Merge pull request soundcloud#29 from bogdan/master

Lhm.cleanup method

Author: Lars Gierth

lib/lhm.rb

@@ -34,8 +34,6 @@ module Lhm
   # @return [Boolean] Returns true if the migration finishes
   # @raise [Error] Raises Lhm::Error in case of a error and aborts the migration
   def self.change_table(table_name, options = {}, &block)
-    connection = Connection.new(adapter)
-
     origin = Table.parse(table_name, connection)
     invoker = Invoker.new(origin, connection)
     block.call(invoker.migrator)
@@ -44,6 +42,23 @@ def self.change_table(table_name, options = {}, &block)
     true
   end
 
+  def self.cleanup(run = false)
+    lhm_tables = connection.select_values("show tables").select do |name|
+      name =~ /^lhm(a|n)_/
+    end
+    return true if lhm_tables.empty?
+    if run
+      lhm_tables.each do |table|
+        connection.execute("drop table #{table}")
+      end
+      true
+    else
+      puts "Existing LHM backup tables: #{lhm_tables.join(", ")}."
+      puts "Run Lhm.cleanup(true) to drop them all."
+      false
+    end
+  end
+
   def self.setup(adapter)
     @@adapter = adapter
   end
@@ -55,4 +70,10 @@ def self.adapter
         ActiveRecord::Base.connection
       end
   end
+
+  protected
+  def self.connection
+    Connection.new(adapter)
+  end
+
 end

lib/lhm/connection.rb

@@ -28,7 +28,7 @@ def sql(statements)
 
       def show_create(table_name)
         sql = "show create table `#{ table_name }`"
-        select_values(sql).last
+        select_one(sql).values.last
       end
 
       def current_database
@@ -51,7 +51,7 @@ def select_one(sql)
       end
 
       def select_values(sql)
-        select_one(sql).values
+        select_all(sql)
       end
 
       def select_value(sql)

spec/integration/cleanup_spec.rb

@@ -0,0 +1,34 @@
+# Copyright (c) 2011 - 2013, SoundCloud Ltd., Rany Keddo, Tobias Bielohlawek, Tobias
+# Schmidt
+
+require File.expand_path(File.dirname(__FILE__)) + '/integration_helper'
+
+require 'lhm'
+
+describe Lhm, "cleanup" do
+  include IntegrationHelper
+  before(:each) { connect_master! }
+
+  describe "changes" do
+    before(:each) do
+      table_create(:users)
+      Lhm.change_table(:users, :atomic_switch => false) do |t|
+        t.add_column(:logins, "INT(12) DEFAULT '0'")
+        t.add_index(:logins)
+      end
+    end
+
+    it "should show temporary tables" do
+      output = capture_stdout do
+        Lhm.cleanup
+      end
+      output.must_include("Existing LHM backup tables")
+      output.must_match(/lhma_[0-9_]*_users/)
+    end
+
+    it "should delete temporary tables" do
+      Lhm.cleanup(true).must_equal(true)
+      Lhm.cleanup.must_equal(true)
+    end
+  end
+end

spec/integration/integration_helper.rb

@@ -50,6 +50,10 @@ def connect!(port)
     end
 
     Lhm.setup(adapter)
+    unless defined?(@@cleaned_up)
+      Lhm.cleanup(true)
+      @@cleaned_up  = true
+    end
     @connection = Lhm::Connection.new(adapter)
   end
 
@@ -154,4 +158,17 @@ def index?(table_name, key_name, type = :non_unique)
   def master_slave_mode?
     !!ENV["MASTER_SLAVE"]
   end
+
+  #
+  # Misc
+  #
+  
+  def capture_stdout
+    out = StringIO.new
+    $stdout = out
+    yield
+    return out.string
+  ensure
+    $stdout = ::STDOUT
+  end
 end