Class: Bdb::Database

Inherits:
Base show all
Defined in:
lib/bdb/database.rb

Instance Attribute Summary collapse

Attributes inherited from Base

#indexes

Instance Method Summary collapse

Methods inherited from Base

#checkpoint, #config, #environment, #index_by, #master?, #path, #synchronize, #transaction

Constructor Details

#initialize(name, opts = {}) ⇒ Database

Returns a new instance of Database


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# File 'lib/bdb/database.rb', line 4

def initialize(name, opts = {})
  @name = name
  super(opts)
end

Instance Attribute Details

#nameObject (readonly)

Returns the value of attribute name


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# File 'lib/bdb/database.rb', line 8

def name
  @name
end

Instance Method Details

#[](key) ⇒ Object


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# File 'lib/bdb/database.rb', line 148

def [](key)
  get(key).first
end

#closeObject


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# File 'lib/bdb/database.rb', line 53

def close
  return unless @db
  synchronize do
    @db.each {|field, db| db.close(0)}
    @db = nil
  end
end

#close_environmentObject


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# File 'lib/bdb/database.rb', line 61

def close_environment
  environment.close
end

#count(field, key) ⇒ Object


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# File 'lib/bdb/database.rb', line 65

def count(field, key)
  with_cursor(db(field)) do |cursor|
    k, v = cursor.get(Tuple.dump(key), nil, Bdb::DB_SET)
    k ? cursor.count : 0
  end
end

#db(index = nil) ⇒ Object


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# File 'lib/bdb/database.rb', line 10

def db(index = nil)
  if @db.nil?
    @db = {}
    open_flags = master? ? Bdb::DB_CREATE : Bdb::DB_RDONLY
    transaction(false) do
      primary_db = environment.env.db
      primary_db.pagesize = config[:page_size] if config[:page_size]
      primary_db.open(transaction, name, nil, Bdb::Db::BTREE, open_flags, 0)
      @db[:primary_key] = primary_db

      indexes.each do |field, opts|
        index_callback = lambda do |db, key, data|
          value = Marshal.load(data)
          index_key = value.kind_of?(Hash) ? value[:field] : value.send(field)
          if opts[:multi_key] and index_key.kind_of?(Array)
            # Index multiple keys. If the key is an array, you must wrap it with an outer array.
            index_key.collect {|k| Tuple.dump(k)}
          elsif index_key
            # Index a single key.
            Tuple.dump(index_key)
          end
        end
        index_db = environment.env.db
        index_db.flags = Bdb::DB_DUPSORT unless opts[:unique]
        index_db.pagesize = config[:page_size] if config[:page_size]
        index_db.open(transaction, "#{name}_by_#{field}", nil, Bdb::Db::BTREE, open_flags, 0)
        primary_db.associate(transaction, index_db, open_flags, index_callback)
        @db[field] = index_db
      end
    end
  end
  @db[index || :primary_key]
rescue Bdb::DbError => e
  # Retry if the database doesn't exist and we are a replication client.
  if not master? and e.code == Errno::ENOENT::Errno
    close
    sleep 1
    retry
  else
    raise(e)
  end
end

#delete(key) ⇒ Object


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# File 'lib/bdb/database.rb', line 162

def delete(key)
  synchronize do
    key = Tuple.dump(key)
    db.del(transaction, key, 0)
  end
end

#get(*keys, &block) ⇒ Object


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# File 'lib/bdb/database.rb', line 72

def get(*keys, &block)
  opts  = keys.last.kind_of?(Hash) ? keys.pop : {}
  db    = db(opts[:field])
  set   = Bdb::ResultSet.new(opts, &block)
  flags = opts[:modify] ? Bdb::DB_RMW : 0
  flags = 0 if environment.disable_transactions?

  keys.each do |key|
    key = get_key(key, opts)
    if key == :all
      with_cursor(db) do |cursor|          
        if opts[:reverse]
          k,v  = cursor.get(nil, nil, Bdb::DB_LAST | flags)          # Start at the last item.
          iter = lambda {cursor.get(nil, nil, Bdb::DB_PREV | flags)} # Move backward.
        else
          k,v  = cursor.get(nil, nil, Bdb::DB_FIRST | flags)         # Start at the first item.
          iter = lambda {cursor.get(nil, nil, Bdb::DB_NEXT | flags)} # Move forward.
        end

        while k
          set << unmarshal(v, :tuple => k)
          k,v = iter.call
        end
      end
    elsif key.kind_of?(Range)
      # Fetch a range of keys.
      with_cursor(db) do |cursor|
        first = Tuple.dump(key.first)
        last  = Tuple.dump(key.last)

        # Return false once we pass the end of the range.
        cond = key.exclude_end? ? lambda {|k| k < last} : lambda {|k| k <= last}
        if opts[:reverse]
          iter = lambda {cursor.get(nil, nil, Bdb::DB_PREV | flags)} # Move backward.
          
          # Position the cursor at the end of the range.
          k,v = cursor.get(last, nil, Bdb::DB_SET_RANGE | flags) || cursor.get(nil, nil, Bdb::DB_LAST | flags)
          while k and not cond.call(k)
            k,v = iter.call
          end
          
          cond = lambda {|k| k >= first} # Change the condition to stop when we move past the start.
        else
          k,v  = cursor.get(first, nil, Bdb::DB_SET_RANGE | flags)   # Start at the beginning of the range.
          iter = lambda {cursor.get(nil, nil, Bdb::DB_NEXT | flags)} # Move forward.
        end
        
        while k and cond.call(k)
          set << unmarshal(v, :tuple => k)
          k,v = iter.call
        end
      end
    else
      if (db.flags & Bdb::DB_DUPSORT) == 0
        synchronize do
          # There can only be one item for each key.
          data = db.get(transaction, Tuple.dump(key), nil, flags)
          set << unmarshal(data, :key => key) if data
        end
      else
        # Have to use a cursor because there may be multiple items with each key.
        with_cursor(db) do |cursor|
          k,v = cursor.get(Tuple.dump(key), nil, Bdb::DB_SET | flags)
          while k
            set << unmarshal(v, :tuple => k)
            k,v = cursor.get(nil, nil, Bdb::DB_NEXT_DUP | flags)
          end
        end
      end
    end
  end
  set.results
rescue Bdb::ResultSet::LimitReached
  set.results
end

#set(key, value, opts = {}) ⇒ Object


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# File 'lib/bdb/database.rb', line 152

def set(key, value, opts = {})
  synchronize do
    key   = Tuple.dump(key)
    value = Marshal.dump(value)
    flags = opts[:create] ? Bdb::DB_NOOVERWRITE : 0
    db.put(transaction, key, value, flags)
    value
 end
end

#syncObject


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# File 'lib/bdb/database.rb', line 176

def sync
  db.sync
end

#truncate!Object

Deletes all records in the database. Beware!


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# File 'lib/bdb/database.rb', line 170

def truncate!
  synchronize do
    db.truncate(transaction)
  end
end