This adds an extra option to allow setting the SQLite page cache size as a regular option.
Prior to this commit it was only possible to set the SQLite page cache size via environment variables.
The option to use environment variables is preserved, and as options from the environment variable are applied after the new setting, environment variables take precedence.
The default value for the new option is to use 1% of the system memory for the page cache. For the restore process, a connection per worker may be made which defaults to half the number of cores, so the maximum amount of memory is 1% * half the CPU cores.
This is just the upper limit, and SQLite may choose not to use all of it.
This fixes#6178
This commit changes the way the new restore flow loads the extra database connections so these will also apply the temporary folder settings and custom pragmas.
This also changes the logic around the SQLite temporary folder. Previously, this folder would unconditionally be set to the general temporary folder, allowing only an override with a custom pragma.
No the setup checks if the system has the environment variable `SQLITE_TMPDIR` set already. If this variable is already set, it will NOT be overwritten.
Actual effects of this change depends on how SQLite internally resolves the temporary folder.
* Rewrite the backend manager.
This creates a new more logic backend manager that handles all backend operations.
For each top-level operation, there is now a single backend manager instance that is passed to sub-commands.
The internals of the backend manager are now rewritten to use async logic instead of threading.
The design uses a single task runner that dispatches operations and honors concurrent settings and limits from one place.
The logic for each operation has been moved into a separate files/classes to make it easier to understand each operation.
This fixes#5804
* Fixed a few issues with not awaiting tasks
* Fixed not creating empty databases
* Fixed an issue with hashes not being recorded on download
* Reworked the download logic to avoid attempting to decrypt the file if it has been modified.
* Review fixes
* Renamed db collector to better reflect the purpose.
* Review fixes
Closes#4593
The logic for finding existing source blocks requires that the same target files and hashes are adjacent in query results, but this was not the case.
Carl Johnsen