ensure token obtain from blocking acquire is the correct lease; chang…

…e expiry to milliseconds instead of seconds

lib/restruct/hls/lock.rb

@@ -7,22 +7,22 @@ module Hls
     # @see #acquire
     # @see #release
     # @see #locked
-    # @attr_reader [::String, nil] token The current token or nil
-    # @attr_reader [Fixnum] expiry The expiry of the underlying redis structures in seconds
-    # @attr_reader [Fixnum, nil] timeout The timeout to wait when attempting to acquire the lock, in seconds
+    # @attr_reader [::String, nil] token the current token or nil
+    # @attr_reader [Fixnum] expiry expiry of the underlying redis structures in milliseconds
+    # @attr_reader [Fixnum, nil] timeout the timeout to wait when attempting to acquire the lock, in seconds
     class Lock < Restruct::Types::Base
       include Restruct::Utils::Scriptable, Restruct::Utils::Coercion
 
-      # The default expiry on the underlying redis keys, in seconds
-      DEFAULT_EXPIRY = 10
+      # The default expiry on the underlying redis keys, in milliseconds
+      DEFAULT_EXPIRY = 1000
 
       # The default timeout when blocking, in seconds; a nil value means it is non-blocking
       DEFAULT_TIMEOUT = nil
 
       attr_reader :token, :expiry, :timeout
 
-      # @param [Integer] expiry In seconds; to prevent infinite locking, each mutex is released after a certain expiry time
-      # @param [Integer] timeout In seconds; if > 0, will block for this amount of time when trying to obtain the lock
+      # @param [Integer] expiry in milliseconds; to prevent infinite locking, each mutex is released after a certain expiry time
+      # @param [Integer] timeout in seconds; if > 0, will block for this amount of time when trying to obtain the lock
       def initialize(expiry: DEFAULT_EXPIRY, timeout: DEFAULT_TIMEOUT, **options)
         super(**options)
 
@@ -65,8 +65,6 @@ def acquire
 
         unless token.nil?
           @token = token
-          # since it was popped from a list, need to update the expiry time of the lease, it could be old
-          @lease.expire(@expiry) if blocking?
           acquired = true
         end
 
@@ -91,23 +89,30 @@ def non_blocking_acquire(token = nil)
 
       def blocking_acquire
         timeout = @timeout == Float::INFINITY ? 0 : @timeout
-        return @tokens.pop(timeout: timeout)
+        token = @tokens.pop(timeout: timeout)
+
+        # Attempt to reacquire in a non blocking way to:
+        # 1) assert we do own the lock (edge case)
+        # 2) touch the lock expiry
+        token = non_blocking_acquire(token) unless token.nil?
+
+        return token
       end
       private :blocking_acquire
 
       # The acquire script attempts to set the lease (keys[1]) to the given token (argv[1]), only
       # if it wasn't already set. It then compares to check if the value of the lease is that of the token,
       # and if so refreshes the expiry (argv[2]) time of the lease.
       # @param [Array<(::String)>] keys The lease key specifying who owns the mutex at the moment
-      # @param [Array<(::String, Fixnum)>] argv The current token; the expiry time in seconds
+      # @param [Array<(::String, Fixnum)>] argv The current token; the expiry time in milliseconds
       # @return [::String] Returns the token if acquired, nil otherwise.
       defscript :acquire_script, <<~LUA
         local token = ARGV[1]
         local expiry = tonumber(ARGV[2])
 
         redis.call('set', KEYS[1], token, 'NX')
         if redis.call('get', KEYS[1]) == token then
-          redis.call('expire', KEYS[1], expiry)
+          redis.call('pexpire', KEYS[1], expiry)
           return token
         end
 
@@ -126,9 +131,9 @@ def blocking_acquire
         local expiry = tonumber(ARGV[3])
 
         if redis.call('get', KEYS[1]) == currentToken then
-          redis.call('set', KEYS[1], nextToken, 'EX', expiry)
+          redis.call('set', KEYS[1], nextToken, 'PX', expiry)
           redis.call('lpush', KEYS[2], nextToken)
-          redis.call('expire', KEYS[2], expiry)
+          redis.call('pexpire', KEYS[2], expiry)
           return true
         end