Concurrent batching support for client

README.md

@@ -221,6 +221,19 @@ coinbase.get('/account/balance').to_hash
 
 Or feel free to add a new wrapper method and submit a pull request.
 
+## Batching
+
+The client can be batched to run multiple requests concurrently. If you have to make a lot of API calls (for example, to get balances for a lot of users simultaneously), this will improve performance significantly. Under the hood, it uses internal threading to take advantage of Ruby's non-blocking IO model (one IO request per thread):
+
+```ruby
+buy_price, sell_price = coinbase.batch do |client|
+  client.buy_price 1
+  client.sell_price 1
+end
+
+buy_price.inspect # => #<Money fractional:1384 currency:USD>
+```
+
 ## Security Notes
 
 If someone gains access to your API Key they will have complete control of your Coinbase account.  This includes the abillity to send all of your bitcoins elsewhere.

lib/coinbase.rb

@@ -3,3 +3,4 @@
 require "coinbase/version"
 require "coinbase/money"
 require "coinbase/client"
+require "coinbase/batch"

lib/coinbase/batch.rb

@@ -0,0 +1,42 @@
+module Coinbase
+  class Batch
+    MAXIMUM_CONCURRENT_REQUESTS = 10
+
+    def initialize(client, opts={}, &block)
+      @client = client
+      @commands = []
+      @opts = opts
+
+      instance_eval &block
+    end
+
+    def run
+      responses = []
+
+      until @commands.empty?
+        threads = []
+        commands = []
+
+        (@opts[:maximum_concurrent_requests] || MAXIMUM_CONCURRENT_REQUESTS).times do
+          break if @commands.empty?
+          commands << @commands.shift
+        end
+
+        commands.each do |c|
+          threads << Thread.new {
+            Thread.current[:resp] = @client.send c[0], *c[1]
+          }
+        end
+
+        threads.each {|t| t.join}
+        threads.each {|t| responses << t[:resp]}
+      end
+
+      responses
+    end
+
+    def method_missing(meth, args=[])
+      @commands << [meth, args]
+    end
+  end
+end

lib/coinbase/client.rb

@@ -141,6 +141,12 @@ def sell! qty
       r
     end
 
+    # Batching
+
+    def batch(&block)
+      Batch.new(self, &block).run
+    end
+
     # Wrappers for the main HTTP verbs
 
     def get(path, options={})

spec/client_spec.rb

@@ -150,6 +150,31 @@
     r.transfer.btc.should == 1.to_money
   end
 
+  it "should batch multiple requests" do
+    buy_api_return = {"amount"=>"13.84", "currency"=>"USD"}
+    sell_api_return = {"amount"=>"15.00", "currency"=>"CAD"}
+    fake :get, "/prices/buy", buy_api_return
+    fake :get, "/prices/sell", sell_api_return
+
+    buy_price, sell_price = @c.batch do |c|
+      c.buy_price 1
+      c.sell_price 1
+    end
+
+    buy_price.to_f.should == 13.84
+    sell_price.to_f.should == 15.00
+
+    # Check to make sure the thread throttle doesn't cause an error
+
+    prices = @c.batch do |c|
+      (Coinbase::Batch::MAXIMUM_CONCURRENT_REQUESTS).times { c.buy_price(1); c.sell_price(1) }
+    end
+
+    prices.length.should == 20
+
+    prices.first.to_f.should == 13.84
+    prices.last.to_f.should == 15.00
+  end
 
   private