Add reset_expire

lib/redis_mutex.rb

@@ -14,6 +14,7 @@ class RedisMutex < RedisClassy
   DEFAULT_EXPIRE = 10
   LockError = Class.new(StandardError)
   UnlockError = Class.new(StandardError)
+  ExpireResetError = Class.new(StandardError)
   AssertionError = Class.new(StandardError)
 
   def initialize(object, options={})
@@ -56,6 +57,15 @@ def try_lock
     return false # Dammit, it seems that someone else was even faster than us to remove the expired lock!
   end
 
+  # Extends the expire time just in case process needs more time
+  def reset_expire
+    raise ExpireResetError, "extend_expire should be called only on locked resources" unless locked?
+    # we've the lock so we can safely set the new expire time
+    now = Time.now.to_f
+    @expires_at = now + @expire
+    set(@expires_at)
+  end
+
   # Returns true if resource is locked. Note that nil.to_f returns 0.0
   def locked?
     get.to_f > Time.now.to_f

spec/redis_mutex_spec.rb

@@ -87,6 +87,27 @@
     end
   end
 
+  it 'resets the expire' do
+    mutex = RedisMutex.new(:test_lock, :expire => 0.5, :block => 0)
+    expect(mutex.lock).to be_truthy
+    sleep 0.3
+
+    mutex.reset_expire
+    sleep 0.3 # now it shouldn't be expired if reset works
+
+    # someone tries to overwrite the reset expired lock
+    mutex2 = RedisMutex.new(:test_lock, :expire => 0, :block => 0)
+    expect(mutex2.lock).to be_falsey
+  end
+
+  it 'raises ExpireResetError if reset_expire is called when lock mutex is not locked' do
+    mutex = RedisMutex.new(:test_lock, :expire => 0.1, :block => 0)
+    expect(mutex.lock).to be_truthy
+    sleep 0.2 # wait enough to make the lock expired
+
+    expect { mutex.reset_expire {} }.to raise_error(RedisMutex::ExpireResetError)
+  end
+
   it 'resets locking state on reuse' do
     mutex = RedisMutex.new(:test_lock, SHORT_MUTEX_OPTIONS)
     expect(mutex.lock).to be_truthy