes=?, "
+      "opened=? WHERE id=?"));
+  BindFilePath(statement, data.path, 0);
+  statement.BindInt64(1, data.received_bytes);
+  statement.BindInt(2, state);
+  statement.BindInt64(3, data.end_time.ToTimeT());
+  statement.BindInt(4, data.total_bytes);
+  statement.BindInt(5, (data.opened ? 1 : 0));
+  statement.BindInt64(6, data.db_handle);
 
   return statement.Run();
 }
 
 bool DownloadDatabase::CleanUpInProgressEntries() {
-  CheckThread();
   sql::Statement statement(GetDB().GetCachedStatement(SQL_FROM_HERE,
       "UPDATE downloads SET state=? WHERE state=?"));
   statement.BindInt(0, kStateCancelled);
@@ -237,8 +215,6 @@ bool DownloadDatabase::CleanUpInProgressEntries() {
 
 int64 DownloadDatabase::CreateDownload(
     const DownloadPersistentStoreInfo& info) {
-  CheckThread();
-
   if (next_db_handle_ == 0) {
     // This is unlikely. All current known tests and users already call
     // QueryDownloads() before CreateDownload().
@@ -249,7 +225,7 @@ int64 DownloadDatabase::CreateDownload(
 
   int state = StateToInt(info.state);
   if (state == kStateInvalid)
-    return false;
+    return kUninitializedHandle;
 
   sql::Statement statement(GetDB().GetCachedStatement(SQL_FROM_HERE,
       "INSERT INTO downloads "
@@ -275,63 +251,24 @@ int64 DownloadDatabase::CreateDownload(
 
     return db_handle;
   }
-  return 0;
-}
-
-void DownloadDatabase::RemoveDownload(DownloadID db_handle) {
-  CheckThread();
-
-  sql::Statement statement(GetDB().GetCachedStatement(SQL_FROM_HERE,
-      "DELETE FROM downloads WHERE id=?"));
-  statement.BindInt64(0, db_handle);
-
-  statement.Run();
+  return kUninitializedHandle;
 }
 
-bool DownloadDatabase::RemoveDownloadsBetween(base::Time delete_begin,
-                                              base::Time delete_end) {
-  CheckThread();
-  time_t start_time = delete_begin.ToTimeT();
-  time_t end_time = delete_end.ToTimeT();
-
-  int num_downloads_deleted = -1;
-  {
-    sql::Statement count(GetDB().GetCachedStatement(SQL_FROM_HERE,
-        "SELECT count(*) FROM downloads WHERE start_time >= ? "
-        "AND start_time < ? AND (State = ? OR State = ? OR State = ?)"));
-    count.BindInt64(0, start_time);
-    count.BindInt64(
-        1,
-        end_time ? end_time : std::numeric_limits<int64>::max());
-    count.BindInt(2, kStateComplete);
-    count.BindInt(3, kStateCancelled);
-    count.BindInt(4, kStateInterrupted);
-    if (count.Step())
-      num_downloads_deleted = count.ColumnInt(0);
-  }
-
-
-  bool success = false;
+void DownloadDatabase::RemoveDownloads(const std::set<DownloadID>& handles) {

[sky, 2012/11/08 20:55:17]

If this is going to delete a download at a time, it should do just that: take a
single download. Have the caller (HistoryBackend) handle repeatedly invoking
this method and move UMA/other stuff out of here.

[benjhayden, 2012/11/08 21:40:03]

Can you say more?
It looks to me like HistoryBackend is a thin layer of glue code w.r.t. the
downloads table. It looks like DownloadDatabase was created specifically to
encapsulate all of the downloads table-related logic.
That strategy would require exposing CountDownloads() just for UMA.
I'd be happy to split the DELETE FROM statement out into a separate private
method on DownloadDatabase if you're just looking for a little more code
organization and modularity.

[sky, 2012/11/09 16:45:50]

We have generally kept the DataBase implementations minimal and pushed as much
logic as possible to the caller. For example, URLDatabase does not have a
DeleteURLRows(std::std<>) even though it could be used. Instead we have
DeleteURLRow(URLID) and left it to callers to invoke it multiple times as
necessary.

[benjhayden, 2012/11/12 18:44:16]

Done.

+  int downloads_count_before = CountDownloads();
   base::TimeTicks started_removing = base::TimeTicks::Now();
-  {
-    // This does not use an index. We currently aren't likely to have enough
-    // downloads where an index by time will give us a lot of benefit.
+  // HistoryBackend uses a long-running Transaction that is committed
+  // periodically, so this loop doesn't actually hit the disk too hard.
+  for (std::set<DownloadID>::const_iterator it = handles.begin();
+       it != handles.end(); ++it) {
     sql::Statement statement(GetDB().GetCachedStatement(SQL_FROM_HERE,
-        "DELETE FROM downloads WHERE start_time >= ? AND start_time < ? "
-        "AND (State = ? OR State = ? OR State = ?)"));
-    statement.BindInt64(0, start_time);
-    statement.BindInt64(
-        1,
-        end_time ? end_time : std::numeric_limits<int64>::max());
-    statement.BindInt(2, kStateComplete);
-    statement.BindInt(3, kStateCancelled);
-    statement.BindInt(4, kStateInterrupted);
-
-    success = statement.Run();
+        "DELETE FROM downloads WHERE id=?"));
+    statement.BindInt64(0, *it);
+    statement.Run();
   }
-
   base::TimeTicks finished_removing = base::TimeTicks::Now();
-
+  int downloads_count_after = CountDownloads();
+  int num_downloads_deleted = downloads_count_before - downloads_count_after;
   if (num_downloads_deleted >= 0) {
     UMA_HISTOGRAM_COUNTS("Download.DatabaseRemoveDownloadsCount",
                          num_downloads_deleted);
@@ -342,8 +279,18 @@ bool DownloadDatabase::RemoveDownloadsBetween(base::Time delete_begin,
                           (1000 * micros) / num_downloads_deleted);
     }
   }
+  int num_downloads_not_deleted = handles.size() - num_downloads_deleted;
+  if (num_downloads_not_deleted >= 0) {
+    UMA_HISTOGRAM_COUNTS("Download.DatabaseRemoveDownloadsCountNotRemoved",
+                         num_downloads_not_deleted);
+  }
+}
 
-  return success;
+int DownloadDatabase::CountDownloads() {
+  sql::Statement statement(GetDB().GetCachedStatement(SQL_FROM_HERE,
+      "SELECT count(*) from downloads"));
+  statement.Step();
+  return statement.ColumnInt(0);
 }
 
 }  // namespace history