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authorAlexey Botchkov <holyfoot@askmonty.org>2018-03-21 12:33:38 +0400
committerAlexey Botchkov <holyfoot@askmonty.org>2018-03-21 12:33:38 +0400
commit96520384536fdf62aa0b0f444dd1be2d36c3a39b (patch)
tree8965033a0842ff5709ff7a63656dc2967e26e9d9 /plugin
parent15051ab14a7fa2d392e8d8068801010d10e36823 (diff)
downloadmariadb-git-96520384536fdf62aa0b0f444dd1be2d36c3a39b.tar.gz
MDEV-14533 Provide information_schema tables using which hardware
information can be obtained. DISKS plugin implementation added to the tree.
Diffstat (limited to 'plugin')
-rw-r--r--plugin/information_schema_disks/CMakeLists.txt5
-rw-r--r--plugin/information_schema_disks/README.txt101
-rw-r--r--plugin/information_schema_disks/information_schema_disks.cc154
3 files changed, 260 insertions, 0 deletions
diff --git a/plugin/information_schema_disks/CMakeLists.txt b/plugin/information_schema_disks/CMakeLists.txt
new file mode 100644
index 00000000000..a0ed929c62c
--- /dev/null
+++ b/plugin/information_schema_disks/CMakeLists.txt
@@ -0,0 +1,5 @@
+IF(NOT WIN32)
+ INCLUDE_DIRECTORIES(${CMAKE_SOURCE_DIR}/sql)
+ MYSQL_ADD_PLUGIN(DISKS information_schema_disks.cc MODULE_ONLY RECOMPILE_FOR_EMBEDDED)
+ENDIF()
+
diff --git a/plugin/information_schema_disks/README.txt b/plugin/information_schema_disks/README.txt
new file mode 100644
index 00000000000..1c9b8fb6283
--- /dev/null
+++ b/plugin/information_schema_disks/README.txt
@@ -0,0 +1,101 @@
+Information Schema Disks
+------------------------
+This is a proof-of-concept information schema plugin that allows the
+disk space situation to be monitored. When installed, it can be used
+as follows:
+
+ > select * from information_schema.disks;
+ +-----------+-----------------------+-----------+----------+-----------+
+ | Disk | Path | Total | Used | Available |
+ +-----------+-----------------------+-----------+----------+-----------+
+ | /dev/sda3 | / | 47929956 | 30666304 | 14805864 |
+ | /dev/sda1 | /boot/efi | 191551 | 3461 | 188090 |
+ | /dev/sda4 | /home | 174679768 | 80335392 | 85448120 |
+ | /dev/sdb1 | /mnt/hdd | 961301832 | 83764 | 912363644 |
+ | /dev/sdb1 | /home/wikman/Music | 961301832 | 83764 | 912363644 |
+ | /dev/sdb1 | /home/wikman/Videos | 961301832 | 83764 | 912363644 |
+ | /dev/sdb1 | /home/wikman/hdd | 961301832 | 83764 | 912363644 |
+ | /dev/sdb1 | /home/wikman/Pictures | 961301832 | 83764 | 912363644 |
+ | /dev/sda3 | /var/lib/docker/aufs | 47929956 | 30666304 | 14805864 |
+ +-----------+-----------------------+-----------+----------+-----------+
+ 9 rows in set (0.00 sec)
+
+- 'Disk' is the name of the disk itself.
+- 'Path' is the mount point of the disk.
+- 'Total' is the total space in KiB.
+- 'Used' is the used amount of space in KiB, and
+- 'Available' is the amount of space in KiB available to non-root users.
+
+Note that as the amount of space available to root may be more that what
+is available to non-root users, 'available' + 'used' may be less than 'total'.
+
+All paths to which a particular disk has been mounted are reported. The
+rationale is that someone might want to take different action e.g. depending
+on which disk is relevant for a particular path. This leads to the same disk
+being reported multiple times. An alternative to this would be to have two
+tables; disks and mounts.
