[sql] Track uploads of diagnostic data to prevent duplication.

components/history/core/browser/thumbnail_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/thumbnail_database.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/bind.h"
@@ skipping 236 matching lines @@
   if (reported)
     return;
 
   uint64 rand = base::RandGenerator(1000000);
   if (error == SQLITE_CORRUPT) {
     // Once the database is known to be corrupt, it will generate a
     // stream of errors until someone fixes it, so give one chance.
     // Set first in case of errors in generating the report.
     reported = true;
 
+    if (!db->ShouldUploadDiagnosticDump())
+      return;

[pkotwicz, 2015/10/15 18:02:29]

Nit - I think that this is slightly clearer:

if (db->ShouldUploadDiagnosticDump()) {
  // Corrupt cases currently dominate, report them very infrequently.
  const uint64 kCorruptReportsPerMillion = 10000;
  if (rand < kCorruptReportsPerMillion)
    ReportCorrupt(db, startup_kb);
}

[Scott Hess - ex-Googler, 2015/10/15 21:12:20]

OK, I pulled all of these to just before the Report line.  I could push the
check into the Report functions, but I'm thinking the entire ball of wax should
be refactored.  If this change successfully moderates the reporting rate, then
it would make sense to remove much of the special-casing in this function.

+
     // Corrupt cases currently dominate, report them very infrequently.
     static const uint64 kCorruptReportsPerMillion = 10000;
     if (rand < kCorruptReportsPerMillion)
       ReportCorrupt(db, startup_kb);
   } else if (error == SQLITE_READONLY) {
     // SQLITE_READONLY appears similar to SQLITE_CORRUPT - once it
     // is seen, it is almost guaranteed to be seen again.
     reported = true;
 
+    if (!db->ShouldUploadDiagnosticDump())
+      return;
+
     if (rand < kReportsPerMillion)
       ReportError(db, extended_error);
   } else {
     // Only set the flag when making a report.  This should allow
     // later (potentially different) errors in a stream of errors to
     // be reported.
     //
     // TODO(shess): Would it be worthwile to audit for which cases
     // want once-only handling?  Sqlite.Error.Thumbnail shows
     // CORRUPT and READONLY as almost 95% of all reports on these
     // channels, so probably easier to just harvest from the field.
     if (rand < kReportsPerMillion) {
       reported = true;
+      if (!db->ShouldUploadDiagnosticDump())
+        return;
       ReportError(db, extended_error);
     }
   }
 }
 
 // NOTE(shess): Schema modifications must consider initial creation in
 // |InitImpl()|, recovery in |RecoverDatabaseOrRaze()|, and history pruning in
 // |RetainDataForPageUrls()|.
 bool InitTables(sql::Connection* db) {
   const char kIconMappingSql[] =
@@ skipping 1089 matching lines @@
   meta_table_.SetVersionNumber(8);
   meta_table_.SetCompatibleVersionNumber(std::min(8, kCompatibleVersionNumber));
   return true;
 }
 
 bool ThumbnailDatabase::IsFaviconDBStructureIncorrect() {
   return !db_.IsSQLValid("SELECT id, url, icon_type FROM favicons");
 }
 
 }  // namespace history