villa.rb

一个小型的基于Hash的Key=>Value的数据库

  end
  ##
  # bool = villa.curput(val, cpmode);
  # Method: Insert a record around the cursor.
  # `val' specifies a value.  Although it must be an instance of String, binary data is okey.
  # `cpmode' specifies detail adjustment: `Villa::CPCURRENT', which means that the value of the
  # current record is overwritten, `Villa::CPBEFORE', which means that a new record is inserted
  # before the current record, `Villa::CPAFTER', which means that a new record is inserted after
  # the current record.  If it is omitted, `Villa::CPCURRENT' is specified.
  # The return value is always true.  However, if the silent flag is true and no record
  # corresponds to the cursor, false is returned instead of exception.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs or no record
  # corresponds to the cursor.
  # After insertion, the cursor is moved to the inserted record.
  #
  def curput(val, cpmode = CPCURRENT)
    if(@cmode == CMPOBJ)
      val = Marshal.dump(val)
    end
    mod_curput(@index, val, cpmode)
  end
  ##
  # bool = villa.curout();
  # Method: Delete the record where the cursor is.
  # The return value is always true.  However, if the silent flag is true and no record
  # corresponds to the cursor, false is returned instead of exception.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs or no record
  # corresponds to the cursor.
  # After deletion, the cursor is moved to the next record if possible.
  #
  def curout()
    mod_curout(@index)
  end
  ##
  # bool = villa.settuning(lrecmax, nidxmax, lcnum, ncnum)
  # Method: Set the tuning parameters for performance.
  # `lrecmax' specifies the max number of records in a leaf node of B+ tree.  If it is not more
  # than 0, the default value is specified.
  # `nidxmax' specifies the max number of indexes in a non-leaf node of B+ tree.  If it is not
  # more than 0, the default value is specified.
  # `lcnum' specifies the max number of caching leaf nodes.  If it is not more than 0, the
  # default value is specified.
  # `ncnum' specifies the max number of caching non-leaf nodes.  If it is not more than 0, the
  # default value is specified.
  # The return value is always true.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs.
  # The default setting is equivalent to `vlsettuning(49, 192, 1024, 512)'.  Because tuning
  # parameters are not saved in a database, you should specify them every opening a database.
  #
  def settuning(lrecmax, nidxmax, lcnum, ncnum)
    mod_settuning(@index, lrecmax, nidxmax, lcnum, ncnum)
  end
  ##
  # bool = villa.sync()
  # Method: Synchronize updating contents with the file and the device.
  # The return value is always true.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs.
  # This method is useful when another process uses the connected database file.  This method
  # should not be used while the transaction is activated.
  #
  def sync()
    mod_sync(@index)
  end
  ##
  # bool = villa.optimize()
  # Method: Optimize the database.
  # The return value is always true.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs.
  # In an alternating succession of deleting and storing with overwrite or concatenate,
  # dispensable regions accumulate.  This method is useful to do away with them.  This method
  # should not be used while the transaction is activated.
  #
  def optimize()
    mod_optimize(@index)
  end
  ##
  # num = villa.fsiz()
  # Method: Get the size of the database file.
  # The return value is the size of the database file.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs.
  # Because of the I/O buffer, the return value may be less than the real size.
  #
  def fsiz()
    mod_fsiz(@index)
  end
  ##
  # num = villa.rnum()
  # Method: Get the number of the records stored in the database.
  # The return value is the number of the records stored in the database.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs.
  #
  def rnum()
    mod_rnum(@index)
  end
  ##
  # num = villa.length()
  # Method: An alias of `rnum'.
  #
  alias length rnum
  ##
  # num = villa.size()
  # Method: An alias of `rnum'.
  #
  alias size rnum
  ##
  # bool = villa.writable()
  # Method: Check whether the database handle is a writer or not.
  # The return value is true if the handle is a writer, false if not.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs.
  #
  def writable()
    mod_writable(@index)
  end
  ##
  # bool = villa.fatalerror()
  # Method: Check whether the database has a fatal error or not.
  # The return value is true if the database has a fatal error, false if not.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs.
  #
  def fatalerror()
    mod_fatalerror(@index)
  end
  ##
  # bool = villa.tranbegin()
  # Method: Begin the transaction.
  # The return value is always true.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs.
  # If a thread is already in the transaction, the other threads block until the prius is out
  # of the transaction.  Only one transaction can be activated with a database handle at the
  # same time.
  #
  def tranbegin()
    @tranmutex.lock()
    MyMutex.synchronize() do
      begin
        mod_tranbegin(@index)
      rescue
        @tranmutex.unlock()
        raise()
      end
    end
  end
  ##
  # bool = villa.trancommit()
  # Method: Commit the transaction.
  # The return value is always true.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs.
  # Updating a database in the transaction is fixed when it is committed successfully.  Any
  # other thread except for the one which began the transaction should not call this method.
  #
  def trancommit()
