check_predecessor_delay = 120
lookup_delay = 10
--- current node (don't worry, globals are duplicated in each process)
+-- current node (don't worry, globals are duplicated in each simulated process)
my_node = {
id = my_id,
next_finger_to_fix = 1,
-- - the id of a guy I know in the system (except for the first node)
function node(...)
- -- TODO simplify the parameters
+ -- TODO simplify the deployment file
local known_id
local args = {...}
my_node.id = tonumber(args[1])
known_id = tonumber(args[2])
end
- simgrid.debug("Hello, I'm a node")
+ -- initialize the node
+ for i = 1, nb_bits do
+ my_node.fingers[i] = my_node.id
+ end
+ my_node.comm_recv = simgrid.task.irecv(my_node.id)
-- join the ring
local join_success = false
local next_check_predecessor_date = now + check_predecessor_delay
local next_lookup_date = now + lookup_delay
- local task, success
- my_node.comm_recv = simgrid.task.irecv(my_node.id)
+ local task, err
while now < max_simulation_time do
- task, success = simgrid.comm.test(my_node.comm_recv)
+ task, err = my_node.comm_recv:test()
if task then
-- I received a task: answer it
my_node.comm_recv = simgrid.task.irecv(my_node.id)
handle_task(task)
- elseif failed then
+ elseif err then
-- the communication has failed: nevermind
my_node.comm_recv = simgrid.task.irecv(my_node.id)
else
elseif now >= next_check_predecessor_date then
check_predecessor()
next_check_predecessor_date = simgrid.get_clock() + check_predecessor_delay
+
elseif now >= next_lookup_date then
random_lookup()
next_lookup_date = simgrid.get_clock() + lookup_delay
end
end
+-- Makes the current node leave the ring
+function leave()
+
+ simgrid.info("Leaving the ring")
+ -- TODO: notify others
+end
+
-- This function is called when the current node receives a task.
-- - task: the task received
function handle_task(task)
if type == "find successor" then
+ simgrid.info("Received a 'find successor' request from " .. task.answer_to ..
+ " for id " .. task.request_id)
+
-- is my successor the successor?
if is_in_interval(task.request_id, my_node.id + 1, my_node.fingers[1]) then
+
+ simgrid.info("Sending back a 'find successor answer' to " ..
+ task.answer_to .. ": the successor of " .. task.request_id ..
+ " is " .. my_node.fingers[1])
+
task.type = "find successor answer"
task.answer = my_node.fingers[1]
task:dsend(task.answer_to)
else
-- forward the request to the closest preceding finger in my table
+
+ simgrid.info("Forwarding the 'find successor' request to my closest preceding finger")
task:dsend(closest_preceding_node(task.request_id))
end
elseif type == "get predecessor" then
+ task.type = "get predecessor answer"
task.answer = my_node.predecessor
task:dsend(task.answer_to)
return id <= b
end
+-- Returns whether the current node is in the ring.
+function has_joined()
+
+ return my_node.fingers[1] ~= nil
+end
+
-- Creates a new Chord ring.
function create()
my_node.predecessor = nil
+ my_node.fingers[1] = my_node.id
end
-- Attemps to join the Chord ring.
-- - return value: true if the join was successful
function join(known_id)
+ simgrid.info("Joining the ring with id " .. my_node.id .. ", knowing node " .. known_id)
+
local successor = remote_find_successor(known_id, my_node.id)
if successor == nil then
+ simgrid.info("Cannot join the ring.")
return false
end
- my_node.finger[1] = successor
+ my_node.predecessor = nil
+ my_node.fingers[1] = successor
return true
end
function closest_preceding_node(id)
for i = nb_bits, 1, -1 do
- if is_in_interval(my_node.fingers[i].id, my_node.id + 1, id - 1) then
+ if is_in_interval(my_node.fingers[i], my_node.id + 1, id - 1) then
-- finger i is the first one before id
- return my_node.fingers[i].id
+ return my_node.fingers[i]
end
end
end
-- Finds the successor of an id
-- id: the id to find
--- return value: the id of the successor, or -1 if the request failed
+-- return value: the id of the successor, or nil if the request failed
function find_successor(id)
if is_in_interval(id, my_node.id + 1, my_node.fingers[1]) then
task.request_id = id
task.answer_to = my_node.id
+ simgrid.info("Sending a 'find successor' request to " .. ask_to .. " for id " .. id)
if task:send(ask_to, timeout) then
-- request successfully sent: wait for an answer
+
+ simgrid.info("Sent the 'find successor' request to " .. ask_to ..
+ " for id " .. id .. ", waiting for the answer")
+
while true do
- task = simgrid.comm.wait(my_node.comm_recv, timeout)
+ task = my_node.comm_recv:wait(timeout)
my_node.comm_recv = simgrid.task.irecv(my_node.id)
if not task then
-- failed to receive the answer
+ simgrid.info("Failed to receive the answer to my 'find successor' request")
return nil
else
-- a task was received: is it the expected answer?
- if task.type ~= "find successor answer" or task[request_id] ~= id then
+ if task.type ~= "find successor answer" or task.request_id ~= id then
-- this is not our answer
+ simgrid.info("Received another request of type " .. task.type)
handle_task(task)
else
-- this is our answer
+ simgrid.info("Received the answer to my 'find successor' request for id " ..
+ id .. ": the successor is " .. task.answer)
return task.answer
end
end
end
+ else
+ simgrid.info("Failed to send the 'find successor' request to " .. ask_to ..
+ " for id " .. id)
end
return successor
if task:send(ask_to, timeout) then
-- request successfully sent: wait for an answer
while true do
- task = simgrid.comm.wait(my_node.comm_recv, timeout)
+ task = my_node.comm_recv:wait(timeout)
my_node.comm_recv = simgrid.task.irecv(my_node.id)
if not task then
end
-- this node is a candidate to become my new successor
- if candidate ~= nil and is_in_interval(candidate, my_node.id + 1, successor -1) then
+ if candidate ~= nil and is_in_interval(candidate, my_node.id + 1, successor - 1) then
my_node.fingers[1] = candidate
end
local id = find_successor(my_node.id + 2^i)
if id ~= nil then
if id ~= my_node.fingers[i] then
- fingers[i] = id
+ my_node.fingers[i] = id
end
my_node.next_finger_to_fix = (i % nb_bits) + 1
end
