class BDB::Txn

The transaction subsystem makes operations atomic, consistent, isolated, and durable in the face of system and application failures. The subsystem requires that the data be properly logged and locked in order to attain these properties. Berkeley DB contains all the components necessary to transaction-protect the Berkeley DB access methods and other forms of data may be protected if they are logged and locked appropriately.

The transaction subsystem is created, initialized, and opened by calls to BDB::Env#open with the BDB::INIT_TXN flag (or BDB::INIT_TRANSACTION) specified. Note that enabling transactions automatically enables logging, but does not enable locking, as a single thread of control that needed atomicity and recoverability would not require it.

The transaction is created with BDB::Env#begin or with begin

Public Instance Methods

abort() click to toggle source

Abort the transaction. This is will terminate the transaction.

# File transaction.rb, line 24
def  abort()
end
assoc(db, ...) click to toggle source

Associate a database with the transaction, return a new database handle which is transaction protected.

# File transaction.rb, line 33
def  assoc(db, ...)
end
associate(db, ...) click to toggle source

same than assoc

# File transaction.rb, line 36
def  associate(db, ...)
end
begin(flags = 0, db, ...) { |txn, db, ... end| ... } click to toggle source

begin a transaction (the transaction manager must be enabled). flags can have the value DBD::TXN_COMMIT, in this case the transaction will be commited at end.

Return a new transaction object, and the associated database handle if specified.

If #begin is called as an iterator, #commit and #abort will terminate the iterator.

env.begin(db) do |txn, b| … end

is the same than

env.begin do |txn| b = txn.assoc(db) … end

An optional hash can be given with the possible keys “flags”, “set_timeout”, “set_txn_timeout”, “set_lock_timeout”

# File transaction.rb, line 67
   def  begin(flags = 0, db, ...) 
      yield txn, db, ...
   end
   #same than <em> begin</em>
   def  txn_begin(flags = 0, db, ...)
   end
   
   #Commit the transaction. This will finish the transaction.
   #The <em>flags</em> can have the value
   #
   #<em>BDB::TXN_SYNC</em> Synchronously flush the log. This means the
   #transaction will exhibit all of the ACID (atomicity, consistency
   #and isolation and durability) properties. This is the default value.
   #
   #<em>BDB::TXN_NOSYNC</em> Do not synchronously flush the log. This
   #means the transaction will exhibit the ACI (atomicity, consistency
   #and isolation) properties, but not D (durability), i.e., database
   #integrity will be maintained but it is possible that this
   #transaction may be undone during recovery instead of being redone.
   #
   #This behavior may be set for an entire Berkeley DB environment as
   #part of the open interface.
   #
   def  commit(flags = 0)
   end
   #same than <em> commit</em>
   def  close(flags = 0)
   end
   #same than <em> commit</em>
   def  txn_commit(flags = 0)
   end
   #same than <em> commit</em>
   def  txn_close(flags = 0)
   end
   
   #only with BDB::VERSION_MAJOR == 3 && BDB::VERSION_MINOR >= 3
   #
   #Discard a prepared but not resolved transaction handle, must be called
   #only within BDB::Env#recover
   #
   def  discard
   end
   #same than <em> discard</em>
   def  txn_discard
   end
   
   #only with BDB::VERSION_MAJOR == 4 && BDB::VERSION_MINOR >= 1
   #
   #remove the database specified by <em>file</em> and <em>database</em>. If no
   #<em>database</em> is <em>nil</em>, the underlying file represented by
   #<em>file</em> is removed, incidentally removing all databases
   #that it contained.
   #
   #The <em>flags</em> value must be set to 0 or <em>BDB::AUTO_COMMIT</em>
   #
   def  dbremove(file, database = nil, flags = 0)
   end
   
   #only with BDB::VERSION_MAJOR == 4 && BDB::VERSION_MINOR >= 1
   #
   #rename the database specified by <em>file</em> and <em>database</em> to
   #<em>newname</em>. If <em>database</em> is <em>nil</em>, the underlying file
   #represented by <em>file</em> is renamed, incidentally renaming all databases
   #that it contained.
   #
   #The <em>flags</em> value must be set to 0 or <em>BDB::AUTO_COMMIT</em>
   #
   def  dbrename(file, database, newname, flags = 0)
   end
   
   #The txn_id function returns the unique transaction id associated
   #with the specified transaction. Locking calls made on behalf of
   #this transaction should use the value returned from txn_id as the
   #locker parameter to the lock_get or lock_vec calls.
   #
   def  id()
   end
   #same than <em> id</em>
   def  txn_id()
   end
   
   #Only with DB >= 4.1
   #
   #open the database in the current transaction. type must be one of
   #the constant <em>BDB::BTREE</em>, <em>BDB::HASH</em>, <em>BDB::RECNO</em>,
   #<em>BDB::QUEUE</em>. See <em>open</em> for other
   #arguments
   #
   def  open_db(type, name = nil, subname = nil, flags = 0, mode = 0)
   end
   