+
+ > select * from information_schema.disks;
+ +-----------+-----------+----------+-----------+
+ | Disk | Total | Used | Available |
+ +-----------+-----------+----------+-----------+
+ | /dev/sda3 | 47929956 | 30666304 | 14805864 |
+ | /dev/sda1 | 191551 | 3461 | 188090 |
+ | /dev/sda4 | 174679768 | 80335392 | 85448120 |
+ | /dev/sdb1 | 961301832 | 83764 | 912363644 |
+ +-----------+-----------+----------+-----------+
+
+ > select * from information_schema.mounts;
+ +-----------------------+-----------+
+ | Path | Disk |
+ +-----------------------+-----------+
+ | / | /dev/sda3 |
+ | /boot/efi | /dev/sda1 |
+ | /home | /dev/sda4 |
+ | /mnt/hdd | /dev/sdb1 |
+ | /home/wikman/Music | /dev/sdb1 |
+ ...
+
+
+Building
+--------
+- Ensure that the directory information_schema_disks is in the top-level
+ directory of the server.
+- Add
+
+ ADD_SUBDIRECTORY(information_schema_disks)
+
+ to the top-level CMakeLists.txt
+
+> Invoke make
+
+ $ make
+
+Installation
+------------
+- Copy information_schema_disks/libinformation_schema_disks.so to the plugin
+ directory of the server:
+
+ $ cd information_schema_disks
+ $ sudo cp libinformation_schema_disks.so plugin-directory-of-server
+
+- Using mysql, install the plugin:
+
+ MariaDB [(none)]> install plugin disks soname 'libinformation_schema_disks.so';
+
+Usage
+-----
+The plugin appears as the table 'disks' in 'information_schema'.
+
+ MariaDB [(none)]> select * from information_schema.disks;
+ +-----------+-----------------------+-----------+----------+-----------+
+ | Disk | Path | Total | Used | Available |
+ +-----------+-----------------------+-----------+----------+-----------+
+ | /dev/sda3 | / | 47929956 | 30666308 | 14805860 |
+ | /dev/sda1 | /boot/efi | 191551 | 3461 | 188090 |
+ | /dev/sda4 | /home | 174679768 | 80348148 | 85435364 |
+ | /dev/sdb1 | /mnt/hdd | 961301832 | 83764 | 912363644 |
+ | /dev/sdb1 | /home/wikman/Music | 961301832 | 83764 | 912363644 |
+ | /dev/sdb1 | /home/wikman/Videos | 961301832 | 83764 | 912363644 |
+ ...
+
diff --git a/plugin/information_schema_disks/information_schema_disks.cc b/plugin/information_schema_disks/information_schema_disks.cc
new file mode 100644
index 00000000000..b5e3a6dc728
--- /dev/null
+++ b/plugin/information_schema_disks/information_schema_disks.cc
@@ -0,0 +1,154 @@
+/*
+ Copyright (c) 2017, MariaDB
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; version 2 of the License.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA */
+
+#include <sys/statvfs.h>
+#include <sys/types.h>
+#include <mntent.h>
+#include <sql_class.h>
+#include <table.h>
+#include <innodb_priv.h>
+
+namespace
+{
+
+struct st_mysql_information_schema disks_table_info = { MYSQL_INFORMATION_SCHEMA_INTERFACE_VERSION };
+
+ST_FIELD_INFO disks_table_fields[]=
+{
+ { "Disk", PATH_MAX, MYSQL_TYPE_STRING, 0, 0 ,0, 0 },
+ { "Path", PATH_MAX, MYSQL_TYPE_STRING, 0, 0 ,0, 0 },
+ { "Total", 32, MYSQL_TYPE_LONG, 0, 0 ,0 ,0 }, // Total amount available
+ { "Used", 32, MYSQL_TYPE_LONG, 0, 0 ,0 ,0 }, // Amount of space used
+ { "Available", 32, MYSQL_TYPE_LONG, 0, 0 ,0 ,0 }, // Amount available to users other than root.