    begin
      mod_trancommit(@index)
    ensure
      @tranmutex.unlock()
    end
  end
  ##
  # bool = villa.tranabort()
  # Method: Abort the transaction.
  # The return value is always true.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs.
  # Updating a database in the transaction is discarded when it is aborted.  The state of the
  # database is rollbacked to before transaction.  Any other thread except for the one which
  # began the transaction should not call this method.
  #
  def tranabort()
    begin
      mod_tranabort(@index)
    ensure
      @tranmutex.unlock()
    end
  end
  ##
  # villa.transaction() do ... end
  # Iterator Method: Perform an iterator block in the transaction.
  # The specified iterator block is performed in the transaction.  If the block returns true,
  # the transaction is committed.  If the block returns false or raises any exception, the
  # transaction is aborted.
  #
  def transaction()
    tranbegin()
    begin
      cmt = yield()
    rescue
      cmt = false
      raise()
    ensure
      if(cmt)
        trancommit()
      else
        tranabort()
      end
    end
  end
  ##
  # villa.each() do |key, val| ... end
  # Iterator Method: Iterate a process with a pair of a key and a value of each record.
  #
  def each()
    MyMutex.synchronize() do
      curfirst()
      while(true)
        begin
          break unless key = curkey()
          val = curval()
          yield(key, val)
          curnext()
        rescue ENOITEM
          break
        end
      end
      curfirst()
    end
    self
  end
  ##
  # villa.each_pair() do |key, val| ... end
  # Iterator Method: An alias of `each'.
  #
  alias each_pair each
  ##
  # villa.each_key() do |key| ... end
  # Iterator Method: Iterate a process with a key of each record.
  #
  def each_key()
    MyMutex.synchronize() do
      curfirst()
      while(true)
        begin
          break unless key = curkey()
          curnext()
          yield(key)
        rescue ENOITEM
          break
        end
      end
      curfirst()
    end
    self
  end
  ##
  # villa.each_value() do |val| ... end
  # Iterator Method: Iterate a process with a value of each record.
  #
  def each_value()
    MyMutex.synchronize() do
      curfirst()
      while(true)
        begin
          break unless val = curval()
          curnext()
          yield(val)
        rescue ENOITEM
          break
        end
      end
      curfirst()
    end
    self
  end
  ##
  # ary = villa.keys()
  # Method: Get an array of all keys.
  # The return value is an array of all keys.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs.
  #
  def keys()
    ary = Array::new(rnum())
    MyMutex.synchronize() do
      begin
        curfirst()
        0.upto(ary.length - 1) do |i|
          ary[i] = curkey()
          curnext()
        end
        curfirst()
      rescue ENOITEM
      end
    end
    ary
  end
  ##
  # ary = villa.values()
  # Method: Get an array of all values.
  # The return value is an array of all values.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs.
  #
  def values()
    ary = Array::new(rnum())
    MyMutex.synchronize() do
      begin
        curfirst()
        0.upto(ary.length - 1) do |i|
          ary[i] = curval()
          curnext()
        end
        curfirst()
      rescue ENOITEM
      end
    end
    ary
  end
  ##
  # str = villa.index(val)
  # Method: Retrieve a record with a value.
  # `val' specifies a value.  Although it must be an instance of String, binary data is okey.
  # The return value is the key of the record with the specified value.
  # An exception of `Villa::EANY' or its sub classes is thrown if an error occurs or no record
  # corresponds.
  # If two or more records correspond, the first found record is selected.
  #
  def index(val)
    key = nil
    MyMutex.synchronize() do
      curfirst()
      while(true)
        break unless tmp = curval()
        if(tmp == val)
          key = curkey()
          break
        end
        curnext()
      end
      curfirst()
    end
    key
  end
  ##
  # num = villa.to_int()
  # Method: An alias of `rnum'.
  #
  alias to_int rnum
  ##
  # num = villa.to_i()
  # Method: An alias of `to_int'.
  #
  alias to_i to_int
  ##
  # str = villa.to_str()
  # Method: Get string standing for the instance.
  #
  def to_str
    if(@index != -1)
      sprintf("#<Villa:%#x:name=%s:state=open:rnum=%d>",
              object_id(), @name, rnum())
    else
      sprintf("#<Villa:%#x:name=%s:state=closed>", object_id(), @name)
    end
  end
  ##
  # str = villa.to_s()
  # Method: An alias of `to_str'.
  #
  alias to_s to_str
  ##
  # ary = villa.to_ary()
  # Method: Get an array of alternation of each pair of a key and a value.
  #
  def to_ary
    ary = Array::new(rnum())
    i = 0
    each() do |key, val|
      ary[i] = [key, val]
      i += 1
    end
    ary
  end
  ##
  # ary = villa.to_a()
  # Method: An alias of `to_ary'.
  #
  alias to_a to_ary
  ##
  # hash = villa.to_hash()
  # Method: Get a hash storing all records.
  #
  def to_hash
    hash = Hash::new()
    each() do |key, val|
      hash[key] || hash[key] = val
    end
    hash
  end
  ##
  # hash = villa.to_h()
  # Method: An alias of `to_hash'.
  #
  alias to_h to_hash
  ##
  # str = villa.inspect()
  # Method: An alias of `to_str'.
  #
  alias inspect to_str
end


#----------------------------------------------------------------
# Alias definition of class methods
#----------------------------------------------------------------
class << Villa
  alias open new
end



# END OF FILE