   #The txn_prepare function initiates the beginning of a two-phase commit.
   #
   #In a distributed transaction environment, Berkeley DB can be used
   #as a local transaction manager. In this case, the distributed
   #transaction manager must send prepare messages to each local
   #manager. The local manager must then issue a txn_prepare and await its
   #successful return before responding to the distributed transaction
   #manager. Only after the distributed transaction manager receives
   #successful responses from all of its prepare messages should it issue
   #any commit messages.
   #
   def  prepare()
   end
   #same than <em> prepare</em>
   def  txn_prepare()
   end
   #same than <em> prepare</em>
   def  txn_prepare(id)    # version 3.3.11
   end

   #Only with DB >= 4.4
   #
   #Return the string associated with a transaction
   #
   def name
   end

   #Only with DB >= 4.4
   #
   #Set the string associated with a transaction
   #
   def name=(string)
   end
   
end
close(flags = 0) click to toggle source

same than commit

# File transaction.rb, line 93
def  close(flags = 0)
end
commit(flags = 0) click to toggle source

Commit the transaction. This will finish the transaction. The flags can have the value

BDB::TXN_SYNC Synchronously flush the log. This means the transaction will exhibit all of the ACID (atomicity, consistency and isolation and durability) properties. This is the default value.

BDB::TXN_NOSYNC Do not synchronously flush the log. This means the transaction will exhibit the ACI (atomicity, consistency and isolation) properties, but not D (durability), i.e., database integrity will be maintained but it is possible that this transaction may be undone during recovery instead of being redone.

This behavior may be set for an entire Berkeley DB environment as part of the open interface.

# File transaction.rb, line 90
def  commit(flags = 0)
end
dbremove(file, database = nil, flags = 0) click to toggle source

only with BDB::VERSION_MAJOR == 4 && BDB::VERSION_MINOR >= 1

remove the database specified by file and database. If no database is nil, the underlying file represented by file is removed, incidentally removing all databases that it contained.

The flags value must be set to 0 or BDB::AUTO_COMMIT

# File transaction.rb, line 122
def  dbremove(file, database = nil, flags = 0)
end
dbrename(file, database, newname, flags = 0) click to toggle source

only with BDB::VERSION_MAJOR == 4 && BDB::VERSION_MINOR >= 1

rename the database specified by file and database to newname. If database is nil, the underlying file represented by file is renamed, incidentally renaming all databases that it contained.

The flags value must be set to 0 or BDB::AUTO_COMMIT

# File transaction.rb, line 134
def  dbrename(file, database, newname, flags = 0)
end
discard() click to toggle source

only with BDB::VERSION_MAJOR == 3 && BDB::VERSION_MINOR >= 3

Discard a prepared but not resolved transaction handle, must be called only within BDB::Env#recover

# File transaction.rb, line 107
def  discard
end
id() click to toggle source

The txn_id function returns the unique transaction id associated with the specified transaction. Locking calls made on behalf of this transaction should use the value returned from txn_id as the locker parameter to the lock_get or lock_vec calls.

# File transaction.rb, line 142
def  id()
end
name() click to toggle source

Only with DB >= 4.4

Return the string associated with a transaction

# File transaction.rb, line 182
def name
end
name=(string) click to toggle source

Only with DB >= 4.4

Set the string associated with a transaction

# File transaction.rb, line 189
def name=(string)
end
open_db(type, name = nil, subname = nil, flags = 0, mode = 0) click to toggle source

Only with DB >= 4.1

open the database in the current transaction. type must be one of the constant BDB::BTREE, BDB::HASH, BDB::RECNO, BDB::QUEUE. See open for other arguments

# File transaction.rb, line 155
def  open_db(type, name = nil, subname = nil, flags = 0, mode = 0)
end
prepare() click to toggle source

The txn_prepare function initiates the beginning of a two-phase commit.

In a distributed transaction environment, Berkeley DB can be used as a local transaction manager. In this case, the distributed transaction manager must send prepare messages to each local manager. The local manager must then issue a txn_prepare and await its successful return before responding to the distributed transaction manager. Only after the distributed transaction manager receives successful responses from all of its prepare messages should it issue any commit messages.

# File transaction.rb, line 169
def  prepare()
end
txn_abort() click to toggle source

same than abort

# File transaction.rb, line 27
def  txn_abort()
end
txn_assoc(db, ...) click to toggle source

same than assoc

# File transaction.rb, line 39
def  txn_assoc(db, ...)
end
txn_begin(flags = 0, db, ...) click to toggle source

same than begin

# File transaction.rb, line 71
def  txn_begin(flags = 0, db, ...)
end
txn_close(flags = 0) click to toggle source

same than commit

# File transaction.rb, line 99
def  txn_close(flags = 0)
end
txn_commit(flags = 0) click to toggle source

same than commit

# File transaction.rb, line 96
def  txn_commit(flags = 0)
end
txn_discard() click to toggle source

same than discard

# File transaction.rb, line 110
def  txn_discard
end
txn_id() click to toggle source

same than id

# File transaction.rb, line 145
def  txn_id()
end
txn_prepare() click to toggle source

same than prepare

# File transaction.rb, line 172
def  txn_prepare()
end