minimal docs for transactions

This commit is contained in:
Brian J. Cardiff 2016-12-14 12:13:46 -03:00
parent ed3ed71501
commit d7ccecae9b
3 changed files with 25 additions and 0 deletions

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@ -1,7 +1,16 @@
module DB
module BeginTransaction
# Creates a transaction from the current context.
# If is expected that either `Transaction#commit` or `Transaction#rollback`
# are called explictly to release the context.
abstract def begin_transaction : Transaction
# yields a transaction from the current context.
# Query the database through `Transaction#connection` object.
# If an exception is thrown within the block a rollback is performed.
# The exception thrown is blubbled unless it is a `DB::Rollback`.
# From the yielded object `Transaction#commit` or `Transaction#rollback`
# can be called explicitly.
def transaction
tx = begin_transaction
begin

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@ -105,6 +105,8 @@ module DB
end
end
# yields a `Transaction` from a connection of the pool
# Refer to `BeginTransaction#transaction` for documentation.
def transaction
using_connection do |cnn|
cnn.transaction do |tx|

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@ -1,14 +1,28 @@
module DB
# Transactions should be started from `DB#transaction`, `Connection#transaction`
# or `Connection#begin_transaction`.
#
# Use `Transaction#connection` to submit statements to the database.
#
# Use `Transaction#commit` or `Transaction#rollback` to close the ongoing transaction
# explicitly. Or refer to `BeginTransaction#transaction` for documentation on how to
# use `#transaction(&block)` methods in `DB` and `Connection`.
#
# Nested transactions are supported by using sql `SAVEPOINT`. To start a nested
# transaction use `Transaction#transaction` or `Transaction#begin_transaction`.
#
abstract class Transaction
include Disposable
include BeginTransaction
abstract def connection : Connection
# commits the current transaction
def commit
close!
end
# rollbacks the current transaction
def rollback
close!
end