Synchronized - critical sections for Lua

The synchronized function ensures that one fiber does not enter a critical section of code while another fiber is in the critical section. If another fiber tries to enter a critical section, it will wait, block, until the key is released.

... = synchronized(key, fun, ...)

• Param key - a key to lock, can be arbitrary Lua object
• Param fun - a function to execute in a critical section
• Param ... - arguments to fun
• Return value - the original results returned by fun

Example

The example below executes criticalsection function as a critical section by obtaining the mutual-exclusion lock for a lock object.

local fiber = require('fiber')
-- Create a new synchronized primitive
local synchronized = require('synchronized')

-- basic synchronization
local result = {}
local function criticalsection(id)
    print(string.format("%d: enter", id))
    fiber.yield() -- do some work
    print(string.format("%d: leave", id))
end
local lock = "somekey"
local function worker(id)
    synchronized(lock, criticalsection, id)
end
for i=1,3 do fiber.create(worker, i, join) end

Output:

./example.lua
entering the event loop
1: enter
1: leave
2: enter
2: leave
3: enter
3: leave

See also

There is alternative implementation of synchronization primitives moonlibs/sync