perf-test: add caching of xapian database

The caching and uncaching seem to be necessarily manual, as timing the
initial notmuch new is one of our goals with this suite.

performance-test/.gitignore

@@ -1,2 +1,3 @@
 tmp.*/
 corpus/
+notmuch.cache.*/

performance-test/Makefile.local

@@ -29,4 +29,4 @@ $(TXZFILE):
 download-corpus:
 	wget -O ${TXZFILE} ${DEFAULT_URL}
 
-CLEAN := $(CLEAN) $(dir)/tmp.* $(dir)/corpus
+CLEAN := $(CLEAN) $(dir)/tmp.* $(dir)/corpus $(dir)/notmuch.cache.*

performance-test/basic

@@ -2,11 +2,16 @@
 
 . ./perf-test-lib.sh
 
+uncache_database
+
 add_email_corpus
 
 print_header
 
 time_run 'initial notmuch new' 'notmuch new'
+
+cache_database
+
 time_run 'second notmuch new' 'notmuch new'
 time_run 'dump *' 'notmuch dump > tags.out'
 time_run 'restore *' 'notmuch restore < tags.out'

performance-test/perf-test-lib.sh

@@ -35,6 +35,8 @@ then
 	exit 1
 fi
 
+DB_CACHE_DIR=${TEST_DIRECTORY}/notmuch.cache.$corpus_size
+
 add_email_corpus ()
 {
     rm -rf ${MAIL_DIR}
@@ -80,8 +82,34 @@ add_email_corpus ()
     fi
 
     cp -lr $MAIL_CORPUS $MAIL_DIR
+
 }
 
+time_start () {
+
+    add_email_corpus
+
+    print_header
+
+    if [ -d $DB_CACHE_DIR ]; then
+	cp -r $DB_CACHE_DIR ${MAIL_DIR}/.notmuch
+    else
+	time_run 'Initial notmuch new' "notmuch new"
+	cache_database
+    fi
+}
+
+cache_database () {
+    if [ -d $MAIL_DIR/.notmuch ]; then
+	cp -r $MAIL_DIR/.notmuch $DB_CACHE_DIR
+    else
+	echo "Warning: No database found to cache"
+    fi
+}
+
+uncache_database () {
+    rm -rf $DB_CACHE_DIR
+}
 
 print_header () {
     printf "[v%4s %6s]          Wall(s)\tUsr(s)\tSys(s)\tRes(K)\tIn/Out(512B)\n" \