cuirass: Perform some database "optimization" at startup.

Add a "optimize" step that occurs when starting up the main Curiass
process. Currently this does two things, but could be extended to do more.

The "PRAGMA optimize;" command prompts SQLite to ANALYZE tables where that
might help. The "PRAGMA wal_checkpoint(TRUNCATE);" command has SQLite process
any unprocessed changes from the WAL file, then truncate it to 0 bytes. I've
got no data to suggest this helps with performance, but I'm hoping that going
from a large WAL file to a small one occasionally might be useful.

* src/cuirass/database.scm (db-optimize): New procedure.
* bin/cuirass.in (main): Run it.

bin/cuirass.in

@@ -124,6 +124,10 @@ exec ${GUILE:-@GUILE@} --no-auto-compile -e main -s "$0" "$@"
                              (min (current-processor-count) 4))))
           (prepare-git)
 
+          (unless (option-ref opts 'web #f)
+            (log-message "performing database optimizations")
+            (db-optimize))
+
           (log-message "running Fibers on ~a kernel threads" threads)
           (run-fibers
            (lambda ()

src/cuirass/database.scm

@@ -38,6 +38,7 @@
             db-init
             db-open
             db-close
+            db-optimize
             db-add-specification
             db-remove-specification
             db-get-specifications
@@ -277,6 +278,13 @@ database object."
   "Close database object DB."
   (sqlite-close db))
 
+(define* (db-optimize #:optional (db-file (%package-database)))
+  "Open the database and perform optimizations."
+  (let ((db (db-open db-file)))
+    (sqlite-exec db "PRAGMA optimize;")
+    (sqlite-exec db "PRAGMA wal_checkpoint(TRUNCATE);")
+    (db-close db)))
+
 (define (last-insert-rowid db)
   (vector-ref (car (sqlite-exec db "SELECT last_insert_rowid();"))
               0))