Report per column family metadata in SHOW ENGINE ROCKSDB STATUS

Summary:
Report the currently available per column family statistics from rocksdb.
Each column family is reported on a separate row. DB stats is on a
separate row. The output is similar to the output from rocksdb's LOG
file.

Since column families aren't currently being cleaned up after a table is
dropped, the show_engine test needs to force the mysql server to
restart. Otherwise, SHOW ENGINE rocksdb STATUS can produce results for
column families whose tables/indicies have been removed.

@update-submodule: rocksdb

Test Plan: mysqltest.sh

Reviewers: maykov, yoshinorim, spetrunia, jonahcohen

Reviewed By: jonahcohen

Differential Revision: https://reviews.facebook.net/D32217

mysql-test/suite/rocksdb/r/show_engine.result

@@ -0,0 +1,22 @@
+DROP TABLE IF EXISTS t1;
+DROP TABLE IF EXISTS t2;
+DROP TABLE IF EXISTS t3;
+DROP TABLE IF EXISTS t4;
+CREATE TABLE t1 (i INT, PRIMARY KEY (i) COMMENT 'cf_t1') ENGINE = ROCKSDB;
+CREATE TABLE t2 (j INT, PRIMARY KEY (j) COMMENT 'cf_t2') ENGINE = ROCKSDB;
+CREATE TABLE t3 (k INT, PRIMARY KEY (k) COMMENT 'cf_t1') ENGINE = ROCKSDB;
+CREATE TABLE t4 (l INT, PRIMARY KEY (l) COMMENT 'cf_t4') ENGINE = ROCKSDB;
+SHOW ENGINE rocksdb STATUS;
+Type	Name	Status
+DB	db	#
+COMPACTION	cf_t1	#
+COMPACTION	cf_t2	#
+COMPACTION	cf_t4	#
+COMPACTION	default	#
+DROP TABLE t1;
+DROP TABLE t2;
+DROP TABLE t3;
+DROP TABLE t4;
+SHOW ENGINE rocksdb MUTEX;
+Type	Name	Status
+SHOW ENGINE ALL MUTEX;

mysql-test/suite/rocksdb/show_engine.result

@@ -1,6 +1,7 @@
 SHOW ENGINE rocksdb STATUS;
 Type	Name	Status
-ROCKSDB	live_files	#
+DB	db	#
+COMPACTION	default	#
 SHOW ENGINE rocksdb MUTEX;
 Type	Name	Status
 SHOW ENGINE ALL MUTEX;

mysql-test/suite/rocksdb/t/show_engine-master.opt

@@ -0,0 +1 @@
+--force-restart

mysql-test/suite/rocksdb/t/show_engine.test

@@ -0,0 +1,30 @@
+#
+# SHOW ENGINE STATUS command
+# Checking that the command doesn't produce an error.
+# If it starts producing an actual result, the result file
+# will need to be updated, and possibly masked.
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+DROP TABLE IF EXISTS t2;
+DROP TABLE IF EXISTS t3;
+DROP TABLE IF EXISTS t4;
+--enable_warnings
+
+CREATE TABLE t1 (i INT, PRIMARY KEY (i) COMMENT 'cf_t1') ENGINE = ROCKSDB;
+CREATE TABLE t2 (j INT, PRIMARY KEY (j) COMMENT 'cf_t2') ENGINE = ROCKSDB;
+CREATE TABLE t3 (k INT, PRIMARY KEY (k) COMMENT 'cf_t1') ENGINE = ROCKSDB;
+CREATE TABLE t4 (l INT, PRIMARY KEY (l) COMMENT 'cf_t4') ENGINE = ROCKSDB;
+--replace_column 3 #
+SHOW ENGINE rocksdb STATUS;
+DROP TABLE t1;
+DROP TABLE t2;
+DROP TABLE t3;
+DROP TABLE t4;
+
+SHOW ENGINE rocksdb MUTEX;
+# For SHOW ALL MUTEX even the number of lines is volatile, so the result logging is disabled
+--disable_result_log
+SHOW ENGINE ALL MUTEX;
+--enable_result_log
+