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66 lines
2.5 KiB
66 lines
2.5 KiB
#!/usr/bin/env bcc-lua
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--[[
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Copyright 2016 Marek Vavrusa <mvavrusa@cloudflare.com>
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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]]
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-- Trace operations on keys matching given pattern in KyotoTycoon daemon.
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-- This can show you if certain keys were modified or read during the lifetime
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-- even if KT doesn't support this. It also shows how to attach to C++ mangled symbols.
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local ffi = require('ffi')
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local bpf = require('bpf')
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local S = require('syscall')
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local function help(err)
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print(string.format('%s [get|set] [key]', arg[0]))
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if err then print('error: '..err) end
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os.exit(1)
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end
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-- Accept the same format as ktremotemgr for clarity: <get|set> <key>
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local writeable, watch_key, klen = 'any', arg[2] or '*', 80
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if arg[1] == 'get' then writeable = 0
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elseif arg[1] == 'set' then writeable = 1
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elseif arg[1] == '-h' or arg[1] == '--help' then help()
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elseif arg[1] and arg[1] ~= 'any' then
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help(string.format('bad cmd: "%s"', arg[1]))
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end
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if watch_key ~= '*' then klen = #watch_key end
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-- Find a good entrypoint that has both key and differentiates read/write in KT
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-- That is going to serve as an attachment point for BPF program
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-- ABI: bool accept(void *this, const char* kbuf, size_t ksiz, Visitor* visitor, bool writable)
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local key_type = string.format('char [%d]', klen)
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local probe = bpf.uprobe('/usr/local/bin/ktserver:kyotocabinet::StashDB::accept',
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function (ptregs)
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-- Watch either get/set or both
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if writeable ~= 'any' then
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if ptregs.parm5 ~= writeable then return end
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end
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local line = ffi.new(key_type)
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ffi.copy(line, ffi.cast('char *', ptregs.parm2))
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-- Check if we're looking for specific key
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if watch_key ~= '*' then
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if ptregs.parm3 ~= klen then return false end
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if line ~= watch_key then return false end
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end
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print('%s write:%d\n', line, ptregs.parm5)
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end, false, -1, 0)
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-- User-space part of the program
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local ok, err = pcall(function()
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local log = bpf.tracelog()
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print(' TASK-PID CPU# TIMESTAMP FUNCTION')
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print(' | | | | |')
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while true do
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print(log:read())
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end
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end)
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