Support for pipelining, optional blocks, and returning values

README.md

@@ -0,0 +1,49 @@
+# Ruby gem for easily pipelining REDIS commands
+https://github.com/mrdanadams/redis_pipeliner
+
+(Inspired by this blog post on [5-10x Speed Ups by Pipeling Multiple REDIS Commands in Ruby](http://mrdanadams.com/2012/pipeline-redis-commands-ruby/) by [Dan Adams](http://mrdanadams.com).)
+
+[Pipelining in REDIS](https://github.com/redis/redis-rb#pipelining) is a great way to stay performant when executing multiple commands. It should also be easy to use.
+
+## Usage
+
+Basic usage involves:
+
+1. Enqueueing a number of REDIS commands inside a `pipelined` block
+2. Doing something with the results either afterwards or inside blocks specific to each command.
+
+Ex: (a bit contrived...)
+
+```ruby
+# Put a bunch of values in a few different hashes
+redis = Redis.connect
+redis.hset "h1", "foo", 1
+redis.hset "h2", "bar", 2
+redis.hest "h3", "baz", 3
+
+# Get the values pipelined and sum them up
+values = RedisPipeliner.pipeline redis do |p|
+  # This would normally be 3 round-trips
+  p.enqueue redis.hget("h1", "foo")
+  p.enqueue redis.hget("h2", "bar")
+  p.enqueue redis.hget("h3", "baz")
+end
+values.map(&:to_i).inject(&:+).should == 6
+```
+
+You can also pass in a block to be called for each value rather than operating on the values afterwards:
+
+```ruby
+results = []
+RedisPipeliner.pipeline redis do |p|
+  [%w(h1 foo), %w(h2 bar), %w(h3 baz)].each do |pair|
+    p.enqueue redis.hget(pair[0], pair[1]) do |value|
+      # referencing pair inside the block
+      results << pair[1] + value
+    end
+  end
+end
+results.first.should == "foo1"
+```
+
+See the specs for executable examples.

lib/redis_pipeliner.rb

@@ -1,5 +1,17 @@
 require "redis_pipeliner/version"
+require "redis"
+require "redis_pipeliner/pipeliner"
 
 module RedisPipeliner
-  # Your code goes here...
+  class << self
+    # Convenience for creating a pipeline, enqueueing, and blocking until the results are processed.
+    def pipeline(redis, &proc)
+      pipeliner = RedisPipeliner::Pipeliner.new(redis)
+      redis.pipelined do
+        proc.call pipeliner
+      end
+
+      pipeliner.values
+    end
+  end
 end

lib/redis_pipeliner/pipeliner.rb

@@ -0,0 +1,44 @@
+module RedisPipeliner
+  # Enqueues commands in a pipeline and waits until they are finished.
+  # Usage pattern is to call #enqueue with each REDIS future and a block to process it,
+  # then call #wait outside the Redis.pipelined call.
+  class Pipeliner
+    def initialize(redis)
+      @redis = redis
+      @commands = []
+    end
+
+    # Adds a command (a Future, actually) with an option block to call when the Future has been realized.
+    def enqueue(future, &proc)
+      @commands << { future: future, callback: proc }
+    end
+
+    # Blocks until all Futures have been realized and returns the values.
+    # This should be called _outside_ the Redis.pipelined call.
+    # Note that the value enqueue is the REDIS return value, not the value returned by any passed block.
+    # Nil values will be included in the return values (if that's what REDIS gives us).
+    def values
+      return @values unless @values.nil?
+
+      @values = []
+      @commands.each do |cmd|
+        while cmd[:future].value.is_a?(Redis::FutureNotReady)
+          sleep(1.0 / 100.0)
+        end
+
+        v = cmd[:future].value
+        cmd[:callback].call(v) unless cmd[:callback].nil?
+        @values << v
+      end
+
+      @values
+    end
+
+    # Returns the enqueue REDIS commands
+    def commands
+      @commands.map {|h| h[:future] }
+    end
+
+    alias_method :wait, :values
+  end
+end

redis_pipeliner.gemspec

@@ -7,9 +7,9 @@ Gem::Specification.new do |s|
   s.version     = RedisPipeliner::VERSION
   s.authors     = ["Dan Adams"]
   s.email       = ["mr.danadams@gmail.com"]
-  s.homepage    = "http://mrdanadams.com"
-  s.summary     = %q{Utility for easily pipelining commands in REDIS}
-  s.description = %q{Utility for easily pipelining commands in REDIS}
+  s.homepage    = "https://github.com/mrdanadams/redis_pipeliner"
+  s.summary     = %q{Easy pipelining of REDIS commands}
+  s.description = %q{Easy pipelining of REDIS commands}
 
   s.rubyforge_project = "redis_pipeliner"
 
@@ -18,6 +18,7 @@ Gem::Specification.new do |s|
   s.executables   = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
   s.require_paths = ["lib"]
 
-  s.add_runtime_dependency "redis"
+  s.add_dependency "redis"
   s.add_development_dependency "rspec"
+  s.add_development_dependency "pry"
 end

spec/pipeliner_spec.rb

@@ -0,0 +1,61 @@
+require 'spec_helper'
+
+describe RedisPipeliner do
+  let :redis do
+    Redis.connect
+  end
+
+  it 'supports basic usage' do
+    redis.del "testhash"
+    redis.hset "testhash", "bar", 1
+    redis.hset "testhash", "foo", 2
+
+    redis.hmget("testhash", "foo", "bar").map(&:to_i).inject(&:+).should == 3
+
+    total = 0
+    values = RedisPipeliner.pipeline redis do |pipe|
+      %w(bar foo).each do |key|
+        pipe.enqueue redis.hget("testhash", key) do |result|
+          total += result.to_i
+        end
+      end
+    end
+    values.map(&:to_i).inject(&:+).should == 3
+  end
+
+  it 'can reference variables outside the proce' do
+    redis.del "testhash"
+    redis.hset "testhash", "bar", 1
+    redis.hset "testhash", "foo", 2
+
+    results = []
+    RedisPipeliner.pipeline redis do |pipe|
+      %w(bar foo).each do |key|
+        pipe.enqueue redis.hget("testhash", key) do |result|
+          results << key+result
+        end
+      end
+    end
+
+    results.should == %w(bar1 foo2)
+  end
+
+  it 'should pipelines commands and return values' do
+    redis.del "testhash"
+    redis.hset "testhash", "bar", 1
+    redis.hset "testhash", "foo", 2
+
+    pipeliner = RedisPipeliner::Pipeliner.new(redis)
+    redis.pipelined do
+      %w(bar foo).each do |key|
+        # allows not having a block
+        pipeliner.enqueue redis.hget("testhash", key)
+      end
+    end
+
+    pipeliner.commands.first.value.should_not be_nil # you can't test this class for type...
+
+    pipeliner.values.map(&:to_i).inject(&:+).should == 3
+    pipeliner.values.should === pipeliner.values
+  end
+end

spec/spec_helper.rb

@@ -1,3 +1,6 @@
+require 'redis_pipeliner'
+require 'pry'
+
 # This file was generated by the `rspec --init` command. Conventionally, all
 # specs live under a `spec` directory, which RSpec adds to the `$LOAD_PATH`.
 # Require this file using `require "spec_helper"` to ensure that it is only