+ { 0, 0, MYSQL_TYPE_NULL, 0, 0, 0, 0 }
+};
+
+int disks_table_add_row(THD* pThd,
+ TABLE* pTable,
+ const char* zDisk,
+ const char* zPath,
+ const struct statvfs& info)
+{
+ // From: http://pubs.opengroup.org/onlinepubs/009695399/basedefs/sys/statvfs.h.html
+ //
+ // f_frsize Fundamental file system block size.
+ // f_blocks Total number of blocks on file system in units of f_frsize.
+ // f_bfree Total number of free blocks.
+ // f_bavail Number of free blocks available to non-privileged process.
+
+ size_t total = (info.f_frsize * info.f_blocks) / 1024;
+ size_t used = (info.f_frsize * (info.f_blocks - info.f_bfree)) / 1024;
+ size_t avail = (info.f_frsize * info.f_bavail) / 1024;
+
+ pTable->field[0]->store(zDisk, strlen(zDisk), system_charset_info);
+ pTable->field[1]->store(zPath, strlen(zPath), system_charset_info);
+ pTable->field[2]->store(total);
+ pTable->field[3]->store(used);
+ pTable->field[4]->store(avail);
+
+ // 0 means success.
+ return (schema_table_store_record(pThd, pTable) != 0) ? 1 : 0;
+}
+
+int disks_table_add_row(THD* pThd, TABLE* pTable, const char* zDisk, const char* zPath)
+{
+ int rv = 0;
+
+ struct statvfs info;
+
+ if (statvfs(zPath, &info) == 0) // We ignore failures.
+ {
+ rv = disks_table_add_row(pThd, pTable, zDisk, zPath, info);
+ }
+
+ return rv;
+}
+
+int disks_fill_table(THD* pThd, TABLE_LIST* pTables, Item* pCond)
+{
+ int rv = 1;
+ TABLE* pTable = pTables->table;
+
+ FILE* pFile = setmntent("/etc/mtab", "r");
+
+ if (pFile)
+ {
+ const size_t BUFFER_SIZE = 4096; // 4K should be sufficient.
+
+ char* pBuffer = new (std::nothrow) char [BUFFER_SIZE];
+
+ if (pBuffer)
+ {
+ rv = 0;
+
+ struct mntent ent;
+ struct mntent* pEnt;
+
+ while ((rv == 0) && (pEnt = getmntent_r(pFile, &ent, pBuffer, BUFFER_SIZE)))
+ {
+ // We only report the ones that refer to physical disks.
+ if (pEnt->mnt_fsname[0] == '/')
+ {
+ rv = disks_table_add_row(pThd, pTable, pEnt->mnt_fsname, pEnt->mnt_dir);
+ }
+ }
+
+ delete [] pBuffer;
+ }
+ else
+ {
+ rv = 1;
+ }
+
+ endmntent(pFile);
+ }
+
+ return rv;
+}
+
+int disks_table_init(void *ptr)
+{
+ ST_SCHEMA_TABLE* pSchema_table = (ST_SCHEMA_TABLE*)ptr;
+
+ pSchema_table->fields_info = disks_table_fields;
+ pSchema_table->fill_table = disks_fill_table;
+ return 0;
+}
+
+}
+
+extern "C"
+{
+
+mysql_declare_plugin(disks_library)
+{
+ MYSQL_INFORMATION_SCHEMA_PLUGIN,
+ &disks_table_info, /* type-specific descriptor */
+ "DISKS", /* table name */
+ "MariaDB", /* author */
+ "Disk space information", /* description */
+ PLUGIN_LICENSE_GPL, /* license type */
+ disks_table_init, /* init function */
+ NULL,
+ 0x0100, /* version = 1.0 */
+ NULL, /* no status variables */
+ NULL, /* no system variables */
+ NULL, /* no reserved information */
+ 0 /* no flags */
+}
+mysql_declare_plugin_end;
+
+}