Separate UIDs and Revisions in main databases

Summary:
- Change revision type from `qint64` to `size_t` for LMDB in a couple of places (LMDB supports `unsigned int` or `size_t` which are `long unsigned int` on my machine)
- Better support for database flags (duplicate, integer keys, integer values for now but is extensible)
- Main databases' keys are now revisions
- Some databases switched to integer keys databases:
  - Main databases
  - the revision to uid mapping database
  - the revision to entity type mapping database
- Refactor the entity type's `typeDatabases` method (if in the future we need to change the main databases' flags again)
- New uid to revision mapping database (`uidsToRevisions`):
  - Stores all revisions (not uid to latest revision) because we need it for cleaning old revisions
  - Flags are: duplicates + integer values (so findLatest finds the latest revision for the given uid)

~~Problems to fix before merging:~~
All Fixed!

- ~~Sometimes Sink can't read what has just been written to the database (maybe because of transactions race conditions)~~
  - ~~Most of the times, this results in Sink not able to find the uid for a given revision by reading the `revisions` database~~
- ~~`pipelinetest`'s `testModifyWithConflict` fails because the local changes are overridden~~

~~The first problem prevents me from running benchmarks~~

Reviewers: cmollekopf

Tags: #sink

Differential Revision: https://phabricator.kde.org/D14974

1 files changed, 5 insertions, 0 deletions

diff --git a/common/storage/key.cpp b/common/storage/key.cpp
index 2327061..a6567ea 100644
--- a/common/storage/key.cpp
+++ b/common/storage/key.cpp
@@ -155,6 +155,11 @@ qint64 Revision::toQint64() const
     return rev;
 }
 
+size_t Revision::toSizeT() const
+{
+    return rev;
+}
+
 bool Revision::isValidInternal(const QByteArray &bytes)
 {
     if (bytes.size() != Revision::INTERNAL_REPR_SIZE) {