使用 zeus 进行 Cucumber 和 RSpec 测试：其他用户正在访问 Postgres

Question

在我的 Rails 3.2.13 应用程序中，我使用的是 Zeus。在测试环境中我使用 PostgreSQL。当我运行 Cucumber，然后运行 ​​RSpec（或相反）时，10 次中有 9 次我收到消息：

PG::Error: ERROR:  database "bp_test" is being accessed by other users
DETAIL:  There are 1 other session(s) using the database.
: DROP DATABASE IF EXISTS "bp_test"

Tasks: TOP => db:test:load => db:test:purge
(See full trace by running task with --trace)

正如here 所描述的，它需要整个不确定的马戏团来尝试终止数据库连接才能使其再次工作。但这并不总是有效，而且也是一个很大的麻烦。对此必须有更好的解决方案。有人知道吗？

Answer 1

受this answer 的启发，我们创建了以下database.rake 文件。原来的答案只适用于 PostgreSQL 9.1，这个被修改为也适用于 PostgreSQL 9.2。该机制并不是最漂亮的：当 9.1 命令失败时，它只是执行 9.2 命令。但最重要的是：它有效！

#{Rails.root}/lib/tasks/databases.rake
# monkey patch ActiveRecord to avoid There are n other session(s) using the database.
def drop_database(config)
  case config['adapter']
  when /mysql/
    ActiveRecord::Base.establish_connection(config)
    ActiveRecord::Base.connection.drop_database config['database']
  when /sqlite/
    require 'pathname'
    path = Pathname.new(config['database'])
    file = path.absolute? ? path.to_s : File.join(Rails.root, path)

    FileUtils.rm(file)
  when /postgresql/
    begin
      ActiveRecord::Base.establish_connection(config.merge('database' => 'postgres', 'schema_search_path' => 'public'))
      ActiveRecord::Base.connection.select_all("select * from pg_stat_activity order by procpid;").each do |x|
        if config['database'] == x['datname'] && x['current_query'] =~ /<IDLE>/
          ActiveRecord::Base.connection.execute("select pg_terminate_backend(#{x['procpid']})")
        end
      end
      ActiveRecord::Base.connection.drop_database config['database']
    rescue # in PG 9.2 column procpid was renamed pid and the query status is checked not using 'current_query' but using 'state'
      ActiveRecord::Base.establish_connection(config.merge('database' => 'postgres', 'schema_search_path' => 'public'))
      ActiveRecord::Base.connection.select_all("select * from pg_stat_activity order by pid;").each do |x|
        if config['database'] == x['datname'] && x['state'] =~ /idle/
          ActiveRecord::Base.connection.execute("select pg_terminate_backend(#{x['pid']})")
        end
      end
      ActiveRecord::Base.connection.drop_database config['database']
    end
  end
end

Answer 2

namespace :db do

  desc 'Clear the database'
  task :clear_db => :environment do |t,args|
    ActiveRecord::Base.establish_connection
    ActiveRecord::Base.connection.tables.each do |table|
      next if table == 'schema_migrations'
      ActiveRecord::Base.connection.execute("TRUNCATE #{table}")
    end
  end

  desc 'Delete all tables (but not the database)'
  task :drop_schema => :environment do |t,args|
    ActiveRecord::Base.establish_connection
    ActiveRecord::Base.connection.execute("DROP SCHEMA public CASCADE")
    ActiveRecord::Base.connection.execute("CREATE SCHEMA public")
    ActiveRecord::Base.connection.execute("GRANT ALL ON SCHEMA public TO postgres")
    ActiveRecord::Base.connection.execute("GRANT ALL ON SCHEMA public TO public")
    ActiveRecord::Base.connection.execute("COMMENT ON SCHEMA public IS 'standard public schema'")
  end

  desc 'Recreate the database and seed'
  task :redo_db => :environment do |t,args|
    # Executes the dependencies, but only once
    Rake::Task["db:drop_schema"].invoke
    Rake::Task["db:migrate"].invoke
    Rake::Task["db:migrate:status"].invoke
    Rake::Task["db:structure:dump"].invoke
    Rake::Task["db:seed"].invoke
  end

end