Class: Rack::State::Store::PreparedPostgres

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/state.rb

Overview

Postgres table-based state storage adapter using prepared statements. Because accessing state is a highly repetitive activity, prepared statements may offer some optimization.

See Postgres for details.

Constant Summary collapse

BINARY = 
1

Instance Method Summary collapse

Constructor Details

#initialize(connection, table = 'state') ⇒ PreparedPostgres

Returns a new instance of PreparedPostgres.



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# File 'lib/rack/state.rb', line 353

def initialize(connection, table = 'state')
  @db = connection
  begin
    @db.prepare 'create_state',
      "INSERT INTO #{table} (token,object) VALUES ($1,$2)"
    @db.prepare 'read_state',
      "SELECT object FROM #{table} WHERE token=$1"
    @db.prepare 'update_state',
      "UPDATE #{table} SET object=$2, mtime=NOW() WHERE token=$1"
    @db.prepare 'delete_state',
      "DELETE FROM #{table} WHERE token=$1"
  rescue PG::DuplicatePstatement
  end
end

Instance Method Details

#create(token, object) ⇒ Object 



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# File 'lib/rack/state.rb', line 368

def create(token, object)
  @db.exec_prepared('create_state', params(token, object)).clear
rescue PG::UniqueViolation
  raise KeyError
end

#delete(token) ⇒ Object 



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# File 'lib/rack/state.rb', line 386

def delete(token)
  @db.exec_prepared('delete_state', params(token)).clear
end

#read(token) ⇒ Object 



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# File 'lib/rack/state.rb', line 374

def read(token)
  @db.exec_prepared('read_state', params(token), BINARY) do |result|
    ::Marshal.load result.getvalue(0,0)
  end rescue nil
end

#update(token, object) ⇒ Object 



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# File 'lib/rack/state.rb', line 380

def update(token, object)
  @db.exec_prepared('update_state', params(token, object)) do |result|
    raise KeyError if result.cmd_tuples == 0
  end
end