feat(lock) exptime can be set per key

README.markdown

@@ -118,12 +118,14 @@ Specifies the maximal step size (i.e., sleep interval, in seconds) allowed. See
 
 lock
 ----
-`syntax: elapsed, err = obj:lock(key)`
+`syntax: elapsed, err = obj:lock(key, exptime)`
 
 Tries to lock a key across all the Nginx worker processes in the current Nginx server instance. Different keys are different locks.
 
 The length of the key string must not be larger than 65535 bytes.
 
+The optional `exptime` argument allows to set an expiration time (in seconds) for the key.
+
 Returns the waiting time (in seconds) if the lock is successfully acquired. Otherwise returns `nil` and a string describing the error.
 
 The waiting time is not from the wallclock, but rather is from simply adding up all the waiting "steps". A nonzero `elapsed` return value indicates that someone else has just hold this lock. But a zero return value cannot gurantee that no one else has just acquired and released the lock.

lib/resty/lock.lua

@@ -117,7 +117,7 @@ function _M.new(_, dict_name, opts)
 end
 
 
-function _M.lock(self, key)
+function _M.lock(self, key, exptime)
     if not key then
         return nil, "nil key"
     end
@@ -127,7 +127,7 @@ function _M.lock(self, key)
     if cdata.key_id > 0 then
         return nil, "locked"
     end
-    local exptime = self.exptime
+    local exptime = exptime or self.exptime
     local ok, err = dict:add(key, true, exptime)
     if ok then
         cdata.key_id = ref_obj(key)
@@ -143,6 +143,9 @@ function _M.lock(self, key)
     local step = self.step
     local ratio = self.ratio
     local timeout = self.timeout
+    if timeout and timeout > exptime then
+        timeout = exptime
+    end
     local max_step = self.max_step
     local elapsed = 0
     while timeout > 0 do

t/sanity.t

@@ -468,3 +468,37 @@ lock 2: unlock: nil, unlocked
 --- no_error_log
 [error]
 
+
+
+=== TEST 14: lock expired by itself when set per key
+--- http_config eval: $::HttpConfig
+--- config
+    location = /t {
+        content_by_lua '
+            local resty_lock = require "resty.lock"
+            local key = "blah"
+            local t, err = ngx.thread.spawn(function ()
+                local lock = resty_lock:new("cache_locks")
+                local elapsed, err = lock:lock(key, 0.1)
+                ngx.say("sub thread: lock: ", elapsed, " ", err)
+                ngx.sleep(0.1)
+                -- ngx.say("sub thread: unlock: ", lock:unlock(key))
+            end)
+
+            local lock = resty_lock:new("cache_locks", { max_step = 0.05 })
+            local elapsed, err = lock:lock(key)
+            ngx.say("main thread: lock: ", elapsed, " ", err)
+            ngx.say("main thread: unlock: ", lock:unlock())
+        ';
+    }
+--- request
+GET /t
+--- response_body_like chop
+^sub thread: lock: 0 nil
+main thread: lock: 0.11[2-4]\d* nil
+main thread: unlock: 1
+$
+--- no_error_log
+[error]
+
+