From 1db4495add83b45d0c57b633a82af12387327821 Mon Sep 17 00:00:00 2001
From: George Christian <georgechristian123@gmail.com>
Date: Sun, 22 Jul 2018 17:05:59 +0100
Subject: [PATCH 1/2] Added compression level system variable

---
 storage/archive/ha_archive.cc | 39 ++++++++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/storage/archive/ha_archive.cc b/storage/archive/ha_archive.cc
index 0f74645e971..2505a48be3e 100644
--- a/storage/archive/ha_archive.cc
+++ b/storage/archive/ha_archive.cc
@@ -210,6 +210,11 @@ static void init_archive_psi_keys(void) {
 */
 static const char *ha_archive_exts[] = {ARZ, NullS};
 
+/*
+  Archive system variable values
+*/
+static int srv_compression_level = -1;
+
 /*
   Initialize the archive handler.
 
@@ -1589,6 +1594,38 @@ bool ha_archive::check_if_incompatible_data(HA_CREATE_INFO *info,
   return COMPATIBLE_DATA_YES;
 }
 
+/*
+  Update the archive_compression_level system variable
+*/
+static void archive_compression_level_update(
+  THD *thd,
+  SYS_VAR *var,
+  void* var_ptr,
+  const void *save)
+{
+  int in_val = *static_cast<const int *>(save);
+  srv_compression_level = in_val;
+}
+
+/*
+  Compression level used by Zlib
+*/
+static MYSQL_SYSVAR_INT(compression_level, srv_compression_level,
+  PLUGIN_VAR_RQCMDARG,
+  "Compression level used by Zlib for archive files."
+  " -1 is Zlib's defualt. Levels 0-9 go in order of increasing compression"
+  " where 0 is no compression at all.",
+  NULL, archive_compression_level_update, -1, -1,
+  9, 0);
+
+/*
+  System variables list
+*/
+static SYS_VAR *archive_system_variables[] = {
+  MYSQL_SYSVAR(compression_level),
+  NULL
+};
+
 struct st_mysql_storage_engine archive_storage_engine = {
     MYSQL_HANDLERTON_INTERFACE_VERSION};
 
@@ -1604,7 +1641,7 @@ mysql_declare_plugin(archive){
     NULL,            /* Plugin Deinit */
     0x0300 /* 3.0 */,
     NULL, /* status variables                */
-    NULL, /* system variables                */
+    archive_system_variables, /* system variables                */
     NULL, /* config options                  */
     0,    /* flags                           */
 } mysql_declare_plugin_end;

From bd18b5801630d2e4372a3189da5832115faebf77 Mon Sep 17 00:00:00 2001
From: George Christian <georgechristian123@gmail.com>
Date: Sat, 4 Aug 2018 22:02:54 +0100
Subject: [PATCH 2/2] Added ability to set compression level

---
 storage/archive/azio.cc       |  2 +-
 storage/archive/azlib.h       |  3 +++
 storage/archive/ha_archive.cc | 17 +++++++++--------
 3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/storage/archive/azio.cc b/storage/archive/azio.cc
index bb1ea286ff5..a3e113d574e 100644
--- a/storage/archive/azio.cc
+++ b/storage/archive/azio.cc
@@ -64,7 +64,7 @@ extern "C" PSI_file_key arch_key_file_data;
 */
 int az_open(azio_stream *s, const char *path, int Flags, File fd) {
   int err;
-  int level = Z_DEFAULT_COMPRESSION; /* compression level */
+  int level = srv_compression_level - 1; /* compression level */
   int strategy = Z_DEFAULT_STRATEGY; /* compression strategy */
 
   memset(s, 0, sizeof(azio_stream));
diff --git a/storage/archive/azlib.h b/storage/archive/azlib.h
index 963a8ad52e1..57e69abe2b9 100644
--- a/storage/archive/azlib.h
+++ b/storage/archive/azlib.h
@@ -200,6 +200,9 @@ extern "C" {
 #define AZ_BUFSIZE_READ 32768
 #define AZ_BUFSIZE_WRITE 16384
 
+/* Required system variables */
+extern int srv_compression_level;
+
 typedef struct azio_stream {
   z_stream stream;
   int z_err;                     /* error code for last stream operation */
diff --git a/storage/archive/ha_archive.cc b/storage/archive/ha_archive.cc
index 2505a48be3e..c77247bdeb2 100644
--- a/storage/archive/ha_archive.cc
+++ b/storage/archive/ha_archive.cc
@@ -211,9 +211,9 @@ static void init_archive_psi_keys(void) {
 static const char *ha_archive_exts[] = {ARZ, NullS};
 
 /*
-  Archive system variable values
+  Archive system variables
 */
-static int srv_compression_level = -1;
+int srv_compression_level = 0;  // Zlib compression level
 
 /*
   Initialize the archive handler.
@@ -1608,15 +1608,16 @@ static void archive_compression_level_update(
 }
 
 /*
-  Compression level used by Zlib
+  Compression level used by Zlib. I have shifted Zlib's default levels
+  up by one because the settings table doesn't support signed integers.
 */
 static MYSQL_SYSVAR_INT(compression_level, srv_compression_level,
   PLUGIN_VAR_RQCMDARG,
   "Compression level used by Zlib for archive files."
-  " -1 is Zlib's defualt. Levels 0-9 go in order of increasing compression"
-  " where 0 is no compression at all.",
-  NULL, archive_compression_level_update, -1, -1,
-  9, 0);
+  " 0 is Zlib's defualt. Levels 1-10 go in order of increasing compression,"
+  " where 1 is no compression at all.",
+  NULL, archive_compression_level_update, 0, 0,
+  10, 0);
 
 /*
   System variables list
@@ -1641,7 +1642,7 @@ mysql_declare_plugin(archive){
     NULL,            /* Plugin Deinit */
     0x0300 /* 3.0 */,
     NULL, /* status variables                */
-    archive_system_variables, /* system variables                */
+    archive_system_variables, /* system variables */
     NULL, /* config options                  */
     0,    /* flags                           */
 } mysql_declare_plugin_end;