dio: provide stats for all devices, rewritten by Joerg

Old dio.lua was moved to contrib. New one is used like CPU widget is,
request the device or parition in the format argument, {sda read_mb}
as an example. New widget doesn't provide scheduler information, but I
don't know anyone who used that. If you think this is wrong let me
know.

1 files changed, 39 insertions, 40 deletions

diff --git a/widgets/dio.lua b/widgets/dio.lua
index edf4638..db6ba39 100644
--- a/widgets/dio.lua
+++ b/widgets/dio.lua
@@ -1,14 +1,17 @@
 ---------------------------------------------------
 -- Licensed under the GNU General Public License v2
---  * (c) 2010, Adrian C. <anrxc@sysphere.org>
+--  * (c) 2011, Jörg T. <jthalheim@gmail.com>
 ---------------------------------------------------
 
 -- {{{ Grab environment
-local ipairs = ipairs
+local pairs = pairs
+local io = { lines = io.lines }
 local setmetatable = setmetatable
-local table = { insert = table.insert }
-local string = { gmatch = string.gmatch }
 local helpers = require("vicious.helpers")
+local os = {
+    time = os.time,
+    difftime = os.difftime
+}
 -- }}}
 
 
@@ -18,54 +21,50 @@ module("vicious.widgets.dio")
 
 -- Initialize function tables
 local disk_usage = {}
-local disk_total = {}
--- Variable definitions
+local disk_stats = {}
+local disk_time  = 0
+-- Constant definitions
 local unit = { ["s"] = 1, ["kb"] = 2, ["mb"] = 2048 }
 
 -- {{{ Disk I/O widget type
-local function worker(format, disk)
-    if not disk then return end
-
-    local disk_lines = { [disk] = {} }
-    local disk_stats = helpers.pathtotable("/sys/block/" .. disk)
-
-    if disk_stats.stat then
-        local match = string.gmatch(disk_stats.stat, "[%s]+([%d]+)")
-        for i = 1, 11 do -- Store disk stats
-            table.insert(disk_lines[disk], match())
-        end
+local function worker(format)
+    local disk_lines = {}
+
+    for line in io.lines("/proc/diskstats") do
+        local device, read, write =
+            -- Linux kernel docs: Documentation/iostats.txt
+	    line:match("([^%s]+) %d+ %d+ (%d+) %d+ %d+ %d+ (%d+)")
+        disk_lines[device] = { read, write }
     end
 
-    -- Ensure tables are initialized correctly
-    local diff_total = { [disk] = {} }
-    if not disk_total[disk] then
-        disk_usage[disk] = {}
-        disk_total[disk] = {}
+    local time = os.time()
+    local interval = os.difftime(time, disk_time)
+    if interval == 0 then interval = 1 end
+
+    for device, stats in pairs(disk_lines) do
+        -- Avoid insane values on startup
+        local last_stats = disk_stats[device] or stats
 
-        while #disk_total[disk] < #disk_lines[disk] do
-            table.insert(disk_total[disk], 0)
+        -- Check for overflows and counter resets (> 2^32)
+        if stats[1] < last_stats[1] or stats[2] < last_stats[2] then
+            last_stats[1], last_stats[2] = stats[1], stats[2]
         end
-    end
 
-    for i, v in ipairs(disk_lines[disk]) do
         -- Diskstats are absolute, substract our last reading
-        diff_total[disk][i] = v - disk_total[disk][i]
-
-        -- Store totals
-        disk_total[disk][i] = v
+        -- * divide by timediff because we don't know the timer value
+        local read  = (stats[1] - last_stats[1]) / interval
+        local write = (stats[2] - last_stats[2]) / interval
+
+        -- Calculate and store I/O
+        helpers.uformat(disk_usage, device.." read",  read,  unit)
+        helpers.uformat(disk_usage, device.." write", write, unit)
+        helpers.uformat(disk_usage, device.." total", read + write, unit)
     end
 
-    -- Calculate and store I/O
-    helpers.uformat(disk_usage[disk], "read",  diff_total[disk][3], unit)
-    helpers.uformat(disk_usage[disk], "write", diff_total[disk][7], unit)
-    helpers.uformat(disk_usage[disk], "total", diff_total[disk][7] + diff_total[disk][3], unit)
-
-    -- Store I/O scheduler
-    if disk_stats.queue and disk_stats.queue.scheduler then
-        disk_usage[disk]["{sched}"] = string.gmatch(disk_stats.queue.scheduler, "%[([%a]+)%]")
-    end
+    disk_time  = time
+    disk_stats = disk_lines
 
-    return disk_usage[disk]
+    return disk_usage
 end
 -- }}}